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WorksheetsEnergy in Chemical Changes Comprehensive Review
Total questions: 67
Worksheet time: 36mins
Using the graph, what is the enthalpy (potential energy) of the reactants?
40 kJ
100 kJ
120 kJ
180 kJ
Using the graph, what is the enthalpy (potential energy) of the products?
40 kJ
100 kJ
120 kJ
180 kJ
Using the graph, what is the activation energy for the reaction with a catalyst?
40 kJ
100 kJ
120 kJ
180 kJ
Using the graph, what is the activation energy for the reaction without a catalyst?
40 kJ
100 kJ
140 kJ
180 kJ
Using the graph, the enthalpy (ΔH) value for this reaction is ______.
40 kJ
80 kJ
100 kJ
140 kJ
A balanced chemical equation has equal numbers of atoms of each type on both sides of the equation. This illustrates the law of _____.
natural selection
action-reaction
conservation of energy
conservation of mass
Sandy conducted an experiment to prove the Law of Conservation of Mass.
1. First, Sandy found the mass of baking soda in a ziploc baggie to be 12 grams.
2. Next, Sandy found the mass of vinegar in another baggie to be 10 grams.
3. Sandy placed the vinegar baggie inside the first baggie, zipped it shut, inverted the baggies,and allowed the reaction to happen, filling the bag with the gas produced.
After the reaction is complete, what does Sandy need to do to prove that mass was conserved?
Mass everything after. It will be 22 grams.
Open the baggie to release the gas. Mass the solid product. It will be 22 grams.
Mass everything after. It will be 12 grams.
Open the baggie to release the gas. Mass the solid product. It will be 12 grams.
Which image best demonstrates the law of conservation of mass?
In the procedure shown, a calcium chloride solution is mixed with a sodium sulfate solution to create the products. Which of the following is demonstrated by this activity?
The Law of Conservation of Mass.
The Theory of Thermal Equilibrium.
The Law of Conservation of Momentum.
The Theory of Covalent Bonding.
Which of the following equations lists the correct states of matter for burning magnesium to produce solid magnesium oxide?
2Mg(s) + O2(s) → 2MgO(s)
2Mg(s) + O2(g) → 2MgO(l)
2Mg(s) + O2(g) → 2MgO(s)
2Mg(l) + O2(g) → 2MgO(s)
Water cools from 2oC to -2oC. During this time, what happens to the motion of the molecules?
The motion of the molecules remains the same.
The motion of the molecules decreases.
The motion of the molecules increases.
The motion of the molecules stops.
Which graph represents an exothermic reaction?
The graph represents the change in energy for two laboratory trials of the same reaction. Which factor could explain the difference in activation energy between the trials?
A catalyst was added to Trial #2.
Trial #1 was stirred.
Heat was added to Trial #2.
Trial #1 was cooled.
A catalyst decreases the activation energy of a reaction by _____
providing an alternate reaction pathway.
decreasing the heat of reaction.
increasing the mass of the reactants.
changing the mole ratio of the reactants.
When lime juice is added to guacamole, it slows the oxidation of the avocados, keeping the guacamole from turning brown. What kind of substance is lime juice?
An inhibitor
An enhancer
A catalyst
A reactant
Most medicines are manufactured in the form of powder instead of pills. How does this affect the rate of reaction?
It increases the concentration of the medicine.
It enhances enzyme action of the medicine.
It increases the surface area to speed up the reaction rate.
It decreases the number of effective collisions of molecules in the medicine.
Referring to the image, changing the pressure from that of container A to container B would have what effect on the rate of the reaction in the container?
It would decrease the rate.
It would increase the rate.
It would have no effect on the rate.
Tim wanted to increase the speed of a reaction he was completing. To do this, he placed the reaction mixture in a water bath that had a temperature of 60°C. Why would increasing the temperature of the reaction mixture increase the reaction rate?
The enzymes in the reaction mixture would be deactivated by the heat.
The molecules would become gaseous and would be more likely to change form.
The bonds of the molecules would become unstable and be broken more easily.
The molecules would move faster and there would be more collisions between molecules.
Which graph represents the reaction:
2NO(g) + O2(g) → 2NO2(g) ΔH= +27 kcal
A store display advertisement for an instant cold pack says: “Drops to 33°F in moments and stays cold for a half-hour. Immediate first-aid for sprains, bruises, and broken bones. Very easy to use. Just squeeze and shake.” What can you infer about the process when you squeeze and shake the cold pack?
It is an endothermic process that transfers heat from the surroundings.
It is an endothermic process that transfers heat to the surroundings.
It is an exothermic process that transfers cold to the surroundings.
It is an exothermic process that tranfers heat from the surroundings.
Which arrow on the graph represents the energy of the activated complex?
1
2
3
4
Which arrow on the graph represents ΔH?
1
2
3
4
Which arrows on the graph would be affected if a catalyst were added?
