Snapquiz - Empirical Formula

Question 1. 89.2g of lead oxide is heated with carbon, which reduces it (removes its oxygen). Afterwards 82.8g of pure lead is left. How would we find the mass of oxygen lost?

Divide both values by A_r values.
89.2g - 82.8g
82.8g - 89.2g
Simplify the ratio 89.2 : 82.8

Question 2. Sulphur has an A_r value of 32 and oxygen has an A_r value of 16. A sulphur oxide contains 6.4g of sulphur and 6.4g of oxygen. What is the empirical formula of the sulphur oxide?

S₂O₂
S₂O
SO₂
SO

Question 3. How would you find the mass increase due to oxygen in the oxidation of magnesium?

Subtract the mass after oxidation from the mass before oxidation.
Add the masses before and after oxidation together.
Subtract the mass before oxidation from the mass after oxidation.
Find the ratios of the masses before and after oxidation.

Question 4. 3.1g of phosphorus reacts with oxygen to make 7.1g of phosphorus oxide. What is the empirical formula of this oxide?

P₂O₅
P₁O_2.5
P_2.5O
PO_2.5

Question 5. Which is the correct sequence of values to calculate to find the empirical formula?

Ratio, A_r values, Masses, Division.
Division, Masses, Ar values, Ratio.
A_r values, Division, Ratio, Masses.
Masses, A_r values, Division, Ratio.

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