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WorksheetsRate of reaction
Total questions: 108
Worksheet time: 55mins
Which of the following describes the rate of a chemical reaction?
It is the rate of change in the concentration of the reactants per unit of time.
It is the rate of change in the concentration of the reactants per unit of pressure.
It is the rate of change in the concentration of the reactants per unit of volume.
It is the rate of change in the concentration of the reactants per unit of area.
A graph with vertical and horizontal axes can be used to explain chemical reaction rates. What are the labels that appear on the vertical and horizontal axes?
Vertical: concentration Horizontal: time
Vertical: rate of reaction. Horizontal: time
Vertical: time Horizontal: rate of reaction
Vertical: time Horizontal: concentration
Consider the chemical reaction: A + B →C
All of the following formula could describe the rate of reaction except :
−dtd[A]
+dtd[C]
−dtd[C]
−dtd[B]
The opposite figure represents the (concentration-time)
relation of the rate of chemical reaction. What is the
hypothetical equation which represents this reaction
A→B
B→A
B→2A
A→2B
Which of the following reactions is most likely to have the fastest rate of reaction?
The setting of epoxy resins and other similar glues.
The cooking of an egg.
The carbonization of dead plants and animals into fossil fuels.
The explosive reaction between hydrogen and oxygen gases.
The rusting of iron.
Here are four different processes :
Which of the following choices is the correct order of how fast these processes happen ? ………..
(1)→(2)→(3)→(4).
(4)→(1)→(2)→(3).
(3)→(2)→(4)→(1).
(4)→(2)→(1)→(3).
The rate of a chemical reaction can be expressed in the following units, except
mol/L
M/min
Kg/s
mol/h
When excess hydrochloric acid reacts with calcium carbonate, carbon dioxide is produced. If 5 grams of calcium carbonate is consumed in 3 minutes and 20 seconds,what is the average rate of reaction?
(a)
In the following reaction, the rate of sulfur formation was determined to be 0.002 g/s:
How much sulfur was formed after 5 minutes?
(a)
Consider the following reaction: It was found that 10 grams of X was consumed in 6 minutes and 40 seconds; thus, the average rate of reaction is . X→Y
0.028 g/s
1.560 g/s
0.025 g/s
0.250 g/s
Consider the following chemical reaction in an industrial plant: If the rate of this reaction is 0.5 M/h, then which of the following is not correct?
A→B
The concentration of A increases by about 0.5 M each hour.
The concentration of A decreases by about 12 M each day.
The concentration of B increases by about 0.5 M each hour.
The concentration of B increases by about 12 M each day.
The opposite graph represents the concentration of reactant (A) over time in the hypothetical reaction : A → B
What is the rate of this reaction at (0 to 10) s time span ? ………..
– 0.7 M/s
– 0.007 M/s
– 0.86 M/s
– 0.014 M/s
The chemical equation:
Represents the production of ammonia using the Haber-Bosch method. If the production rate of ammonia equals 2.5 x 10-4 mol.L-1.s-1 , then the rate of consumption of the nitrogen gas is …. mol.L-1.s-1 .
- 3.75 x 10-4
- 2.50 x 10-4
- 5.00 x 10-4
- 1.25 x 10-4
In the reaction: 2A + B ⇌ 2C , which of the following relations is correct?
- Δ[A] = 2Δ[C]
-2Δ [A] = Δ[C]
Δ[A]= Δ[C]
-Δ[A]= Δ[C]
In the hypothetical reaction : 2A + B → C
Which of the following relations is correct ? ………..
∆[A]=∆[C]
-∆[A]=∆[C]
-2∆[A]=∆[C]
-∆[A]=2∆[C]
In aqueous solutions, molecular bromine reacts with methanoic acid (HCOOH) as shown:
An experiment was designed to study the kinetics of the reaction. The initial Br2 concentration in the reaction vessel was 0.0120 mol.dm-3, and after 50 seconds, the value had dropped to 0.0101 mol.dm-3.
What is the average rate of the reaction over the first 50 seconds ? Give your answer to 2 decimal places.
