a diagram of the electromagnetic spectrum is shown. which wavelength is the longest safest wavelengths for humans？ Helppp pleaseee

Several reagents can be used to effect addition to a double bond, including acid and water, hydroboration-oxidation reagents, and oxymercuration-demercuration reagents. The reasons why oxymercuration-demercuration was chosen to effect the following transformation instead of the other reagents are as follows:

1. Oxymercuration-demercuration reagents prevent sigmatropic rearrangements

2. Hydroboration-oxidation reagents yield the anti-Markovnikov product of addition.

3. The reaction requires the Markovnikov product without sigmatropic rearrangement.

The answer is option A, option D, and option F.

Oxymercuration-demercuration reagents are used to prevent sigmatropic rearrangements. The product produced by the hydroboration-oxidation of alkene is the anti-Markovnikov product of addition while oxymercuration-demercuration reagents give the Markovnikov product of addition. The reaction required the Markovnikov product without sigmatropic rearrangement.Therefore, the reasons why oxymercuration-demercuration was chosen to effect the following transformation instead of the other reagents are oxymercuration-demercuration reagents prevent sigmatropic rearrangements, hydroboration-oxidation reagents yield the anti-Markovnikov product of addition, and the reaction requires the Markovnikov product without sigmatropic rearrangement. The answer is option A, option D, and option F.

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A)Acid Dissociation Reactions of Oxalic Acid. The ionization constant (Ka) of oxalic acid is given by the reaction:H_{2}C_{2}O_{4 }+ H_{2}O ⇌ H_{3}O+ + HC_{2}O_{4-}.

B)The equilibrium constant for the basic dissociation of a conjugate base is given by Kb. Kb values are the opposite of Ka values (Kb = Kw/Ka) and are also used to compare the strength of a base's conjugate acid.

A) Acid Dissociation Reactions of Oxalic Acid. The ionization constant (Ka) of oxalic acid is given by the reaction:H_{2}C_{2}O_{4 }+ H_{2}O ⇌ H_{3}O+ + HC_{2}O_{4-}; Ka1 = 5.90 × 10-2 The reaction above describes the primary ionization of oxalic acid, where one of the two acidic hydrogen ions (protons) is lost. The loss of the second hydrogen ion is given by the second equilibrium:H_{2}C_{2}O_{4 }+ H_{2}O ⇌ H_{3}O^{+}+ C_{2}O_{4}^{2-}; Ka2 = 6.40 * 10^{-5} Oxalic acid is a diprotic acid, implying that it has two dissociable protons. It can thus release two protons when dissolved in water. The stronger the acid, the weaker its conjugate base, which means that the conjugate base of the first equilibrium is stronger than that of the second equilibrium.

B) Base Reaction with Water for Each Conjugate BaseThe corresponding base reactions with water for the conjugate bases are:H_{2}C_{2}O_{4 }+ H_{2}O ⇌ H_{3}O+ + HC_{2}O_{4-}; Ka1 = 5.90 * 10-2 H_{2}C_{2}O_{4 }+ H_{2}O ⇌ H_{3}O^{+}+ C_{2}O_{4}^{2-}; Ka2 = 6.40 × 10-5.The equilibrium constant for the basic dissociation of a conjugate base is given by Kb. Kb values are the opposite of Ka values (Kb = Kw/Ka) and are also used to compare the strength of a base's conjugate acid.

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The change in enthalpy (ΔH) for the reaction 2NaHSO4(s) ⟶ Na2SO4(s) + H2O(g) + SO3(g) is given as -231.3 kJ. To determine the change in enthalpy when 3.60 g of NaHSO4 reacts, we need to calculate the moles of NaHSO4 and then use the stoichiometry of the reaction to find the corresponding change in enthalpy.

To calculate the moles of NaHSO4, we divide the given mass (3.60 g) by its molar mass. The molar mass of NaHSO4 is the sum of the atomic masses of sodium (Na), hydrogen (H), sulfur (S), and four oxygen (O) atoms:

Molar mass of NaHSO4 = 22.99 g/mol + 1.01 g/mol + 32.07 g/mol + (4 × 16.00 g/mol) = 120.05 g/mol

Moles of NaHSO4 = mass / molar mass = 3.60 g / 120.05 g/mol ≈ 0.03 mol

The change in enthalpy is given per mole of NaHSO4, so to find the change in enthalpy for 0.03 mol, we multiply the given value of ΔH (-231.3 kJ/mol) by the number of moles:

Change in enthalpy = ΔH × moles = -231.3 kJ/mol × 0.03 mol ≈ -6.939 kJ

Therefore, the change in enthalpy for the reaction, when 3.60 g of NaHSO4 reacts, is approximately -6.939 kJ (rounded to three decimal places).

