Vocab
Multiple Choice
Short Response
Law of Conservation of Mass
Miscellaneous
100
Formed when two or more atoms combine
Molecule
100
In a chemical reaction known as decomposition, carbonic acid breaks down into water, and what other compound?
A.
B.
C.
D.
B.
100
What does the Law of Conservation of Mass say about matter?
Matter cannot be created or destroyed and therefore the mass will not change after a reaction.
100
According to the Law of Conservation of Mass, if 10 grams of reactants undergo a chemical reaction, the mass of the products will be:
A) Less than 10 grams.
B) Greater than 10 grams.
C) Exactly 10 grams.
D) Variable depending on the type of reaction.
C
100
When a chemical reaction occurs in a closed system, what happens to the mass of the system?
A) The mass decreases.
B) The mass increases.
C) The mass stays the same.
D) The mass fluctuates.
C
200
The smallest part of a substance
Atom
200
A student is using the following key to model the chemical equation provided.
Chemical Equation: MgCl2 + 2NaF -> MgF2 + 2NaCl
The reactants are on the left and the products are on the right. How many blue beads will the student need to model each side of the equation?
A. 1 for the products and 1 for the reactants
B. 2 for the products and 2 for the reactants
C. 2 for the products and 1 for the reactants
D. 1 for the products and 2 for the reactants
B. 2 for the products and 2 for the reactants
200
Hydrogen peroxide (H2O2 ) is unstable under certain conditions and decomposes as follows:
2H2O2 → 2H2O +O2
40 g ?
What will be the result when starting with 40 grams of hydrogen peroxide?
40g of total products because of the Law of Conservation of Mass
200
Which of the following best describes the Law of Conservation of Mass?
A) Matter can be created or destroyed in a chemical reaction.
B) The total mass of reactants is always equal to the total mass of products in a chemical reaction.
C) Mass is not involved in physical changes.
D) Only chemical reactions conserve mass, but not physical changes.
B
200
Which of the following statements is true?
A. Cutting paper is an example of a chemical reaction because a new substance is formed and the process cannot be undone.
B. Freezing water is an example of a chemical reaction because a new substance is formed and the process cannot be undone.
C. Burning paper is an example of a chemical reaction because a new substance is formed and the process cannot be undone.
D. Melting ice is an example of a chemical reaction because a new substance is formed and the process cannot be undone.
C
300
The substances initially involved in a chemical reaction
Reactants
300
Students want to gather evidence for the claim that the number of atoms present before a chemical reaction is equal to the number of atoms present after the chemical reaction. They decide to react vinegar and baking soda in a sealed plastic bag. Which of the following would provide the evidence the students need?
A. The mass of the plastic bag, baking soda, and vinegar before the reaction was equal to the mass after the reaction.
B. Bubbles were produced during the reaction, which meant that a gas was being produced.
C. The plastic bag did not change in any way, indicating that it was not involved in the reaction.
D. The mass of baking soda was exactly equal to the mass of the vinegar used to create the chemical reaction.
A. The mass of the plastic bag, baking soda, and vinegar before the reaction was equal to the mass after the reaction.
300
Describe an experiment that can be done to prove the law of conservation of mass.
Vinegar baking soda with balloon on top. Any closed system in which a chemical reaction occurs.
300
If a piece of wood burns completely in a closed container, what happens to the mass of the system?
A) The mass decreases because the wood burns.
B) The mass increases because new substances form.
C) The mass remains the same as it was before the wood was burned.
D) The mass is lost as heat.
C
300
What is the best explanation for what happens during a chemical reaction?
A. The mass of the products must be more than the mass of the reactants.
B. The mass of the substances do not change, but the individual elements always change.
C. The atoms are rearranged to form different substances with new unique properties.
D. The number of atoms of each element must be greater than the reactants.
C
400
A process that leads to the transformation of one set of chemical substances to another
Chemical reaction
400
Which of the following atomic models of chemical reactions correctly demonstrates the Law of Conservation of Matter?
A.
B.
C.
D.
B.
400
What is an example in nature where a chemical reaction occurs in an open system?
Examples include cooking in an open pan, camp fire, rotting roadkill, etc.
400
A cup containing 100 grams of water is left open at room temperature. Over several days, the water begins to evaporate, and the mass of the water decreases. After a week, only 70 grams of water remain in the cup. However, the air around the cup contains the evaporated water vapor.
How does this situation relate to the Law of Conservation of Mass?
A) The mass of the water decreases because mass can be destroyed during evaporation.
B) The mass of the water decreases, but the total mass in the system is conserved; the evaporated water has simply moved into the air.
C) The decrease in mass shows that evaporation violates the Law of Conservation of Mass.
D) The air around the cup has gained mass, but the total mass of the water remains the same.
B) The mass of the water decreases, but the total mass in the system is conserved; the evaporated water has simply moved into the air.
400
During the baking soda/vinegar/balloon lab, which experiment would NOT give evidence for the Law of Conservation of Mass? Why?
The open system which does not contain the products, because the mass changes after the reaction takes place. ex: open baking soda and vinegar flask allows gases to escape
500
The substance that is produced from a chemical reaction
Product
500
Which of the following is true regarding the atoms involved in a chemical reaction?
A. The same number of each type of atom will always be present before and after a chemical reaction takes place.
B. Some of the atoms present before the reaction will always be lost during a chemical reaction.
C. Some of the atoms will always be changed into a different type of atom by a chemical reaction.
D. During a chemical reaction, atoms will always be combined into much larger molecules.
A. The same number of each type of atom will always be present before and after a chemical reaction takes place.
500
An experiment is performed in which a crystalline substance is added to a beaker filled with room-temperature water. The following observations are made:
1- The crystals dissolve.
2- A precipitate forms.
3- The bottom of the beaker feels warm to the touch.
4- Bubbles begin to form in the water.
Which of the above observations are evidence that a chemical reaction is taking place? Explain
2,3,4 because they have evidence of chemical changes. 1 is a physical change and does not create a new substance.
500
You have a sealed soda can that contains 300 grams of liquid soda. The can is then shaken vigorously, causing carbonation to occur, and some gas is released. After opening the can, you weigh the contents and find that the remaining liquid weighs 295 grams.
Which of the following best explains the change in mass?
A) The Law of Conservation of Mass has been violated because mass is not conserved.
B) Some gas escaped when the can was opened, reducing the mass of the liquid soda.
C) The carbonation process created new mass, causing the total mass to decrease.
D) The remaining liquid lost mass through evaporation.
B) Some gas escaped when the can was opened, reducing the mass of the liquid soda.
500
Describe the difference between physical and chemical reactions.
Physical only changes shape or form and can be undone, chemical creates a new substance and changes its properties like color, smell, flammability, or gases produced.