Chemical measurements, conservation of mass and the quantitative interpretation of chemical equations

Question 1

What is the Law Conservation of Mass?

Answer 1

no atoms are made or lost during a chemical reaction so the mass of products = mass of reactants

Question 2

What does the Law Conservation of Mass mean for equations?

Answer 2

the equation must be balanced - there must be exactly the same number of atoms on each side

Question 3

What is the relative formula mass of a compound?

Answer 3

sum of the relative atomic masses of the atom in the numbers shown in the formula

Question 4

Mass changes when a reactant or product is a gas:

Answer 4

• if a reaction appears to involve a change in mass, check to see whether this is due to a reactant or a gas product has been released into the atmosphere