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. 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?

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

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?


Question 3. What's the next step once you've found the mass in grams of an element in your compound and its Ar value?

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

Question 4. How would you find the mass increase due to oxygen in the oxidation of magnesium?

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

Question 5. 3.1g of phosphorus reacts with oxygen to make 7.1g of phosphorus oxide. What is the empirical formula of this oxide?


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