Question

How many grams of water can be produced when 8 g of hydrogen react with 8 g oxygen?

• A. 8 g
• B. 9 g
• C. 18 g
• D. 27 g
• E. 30 g

Answer 1

Answer: (B)

9 g

The molecular masses of hydrogen, oxygen and water are 2 g/mole, 32 g/mole and 18 g/mole respectively.
$2H_2+O_2\to 2H_{2}O$
$2\times 2=4$ g of hydrogen reacts with $1\times 32=32$ g of oxygen to form $2\times 18=36$ g of water.
Hence, $\frac{4}{4}=1$ g of hydrogen reacts with $\frac{32}{4}=8$ g of oxygen to form $\frac{36}{4}=9$ g of water.

9 grams of water can be produced when 8 g of hydrogen reacts with 8 g oxygen.