Which of the following is an indicator that a chemical reaction occurred?
A precipitate is formed
The state of matter changed
It was melted
The identity of the substance did not change​

A direct current power supply of low voltage (less than 10 volts) has lost the markings that indicate which output terminal is positive and which is negative. A chemist suggests that the power supply terminals be connected to a pair of platinum electrodes that dip into 0.1-molar KI solution.  Only (B) A gas will be evolved only at the negative electrode correctly identifies the polarities of the power supply terminals.

When the power supply terminals are connected to a pair of platinum electrodes dipping into a 0.1-molar KI solution, the electrolysis of the solution will occur. In the process of electrolysis, the positive electrode (anode) attracts negatively charged ions (anions) and the negative electrode (cathode) attracts positively charged ions (cations).

In this case, when a gas is evolved, it indicates that reduction is occurring at the electrode. The gas evolved will be hydrogen gas (H₂) from the reduction of H⁺ ions in the KI solution.

Since hydrogen gas is evolved only at the negative electrode (cathode), the correct identification of the polarities of the power supply terminals is that a gas will be evolved only at the negative electrode.

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Answer: A. AgBr: pH would have little to no effect on its solubility.

B. LiF: pH would have little to no effect on its solubility.

C. Ca(OH)2: more soluble in a basic solution.

D. FeI3: more soluble in an acidic solution.

Explanation:)

Solubility of AgBr, LiF, Ca(OH)2, FeI2 based on acidic, basic, or neutral pHThe pH of the solution has an effect on the solubility of several compounds. Salts of weak acids or bases dissolve more in a basic or acidic environment, respectively, than in neutral water.

On the other hand, salts of strong acids and bases are mostly soluble in water and are not affected by the pH of the solution. The solubility of the given compounds will be affected as follows:AgBr: AgBr will dissolve more in an acidic solution because it is an ionic compound of a weak acid HBr. The equation for the dissociation of HBr is HBr⇌H+ + Br-. When the pH is reduced, H+ concentration increases, leading to the reaction moving to the left, ultimately resulting in the formation of more HBr. LiF: LiF is a salt of a strong acid (hydrofluoric acid) and a strong base (lithium hydroxide). Its solubility will not be affected by pH since it is mostly soluble in water.Ca(OH)2: Calcium hydroxide is a salt of a strong base (calcium oxide) and a strong acid (water). Its solubility will not be influenced by pH since it is mostly soluble in water.FeI2: Iron (II) iodide is an ionic compound with a weak acid (HI) and a strong base (Fe(OH)2). Its solubility would increase in an acidic environment. Since I- is a weak conjugate base of HI, the equation for the dissociation of HI would shift to the left in the presence of H+ ions in the acidic solution. Hence FeI2 will dissolve more in an acidic environment.

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A coffee cup temperature  with a heat capacity of 6. 70 J/∘ C was used to measure the change in enthalpy of a precipitation reaction.The value of ΔHrxn was found to be 61.9 kJ/mol.

Calculate the enthalpy of reaction, ΔHrxn, per mole of precipitate formed (AgSCN). Assume the specific heat of the product solution is 4. 11 J / (g⋅∘C) and that the density of both the reactant solutions is 1. 00 g/mL.1. Calculation of Moles of precipitate formed from AgNO3:To find the value of ΔHrxn, we used the formula ΔHrxn = Qsolution/n, where Qsolution is the heat change produced by the solution process and n is the number of moles of AgSCN formed.

To find the value of n, we first calculated the number of moles of AgNO3 and KSCN used in the reaction using the formula n = M × V.To find the heat change produced by the solution process, we used the formula

Q = m × c × ∆T,

where Q is the heat change, m is the mass of the product solution, c is the specific heat capacity of the product solution, and ∆T is the change in temperature of the solution.The value of ΔHrxn was found to be 61.9 kJ/mol.

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The reason behind the most absorbance when the solution and beam colors are different is due to the absorption spectrum.

The absorption spectrum is the range of electromagnetic radiation that a substance can absorb, and it's unique to every substance. When a beam of light passes through a substance, the substance's molecules absorb some of the light's energy.