1, 2, 3, 4
1, 2
2, 3
1, 4
The reaction shown by the graph is _____.
endothermic
exothermic
neither endothermic or exothermic.
both endothermic and exothermic.
Which statement is true about energy of this reaction?
CH4(g) + 2O2(g) → 2H2O(g) + CO2(g) + energy
The reaction is exothermic because it releases energy.
The reaction is exothermic because it absorbs energy.
The reaction is endothermic because it releases energy.
The reaction is endothermic because it absorbs energy.
Some chemical reactions absorb energy, while others release energy. Two examples of chemical reactions are burning wood and exploding hydrogen. Which of these chemical reactions will release energy?
Burning wood only.
Exploding hydrogen only.
Neither burning wood nor exploding hydrogen.
Both burning wood and exploding hydrogen.
According to the graphs, for which reaction(s) will the temperature of the surroundings increase?
A
B
Both A and B.
Neither A nor B.
__Ca(OH)2(aq) + __Al2(SO4)3(aq) → __CaSO4(aq) + __Al(OH)3(s)
3, 2, 2, 1
2, 1, 1, 2
3, 1, 3, 2
1, 1, 1, 1
_____CH4(g) + _____O2(g) _____H2O(g) + _____CO2(g)
1, 2, 2, 1
1, 1, 2, 1
2, 3, 4, 2
2, 3, 2, 2
A student uses a mortar and pestle to crush 1.0g of marble chips and places them in a test tube. A whole 1.0 g marble chip is placed in a second test tube. Then 5.0 mL of 6M HCl is added to each test tube. The bubbling speed of the produced CO2 gas is noted. This experiment is designed to study the effect of the _____
temperature of a reactant on reaction rate.
surface area of a reactant on reaction rate.
introduction of a catalyst on reaction rate.
type of acid added on reaction rate.
Referring to the image, changing the pressure from container A to container B would have what effect on the reaction rate in the container?
The rate of the reaction would decrease because decreasing pressure decreases the concentration of gases.
The rate of the reaction would increase because increasing the pressure decreases the concentration.
The rate of the reaction would remain the same because decreasing the pressure does not effect concentration of gases.
The rate of the reaction would increase because increasing pressure increases the concentration of gases.
Using the graph, what will happen to the temperature of the surroundings?
The temperature will decrease.
The temperature will increase.
Unable to determine.
The temperature will stay the same.
The graph shows how potential energy changes as nitrogen and oxygen react to form nitrogen monoxide. Which of the following conclusions about the reaction is supported by the data?
It is an endothermic reaction.
Does not form an activated complex.
Potential energy of the reactants is greater.
It is an exothermic reaction.
Nitrogen gas is used as a reactant. If the reaction requires 18.2 grams of nitrogen gas, how many moles of nitrogen are used?
1.30 mol
0.650 mol
0.769 mol
1.54 mol
Is the reaction shown endothermic or exothermic?
Endothermic
Exothermic
Unable to determine.
Which of the following shows the correct way to calculate the ΔH for the combustion of methane?
[-74.85 kJ + 0 kJ] + [-393.5 kJ + 2(-285.8 kJ)]
[-393.5 kJ + 2(-285.8 kJ)] + [-74.85 kJ + 0 kJ]
[-393.5 kJ + 2(-285.8 kJ)] – [-74.85 kJ + 0 kJ]
[-74.85 kJ + 0 kJ] – [-393.5 kJ + 2(-285.8 kJ)]
Which statement best describes the following chemical equation?
CaO(s) + H2O(l) → 65.2 kJ + Ca(H2O)2(s)
Energy is being absorbed from the surroundings, so the reaction is endothermic.
Energy is being released to the surroundings, so the reaction is endothermic.
Energy is being absorbed from the surroundings, so the reaction is exothermic.
Energy is being released to the surroundings, so the reaction is exothermic.
The graph shows the potential energy levels of products and reactants during a reaction. Which statement best describes the reaction shown?
It is endothermic because the reactants have more energy than the products.
It is exothermic because the products have less energy than the reactants.
It is endothermic because the products have more energy than the reactants.
It is exothermic because the reactants have less energy than the products.
The total energy released or absorbed during a reversible chemical reaction is equal to _____.
the activation energy of the endothermic reaction
the activation energy of the exothermic reaction
the difference between the potential energy of the products and the potential energy of the reactants
the sum of the potential energy of the products and the potential energy of thereactants
In the reaction shown, calcium reacts with zinc carbonate to form calcium carbonate and zinc. According to the law of conservation of mass, how much zinc was present in the zinc carbonate?
40 g
88 g
104 g
256 g
According to the reaction, when 127 g of copper reacts with 32 g of oxygen gas to form copper (II) oxide, no copper or oxygen is left over.
2Cu + O2 → 2CuO
How much copper (II) oxide is produced?
