Quiz

QUIZ

1. Why does heat help aid in the occurrence of a chemical reaction?

a. It cause molecules to line up in the right orientation. b. It weakens chemical bonds. c. It allows for more mixing of reactants. d. It increases the kinetic energy of the reactants

Answer: d. Heat will increase the kinetic energy of the reactants, increasing the chance of collisions between the molecules in the reaction.

2. What is true of the activation energy in an exothermic reaction?

a. It will be a negative number in this type of reaction b. It is independent of the fact that the reaction is exothermic c. It will be zero in an exothermic reaction d. It will contribute to the change in enthalpy of the reaction if positive

Answer: b. The activation energy in an exothermic reaction is independent of the fact that the reaction is exothermic.

3. In what type of reaction is heat the primary end product?

a. Combustion reaction b. Precipitation reaction c. Decomposition reaction d. Neutralization reaction

Answer: a. A combustion reaction is basically a burning of a combustible product with heat as the major end-product.

4. In what type of reaction is water the primary end product?

a. Combustion reaction b. Precipitation reaction c. Decomposition reaction d. Neutralization reaction

Answer: d. In a neutralization reaction, water and salt are the end products of the neutralization of acids and bases.

5. In this reaction: 2 HNO3 (aq) + Sr(OH)2 (aq) → Sr(NO3)2 (aq) +2 H2O (l), what is the acid in this equation?

a. Sr(OH)2 b. HNO3 c. Sr(NO3)2 d. H2O

Answer: b. HNO3 is nitric acid, which is the acid that goes into this neutralization reaction, leading to a salt and water. In this case, the base is strontium hydroxide.

6. In the reaction, two moles of nitric acid plus one mole of Strontium hydroxide goes to one mole of strontium nitrate, a total of 0.85 moles of the salt are created. What is the percent yield of product with respect to strontium hydroxide?

a. 0.85 percent b. -0.85 c. 85 percent d. 1.85

Answer: c. The percent yield will be 0.85 moles divided by an expected yield or theoretical yield of 1 mole to get 85 percent yield.

7. What is most true of a catalyst in a chemical reaction?

a. It will increase the likelihood of an exothermic reaction. b. It will be consumed as part of the reaction process. c. It will change the overall enthalpy of the reaction. d. It will change the activation energy of the reaction.

Answer: d. A catalyst will not change the overall enthalpy of the reaction and does not get consumed as part of the reaction. It will change the characteristics of the transition phase in the reaction so that it will decrease the activation energy.

8. What is the role of an enzyme in biochemical reactions?

a. They change the stoichiometry of the reaction. b. They will catalyze certain biochemical reactions. c. They change the energy state of the beginning substrates, favoring the reaction. d. The can inhibit or favor a biochemical reaction.

Answer: b. The role of the enzyme in biochemical reactions is to act as a catalyst in biochemical reactions. They will not inhibit a biochemical reaction nor will they change the stoichiometry or the energy states of the reactants and products.

9. Which law of thermodynamics refers directly to an increase in the energy of a given system?

a. Law of conservation of energy b. First law of thermodynamics c. Second law of thermodynamics d. Third law of thermodynamics

Answer: c. The second law of thermodynamics states that entropy in a system or in the universe, unless acted on by a force, is always increasing.

10. What is the amount of heat in a system that is necessary to raise an object of one kilogram of mass up 1-degree Kelvin?

a. Heat capacity b. Specific heat c. Calorie d. Thermal capacity

Answer: b. The specific heat of a substance such as water (or any other substance) is the amount of heat necessary to raise a kilogram of the substance by one-degree Kelvin.