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The substances in the list can be used to write a complete combustion reaction are:

To write a complete combustion reaction, we need a fuel (usually a hydrocarbon or carbon-based compound) and an oxidizing agent (typically oxygen). Based on the provided list of chemical substances, the following substances can be used to write a complete combustion reaction:

Al (aluminum)

O₂ (oxygen)

H₂O (water)

CO₂ (carbon dioxide)

These substances can be combined to form a complete combustion reaction. For example, the reaction between aluminum (Al) and oxygen (O2) can result in the formation of aluminum oxide (Al₂O₃):

4 Al + 3 O₂ → 2 Al₂O₃

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The oxygen in water behaves as though it’s electronegative, and the hydrogens behave as though they’re electropositive. This is due to the difference in electronegativity between oxygen and hydrogen.

Oxygen is more electronegative than hydrogen, which means that it has a stronger attraction for electrons. As a result, the electrons in a water molecule spend more time around the oxygen atom than they do around the hydrogen atoms.

The oxygen in water is said to be electronegative, while the hydrogens behave as if they're electropositive. This is due to the disparity in electronegativity between the two atoms. Oxygen is more electronegative than hydrogen, implying that it has a stronger attraction for electrons.

Electronegativity is a measure of an atom's ability to attract electrons. It helps to explain why the electrons in a water molecule spend more time around the oxygen atom than they do around the hydrogen atoms.

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It will exhibit different resonance structures.

The Lewis structure for NO3 represents the electronic structure of nitrate ion. This structure includes resonance, meaning that the double bonds in the compound are not found at a specific location but rather can be present in different places.The Lewis structure for NO3 is shown below:Option a is the correct statement. The Lewis structure for NO3 will exhibit different resonance structures, as mentioned earlier. Since the double bond in the molecule can occur in different places, the molecule exhibits resonance. This is what is meant by different resonance structures.Options b, c, and d are incorrect as they contain false information. The formal charge on each atom in NO3 is not zero, but rather, the central nitrogen atom in NO3 has a formal charge of +1, while each of the oxygen atoms has a formal charge of -1. The number of valence electrons in NO3 is 24, and the structure includes both single and double bonds.

Option A is the correct answer of this question.

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When the weak acid HCN (hydrocyanic acid) dissolves in water, it forms the hydronium ion (H3O+) and the cyanide ion (CN-).

The balanced chemical equation for the reaction of HCN with water is: HCN (aq) + H2O (l) ⇌ H3O+ (aq) + CN- (aq)The Ka expression for this reaction is as follows:Ka = [H3O+][CN-] / [HCN]Where [H3O+] represents the concentration of the hydronium ion, [CN-] represents the concentration of the cyanide ion, and [HCN] represents the concentration of HCN.The Ka expression can be used to calculate the acid dissociation constant, which is a measure of the strength of the acid. The larger the Ka value, the stronger the acid. The Ka expression can also be used to calculate the pH of the solution.

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The electron affinity (Ea) of an element is the energy change that occurs when an electron is added to a neutral atom, and it is defined as a negative quantity because energy is absorbed in the process. The greater the electron affinity of an element, the more energy it requires to add an electron to its atom.

Among the following neutral electron configurations in which n has a constant value, the configuration that would belong to the element with the most negative electron affinity, Ea is 5s25p2 (option C)

Among the provided electron configurations, the element with the most negative electron affinity (Ea) will be the one that requires the most energy to add an electron to its neutral atom. If an electron is added to an atom with a large electron affinity, the resulting anion will be unstable, and the added electron will undergo rapid decay. Thus, the greater the electron affinity, the less stable the resulting anion. The electron affinity of an atom is influenced by its atomic radius, electron configuration, and other factors. Among the provided configurations, 5s25p2 belongs to the element with the most negative electron affinity.

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A "percolating stream" is a stream from which water is moving downward to the water table.

A percolating stream generally refers to a type of stream or water flow that occurs when water moves downward through permeable materials such as soil, sand, or rock, gradually infiltrating into the ground. The water follows a vertical or nearly vertical path, seeping through the interconnected spaces and pores within the subsurface layers.

This movement is often driven by gravity, as water percolates or filters through the porous medium. Percolating streams contribute to groundwater recharge, replenishing underground water reservoirs and influencing the overall hydrological cycle.

