# Snapquiz - Empirical Formula

This is the Snapquiz on Empirical Formula. Click here or use the embedded video if you haven't watched the lesson yet.

Question 1. What's the next step once you've found the mass in grams of an element in your compound and its Ar value?

Divide the mass by the Ar value.
Find the ratio of the Ar values to each other.
Subtract the Ar value from the mass.
Find the ratio of the mass to the Ar

Question 2. Sulphur has an Ar value of 32 and oxygen has an Ar 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?

S2O
SO
SO2
S2O2

Question 3. 3.1g of phosphorus reacts with oxygen to make 7.1g of phosphorus oxide. What is the empirical formula of this oxide?

PO2.5
P2O5
P1O2.5
P2.5O

Question 4. 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 Ar values.
Simplify the ratio 89.2 : 82.8
82.8g - 89.2g
89.2g - 82.8g

Question 5. What is the Ar value of an element?

The charge on an atom.
The proton number of an atom.
The number of neutrons in an atom.
The mass number of an atom.