Law of Conservation of Mass Review

Does this equation follow the law of conservation of mass?

• Yes, because the mass is the same.

• Yes, because the mass is not the same.

• No, because the mass is the same.

• No, because the mass is not the same.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Which equation follows the law of conservation of mass?

• Na + Cl₂ --> NaCl

• Na + Cl₂ --> 2NaCl

• 2Na + Cl₂ --> NaCl

• 2Na + Cl₂ --> 2NaCl

Tags

NGSS.MS-PS1-5

Suppose 20 g of liquid hydrogen peroxide is heated so it completely breaks down into liquid water and oxygen gas. Which best describes the total mass of the water and oxygen that was produced?

• more than 20 g because of the addition of heat

• more than 20 g because there are now two substances

• less than 20 g because oxygen gas is very light

• 20 g because no matter is added or removed

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Anthony is performing an experiment. He adds 0.25 grams of baking soda to 5 grams of water and stirs. Anthony watches as the baking soda dissolves in the water. If Anthony weighs the water and baking soda solution, what will its mass be?

• 4.75 grams

• 5.0 grams

• 5.25 grams

• 7.5 grams

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

According to the law of conservation of mass, how much zinc was present in the zinc carbonate?

• 104 g

• 88 g

• 110 g

• 40 g

Tags

NGSS.MS-PS1-5

Students react baking soda & vinegar.
Which of the following would provide the evidence that the number of atoms present before a chemical reaction is equal to the number of atoms present after the chemical reaction?

• The mass of the plastic bag, baking soda, and vinegar before the reaction was equal to the mass after the reaction.

• Bubbles were produced during the reaction, which meant that a gas was being produced.

• The plastic bag did not change in any way, indicating that it was not involved in the reaction.

• The mass of the baking soda was exactly equal to the mass of the vinegar used to create the chemical reaction.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

After the reaction, how many grams will Time 2 Setup equal?

• 30 g

• 275 g

• 300 g

• 305 g

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

This chemical equation represents what happens when a nail rusts: 4Fe + 3O₂ –› 2Fe₂O₃. The total mass after the reaction is

• not considered before the reaction.

• 5 times less than before the reaction.

• exactly the same as before the reaction.

• about twice as much as before the reaction.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

A student notices that an inflated balloon gets larger when it is warmed by a lamp. Which best describes the mass of the balloon as a result of this change?

• The mass of the balloon increases because the size of the balloon has increased.

• The mass of the balloon increases because the temperature of the balloon has increased.

• The mass of the balloon stays the same because the gas inside the balloon still has the same mass after it warms up.

• The mass of the balloon stays the same because warming decreases the mass enough to cancel out the effect of increasing the size.

Tags

NGSS.MS-PS1-4

Which of the following chemical equations correctly demonstrates the law of conservation of mass?

• @@ ext{H}_2 + ext{O}_2 ightarrow ext{H}_2 ext{O}@@

• @@2 ext{H}_2 + ext{O}_2 ightarrow 2 ext{H}_2 ext{O}@@

• @@ ext{H}_2 + ext{O}_2 ightarrow 2 ext{H}_2 ext{O}@@

• @@2 ext{H}_2 + ext{O}_2 ightarrow ext{H}_2 ext{O}@@

Tags

NGSS.MS-PS1-5