Law of conservation of mass

Matter can not be created nor destroyed: it can only be

• Destroyed a little bit
• Invisible
• Transformed, changed
• None of the above

If reaction starts with 20g of reactants it should produce 

• a total of 40g of products
• a total of 10g of products
• a total of 80 g of products
• a total of 20g of products

The Law of Conservation of Mass States

• Energy cannot be created nor destroyed, it can only change form.

• Mass cannot be created nor destroyed, it can only change form.

• Mass can be created or destroyed, it cannot change form.

Which of the models of a chemical reaction best represents the Law of Conservation of Mass?

• A

• B

• C

• D

Which of the models of a chemical reaction best represents the Law of Conservation of Mass?

• A

• B

• C

• D

Which of the models of a chemical reaction best represents the Law of Conservation of Mass?

• A

• B

• C

• D

A student pours hydrochloric acid (HCl) into an open beaker that contains a piece of magnesium (Mg). A chemical reaction occurs, and the data for the reaction is shown in the image. Was there a total mass increase or a total mass decrease for this experiment?

• There was a increase in mass.

• There was a decrease in mass.

• There was no change in mass.

A student heated a 10 gram sample of a chemical in an open container. A chemical reaction occurred, and the mass of the sample was measured again. The mass of the sample was found to be less than before the reaction. Which of the following best explains the decrease in mass of the sample?

• The heat caused the chemical to become less dense.

• The reaction gave off more heat than was added.

• Some of the lighter particles were destroyed.

• Some of the particles escaped as a gas formed.

A student dissolved 25 grams of salt into 1,000 grams of water. What should the mass of the saltwater mixture be?

• 975 grams

• 1,000 grams

• 1,025 grams

• 2,500 grams

A student measures the mass of an iron nail to be 25 grams. The student heats the nail over a bunsen burner and measures the mass of the nail afterwards. The mass of the nail is found to be greater after burning. Which of the following best explains the increase in mass of the nail?

• The heat caused the compound to become more dense.

• The reaction gave off less heat than was added.

• Some of the heavier particles multiplied inside the nail.

• Extra particles from the air were added to the nail during burning.