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Hydrazine, N2H4 is a weak base. Its dissociation process in water is: N2H4 + H2O ↔ N2H5+ + OH¯Given the base dissociation constant, Kb = 1.3 × 10⁻⁶ M.Hydrazine (N2H4) is a weak base that undergoes hydrolysis when dissolved in water.

A hydrolysis reaction occurs when a molecule reacts with water to create an acidic or basic solution. The pH of a 0.10 mm solution of hydrazine, N2H4, with Kb of 1.3×10−6 can be calculated as follows:Step 1: Calculate the concentration of OH- ions produced when N2H4 undergoes hydrolysis.N2H4 + H2O → N2H5+ + OH-Initial concentration = 0.10 mol/L0.10 ----- 0 ----- 0After hydrolysis, the amount of OH- produced is x, so the concentration of OH- is x mol/L.Using the Kb value and the equation:Kb = [N2H5+][OH-] / [N2H4][OH-] = Kb * [N2H4] / [N2H5+]x^2 / (0.10 - x) = 1.3 × 10⁻⁶x^2 = (1.3 × 10⁻⁶)(0.10 - x)x = [OH⁻] = 1.13 × 10⁻⁵ MStep 2: Calculate the pOHpOH = -log [OH⁻] = -log (1.13 × 10⁻⁵)= 4.95Step 3: Calculate the pHpH = 14 - pOH = 14 - 4.95 = 9.05Therefore, the pH of a 0.10 mm solution of hydrazine, N2H4, with Kb of 1.3×10−6 is 9.05.

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Sn₂+ + H₂O₂ + 2H+ ==> Sn₄ + + 2H₂O is balanced redοx reactiοn.

Organic mοlecules undergο redοx prοcesses knοwn as οrganic reductiοns, οrganic οxidatiοns, οr οrganic redοx reactiοns. Because many prοcesses gο by the label οf redοx but dοn't actually invοlve an electrοn transfer, οxidatiοns and reductiοns in οrganic chemistry differ frοm regular redοx reactiοns.

Redοx reactiοns are defined as chemical prοcesses in which οne οr mοre οf the chemical species invοlved undergοes changes in οxidatiοn number. Oxidatiοn and reductiοn οccur simultaneοusly in this kind οf chemical reactiοn. Electrοns are lοst οr gained during οxidatiοn and reductiοn, respectively.

Sn₂ +  ==> Sn₄ + + 2e-  is οxidatiοn half

H₂O₂ ==> H₂Ois reductiοn half

Sn₂ + ==> Sn₄ + + 2e-  

H₂O₂ ==> H₂O+ H₂O

H₂O₂ + 2H+ ==> H₂O+ H₂O

H₂O₂ + 2H+ + 2e-==> H₂O+ H₂O

Sn₂ + ==> Sn₄ + + 2e-

H₂O₂ + 2H+ + 2e-==> H₂O+ H₂O

Sn₂ + + H₂O₂  + 2H+ + 2e- ==> Sn₄ + + 2e- + H₂O+ H₂O

Sn₂ + + H₂O₂ + 2H+ ==> Sn₄ + + 2H₂O balanced redοx equatiοn

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The length of time it takes for an object to complete one full orbit around another object is known as the orbital period. The amount of time it takes for an item to return to the same place in its orbit is another way to put this. The orbital period is 1.79 × 10³⁷ s.

The smallest velocity that a body must sustain to remain in orbit is called orbital velocity. The tendency of the moving body to move forward in a straight line is caused by its inertia.

The expression used to calculate orbital velocity is:

v₀ = √GM/R

Where 'G' is the gravitational constant, 'M' is the mass of the earth, and 'R' is the radius of the earth.

The orbital period is:

T = 2πR / v₀

T² = 4π²R³ / GM

M =  6 × 10²⁴ Kg

G = 6.67 × 10⁻¹¹

T² = 4 × 3.14²×  (3.20 × 10⁷)³ /  6.67 × 10⁻¹¹ × 6 × 10²⁴

T = 1.79 × 10³⁷ s

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The correct answer among the following is option C which is Tempera paint.

Explanation: A colloid is a heterogeneous mixture in which one substance is dispersed throughout another substance. The dispersed substance can either be a solid, liquid or gas and is referred to as the dispersed phase or internal phase and the substance in which it is dispersed is called the continuous phase or external phase. In tempera paint, pigment is dispersed throughout an emulsion of water and egg yolk, making it a colloid.

Brass is an alloy of copper and zinc, and is therefore a homogeneous mixture. Air is a mixture of gases, and is not a colloid. An opal is a mineral and not a mixture. Therefore, the correct answer is option C which is Tempera paint.