- 1.90 x 10-4 mol.dm-3/s
- 2.42 x 10-7 mol.dm-3/s
- 1.90 x 10-5 mol.dm-3/s
- 4.42 x 10-4 mol.dm-3/s
- 3.80 x 10-5 mol.dm-3/s
What is the name of the theory that explains why chemical reactions can only take place when reacting particles collide with each other with sufficient energy?
Collision theory
Rate theory
Activation theory
Reaction theory
Chaos theory
Collision theory states that chemical reactions occur when particles (e.g., atoms or molecules) collide. Which of the following, according to collision theory, does not play a part in determining the rate of a reaction?
The activation energy for the reaction
The number of particles analyzed
The frequency with which particles collide
The energy with which particles collide
Fill in the blank: After particles collide, the minimum amount of energy they must have in order to react is referred to as the .
exothermic energy
initiation energy
collision energy
activation energy
launch energy
When two reactive particles collide, there are many factors that affect whether a reaction will occur.Which of the following factors does not have an effect?
The energy of the collision
The activation energy
The orientations of particles
The temperature
The number of products
Which of the following changes increases the chemical reaction rate without affecting the equilibrium yield constant?
Adding a catalyst to the reaction mixture
Heating the reaction mixture
Decreasing the surface area of the reactants
Changing the reactant concentrations
Which of the following will never affect the position of an equilibrium?
The temperature
A catalyst
The concentration of reactants
The pressure
The concentration of products
Which one of the following statements about catalysts is false?
Catalysts are unreactive.
After catalysts react, they are regenerated.
Catalysts increase the rate of a reaction.
Catalysts do not appear in the overall reaction equation.
The opposite energy diagram shows the effect of adding the substance X on the progression of the reaction. what is the change which occurred when substance X was added to the reaction mixture?
The reaction become less exothermic
The reaction speed decreased
The reaction speed increased
The reaction became more exothermic
For the given reaction what effect does using a catalyst have on the amount of ammonia produced?
The amount of ammonia produced will be the same.
The amount of ammonia produced will be more.
The amount of ammonia produced will be less.
Which of the following is not a benefit of using catalysts in industrial processes?
Reactions can operate at lower temperatures.
The products are made more quickly.
Catalysts do not need to be replaced often.
Reactions can operate at lower pressures.
Catalysts are often rare transition metals.
The shown reaction is the decomposition of hydrogen peroxide to form water and oxygen: Which of the following is the purpose of using a catalyst in this reaction?
To enable the reaction to take place
To produce more oxygen
To decrease the rate of reaction
To increase the rate of reaction
To make the reaction safer to perform
Which of the following is an example of catalysis?
The hydrogenation of vegetable oil in the presence of nickel to make margarine
The destruction of ozone in the atmosphere by chlorofluorocarbons (CFCs)
The use of vanadium(V) oxide in the conversion of sulfur dioxide to sulfur trioxide
The use of Pt,Pd,or Rh in car exhausts to convert poisonous molecules into harmless ones
All of the above
In the following two diagrams, which two letters indicate reaction pathways which have been catalysed?
B and C
B and D
A and C
A and D
Consider the following reaction: What is the enthalpy change for the backward reaction according to the data provided in the energy pathway diagram?
(a)
The reversable reaction W + X ⇌ Y + Z is represented
by the opposite graphical figure. what is the activation energy of the catalytic backward reaction?
-40 kj
+30 kj
-10 kj
+40 kj
Which of the following statements about catalysts is untrue?
Catalysts are often transition metals.
Catalysts increase the overall frequency of collisions between particles.
Catalysts are not used up in a reaction.
Catalysts decrease the time it takes for a reaction to finish.
Catalysts decrease the activation energy.
The following chemical equations describe part of the chemical reactions of ozone in the stratosphere: According to these equations, which of the following is the catalyst in this process?
NO2
NO
CO
O3
Which of the following equations represents a catalyzed reaction ? ……….
A+B→D+B
A+B→C+D
A+A→D
A→B+C
Which of the following could be used in catalytic converters present in cars’ exhaust pipes to convert the gaseous combustion products, which cause air pollution, into safe products?
Rhodium
Platinum
Palladium
All of the answers are correct.