32 g
95 g
127 g
159 g
A log burns in a fireplace. The large log leaves a handful of ashes. Which of the following statements best explains the difference in mass of the log and the ashes?
Mass was destroyed during the reaction.
The difference in mass was converted to released energy.
Mass was not lost because the density of the ashes is greater than the density of the log.
The mass of the log and oxygen equals the mass of the ash and product gases.
Which of the following changes involved with automobiles is a chemical change?
Making steel (an alloy) by mixing iron, carbon, and other metals.
Applying paint to the body of the automobile.
Rolling out steel into sheets.
An airbag expands after a collision because of the production of gas.
In a chemistry lab, Tom places a piece of metal and hydrochloric acid into the same test tube. He notes that a gas is produced and that the outside of the test tube feels warm. What can he conclude about the process that has occurred?
It is an exothermic process that transfers cold from the surroundings.
It is an endothermic process that transfers heat from the surroundings.
It is an endothermic process that transfers heat to the surroundings.
It is an exothermic process that tranfers heat to the surroundings.
You know that a chemical reaction is occurring here because you see __________________ . (Pick 3)
purple color
smoke
ice formation
fire
a yellow precipitate
In this chemical reaction, what was the first evidence that you saw?
Production of fire
Production of light
Production of purple smoke
Production of white powder
The result of the experiment between Iodine and Aluminum was the production of __________________.
clear liquid.
a white powder.
yellow precipitate.
bubbles.
When zinc reacted with hydrochloric acid, what was the result of this reaction?
a white powder
a blue liquid
a brown precipitate
a gas
We know that there was a chemical reaction occurring when 2 clear liquids were mixed together. That is because we show the production of a _____________.
solid.
precipitate.
gas.
A precipitate is a ___________ that forms when 2 liquids react together.
solid
liquid
gas
plasma
Reactants are the chemicals that are present at the beginning of an experiment. Reactants react together to make the product.
We can know that a chemical reaction is occurring when we see ______.
that the product looks just like the reactants.
nothing new.
that the product looks different from the reactants.
Which of the following is evidence of a chemical reaction?
Tearing paper.
Change in color.
Production of a gas.
Change in temperature.
Production of a precipitate.
How many Carbons are present on the reactant side?
1
2
3
4
How many Hydrogens are on the product side of this chemical equation?
1
2
3
4
How many Oxygens are on the product side of this chemical equation?
1
2
3
4
Why are chemical equations always balanced? Select ALL that apply.
Matter cannot be created.
Matter cannot be destroyed.
Matter can only be rearranged/conserved.
Matter doesn't matter.
In a chemical reaction, if the reactants are heated, the reaction usually happens
slower
faster
at the same rate
in a smaller volume
Some chemical reactions require a substance called a catalyst. The purpose of a catalyst is
to warm up the reaction
to speed up the reaction
to create more reactants
to stop the reaction
What does it mean for a reaction to be endothermic? Choose 2 of the following.
When two substances react, the temperature of the mixture decreases.
When two substances react, the temperature of the mixture increases.
There is less energy going into the reactant to break the bond than there is energy leaving the product.
There is more energy going into the reactant to break the bond than there is energy leaving the product.
The amount of energy entering and leaving is the same.
What does it mean for a reaction to be exothermic? Choose 2 of the following.
When two substances react, the temperature of the mixture decreases.
When two substances react, the temperature of the mixture increases.
There is less energy going into the reactant to break the bond than there is energy leaving the product.
There is more energy going into the reactant to break the bond than there is energy leaving the product.
The amount of energy entering and leaving is the same.
Which is the correct word equation for photosynthesis?
water + glucose + oxygen ---> energy + carbon dioxide
energy + oxygen + carbon dioxide ---> water + glucose
water + carbon dioxide + energy ---> glucose + oxygen
glucose + oxygen ---> water + carbon dioxide + energy
Which of the following is the word equation for cellular respiration?
water + carbon dioxide + energy ---> glucose + oxygen
water + glucose ---> energy + carbon dioxide + oxygen
oxygen + carbon dioxide ---> water + energy + glucose
glucose + oxygen ---> water + carbon dioxide + energy
Photosynthesis takes place in the
mitochondria
chloroplast
nucleus
cytoplasm
cellular respiration takes place in the
mitochondria
chloroplast
nucleus
cytoplasm
What is the purpose of photosynthesis. Select all that apply.
to form glucose, food for the plant
to form carbon dioxide
to form oxygen
to form energy
to form water
What is the purpose of cellular respiration. Select all that apply.
to form glucose
to form oxygen
to form carbon dioxide
to form energy
to form water
Which of the following is a common sign that a chemical change has occurred?
A chemical has turned a different color, bubbled, and/or changed temperature.
A chemical has changed to a different state of matter, such as a liquid to a solid.
A chemical has changed size.
A chemical has become a different shape.
