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

Question 1

3.1.1 Conservation of mass and balanced chemical equations

What is the law of conservation of mass?

Answer 1

• states that no atoms are lost or made during a chemical reaction
• mass of products equals the mass of reactants

Question 2

3.1.1 Conservation of mass and balanced chemical equations

What is balanced in a chemical reaction

Answer 2

• the number of each element involved is balanced on both sides of the equation

Question 3

3.1.2 Relative formula mass

What is the relative formula mass (Mr) ?

Answer 3

The Mr of a compound is the sum of the relative atomic mass of each atoms.

eg: Mr of H20 = (2x1)+(1x16) = 18

Question 4

3.1.3 Mass changes when a reactant or product is a gas

Why is there a change in mass in some chemical equations?

Answer 4

• The reactant is a gas (decrease in mass)
• gas can escape when it is non-enclosed
• the product is a gas (increase in mass)
• mass has not been taken into account

Question 5

3.1.4 Chemical measurements

How to calculate uncertainty

Answer 5

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