Quantitative Chemistry

Question 1

How to find the relative formula mass:

Answer 1

Add up the relative atomic masses together (times by the small number at the end if there is one)

Question 2

Percentage mass of an element in a compound

Answer 2

Ar x number of atoms of that element

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Question 3

How to find the percentage mass of sodium carbonate Na2CO3

Answer 3

Find the Mr = 106

Percentage mass of sodium=43%

Question 4

Describe the law of conservation of mass:

Answer 4

The law of conservation of mass says that no atoms can be created or destroyed in a chemical reaction. Therefore, the total mass of reactants must equal the total mass of products.

Question 5

What is the Law of Conservation of mass?

Answer 5

Total mass of reactants=total mass of products

Question 6

What is relative (molecular) mass?

Answer 6

Mr= sum of (Ar)