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WorksheetsReview - Reaction Rates
Total questions: 127
Worksheet time: 2hrs 23mins
What criteria must be met for reactant collisions to result in a successful product?
The reactants must collide with each other
The reactants must collide with enough energy and be in the right positions
The reactants must have enough energy to form the activated complex
Which has more surface area?
Large chunks of chalk
Cube of sugar
Powdered sugar
Small chunks of sugar
Which 2 trials show the effect of a catalyst on reaction rate, and what is the effect of adding a catalyst?
1 and 5; rate increases when a catalyst is added
2 and 5; rate decreases when a catalyst is added
3 and 5; rate increases when a catalyst is added
4 and 5; rate decreases when a catalyst is added
Which 2 trials show the effect of increasing [HgCl2] on reaction rate, and what is the effect of increasing [HgCl2]?
1 and 3; rate stays the same when [HgCl2] increases; thus HgCl2 is a zero order reactant
2 and 3; rate increases (quadruples) when [HgCl2] increases (doubles); thus HgCl2 is a second order reactant
3 and 4; rate increases when [HgCl2] increases and is somewhere between second and third order
4 and 6; rate increases when [HgCl2] increases and is somewhere between first and second order
What effect does chopping vegetables have on their cooking time and why? (using principles of collision theory)
Chopped vegetables are at a higher temperature and therefore take less time to cook
Chopped vegetables have catalysts and therefore take less time to cook
Chopped vegetables have increased surface area and therefore take less time to cook
Chopped vegetables are more concentrated and therefore take more time to cook
What factors affect reaction rate?
size of atoms
temperature
concentration
surface area
catalysts
What is necessary for a chemical reaction to occur?
Correct orientation of particles when they collide
particle collisions
an increase or decrease in temperature
particle collisions with sufficient energy
a catalyst
What happens to reaction rate when a reactants concentration is increased?
it increases
it decreases
it remains the same
What does a catalyst do to speed up a reaction?
It reduces the surface area of the reactants
It increases the surface area of the reactants.
It reduces the required energy for a chemical reaction to occur
It increases the required energy for a chemical reaction to occur
A reactants concentration is increased. What happens?
more collisions occur
the same number of collisions occur
greater collision energy
less collision energy
the same collision energy
The minimum quantity of energy which the reacting species must possess in order to undergo a specific reaction.
collision theory
activation energy
reaction rate
chemical reaction
A substance that increases the rate of a chemical reaction without itself undergoing any permanent chemical change.
catalyst
products
reactants
chemical reaction
A substance that is formed as the result of a chemical reaction.
products
reactants
catalyst
collision
A process that involves rearrangement of the molecular or ionic structure of a substance, as opposed to a change in physical form or a nuclear reaction.
collision theory
reaction rate
chemical reaction
activation energy
How could we make this reaction happen more quickly?
Decrease the concentration of the acid
crush the chalk to increase the surface area
Put the test tube in an ice bath
Why does a higher concentration increase the rate of reaction?
it increases the amount of reactants
it lowers the activation energy
it increases the energy of particle collisions
it increases the frequency of particle collisions
What the Activation energy?
The maximum energy a reaction can release
The minimum amount of energy that reacting particles must have when colliding to form products
The energy added by a catalyst
The energy possessed by the products
As a reaction proceeds, the concentration of reactants will _______ and the concentration of products will ________.
increase, decrease
increase, increase
decrease, decrease
decrease, increase
A temperature increase causes the particles ......
to slow down
move faster
collide higher
in the right order
As the frequency of ______________ increases, the rate of reaction increases.
Time
Reactions
Collisions
Reactants
orientation and direction
energy and orientation
temperature and kinetic energy
Which one of the following is NOT a key concept of the collision theory:
particles must collide in order to react
particles must move slowly when they collide, otherwise they simply “bounce off” one another
particles must collide with the proper orientation
particles must collide with sufficient energy to reach the activated complex in order to react
Which one of the following is NOT a key concept of the collision theory:
particles must collide in order to react
particles must move slowly when they collide, otherwise they simply “bounce off” one another
particles must collide with the proper orientation
particles must collide with sufficient energy to reach the activated complex in order to react
What happens to a catalyst in a reaction?
It remains unchanged.
It is incorporated into the reactants.
It is incorporated into the products.
It evaporates.
What is the name given to a catalyst in the human body? (a)
What is the energy of the activated complex? (a)
Based on the collision model, the atoms in the top of potential energy ‘’hill’’ are called (a)
When surface area is decreased the rate of reaction...
Decreases, because there are LESS possible sites for correct collisions
Increases, because there are LESS possible sites for correct collisions
Decreases, because there are MORE possible sites for correct collisions
Increases, because there are MORE possible sites for correct collisions
A Catalyst speeds up a reaction, where a ___________ slows down the reaction.
Inhibitor
De-Catalyst
Fractioning Tower
Burett
The activation energy, Ea, for the reverse reaction is
+ 50 kJ
+ 200 kJ
-150 kJ
+ 150 kJ
Which one of the following statements concerning rates of reactions is FALSE?
