Chemistry B- Final Exam

What happens when there is an increase in temperature for a reaction rate?

Select all that apply.

It increases the total number of molecular collisions that occur

It increases the percentage of collisions that result in a reaction

What is latent heat of condensation?

the amount of heat released when a certain mass of a substance changes from a gas to a liquid

The greater the average kinetic energy of the particles in a sample of matter, __________.

the higher the temperature

Why do water molecules tend to stick to each other to form a liquid?

The exposed charge on hydrogen's protons are attracted to unshared electron pairs on oxygen atoms.

A solution is formed by dissolving 83.2 grams of copper II chloride (CuCl22) in 2.5 liters of water. The molar mass of CuCl22 is 134.45 g/mol.

What is the molarity of the solution?

0.25

A mixture consists of 45% oxygen, 12% argon, and 43% nitrogen by volume. A sample of this mixture has a pressure of 2.0 atm in a 5.3 L container at 350 K temperature. How many moles of gas are in the container?

0.369

What type of reaction is shown in the graph, and why?

Exothermic: Energy is released to the environment during the formation of the products.

Examine the image, which shows four chemical systems of colliding molecules. Which chemical system has the highest reaction rate?

D

Study the following equation.Fe(s) + 2 HCl(aq) ⇌ H22(g) + FeCl22(aq)

What happens to the iron metal when it is reacted in a closed container to produce hydrogen gas in this manner?

Select all that apply.

The rate of the forward reaction is at its maximum when the reaction first starts.

The rate of the reverse reaction increases as hydrogen gas accumulates.

Magnesium metal reacts with oxygen according to the equation:Mg(s) + O22(g) → 2MgO22(s)

Which of the following would increase the rate of the reaction?

grinding the magnesium metal into a fine powder

Examine the table.

What is the average half-life for the radioactive isotopes listed in the table?

2.67 x 10^4 years

Study the reaction.H22SO44(l) + CaCO33(s) ⇌ CO22(g) + H22O(l) + CaSO44(aq)

Which of the following would cause the equilibrium to shift, producing more carbon dioxide gas?

Select all that apply.

removing water from the system

adding CaCO33 to the system

removing carbon dioxide gas from the system

What is true at chemical equilibrium?

the forward reaction rate is equal to the reverse reaction rate

A sample of a substance burns more rapidly in pure oxygen than in air. Which factor is most responsible for this high rate of reaction?

the concentration of the reactants

What statements accurately describe kinetic molecular theory? Select all that apply.

The mobility of particles is dependent on their kinetic energy.

Matter is made up of particles.

What does Le Châtelier's principle state about a disturbance to a chemical reaction?

The equilibrium position of a reaction shifts to minimize the disturbance.

950 J of energy is used to heat an unknown mass of copper from 20.0° C to 95.0° C. The specific heat of copper = 0.39 J/(g·°C).

What is the mass of the copper?

32

A sample of oxygen gas has a volume of 2.1 L at 3.6 atm pressure and 200 K temperature.

What would the volume of this sample be at 1.0 atm and 400 K?

15.1

Study the table of polar and nonpolar substances.

If the substance X is known to be nonpolar, which of the other substances are also nonpolar?

Z and Q

Study the reaction.CH44 + 2O22 → CO22 + 2H22OIf 7.4 moles of carbon dioxide (CO22) form at the end of the reaction, how many moles of methane (CH44) and oxygen gas (O22) entered the reaction?

7.4 moles of methane and 14.8 moles of oxygen gas

Americium-241 is a radioactive isotope used in household smoke detectors. It decays by alpha decay. Which of the following describes the properties of this radiation?

Select all that apply.

positively charged

made of 4 particles joined together

unlikely to escape the smoke detector

What describes the emissions of an isotope that gives off both beta and gamma radiation?

negatively charged particles and high energy photons

Which of the following describes a nuclear fusion reaction?

Two nuclei with low mass combine to form one larger nucleus.

What can be concluded from the following phase diagram?

There exists a temperature and pressure combination at which all 3 phases of the substance can exist in equilibrium at once.

A sealed container of liquid develops some vapor pressure. Which of the following would reduce the vapor pressure?

decrease the temperature

The activation energy for a reaction is the energy difference between what two components of a reaction?

reactant and the activated complex

What does adding a catalyst to a reaction do?

Select all that apply.

alter the orientation of reactants in the reaction

lower the activation energy of the reaction

increase the rate of the reaction

What is the molarity of an NaCl solution if 0.30 moles of salt are dissolved in 200.0 milliliters of water?

1.5

What happens when ice melts?

Select all that apply.

Energy is taken in from the environment.

The kinetic energy of the particles overcomes the intermolecular bonds.

Study the equilibrium system. 2CO(g) + O22(g) ⇌ 2CO22(g)

What will happen if the pressure on the system increases?

The quantity of CO22(g) increases.