Chemical calculations,volumes and concentratiom

Question 1

State the law of conservation of mass

Answer 1

Mass of reactants = Mass of products
No atoms are lost or made during a chemical reaction

Question 2

How do we show that mass is conserved in a chemical reaction?

Answer 2

Balancing symbol equations

Question 3

State one example of when a reaction may appear to lose mass?

Answer 3

When a gas is produced and escapes

Question 4

State one example of when a reaction may appear to gain mass?

Answer 4

When a gas reacts with a solid adding onto it

Question 5

In a chemical reaction the sum of the Mr of reactants must equal…

Answer 5

The sum of the Mr of the products

Question 6

State the units of mass

Answer 6

grams (g)

Question 7

What is the percentage by mass of hydrogen, in H2O? Answer to two significant figures
H=1 H2O=18

Answer 7

% compostion = ((2 x 1) / 18) x 100 = 11%

Question 8

How many cm3 are in 1 dm3?
State how to convert cm3 into dm3

Answer 8

1000cm3 = 1 dm3
divide by 1000