Manganese dioxide is used as a catalyst in the decomposition of hydrogen peroxide to form water and oxygen: Which statement is not true when using MnO2 as a catalyst?
The catalyst remains unchanged at the end of the experiment..
The oxygen will be formed more quickly.
An alternative reaction pathway is provided by the catalyst.
The mass of MnO2 before and after the reaction will be the same.
More oxygen will be produced.
Experiment A relies upon a catalyst. If a greater
quantity of the catalyst is used, what changes to the
graph would be most likely?
The graph would be the same shape,
and the final volume of gas collected would be lesser.
The graph would initially be less steep, and the final volume of gas collected would be the same.
The graph would be the same shape, and the final volume of gas collected would be greater.
The graph would initially be steeper, and the final volume of gas collected would be the same.
The graph would initially be less steep, and the final volume of gas collected would be lesser.
Ammonia is an essential starting material for fertilisers, which help improve crop yields. Iron is used as a catalyst in the manufacture of ammonia by the Haber–Bosch method. The role of iron is to achieve rates at temperatures, which leads to saving energy and reducing the cost of ammonia production.
lower, lower
lower, higher
higher, lower
higher, higher
What is the role of a catalyst in a reaction?
It shifts the equilibrium toward the products according to Le Chatelier’s law.
It donates electrons to break or form bonds as needed until it is entirely consumed.
It provides an alternate route with a lower activation energy for the reaction to proceed.
It forms bridging complexes that align the molecular orbitals of the reactants.
All of the above
Why do we often use small amounts of the catalyst compared to much greater amounts of the reactants when performing a reaction?
Catalysts work better in smaller quantities.
Catalysts should be used in low concentrations.
Catalysts have very large surface areas.
Catalysts are not consumed in reactions.
Catalysts are hazardous chemicals.
A catalyst is a substance that causes a change in the rate of a chemical reaction. Among the properties of a catalyst is that it .
increases the rate of the forward reaction only
changes the position of the equilibrium in reversible reactions
increases the activation energy of the reaction
remains unchanged at the end of the reaction
Which of the following statements explains how catalysts increase the rate of reaction?
Catalysts are consumed in the reaction, providing an alternate chemical pathway.
Catalysts provide an alternate chemical pathway with higher activation energy.
Catalysts provide alternate conditions with the same chemical pathway.
Catalysts are consumed in the reaction, providing a greater surface area.
Catalysts provide an alternate chemical pathway with a lower activation energy.
Titanium dioxide is used as a catalyst for certain photochemical reactions. Which of the following catalysts would have the lowest catalytic activity? Recall that the surface area unit of solid catalysts could be expressed as m2/g.
TiO2(75m/g)
TiO2(10m/g)
TiO2(50m/g)
TiO2(25m/g)
The surface area of a catalyst is one of the factors affecting the rate of chemical reactions. For example, nickel is used as a catalyst in the hydrogenation process of oils; which of the following can achieve the highest reaction rate?
A Divided nickel powder
A nickel strip (1 cm2)
A nickel strip (3 cm2)
A nickel strip (2 cm2)
……are molecules that have kinetic energy that equals or exceeds the activation energy, and the presence of a catalyst leads to the ……….of these molecules.
Activated molecules, decrease
Excited molecules, decrease
Excited molecules, increase
Activated molecules, increase
Which of the following is shown by the red arrow in the sketch graph?
The heat loss
The exothermic change
The endothermic change
The activation energy
The enthalpy change
In the opposite energy of the forward reaction the activation equals the result of subtracting ………….
X – Y
Y – X
Y – Z
Z – Y
Considering the diagram, which of the following statements is not true of a catalysed reaction?
The catalyst provides an alternative reaction pathway.
The activation energy is smaller.
The overall energy change is the same.
Fewer particles have sufficient energy to react.
The catalyst is not consumed during the reaction.
Catalysts are often used in the form of powder, mesh, small beads, or lattice. Which other factor that affects the rate of reaction is used here to enhance the effect of the catalyst?