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The ending generally associated with a monatomic anion is option D, "...ide."

Monatomic anions are formed when an atom gains one or more electrons, resulting in a negatively charged ion.

The names of monatomic anions typically end in "...ide."

To illustrate this, let's consider a few examples:

- Chlorine, an element in Group 17 of the periodic table, forms a monatomic anion by gaining one electron. The resulting ion is called chloride (Cl^-).

- Oxygen, an element in Group 16 of the periodic table, forms a monatomic anion by gaining two electrons. The resulting ion is called oxide (O^2-).

- Nitrogen, an element in Group 15 of the periodic table, forms a monatomic anion by gaining three electrons. The resulting ion is called nitride (N^3-).

From these examples, we can observe that the names of monatomic anions end in "...ide."

In conclusion, the ending generally associated with a monatomic anion is option D, "...ide."

This ending is characteristic of anions formed when atoms gain electrons to achieve a stable electron configuration.

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The correct order of increasing oxidation states of the given compounds is as follows.1 < 3 < 2.

The oxidation state (oxidation number) of an atom reflects the number of electrons lost or gained by the atom while forming a chemical bond. The oxidation states can be used to determine the relative degree of oxidation of a substance. Here, we will determine the correct order of increasing oxidation states of the given compounds.

Option (C) 1 < 3 < 2 is the correct option among the given options.

The oxidation state of each compound is as follows:

CH3CHO The oxidation state of the carbon atom of the carbonyl group is +2. Oxidation state of the carbon atom of the carbonyl group = +2

Oxidation state of the carbon atom of the CH3 group = -3

The oxidation state of the carbon atom of the carbonyl group and CH3 group can be determined as follows. The oxygen atom has an oxidation state of -2 and the hydrogen atom has an oxidation state of +1. Applying these oxidation states to the molecule, we get the oxidation state of the carbon atom of the carbonyl group and CH3 group as follows.-2 + (2 * -1) = -4 (For carbonyl carbon)1 * 3 = 3 (For CH3 group carbon)

Adding up the oxidation states of carbon in CH3CHO gives -4 + 3 = -1

CH2=CH2

The oxidation state of each carbon atom in ethene is -1.The oxygen atom has an oxidation state of -2 and the hydrogen atom has an oxidation state of +1. Applying these oxidation states to the molecule, we get the oxidation state of the carbon atom as follows.-2 + (2 * -1) = -4 (For both carbons)

Adding up the oxidation states of carbon in CH2=CH2 gives -4 + (-4) = -8

CH3CO2H

The oxidation state of the carbon atom of the carboxyl group is +3, the carbon atom of the carbonyl group is +2, and the other two carbon atoms are -2. The oxidation state of the carbon atom of the carboxyl group = +3

The oxidation state of the carbon atom of the carbonyl group = +2The oxidation state of the other two carbon atoms = -2

The oxygen atom has an oxidation state of -2 and the hydrogen atom has an oxidation state of +1. Applying these oxidation states to the molecule, we get the oxidation state of the carbon atom as follows.2 * -2 = -4 (For carbonyl carbon)1 * 3 = 3 (For carboxyl carbon)2 * -2 = -4 (For other carbons)

Adding up the oxidation states of carbon in CH3CO2H gives -4 + 3 + (-4) + (-2) = -7

Therefore, the correct order of increasing oxidation states of the given compounds is as follows.1 < 3 < 2

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HF acid would be classified as the strongest.

HF would be classified as the strongest acid.Hydrogen fluoride (HF) is a colorless liquid or gas, that is extremely corrosive and capable of corroding glass. It's also recognized as an acid of Lewis because of its polar covalent bond and high electron negativity difference. HF is widely used in industrial processes like glass etching, metal pickling, and oil well acidizing.The acidic strength of an acid is determined by its ability to donate a proton or H+ ion. Hydrogen fluoride, also known as hydrofluoric acid (HF), is a highly polar molecule with a hydrogen ion that can easily dissociate when it comes into touch with water. This is the primary reason why HF is known to be the strongest acid in this list. Therefore, option D (HF) would be the correct answer.