The higher the activation energy barrier, the faster the reaction.
Increasing the concentration of a reactant may increase the rate of a reaction.
Adding a catalyst speeds up the rate of reaction for both the forward and reverse reactions.
Increasing the concentration increases the rate of a reaction, because it increases the number of collisions.
When you crush an alka-seltzer tablet, what property of the tablet changes?
mass of tablet
size of tablet
color of tablet
phase of tablet
Which of the following increase the reaction rate?
less surface area
lower temperature
increasing pressure
increased concentration
Pick the TWO (2) options that will INCREASE the rate of a reaction.
Reducing Heat
Adding Catalyst
Adding Heat
Removing Catalyst
What does the temperature of a substance represent?
The average potential energy of the particles
The average kinetic energy of the particles
The total energy of the particles
The chemical energy of the particles
Which of the following statements about rates and the collision theory model is true?
Endothermic reactions are always slower than exothermic reactions.
All particles have the same kinetic energy at a fixed temperature.
Reactant particles need to collide with sufficient energy to react.
The rate of a reaction at a constant temperature increases as the reaction proceeds.
Why do nails on the sun-exposed side of a boat rust faster than those on the shaded side?
Higher temperature increases reaction rate
Sunlight prevents rusting
Shaded side is wetter
Sunlight decreases reaction rate
What factors affect the rate of a chemical reaction?
Temperature, surface area, concentration, gas pressures, presence of a catalyst, activation energy, and orientation
Only temperature and concentration
Only surface area and gas pressures
Only presence of a catalyst and activation energy
A catalyst for a reaction will
reduce the difference between the energy of the products and the energy of the reactants.
increase the proportion of successful collisions at a given temperature.
require an increase in temperature in order to work successfully.
only work for gaseous reactions.
Suppose you held a lighted match to a solid hunk of wood and another match to a pile of wood shavings. Which form of wood will catch fire more easily?
Wood chunk because of smaller surface area
Wood chunk because of larger surface area
Wood shavings because of smaller surface area
Wood shavings because of larger surface area
According to the trends of collision theory, which concentration of catalyst would have the highest reaction rate
0.15 mol / L
0.5 mol / L
1.0 mol / L
0.1 mol / L
6 CO2+ 6 H2O + Energy → C6H12O6 + 6 O2
endothermic reaction
exothermic reaction
6. Which of these processes is always exothermic?
A. evaporation
B. burning
C. insulation
D. melting
A log is burning in a campfire. If the concentration of oxygen reaching the log is increased, what will happen to the reaction rate?
reaction rate decreases
reaction rate increases
reaction rate remains the same
A substance that takes part in and undergoes change during a reaction.
products
reactants
catalyst
collision
Endothermic reactions feel
warm
cold
When we investigate the rate of reaction we are looking at the...
amount of product formed
speed of reaction
concentration of reacting particles
combining reactants with products
Catalysts permit reactions to proceed along a ___________energy path.
lower
higher
magnetic
psycho's
Such reactions which continue in both directions are called:
Irreversible reactions
Reversible reactions
Non-reactive reactions
dynamic reactions
What is the Keq expression for this reaction?
2 NO(g) + O2(g) ⇌ 2 NO2(g)
Keq = [NO2]2 / [NO]2 [O2]
Keq = [NO]2 [O2] / [NO2]2
Keq = [NO]2 [O2] [NO2]2
Keq = [NO2]2 / [NO]2 + [O2]
Which one of the following statements concerning rates of reactions is FALSE?
The higher the activation energy barrier, the faster the reaction.
Increasing the concentration of a reactant may increase the rate of a reaction.
Adding a catalyst speeds up the rate of reaction for both the forward and reverse reactions.
Increasing the concentration increases the rate of a reaction, because it increases the number of collisions.
N2(g) + 3H2(g) ↔ 2 NH3(g) + heat
Increasing the temperature will cause the equilibrium to:
Shift right
Shift left
Have no change
Speed up
What happens to reaction rate when temperature is decreased?
it increases
it decreases
it stays the same.
Which of the following will lower the rate
of reaction?
adding an enzyme to the reaction
decreasing the temperature from 40°C to
10°C
breaking a chunk of calcium up into
smaller pieces
increasing the amount of solute
dissolved in a solution
What letter represents the activation energy of the forward reaction?
A
B
C
D
What type of reaction is this?
Endothermic
Exothermic
Define collision theory
Molecules must collide in the correct orientation and with enough energy for a reaction to occur.
Molecules need enough activation energy for a reaction to occur.
Atoms are constantly colliding and reacting.
The minimum amount of energy needed to speed up the rate of a reaction.
Explain how a catalyst increases the rate of reaction.
Increases the activation energy, which provides an alternate path for the reaction.
Lowers the activation energy, which provides an alternate path for the reaction.
Lowers the energy of reactants, which provides an alternate path for the reaction.
Lowers the energy of products, which provides an alternate path for the reaction.
Explain why increasing the temperature of a reaction increases the rate of reaction.