Increased temperature
Increased pressure
Increased light intensity
Increased surface area
Increased concentration
Copper(II) oxide and chromium(III) oxide can both be used as catalysts for the decomposition of hydrogen peroxide, as shown:In experiment A, copper(II) oxide is used, and in experiment B, chromium(III) oxide is used. The results are shown on the graph below. Which of the catalysts is the best and why?
Chromium(III) oxide is the better catalyst; the less
steep slope indicates a faster rate of reaction.
Chromium(III) oxide is the better catalyst;
the steeper slope indicates a faster rate of reaction.
Copper(II) oxide is the better catalyst; the less steep
slope indicates a faster rate of reaction.
Copper(II) oxide is the better catalyst; the steeper
slope indicates a faster rate of reaction.
Methane gas combusts slowly in the atmospheric air at the room temperature, but when a piece of platinum is added to the vessel of the reaction which contains a mixture of methane and air, methane combusts instantaneously .. What is this role of platinum in this reaction ? ………..
Reducing the activation energy of the reaction.
Increasing the value of of the reaction.
Releasing the stored energy in the reactions.
Decreasing the rate of the reaction.
All the following increase the rate of the chemical reaction .. Except ……..
raising the temperature.
increasing the reactions oncentrations.
ncreasing the activation energy.
using a catalyst.
Which of the following graphical figures represents the relation between the activation energy Ea and the rate of the chemical reaction ? ………….
In terms of the equation :
If the activation energy of the forward reaction equals 120 KJ/mol , so what is the value of the activation energy of the backward reaction ? ………..
35 KJ/mol
85 KJ/mol
120 KJ/mol
205 KJ/mol
The opposite figure represents the energy diagram of an exothermic reaction… What is the correct choice which represents the numbers (1): (4)?
a
b
c
d
According to the opposite energy diagram representing a chemical reaction, what is the effect of adding a catalyst on the values of the activation energy EA and the reaction enthalpy ∆H?
a
b
c
d
Oxalic acid (COOH)2 reacts slowly with acidified potassium permanganate at the beginning of the reaction represented by the equation :
By time, Mn2+ ion produced from the reaction acts as a catalyst ..
Which of the following graphical figures represents the concentration of oxalic acid durin the occurrence of the reaction ? …………….
Which of the following is not correct about enzymes?
They are produced in living cells.
They act as catalysts for many biological and industrial processes.
They can behave as inhibitors.
They are high molecular weight proteins.
Fill in the blank: Specific protein-based catalysts in the human body are known as .
enzymes
lipids
chloroplasts
cells
nuclei
When a reaction mixture is heated, the particles collide more frequently. Which of the following is the best explanation of this effect?
The particles get larger.
The particles get closer together.
The particles break apart.
The particles exert stronger attractive forces.
The particles move faster.
which of the following depicts a system with the highest possible reaction rate?
Which alteration to the conditions of a reaction results in an increase in collision rate and a greater percentage of colliding molecules having sufficient energy to react?
Increasing the pressure
Increasing the surface area
Increasing the concentration
Adding a catalyst
Increasing the temperature
Which statement about the enthalpy change for the backward reaction in a reversible reaction is true?
The enthalpy change for the backward reaction is half the amount of the enthalpy change for the forward reaction.
The enthalpy change for the backward reaction is greater in magnitude than the enthalpy change for the forward reaction.
The enthalpy change for the backward reaction equals the activation energy plus the enthalpy change for the forward reaction.
The enthalpy change for the backward reaction is the same in magnitude as the enthalpy change for the forward reaction.
The enthalpy change for the backward reaction is less in magnitude than the enthalpy change for the forward reaction.
In the following chemical reaction, the forward reaction is endothermic: What must be true about the reverse reaction?
The reverse reaction has a lesser overall energy change.
The reverse reaction has a greater overall energy change.
The reverse reaction is also endothermic.
The reverse reaction is exothermic.
The reverse reaction absorbs heat from the surroundings.
For a simple reaction between gases A and B,which of the following temperatures will give the highest reaction rate?
0 ∘C
50 ∘C
100 ∘C
25 ∘C
75 ∘C
Iron filings will not react with powdered sulfur when mixed at room temperature. If a mixture of iron filings and powdered sulfur is heated strongly using a Bunsen burner, a reaction takes place. Which statement best describes why the heated mixture reacts?