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Among the following options, HF (hydrofluoric acid) would be classified as the strongest acid.What is an acid?An acid can be defined as any substance which when dissolved in water releases hydrogen ions. The strength of the acid is directly proportional to the concentration of hydrogen ions in the solution.What makes HF the strongest acid among the options?HF is classified as the strongest acid because it is a covalent compound and the bond between hydrogen and fluorine is highly polarized. As a result, when HF is dissolved in water, it releases hydrogen ions easily and exhibits strong acidic properties.On the other hand, the other options listed are either covalent compounds with weaker polarized bonds or bases. For example, CH4 is a covalent compound that does not release hydrogen ions, NH3 is a weak base that accepts hydrogen ions, H2O is a neutral compound, and PH3 is a weaker acid compared to HF.

The larger atom from each of the following pairs are Al or In:In is a larger atom. Si or N:N is a larger atom.P or Pb:Pb is a larger atom.Si or Cl:Cl is a larger atom

This is because the atomic radius increases down a group and In is below Al in the periodic table. Atomic radii of Al and In are 143 pm and 167 pm, respectively.Si or N:N is a larger atom. This is because the atomic radius increases down a group and N is below Si in the periodic table. Atomic radii of Si and N are 111 pm and 155 pm, respectively.P or Pb:Pb is a larger atom. This is because the atomic radius increases down a group and Pb is below P in the periodic table. Atomic radii of P and Pb are 98 pm and 202 pm, respectively.Si or Cl:Cl is a larger atom. This is because the atomic radius increases down a group and Cl is below Si in the periodic table. Atomic radii of Si and Cl are 111 pm and 99 pm, respectively.

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HIO₃ is a strong acid, it will release a higher concentration of H⁺ ions, leading to a greater concentration of hydroxide ions compared to the other species listed. Hence, option C is correct.

The species that will produce the greatest concentration of hydroxide ions in solution is option C: HIO₃.

HIO₃ is an acid called iodic acid. When it dissolves in water, it will dissociate to release H⁺ ions and IO₃⁻ ions. The H⁺ ions can react with water molecules to form hydronium ions (H₃O⁺), while the IO₃⁻ ions do not directly produce hydroxide ions.

However, in the presence of excess water, the hydronium ions can react with water in a reversible reaction to generate hydroxide ions (OH⁻). This reaction is known as the autoionization of water:

2H₃O⁺ (hydronium ions) ⇌ H₂O + H₃O⁺ + OH⁻

As a result, the concentration of hydroxide ions (OH⁻) increases in the solution. Since HIO₃ is a strong acid, it will release a higher concentration of H⁺ ions, leading to a greater concentration of hydroxide ions compared to the other species listed.

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An increase in temperature of ten degrees Celsius will typically have a significant effect on the rate of a reaction. The specific outcome, whether the rate doubles, quadruples, is halved, or depends on the reaction, depends on the nature of the reaction and the associated rate equation.

The effect of temperature on the rate of a reaction can be determined by the Arrhenius equation and the concept of reaction rate constant (k). In general, an increase in temperature leads to an increase in the rate of a reaction. The Arrhenius equation states that the rate constant (k) is exponentially dependent on temperature (T) through the term exp(-Ea/RT), where Ea is the activation energy, R is the gas constant, and T is the absolute temperature.

When the temperature increases, the exponential term in the Arrhenius equation becomes larger, resulting in a higher rate constant. As a consequence, the rate of the reaction tends to increase. However, the exact relationship between temperature and rate depends on the specific rate equation for the reaction. Therefore, without knowledge of the specific reaction and its rate equation, it is not possible to determine the exact outcome of increasing the temperature by ten degrees Celsius. It could lead to the rate doubling, quadrupling, being halved, or having a different effect altogether, depending on the particular reaction and its associated rate equation.

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The compound that will not be soluble in water is BaSO₄ (barium sulfate). Option B is correct.

BaSO₄ (barium sulfate) is the compound that is not soluble in water. Solubility in water depends on the nature of the compound and the interactions between its constituent ions and water molecules. In the case of BaSO₄, the strong electrostatic forces of attraction between the barium (Ba²⁺) and sulfate (SO₄²⁻) ions result in a very low solubility in water. The solubility rules dictate that most sulfates are soluble in water, but barium sulfate is an exception.

It forms a solid precipitate when barium ions and sulfate ions come into contact in an aqueous solution. On the other hand, K₂S (potassium sulfide), NaNO₃ (sodium nitrate), and LiOH (lithium hydroxide) are all soluble in water and will dissociate into their constituent ions when dissolved, resulting in a homogeneous solution. Option B is correct.

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The correct option among the given options in the question is false statement about isotopes is Isotopes are atoms with the same atomic number but different mass numbers.