This means that some of the light is lost, and the rest is transmitted. The amount of energy absorbed by the substance is dependent on the wavelength of the light and the substance's properties.The color of a substance is due to its ability to absorb some wavelengths of light and reflect others.

For example, a blue object reflects blue light and absorbs all other colors of light. When a blue solution is exposed to a beam of orange light, the blue solution will absorb the orange light, causing the solution to appear darker and resulting in high absorbance.

This phenomenon is known as complementary colors and is seen when a solution and a beam of light are different colors, leading to high absorbance of light.

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Answer:

hydroxyl (OH)

Explanation:

hydroxyl (OH)

The mass (in grams) of solute in 500 mL of 0.179 M potassium hydroxide, KOH solution is 5.02 grams (option A)

First, we shall obtain the mole of KOH in the solution. Details below:

Mole of solute = molarity × volume

Mole of KOH = 0.179 × 0.5

Mole of KOH = 0.0895 mole

Finally, we shall determine the mass of solute, KOH in the solution. Details below:

Mass = Mole × molar mass

Mass of KOH = 0.0895 × 56

Mass of KOH = 5.02 grams

Therefore, the mass of KOH present in the solution is 5.02 grams (option A)

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Answer:

Argon

Explanation:

Because, it is positioned down on the periodic table

Answer:

Argon

Explanation:

Answer:

NaBr

Explanation:

Answer:

um...id.k how to do chemistry...help please?

Explanation:

NaBr

Answer:

A

Explanation:

the answer is A because when your working cooperative people are helping you and non cooperative is where people are working against you by them selves

Answer:

Maybe later, not right now. Tell you when.

hot cheetos hot cheetossss

Answer:

This regulatory mechanism is in conjunction with the endocrine system, particularly in the posterior pituitary gland. This is related in the secretion of vasopressin or antidiuretic hormone (ADH). In the event of dehydration or extreme thirst, the body will conserve as much fluid as possible and the posterior pituitary will secrete more ADH that will signal the kidney to reabsorb more water in the collecting tubules.

Answer:

to much sause

Explanation:

Dispersion forces (London dispersion forces), dipole-dipole, and hydrogen bonding will occur between two molecules of CH3NH2.

Molecule of CF4, the molecular geometry is tetrahedral. The C-F bonds are polar and tetrahedral. The molecule is nonpolar.Intermolecular forces are forces that hold molecules together. There are three types of intermolecular forces: dispersion forces, dipole-dipole forces, and hydrogen bonding. The forces are affected by the type of molecule and the presence of polar groups. The intermolecular forces between two molecules of CH3NH2 are dispersion forces and hydrogen bonding. The correct options are:A) Dispersion forces (London dispersion forces)B) Dipole-dipoleC) Hydrogen bondingD) Ion-dipole forcesExplanation: CH3NH2 has a dipole moment, so it can participate in dipole-dipole interaction. Also, it has H atoms attached to nitrogen which makes it capable of forming hydrogen bonding. Thus, dispersion forces (London dispersion forces), dipole-dipole, and hydrogen bonding will occur between two molecules of CH3NH2.

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tip

this is just a tip not the true answer but try to add the given number

To determine the weight of an empty cylinder, we will consider the given information below:Half full of water cylinder weighs 11.6 kgFilled with a third of water, the cylinder weighs 10 kg.The glass cylinder is unmarked.Let's assume that the empty cylinder weighs x kg.

Since water was used to fill the cylinder, we know that the density of water is 1 g/cm³ or 1 kg/L.To find the volume of water needed to fill half of the cylinder, we will subtract the weight of the empty cylinder from the weight of the half-filled cylinder. Thus, volume of water filled in the cylinder is 11.6 kg - x kg. Since the cylinder is half-full, we will multiply the volume of water by 2, then divide by the total volume of the cylinder. Thus, we have:[tex]\frac{2\cdot(11.6kg-x kg)}{Volume}[/tex]Similarly, we can find the volume of water needed to fill a third of the cylinder using the formula above. Thus, we have:[tex]\frac{3\cdot(10kg-x kg)}{Volume}[/tex]Since the density of water is 1 kg/L, we know that the volume of water is equal to the weight of the water. Equating the two expressions, we have:2(11.6 - x) = 3(10 - x)Solving for x, we have x = 2.8 kg. Therefore, the empty cylinder weighs 2.8 kg.Answer: The empty cylinder weighs 2.8 kg.