The reaction is exothermic.
The Bunsen flame acts as a catalyst.
The iron and sulfur particles have collided.
The surface area of the powders has increased.
The required activation energy has been achieved.
Consider the following reaction that is exothermic in the forward direction:
If the reaction is at equilibrium, which of the following statements best describes what will happen if the temperature was decreased from 250 K to 200 K.
The rate of the reverse reaction would stay the same.
The rate of the forward reaction would stay the same.
The rate of the forward reaction would increase.
The rate of the forward reaction would decrease.
The rate of the reverse reaction would increase.
A trip of magnesium reacts with excess hydrochloric acid according to the equation :
Why does the rate of this reaction increaase in the first seconds ? Due to ……….
the decrease in the amount of mangnesium.
that mangnesium acts as a catalyst.
the elevation of the temperature of the solution.
the increase in the ssurface area of magnesium.
According to the law of mass action, the rate of a chemical reaction is directly proportional to the concentration of the reactant. Which of the following can explain this?
The increase in the number of reactive molecules increases the possible effective collisions.
The decrease in the required activation energy leads to the increase in the effective collisions.
The increase in the concentration leads to the increase in the kinetic energy of the reactant molecules.
None of the answers are correct.
Which of the following when reacts with 4 g of magnesium, the rate of the reaction becomes the highest at the beginning?
20 mL of 1 M sulphuric acid.
15 mL of 2 M nitric acid.
30 mL of 2 M acetic acid.
20 mL of 1 M hydrochloric acid.
A series of experiments were carried out using uniform pieces of magnesium ribbon and excess hydrochloric acid of varying concentrations. Assuming the proportionality of the rate to the concentration of acid and the number of pieces of magnesium, what are the correct values for 𝐴,𝐵,and 𝐶?
𝐴:2.0 𝐵:30 𝐶:15
𝐴:0.5 𝐵:30 𝐶:15
𝐴:0.5 𝐵:60 𝐶:30
𝐴:0.5 𝐵:30 𝐶:60
𝐴:1.0 𝐵:15 𝐶:15
To preserve the solution of the substance (X) , this requires using opaque glassware ..
Which of the following choices represents both the chemical formula of (X) and the reason for preserving it in opaque glassware ? …………
a
b
c
d
An insoluble solid is reacted with dilute acid. Why does breaking up the solid into smaller particles increase the rate at which it can react?
Splitting the solid into smaller particles increases the kinetic energy of colliding molecules.
Reducing the particle size of the solid allows more molecules to dissolve and collide with acid molecules.
Increasing the surface area of the solid results in more collisions with acid molecules.
Breaking bonds between molecules in the solid liberates bonding electrons to react with acid molecules.
Weakening the interactions between molecules in the solid produces gaps to accommodate acid molecules.
In a reaction with hydrochloric acid, which of the following forms of calcium carbonate would react most rapidly, assuming the same total mass of calcium carbonate is used?
A fine powder
A cluster of fine needles
A single thin plate
In experiment 1, excess hydrochloric acid is reacted with a magnesium ribbon weighing 0.5 g in total. In experiment 2, the same experiment is performed with 0.5 g of magnesium powder rather than a ribbon. Which of the following statements describes and explains the differences in the rate of reaction?
Experiment 2 has a faster rate of reaction as the magnesium powder is more concentrated.
Experiment 1 has a faster rate of reaction as the magnesium ribbon is more concentrated.
Experiment 1 has a faster rate of reaction as the magnesium ribbon has a greater surface area.
Experiment 1 has a faster rate of reaction as the magnesium ribbon is under more pressure.
Experiment 2 has a faster rate of reaction as the magnesium powder has a greater surface area.
The following combinations of shapes all have the same total volume. Which has the greatest total surface area ?
Consider a cube with sides that are exactly 10 cm long, as shown:
What is the volume of the cube?
(a)
Consider a cube with sides that are exactly 10 cm long, as shown:
What is the surface area of the cube?
(a)
If the cube were cut in two, would the total volume and the total surface area increase, decrease, or stay the same?
The total volume would increase and the total surface area would stay the same.