The definition of isotopes states that isotopes are atoms of the same element that have different numbers of neutrons. For instance, carbon has three isotopes: carbon-12, carbon-13, and carbon-14.Isotopes are atoms with the same atomic number but different mass numbers because they have the same number of protons and electrons as the element, but a different number of neutrons. The number of neutrons determines the isotope.

Option C is the correct answer of this question.

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The preferred chair to sit on a sunny day is the one made of aluminum. It offers a more comfortable seating experience compared to the iron chair. The aluminum chair's higher specific heat capacity helps it absorb less heat and stay cooler.

Aluminum is the preferred choice for sitting on a sunny day due to its higher specific heat capacity (c=0.89 J/g°C) compared to iron (c=0.45 J/g°C). Specific heat capacity refers to the amount of heat energy required to raise the temperature of a substance by one degree Celsius per gram.

When exposed to the sun, both chairs will absorb heat energy from the sunlight. However, aluminum has a higher specific heat capacity, meaning it can absorb more heat energy per gram compared to iron. This results in the aluminum chair heating up at a slower rate than the iron chair.

The slower rate of heat absorption by the aluminum chair makes it more comfortable to sit on during a sunny day. It will take longer for the aluminum chair to reach an uncomfortable temperature compared to the iron chair, providing a more pleasant seating experience.

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a) Calculation of pH of the given buffer:Given, Mass of (CH3)2NH2I = 49.9 gVolume of (CH3)2NH2I solution = 250.0 mLConcentration of (CH3)2NH = 1.42M= 1.42 moles/L

Let's first calculate the moles of (CH3)2NH and (CH3)2NH2+CH3NH2+(aq) ⇌ CH3NH3+(aq) + OH-(aq)Kb = 5.4 × 10^-4Kw = 1.0 × 10^-14Kb = [CH3NH3+][OH-]/[CH3NH2+][OH-]= [CH3NH3+]/[CH3NH2+][OH-]Initial concentration of CH3NH2+ = 1.42MInitial concentration of CH3NH3+ = 0pH of the buffer is calculated using the following formula:pH = pKa + log [A-]/[HA]The pKa of (CH3)2NH is 10.73, and at pH 10.73, the ratio [A-]/[HA] is 1, so the pH of the buffer can be calculated from the following equation:pH = pKa + log [A-]/[HA]pH = 10.73 + log (0.0045/0.0045)pH = 10.73b) Calculation of pH of buffer after addition of 0.300 mol of H+:The balanced chemical equation for the addition of H+ is:CH3NH2(aq) + H+(aq) ⇌ CH3NH3+(aq)Initial concentration of CH3NH2+ = 1.42 MInitial concentration of CH3NH3+ = 0 molesLet x be the concentration of H+ after it is added.CH3NH2+(aq) + H+(aq) ⇌ CH3NH3+(aq)H+ is consumed by CH3NH2 and added to CH3NH3+.[H+] = [CH3NH3+] - [CH3NH2+]Let [CH3NH2+] = y[H+] = 0.3 mol/L – y[CH3NH3+] = yKb = [CH3NH3+][OH-]/[CH3NH2+][OH-]5.4 × 10^-4 = y(0.3-y)/ yMoles of CH3NH3+ = yMoles of CH3NH2+ = 0.42 - y1.42 = (y/0.3-y)y = 0.042 mol/L[OH-] = Kb * [CH3NH3+]/[CH3NH2+]5.4 × 10^-4 = 0.042(0.042)/0.258pOH = 3.298pH = 14 – 3.298 = 10.702c) Calculation of pH of buffer after the addition of 0.120 mol of OH-:The balanced chemical equation for the addition of OH- is:CH3NH2(aq) + OH-(aq) ⇌ CH3NH3+(aq) + H2O(l)Initial concentration of CH3NH2+ = 1.42 MInitial concentration of CH3NH3+ = 0 molesLet x be the concentration of OH- after it is added.CH3NH2+(aq) + OH-(aq) ⇌ CH3NH3+(aq) + H2O(l)OH- is consumed by CH3NH3+ and added to CH3NH2+.[OH-] = [CH3NH2+] - [CH3NH3+]Let [CH3NH2+] = y[OH-] = 0.120 mol/L – y[CH3NH3+] = yKb = [CH3NH3+][OH-]/[CH3NH2+][OH-]5.4 × 10^-4 = y(y)/ (1.42 – y)Moles of CH3NH3+ = yMoles of CH3NH2+ = 1.42 – y(5.4 × 10^-4 = y^2 / (1.42 – y)0 = y^2 – 5.4 × 10^-4 y – 7.668 × 10^-4y = (0.00054 ± sqrt((5.4 × 10^-4)^2 + 4(7.668 × 10^-4)) / 2 = 0.00729 mol/LCH3NH2+ = 1.42 – y = 1.41 M[OH-] = Kb * [CH3NH3+]/[CH3NH2+]5.4 × 10^-4 = y(0.00729)/1.41[OH-] = 2.786 × 10^-6pOH = 5.56pH = 8.44 (as pOH + pH = 14)

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The activation energy of a chemical reaction can be increased or decreased by various factors. These factors can influence the rate of reaction and can result in a change in the potential energy barrier height. The height of the potential energy barrier in a chemical reaction is directly proportional to the energy of activation.