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Answer:

13.89% p/p

Explanation:

El porcentaje peso a peso de una solución (%p/p) es definido como cien veces la relación entre la masa del soluto (En este caso, cloruro de calcio) y la masa de la solución. La ecuación es:

%p/p = Masa cloruro de calcio (250g)/ Masa solución * 100

Para hallar la masa de la solución debemos usar el volumen y la densidad de este:

1500mL * (1,2g / mL) = 1800g

Así, el %p/p será:

250g / 1800g * 100

Answer:

7 mol.dm^3

Explanation:

formula for calculating concentration: C = n/v

Start by changing 5000ml solution to dm^3 because volume is in dm^3

1 ml = 1cm^3

then from a cm^3 to dm^3 you divide by 1000

5000ml = 5000cm^3

5000÷1000= 5dm^3

c = n/v

= 35/5

= 7mol.dm^3

Answer:

Alright, We all know fruits contains enzyme, so there is a reaction name enzymic browning! Actually what happens when we cut the apple and keep it open the organic enzyme molecules starts reacting with oxygen of surroundings and oxidises it!

Answer:

commensalism

Explanation:

It's not parasitism as the shark is not harmed in the relationship

Answer:

Length of RT = 9.22 cm to the nearest hundredth

Explanation:

Considering the image up in the attachment, ΔRST is a right-angled triangle.

The length of two sides of ΔRST is given as 11cm and 6 cm. The length of the third side which is RT can be obtained using Pythagoras ' rule which says that the sum of the squares of two sides of a right-angled triangle is equal to the square of the hypotenuse.

This rule is given as: c² = b² + a² where c is the hypotenuse and a and b are the other two sides of the right-angled triangle.

In ΔRST, the length of the hypotenuse = 11 cm, the length of one of the two sides = 6cm, length of RT = x

Solving for x: (11 cm)² =  (x cm)² + (6 cm)²

(x cm)² = 121 cm² - 36 cm²

(x cm)² = 85 cm²

x cm = √85

x = 9.22 cm to the nearest hundredth

Therefore, length of RT = 9.22 cm to the nearest hundredth

Answer:

Valence electrons are outer shell electrons with an atom and can participate in the formation of chemical bonds. In single covalent bonds, typically both atoms in the bond contribute one valence electron in order to form a shared pair. The ground state of an atom is the lowest energy state of the atom.

A chemical equation must balance according to the rule of conservation of mass. According to the rule, mass cannot be generated or removed during a chemical process. The number of moles of hydroxide ions in the given balanced equation is 2.

A chemical equation is said to be balanced if the quantity of each type of atom in the reaction is the same on both the reactant and product sides. In a balanced chemical equation, the mass and charge are both equal.

The numbers which are used to balance the given chemical equation are known as the coefficients.

Here the balanced equation is:

2NO₃⁻(aq) + 3ClO⁻(aq) + H₂O(l) → 2NO(g) + 3ClO₂⁻(aq) + 2OH⁻(aq)

The moles of OH⁻ required is 2.

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A chemical substance that is extremely stable and takes years to break down into a less toxic form would be considered to be persistent. Persistence refers to the ability of a substance to resist degradation or breakdown over time.

Persistent chemicals have a long environmental or biological half-life, meaning it takes a significant amount of time for them to degrade or transform into less harmful substances.

Persistence can have negative implications because these substances can persist in the environment, accumulate in living organisms, and potentially cause adverse effects.

Examples of persistent substances include certain synthetic chemicals like some pesticides, certain industrial pollutants, and some persistent organic pollutants (POPs) such as polychlorinated biphenyls (PCBs) and certain chlorinated pesticides.

The persistence of a chemical is an important factor to consider when assessing its potential environmental and health impacts.

