Snapquiz - Empirical Formula

Question 1. 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 before oxidation from the mass after oxidation.
Subtract the mass after oxidation from the mass before oxidation.

Question 2. Butene contains four carbon atoms and eight hydrogen atoms. What is its empirical formula (not its molecular formula)?

CH
C₄H₈
CH₂
C₂H₄

Question 3. A carbon oxide is found to have a 1:1 ratio of carbon to oxygen. What is its correctly-written empirical formula?

CO₂
C₁O₁
C₂O
CO

Question 4. What is the A_r value of an element?

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

Question 5. 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
Simplify the ratio 89.2 : 82.8
82.8g - 89.2g

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