Molecules gain kinetic energy with higher temperature. This means molecules will be moving faster, increasing the number of effective collisions that occur with enough energy to activate a reaction.
Molecules gain kinetic energy with higher temperature. This means molecules will be closer to each other, increasing the probability that they will collide in the correct orientation and react.
Molecules gain kinetic energy with higher temperature. This means molecules will be moving faster, increasing the probability that they will collide in the correct orientation and react.
Molecules gain kinetic energy with higher temperature. This means molecules will instantly have enough energy to collide and cause a chemical reaction.
Explain why decreasing the concentration of reactants decreases the rate of reaction. (Assume no change in temperature occurs).
With less molecules available to react, the number of effective collisions that could potentially occur decreases.
With less molecules available to react, the number of effective collisions that could potentially occur increases due to more space being available.
Molecules will be moving faster due to having more space; this increases the probability that they will collide in the correct orientation and react.
Molecules will be moving slower due to having more space; this decreases the probability that they will collide in the correct orientation and react.
During equilibrium, the amount of the products and the amount of the reactants are __________.
equal
constant (unchanging)
constantly increasing
constantly decreasing
According to the diagram, identify if the reaction is product favored or reactant favored at equilibrium.
Reactant favored
Product favored
_______ refers to how much solute is dissolved in
a solution.
Surface Area
Catalyst
Temperature
Concentration
Billows are often used to pump more air into a fire. Which statements would be true about the results (two correct)?
The fire would burn hotter and brighter
There would be no change in the brightness.
The wood fuel source would be used up sooner.
Less smoke would be produced
The total energy released would be greater than without billows
If a chemical reaction is EXOTHERMIC, the temperature of the surrounding would....
Stay the same
Increase
Decrease
A student mixed two chemicals to allow them to react. The temperature before the reaction was 25 ° C. The temperature after the reaction was 18° C. Which of the following is true?
The temperature did not change.
It is an endothermic reaction
It is an exothermic reaction
Energy is released from the reaction into the surrounding.
Photosynthesis takes place inside of leaf cells. Sunlight is required. Is this an Exothermic or an Endothermic reaction?
Endothermic
Exothermic
What type of reaction occurs in a hand warmer?
exothermic
endothermic
What instrument would you use to detect an endothermic or exothermic reaction?
triple beam balance
ruler
thermometer
During chemical reactions, bonds are...
broken only
formed only
both broken and formed
none of the above are correct
Energy is released when bonds are _________________.
Broken
Formed
The bond energy to break a C-H bond is about 400 Kj. How much energy will it take to break all the bonds in methane (CH4)?
About 800
About 1600
About 3000
Way more than 3000
What is a common everyday example of an exothermic reaction?
The heat produced when burning a candle.
The cooling effect of melting ice.
The absorption of heat when water evaporates.
The heat released during the dissolution of salt in water.
What is the role of heat in endothermic reactions?
Heat is released as a product in the reaction.
Heat is absorbed as a reactant in the reaction.
Heat has no effect on the reaction.
Heat is a catalyst in the reaction.
In the figure, heat energy is _____ during the reaction.
released
absorbed
The Law of Conservation of Energy states that
energy cannot be created nor destroyed, only transformed or transferred
energy can be destroyed but not created
energy can be created but not destroyed
energy is just energy
How much potential energy is at the top of a hill on a roller coaster ride
100%
50%
0%
20%
Which is the best example that something has kinetic energy?
a car parked on a steep hill
a tennis ball rolling across the court
a picture hanging on the wall
a piece of coal before it burned
The Law of Conservation of Energy states that
energy cannot be created nor destroyed, only transformed or transferred
energy can be destroyed but not created
energy can be created but not destroyed
energy is just energy
A reaction that the system absorbs energy from its surrounding in the form of heat is called ________ reaction
Endothermic
Exothermic
Decomposition
Combination
A student mixed two chemicals to allow them to react. The temperature before the reaction was 25 ° C. The temperature after the reaction was 18° C. Which of the following is true?
The temperature changed
It is an endothermic reaction
It is an exothermic reaction
Its an endothermic reaction and the temperature changed
Its an exothermic reaction and the temperature changed
Some chemical reactions require a substance called a catalyst. The main purpose of a catalyst is
To warm up the reaction
To speed up the reaction
To create more reactants
To stop the reaction
If a reaction is exothermic,
It takes more energy to break the bonds of the reactants than is released when the bonds in the products are formed
More energy is released when the bonds in the products are formed than is used to break the bonds in the reactants
The same amount of energy is used to break the bonds of the reactants as is released when the bonds in the products are formed
The temperature goes down
The graph above is from which type of reaction?
Endothermic reaction
Exothermic Reaction
The Law of Conservation of Mass states
that matter exists in all states and reacts the same
that matter can only be changed into new substances by introducing a catalyst
that matter exists in the same state throughout any chemical change
that matter cannot be created or destroyed and that the mass of the products must equal the mass of the reactants
_Fe + _S --> _FeS
4Fe + _O2 → 2Fe2O3
