Question

8. Based on the Law of Conservation of Matter: At the start of the reaction 20g of

one material and some amount of another material were reacted and produced
30g of solid and 70g of a gas. What is the other amount of reactant used?
a. 20
b. 60g
c. 80g
d. 100g

Answer 1

80g

Step-by-step explanation:

The law of conservation of matter states that matter cannot be created nor destroyed. Basically, whatever mass you have at the beginning of a reaction, should be the same as at the end of the reaction on the product side.

Since here it lets you know that a total of 100g (30g + 70g) were produced on the product side, that means that we started off with 100g in our reactant side.

We have given that one material is 20g on our reactant side but we need the mass of the other. To find the mass of the other material, simply subtract 20g from the total mass created on the product side.

100g - 20g = 80g

The 80g would be the missing amount from the reactant side that isn't stated.