AnswersCR03101 ChemistryLab: Reaction Rate

Lab: Reaction Rate — Unit test Answers

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1
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Which statement best applies collision theory to preventing a dangerous reaction from occurring?

A
Store the reactants together at a low pressure.
B
Keep all sparks or flames away from the reactants.
C
Store the reactants together at a low temperature.
D
Keep the reactants in separate containers.
2
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A reaction occurs when solid X is placed into solution Y. As a result, the temperature of the new solution increases by 3°C. The temperature rises another 2°C when more of solid X is added to the solution. What does this indicate about the effect of adding more solid?

A
It increased the number of molecular collisions.
B
It decreased the number of molecular collisions.
C
It decreased the space between the molecules and lowered the reaction rate.
D
It increased the space between the molecules and increased the reaction rate.
3

Which energy graph represents the nonspontaneous transition of graphite into diamond?

A
A graph with Reaction progression on the horizontal axis and energy on the vertical axis. A line starts low on the vertical axis, runs briefly parallel to the horizontal axis, slopes up sharply, curves down a short distance, and levels out.
Option A
B
A graph with Reaction progression on the horizontal axis and energy on the vertical axis. A line starts midway up the vertical axis, runs briefly parallel to the horizontal axis, slopes up sharply, curves down sharply, and levels out below the initial starting point.
Option B
C
A graph with Reaction progression on the horizontal axis and energy on the vertical axis. A line starts midway up the vertical axis, runs briefly parallel to the horizontal axis, slopes up a small amount, then curves down to level out below the initial starting point.
Option C
D
A graph with Reaction progression on the horizontal axis and energy on the vertical axis. A line starts midway up the vertical axis, runs briefly parallel to the horizontal axis, slopes up a moderate amount, then curves down sharply to level out below the initial starting point.
Option D
4

What happens as the activation energy increases?

A
The pressure of the system decreases.
B
The kinetic energy of colliding molecules changes.
C
The reactant surface area decreases.
D
The reaction begins to slow down.
5

Consider the reaction below.Which is most likely the effect to the forward reaction if there is an increase in pressure of the system?

Question illustration
A
The reactant surface area increases.
B
The reaction rate decreases.
C
The reaction is not affected at all.
D
The reaction stops completely.
6

A solid reactant is placed into a beaker of a warm water. The liquid vigorously bubbles as the solid dissolves into the solution. What will most likely happen if the temperature of the liquid is slightly reduced?

A
More bubbles will be produced because the solution is becoming more concentrated.
B
Fewer bubbles will be produced because of fewer collisions of reactant molecules.
C
The solid will get smaller at a faster rate because of more collisions of reactant molecules.
D
The solid will get larger at a slower rate because precipitate is coming out of the solution.
7

Ben observes how quickly some dry wood is burning in a campfire. Which term best relates to Ben’s observation?

A
reaction rate
B
activation energy
C
collision theory
D
spontaneous reaction
8

A change in which factor will affect the rate of reaction only when gases are involved?

A
temperature
B
pressure
C
surface area
D
concentration
9

Consider the energy diagram below.xn.Which line indicates a higher reaction rate?

Question illustration
A
A because it has a lower activation energy.
B
B because it has a lower activation energy.
C
A because its Grxn is much lower.
Option C
D
B because its Grxn is much lower.
Option D
10

Which applies to the collision theory?

A
Particles need to collide in order to react.
B
Particles may obtain successful collisions in any molecular orientation.
C
Temperature increase causes kinetic energy of particles to decrease.
D
Reactions do not have to begin with collision of molecules or particles.
11

An increase in temperature affects the reaction rate by

A
decreasing the velocities of particles that collide in the reaction.
B
increasing the number of molecules that have sufficient kinetic energy to react.
C
increasing the number of molecules that have sufficient potential energy to react.
D
decreasing the energy that particles need to overcome the energy activation barrier.
12

Which term refers to the speed at which reactants are converted into products?

A
reaction rate
B
activation energy
C
meta stable state
D
spontaneous reaction
13

The production of water proceeds according to the following equation.2H2(g) + O2(g) 2H2O(g)Which describes a way to speed up the collisions between hydrogen and oxygen molecules to produce more water?

Question illustration
A
Use a less-intense source of heat on the reactants.
B
Maintain the same temperature of the reactants.
C
Place the reactants in a smaller container.
D
Reduce the concentration of the reactants.
14

Which will cause an increase in the reaction rate between molecules?

A
Molecules have strong internal bonding.
B
Molecules collide more frequently.
C
Electrons in the bonds remain in a meta-stable state.
D
Electrons do not have enough energy to leave the bonds.
15

Consider the reaction below.C2H4(g) + H2(g) C2H6(g)Which change would likely cause the greatest increase in the rate of the reaction?

Question illustration
A
decrease temperature and decrease pressure
B
increase temperature and decrease pressure
C
decrease temperature and increase pressure
D
increase temperature and increase pressure
16

Magnesium oxide does not readily decompose into magnesium and oxygen. The reaction is shown below.MgO(s) + 601.7 kJ Mg(s) + ½O2(g)Which factor plays the most important role in allowing this reaction to occur?

Question illustration
A
temperature
B
concentration
C
pressure
D
surface area
17

The diagram below shows the movement of particles.What does this piece of evidence best support?

Question illustration
A
the collision theory
B
the Maxwell-Boltzmann distribution
C
the effect of pressure on reaction rates
D
the effect of temperature on reaction rates
18

Which best explains why sawdust burns more quickly than a block of wood of equal mass under the same conditions?

A
The molecules move more quickly in the sawdust than in the block of wood.
B
The pressure of oxygen is greater on the sawdust.
C
More molecules in the sawdust can collide with oxygen molecules.
D
Oxygen is more concentrated near the sawdust than the block of wood.
19

Which topic is commonly used to explain activation energy and how chemical reactions happen?

A
reaction rate
B
collision theory
C
velocity distribution
D
spontaneous reaction

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