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Answer:

mushrooms bacteria mold

Explanation:

Calculate the percentage composition of Ca(MnO4)2.

Firstly, we see how many atoms are there for each element in the formula.

Ca= 1 atom

Mn= 2 atoms

O= 8 atoms

Next, we are going to consult our periodic table for the atomic mass of each element.

Ca= 40

Mn= 55

O= 16

Then, we have to find the molar mass for the compound..

Here is the formula for calculating molar mass of an element:

Molar Mass= ( no. of atoms of the element × atomic mass of the element)

Now, we have to calculate the atomic mass of the compound. So using the molar mass formula for an element, we calculate the molar mass for each element then we sum up their molar masses to get the compounds molar mass.

Molar mass (Ca)= 1× 40

(Ca)= 40

Molar mass (Mn)=2×55

(Mn)= 110

Molar mass (O)= 8×16

(O)= 128

Now: Molar mass( compound)= (Ca)+(Mn)+(O)

= 40+ 110 128

= 278

This is everything we need to calculate our percentage composition for each element..

* The example says to find the percentage composition for Ca. So we only find for Ca, Which is already done using the formula and the answer is 14.39%.

To prove that your answer is correct, find the percentage composition for Mn and O as well. Then you add up their percentage compositions.

If you do and you get 100 as your answer, then your percentage compositions are correct.

Why don't you try finding the percentage composition for Mn and O, then add up all the three percentage compositions. If you 100 as their sum, then your percentage composition for each of the elements are correct.

Answer:

2.41*10² m equals 2.41*10⁴ cm

Explanation:

The rule of three or is a way of solving problems of proportionality between three known values and an unknown value, establishing a relationship of proportionality between all of them. That is, what is intended with it is to find the fourth term of a proportion knowing the other three. Remember that proportionality is a constant relationship or ratio between different magnitudes.

If the relationship between the magnitudes is direct, that is, when one magnitude increases, so does the other (or when one magnitude decreases, so does the other) , the direct rule of three must be applied. To solve a direct rule of three, the following formula must be followed:

a ⇒ b

c ⇒ x

So: [tex]x=\frac{c*b}{a}[/tex]

In this case the rule of three can be applied as follows: if 1 m equals 100 cm, 2.41*10² m equals how many cm?

[tex]cm=\frac{2.41*10^{2} m*100 cm}{1 m}[/tex]

cm= 24100 = 2.41*10⁴

2.41*10² m equals 2.41*10⁴ cm

The linear atomic density in atoms per millimeter can be calculated for different crystallographic directions in bcc tantalum, which has a lattice constant of 0.33026 nm. The linear atomic density for the [100], [110], and [111] directions can be determined by dividing the number of atoms along the direction by the length of the direction.

The linear atomic density in atoms per millimeter can be calculated by dividing the number of atoms along a specific crystallographic direction by the length of that direction. In bcc (body-centered cubic) crystals, there are specific arrangements of atoms along different crystallographic directions.

(a) For the [100] direction, there is one atom per unit cell. The length of the [100] direction can be determined using the lattice constant, which is 0.33026 nm. Therefore, the linear atomic density for the [100] direction is 1 atom / (0.33026 nm) = 3.027 atoms/nm or 30.27 atoms/mm.

(b) For the [110] direction, there are two atoms per unit cell. The length of the [110] direction can be calculated by multiplying the lattice constant by the square root of 2. Therefore, the linear atomic density for the [110] direction is 2 atoms / (0.33026 nm √2) = 6.054 atoms/nm or 60.54 atoms/mm.

(c) For the [111] direction, there are three atoms per unit cell. The length of the [111] direction can be calculated by multiplying the lattice constant by the square root of 3. Therefore, the linear atomic density for the [111] direction is 3 atoms / (0.33026 nm √3) = 9.090 atoms/nm or 90.90 atoms/mm.

Thus, the linear atomic density in atoms per millimeter for the [100], [110], and [111] directions in bcc tantalum are approximately 30.27 atoms/mm, 60.54 atoms/mm, and 90.90 atoms/mm, respectively.

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