When the energy of activation of a system increases, the height of the potential energy barrier increases and the rate of reaction decreases.The height of the potential energy barrier corresponds to the amount of energy required to overcome the energy of activation. When the energy of activation is increased, the energy required to overcome the barrier also increases. This means that more energy is required to initiate the reaction and overcome the potential energy barrier. The rate of reaction decreases as a result of the increase in energy of activation. On the other hand, if the energy of activation decreases, the height of the potential energy barrier also decreases. This means that less energy is required to initiate the reaction and overcome the barrier. The rate of reaction increases as a result of the decrease in energy of activation.In summary, the height of the potential energy barrier increases when the energy of activation of a system increases. Conversely, the height of the potential energy barrier decreases when the energy of activation of a system decreases.

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If a saturated solution of a solute is made using 41.0 g of H2O at 20.0 °C, the amount of additional solute that can be added when the temperature is increased to 30.0 °C depends on the solubility of the solute. The solubility of most substances tends to increase with temperature, so more solute can be dissolved. The specific solubility data or a solubility curve is needed to determine the exact amount of additional solute that can be added.

When the temperature of a solvent increases, the solubility of many substances generally increases as well. This means that more solute can be dissolved in the solvent. However, the amount of additional solute that can be added when the temperature is increased from 20.0 °C to 30.0 °C depends on the solubility characteristics of the specific solute.

To determine the exact amount of additional solute that can be added, one would need to consult the solubility data or a solubility curve for the particular solute at different temperatures. These resources provide information on the maximum amount of solute that can be dissolved in a given amount of solvent at various temperatures. By referring to the solubility data, one can find the maximum solubility of the solute at 30.0 °C and calculate the difference between the currently saturated solution and the new solubility value to determine how much more solute can be added.

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The energy change (ΔE) for the decomposition of hydrogen peroxide is -628 kJ/mol, indicating an exothermic reaction.

To calculate the energy change (ΔE) for the decomposition of hydrogen peroxide, we need to determine the total bond energies of the reactants and products and then calculate the difference between the two.

Reactants:

2 [tex]H_{2} O_{2}[/tex](g)

Products:

2 [tex]H_{2} O[/tex](g)

[tex]O_{2}[/tex](g)

First, let's calculate the bond energy for the reactants:

H-H bonds:

2 H-H bonds in[tex]H_{2} O_{2}[/tex] = 2 * 436 kJ/mol = 872 kJ/mol

O-H bonds:

4 O-H bonds in[tex]H_{2} O_{2}[/tex] = 4 * 463 kJ/mol = 1852 kJ/mol

O-O bonds:

1 O-O bond in [tex]H_{2} O_{2}[/tex] = 1 * 146 kJ/mol = 146 kJ/mol

Total bond energy of the reactants:

872 kJ/mol (H-H) + 1852 kJ/mol (O-H) + 146 kJ/mol (O-O) = 2870 kJ/mol

Next, let's calculate the bond energy for the products:

H-H bonds:

4 H-H bonds in [tex]H_{2} O[/tex]= 4 * 436 kJ/mol = 1744 kJ/mol

O=O bonds:

1 O=O bond in [tex]O_{2}[/tex]= 1 * 498 kJ/mol = 498 kJ/mol

Total bond energy of the products:

1744 kJ/mol (H-H) + 498 kJ/mol (O=O) = 2242 kJ/mol

Finally, calculate the energy change (ΔE) by taking the difference between the total bond energy of the products and the total bond energy of the reactants:

ΔE = Total bond energy of products - Total bond energy of reactants

= 2242 kJ/mol - 2870 kJ/mol

= -628 kJ/mol

Therefore, the energy change (ΔE) for the decomposition of hydrogen peroxide is -628 kJ/mol. The negative sign indicates that the reaction is exothermic, meaning it releases energy.

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The emission spectrum of hydrogen was used to calibrate the spectroscope because hydrogen has a relatively simple and well-understood atomic structure.

