Unit B Section 4.2

Question 1

Is the total mass of these products is always the

same as the total mass of the reactants.

Answer 1

yes

Question 2

What is the conservation of mass?

Answer 2

It states that matter is not created or destroyed in a chemical reaction.

For example, combining 24.3 g of magnesium and 32.1 g of sulfur creates a new substance called magnesium sulfide. The law of conservation of mass predicts that the mass of the product will be the sum of these two masses: 56.4 g.

Question 3

What is a closed system

Answer 3

closed systems, where no additional material is allowed to enter or leave

Ex. Biosphere

Question 4

What is an open system?

Answer 4

Where substances can easily enter and leave.

Ex.adding 10 g of Alka-Seltzer to 100 g of water in a
beaker causes carbon dioxide gas to be given off.

The outcome is 106 grams instead of 110 grams

Question 5

Which system are careful experiments mostly done

Answer 5

closed systems

Question 6

In a nuclear reaction,
some of the mass is
converted to energy

Answer 6

Yeas