The total volume would stay the same and the surface area would decrease.
The total volume would decrease and the total surface area would increase.
The total volume would stay the same and the total surface area would increase.
The total volume and total surface area would both stay the same.
Consider the reaction: It was found that the addition of zinc powder causes an increase in the rate of reaction. Which of the following can explain this?
Decreasing the remaining amount of HCl(aq)
Increasing the concentration of the reactant
Zinc acting as an oxidizing agent
Increasing the surface area of zinc exposed to the reaction
A student is performing a catalytic cracking of liquid paraffin, using porcelain chips as the catalyst. To accelerate the reaction, the surface area of the porcelain chips must be increased. Which of the following tools would be most suitable for this task ?
Pestle and mortar
Calipers
Bunsen burner
Glass rod
Ice-water bath
The oposite figure represents the volume of carbon dioxide
gas produces from two experiments for the reaction of two
equal masses of calcium carbonate with excess hydrochloric
acid. one of them is in the form of medium sized pieces and the other is in the form of small sized pieces which of the
following choices is correct?
The medium sized pieces remain present in the reaction
medium after 300 s.
The Curve X represents the reaction of the medium sized
pices with the acid
The small sized pices disappear after passing 200 s
The Curve Y represents the reaction of the small sized pieces with the acid
Which statement explains why coal dust forms an explosive mixture with air?
coal dust catalysis the explosion.
coal dust has a large surface area.
crushing coal increases the concentration of the coal.
crushing coal increases the temperature of the coal.
Solution A is aqueous sodium thiosulfate and solution B is hydrochloric acid. Upon mixing, the given reaction takes place: Which of the following alterations to this experiment would not result in an increase in the rate of reaction?
Adding water to solution B
Carefully warming solution B
Dissolving more sodium thiosulfate into solution A
Increasing the temperature of solution A
Increasing the concentration of solution B
In which of the following diagrams will the rate of reaction be slowest?
In which of the following diagrams will the rate of reaction be fastest?
polyethylene is formed from ethene gas. Which of the following combinations of conditions would lead to the fastest rate of reaction?
Low temperature and low pressure
High temperature and high pressure
High temperature and low pressure
Low temperature and high pressure
Consider the following reaction between an Mg strip and HCl: Which of the following can enhance the rate of the reaction?
Increasing the concentration of HCl(aq)
Increasing the temperature
Replacing the Mg strip with Mg powder
All of the answers are correct.
Which of the following factors does not increase the frequency of collisions in a chemical reaction?
Increasing the pressure of reacting gases
Increasing the activation energy
Increasing the temperature
Increasing the surface area of solid reactants
Increasing the concentration of reactants in a solution
Which of the following changes will increase the collision frequency and enhance the reaction rate?
Increasing the pressure
Increasing the concentration
Increasing the temperature
All of the answers are correct.
All of the following can increase the rate of reaction through increasing the collision rate except .
the addition of a catalyst
the increase in the reactant concentration
the increase in the temperature
the increase in the pressure of the reactants
Which one of the following would not increase the rate of a reaction, according to collision theory?
A higher activation energy
A higher particle concentration
Particles colliding more frequently
A higher temperature
Particles having more energy
Aluminum (Al) corrosion can occur in acidic media with the evolution of hydrogen gas H2 Which of these reactions can produce hydrogen gas with higher rates?
Al powder with HCl (1 M)
Al strip with HCl (1 M)
Al powder with HCl (2 M)
Al strip with HCl (2 M)
Consider the following reaction: Which of the following conditions will lead to increasing the rate of zinc dissolution?
2.0MHCl at 50 ∘C
2.0MHCl at 25 ∘C
0.2MHCl at 25 ∘C
0.2MHCl at 50 ∘C
Consider two vessels A and B that contain the same reactants with the same concentrations. The pressure of the reactants in vessel A is higher than the pressure of the reactants in vessel B. Which of the following is not correct?
The effective collisions in vessel A are greater than the effective collisions in vessel B.
The amount of products in vessel A is greater than the amount of products in vessel B.
The rate of reaction in vessel A is greater than the rate of reaction in vessel B.
The activation energy in vessel A is greater than the activation energy in vessel B.