The simplest and most prevalent element in the universe is hydrogen. Its atomic structure is made up of one electron orbiting the nucleus in various energy levels or orbitals and a single proton in the nucleus.

An electron emits energy in the form of light at particular wavelengths or frequencies when it moves from a higher energy level to a lower energy level. The hydrogen spectral lines, which are a distinctive pattern of lines in the emission spectrum, are produced by these wavelengths.

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The tension in the string is approximately 39.2 N.

The closest option provided is D) 40 N. Hence, option D is correct.

Given:

Mass of iron cylinder = 4.0 kg

Density of iron = 7860 kg/m³

Density of water = 1000 kg/m³

Gravitational acceleration = 9.8 m/s²

To calculate the tension in the string, we need to compare the weight of the iron cylinder with the buoyant force exerted on it.

Weight of the iron cylinder = mass of iron cylinder × gravitational acceleration

Buoyant force = weight of water displaced = weight of the iron cylinder

Since the iron cylinder is submerged in water, the buoyant force is equal to the weight of the iron cylinder.

Now let's calculate the tension in the string:

Weight of the iron cylinder = mass of iron cylinder × gravitational acceleration

Weight of the iron cylinder = 4.0 kg × 9.8 m/s²

Since the weight of the iron cylinder is equal to the buoyant force, the tension in the string is also equal to the weight of the iron cylinder.

Therefore, the tension in the string supporting the submerged iron cylinder is:

Tension = Weight of the iron cylinder

Now we can calculate the tension:

Tension = 4.0 kg × 9.8 m/s²

Tension = 39.2 N

So, the tension in the string is approximately 39.2 N.

The closest option provided is D) 40 N. Hence, option D is correct.

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The radius of an Na+ ion is approximately 1.86 × [tex]10^{-10}[/tex] meters.

The radius of an Na+ ion, commonly known as a sodium ion, can be converted to meters using the given data.

The atomic radius of sodium is approximately 186 picometers (pm).

However, when sodium loses an electron and forms a sodium ion (Na+), the ion becomes smaller due to the removal of an electron shell.

To convert the radius to meters, we need to use the conversion factor: 1 meter = 1 × [tex]10^{12}[/tex] picometers.

By multiplying the atomic radius by this conversion factor, we can obtain the radius in meters.

Radius of Na+ ion = Atomic radius of sodium = 186 pm

Converting the radius to meters:

Radius in meters = 186 pm × (1 m / 1 × [tex]10^{12}[/tex]pm)

Simplifying the expression:

Radius in meters = 186 × [tex]10^{12}[/tex] meters

Hence, the radius of an Na+ ion is approximately 1.86 × [tex]10^{10}[/tex] meters.

In summary, the radius of an Na+ ion is approximately 1.86 × [tex]10^{10}[/tex]meters after converting the atomic radius of sodium (186 picometers) to meters using the conversion factor 1 meter = 1 × [tex]10^{12}[/tex] picometers.

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The radius of an Na+ ion is typically about 0.095 nanometers. Using conversion factors, we can convert this number to 9.5 x 10^-11 metres.

In order to convert the radius of an Na+ ion to meters, first, we need to know the actual radius. The radius of a sodium ion (Na+) is approximately 0.095 nanometers. To convert that to meters, you would use the fact that one meter equals 1 billion nanometers. So you simply multiply 0.095 by 1 billion (10^9) to convert from nanometers to meters. Therefore, the radius of a Na+ ion in meters is 0.095 x 10^-9 meters, which equals 9.5 x 10^-11 meters.

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The power radiated by the radiator changes by a factor of 14.1573 when the temperature is increased from 27°C to 54°C.

The formula that relates the power radiated by an object with the fourth power of the temperature is known as the Stefan-Boltzmann Law. It is stated as follows: P = σA(T⁴), where P is the power radiated, σ is the Stefan-Boltzmann constant (5.67 × 10⁻⁸ W/m²K⁴), A is the surface area of the radiator, and T is the temperature in Kelvin.

We must first convert the temperature to Kelvin:

TK = T°C + 273.15

TK1 = 27°C + 273.15 = 300.15 K

TK2 = 54°C + 273.15 = 327.15 K

The factor by which the power radiated changes is the ratio of the power at the new temperature to the power at the original temperature. The equation is as follows:

P2/P1 = (T2/T1)⁴

Substituting the given values:

P2/P1 = (327.15/300.15)⁴

P2/P1 = 1.8856⁴

P2/P1 = 14.1573

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