Unit 12 Exam Review

Question 1

Energy that is available to do work is called:

Answer 1

Gibbs’ Free Energy

Question 2

______ is defined as the number of atoms, ions, or molecules that react in a given time to form products:

Answer 2

reaction rate

Question 3

What is the name of the minimum energy that colliding particles must have in order to react?:

Answer 3

activation energy

Question 4

What is the arrangement of atoms at the peak of an energy barrier?:

Answer 4

activated complex

Question 5

At equilibrium, what is the rate of production of reactants compared with the rate of production of products?:

Answer 5

the same

Question 6

The rate of a chemical reaction normally ______ as reactant concentration increases:

Answer 6

increases

Question 7

The amount of disorder in a system is measured by its _______:

Answer 7

Entropy

Question 8

If a reaction has an equilibrium constant (Keq) just greater than 1, how do we interpret that information?:

Answer 8

Products are favoured

Question 9

Which variable is NOT required to calculate the Gibbs free-energy change for a chemical reaction?:
     A. Change in enthalpy
     B. Change in entropy
     C. Temperature in ºC
     D. Temperature in K

Answer 9

Temperature in ºC

Question 10

What is the effect of adding more water to the following equilibrium reaction … CO2 + H2O H2CO3

Answer 10

Concentration of H2CO3 increases

Question 11

In an endothermic reaction at equilibrium, what is the effect of raising the temperature?:

Answer 11

Shift to the products

Question 12

What is the numerical value ( + or – ) of Gibbs free-energy for a spontaneous reaction?:

Answer 12

∆G is negative

Question 13

At what stage of a reaction do atoms have the highest energy?:

Answer 13

At the transition stage (activated complex)

Question 14

Which of the following systems has the highest entropy: 
     A. 10 mL of HCL at 50ºC
     B. 10 mL of HCL at 100ºC
     C. 10 mL of HCL at 75ºC
     D. 10 mL of HCL at 10ºC

Answer 14

10 mL of HCL at 100ºC

Question 15

An elementary reaction converts reactants to products in ______:

Answer 15

a single step

Question 16

Consider the reaction … N2(g) + 3H2(g) 2NH3(g) … What is the effect of decreasing the volume on the contained gases?:

Answer 16

Concentration of NH3 increases, concentration of H2 decreases

Question 17

Spontaneous reactions always __________ free energy:

Answer 17

release

Question 18

What physical state of nitrogen has the highest entropy?:

Answer 18

gas

Question 19

What is another name for the catalysts in your body?:

Answer 19

Enzyme

Question 20

In an equilibrium reaction with a Keq of 1 x 10^8 , the ________ are favoured:

Answer 20

products

Question 21

In which of these systems is the entropy decreasing:
     A. salt dissolving in water
     B. a liquid cooling
     C. heating a liquid
     D. breaking apart a sugar cube

Answer 21

a liquid cooling

Question 22

In a two-step mechanism, how many elementary reactions occur?:

Answer 22

2

Question 23

The Keq of a reaction is 4 x 10^-7 . At equilibrium, the ______ are favoured:

Answer 23

reactants

Question 24

Another name for the activated complex is _______:

Answer 24

transition state

Question 25

A catalyst works by:

Answer 25

decreasing the needed activation energy