Which of the following is correct about the reasons of explosions in flour mills?
The fine airborne particles may explode if they are electrostatically charged.
The flour dust has a large surface area resulting in a high collision rate.
The fine airborne particles may ignite if they are overheated.
All of the answers are correct.
Dust explosions in flour mills are a serious safety concern. Why is the reaction between the flour particles and the oxygen in the air so fast?
The flour dust acts as a catalyst.
The flour dust has a large surface area resulting in a high collision rate.
Dust explosions create pressure pockets in the air, increasing the rate of reaction.
A dust explosion is exothermic.
The flour dust is highly flammable and concentrated in the air.
In a reaction between 5 blocks of CaCO3(s) and about 500 mL of HCl(aq),which of the following changes will not affect the rate of the reaction?
Grinding the blocks of CaCO3 into fine powder
Increasing the volume of HCl
Increasing the temperature
Increasing the concentration of HCl
Some chemical processes can be accelerated by light, and the employed catalysts are called photocatalysts. For example, ZnO(s) is a common photocatalyst; however, it suffers from corrosion in acidic media. Which of the following will decrease the rate of this photochemical reaction?
The increase of the surface area of ZnO(s)
The addition of hydrochloric acid
The increase of the light intensity of the irradiation source
None of the answers are correct.
Metal corrosion occurs in higher rates in strong acidic media and strong basic media. Which of the following conditions can decrease the rate of corrosion of a metal drain tube in a chemistry laboratory to increase its lifetime to some extent?
Adjusting the pH of the poured solutions in the pH range 11–14
Warming the solutions before pouring
Diluting the poured solutions
Adjusting the pH of the poured solutions in the pH range 1–3
Which of the following factors does not affect the rate of a chemical reaction?
The pressure of reacting gases
The surface area of solid reactants
The reversibility of the reaction
The concentrations of reactants in a solution
The presence of a catalyst
Which one of the following would not increase the rate of a reaction, according to collision theory?
Increasing the pressure
Using a catalyst
Increasing the surface area of particles
Increasing the temperature
Using a differently shaped container with the same volume
When lightning strikes, molecules of oxygen O2 and nitrogen N2 in the atmosphere are given enough energy to combine together to form nitric oxide NO Under normal conditions, oxygen and nitrogen molecules collide but do not react. What does this suggest about the reaction?
It cannot be performed without a catalyst.
It is irreversible.
It is reversible.
It is catalyzed by lightning.
It has a very large activation energy.
The reaction between warm hydrochloric acid and magnesium has a faster rate of reaction than the reaction between cold hydrochloric acid and magnesium. Which statement explains this observation?
The particles are moving faster and with greater energy.
The particles are more concentrated and have a greater mass.
The particles are more concentrated and have greater energy.
The particles are moving faster and have a greater surface area.
The particles are moving faster and have a greater mass.
Three different experiments are performed by using a balance as shown in the figure to measure the rate of the Reaction of calcium carbonate with dilute hydrochloric
acid: The results of the three
experiments are represented by the
opposite graphical figure. Which of
the following choices is correct?
Curve (Y) represents the second experiment.
Curve (Z) represents the third experiment.
Curve (X) represents the first experiment.
Curve (Y) represents the first experiment
Curve (X) in the opposite graphical figure represents the volume of hydrogen gas evolving over time, when 0.01 mol of zinc powder is added to 100 mL of 0.1 M hydrochloric acid at 25 ° C, what is the curve which represents the volume of hydrogen gas evolving over time when the previous experiment is repeated using 0.01 mol of zinc granules with 100 mL of 0.2 M hydrochloric acid at 50 °C?
A
B
D
C
Two experiments are carried out to measure the rate of the evolution of oxygen gas produced from the decomposition of hydrogen peroxide, two solutions different in their volumes and concentrations are used in these experiments as in the following table: What is the graphical figure which represents the results of these experiments?
One of the students carried out three experiments to produce carbon dioxide gas by using excess of zinc carbonate with dilute sulphuric acid (at 30C) :
In terms of the previous figure and table .. Which of the following choices represents the curve of each the experiments ? ………….
a
b
c
d
