Conservation of Mass Review

Which of the following statements best defines the law of conservation of mass?

• Mass cannot be conserved during a chemical reaction; a little bit of mass is always lost

• Mass cannot be created but it can be destroyed under extreme pressures

• The mass of a closed system cannot change over time; mass cannot be created nor destroyed

• When added to a system, energy can destroy mass

Tags

NGSS.MS-PS1-5

In a chemical reaction, 300 grams of reactant A are combined with 100 grams of reactant B. Both A and B react fully to create a product. How much mass will the product(s) have?

• 400 g

• 300 g

• It depends on if the system is open or closed

• 200 g

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

In a reaction, 25 grams of reactant AB breaks down into 10 grams of product A and an unknown amount of product B. Using the law of conservation of mass, how much mass does product B have?

AB -> A + B

• 15 g

• 25 g

• 35 g

• 50 g

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

If all the reactants in a chemical reaction are completely used, which of the following statements accurately describes the relationship between the reactants and the products?

• The total mass of the reactants must equal the total mass of the products

• The density of the reactants must equal the density of the products

• The products must have different state of matter than the reactants

• The reactants must contain more complex molecules than the products do

Tags

NGSS.MS-PS1-5

Mrs. Ballard measured the mass of a closed beaker containing several ice cubes. The mass was 100 g. An hour later, after the ice cubes had melted, Mrs. Ballard measured the mass of the beaker again. What was the mass of the beaker the second time?

• A little more than 100 g

• 100 g

• A little less than 100 g

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

During a physical change in a closed system, mass will...

• increase

• decrease

• stay the same

• increase, decrease, or stay the same

Tags

NGSS.MS-PS1-5

During a chemical reaction in a closed system, mass will...

• increase

• decrease

• stay the same

• increase, decrease, or stay the same

Tags

NGSS.MS-PS1-5