Question

A solution of ammonia and water contains 4.20×1025 water molecules and 6.20×1024 ammonia molecules. how many total hydrogen atoms are in this solution? enter your answer numerically.

Answer 1

The molecular formula of water and ammonia is $H_2O$ and $NH_3$ respectively.

From the atomic symbol of water it is clear that 1 mole of water contains 2 moles of hydrogen.

So, $4.20\times 10^{25}$ molecules of water contains $2\times 4.20\times 10^{25} = 8.40\times 10^{25}$ atoms of hydrogen.

From the atomic symbol of ammonia it is clear that 1 mole of ammonia contains 3 moles of hydrogen.

So, $6.20\times 10^{24}$ molecules of ammonia contains $3\times 6.20\times 10^{24} = 18.6\times 10^{24}$ atoms of hydrogen.

Total number of hydrogen atoms present in the solution = number of hydrogen atoms in water + number of hydrogen atoms in ammonia.

Substituting the values,

Total number of hydrogen atoms present in the solution = $8.40\times 10^{25}+1.86\times 10^{25}$

Total number of hydrogen atoms present in the solution = $10.26\times 10^{25} atoms$.

Hence, the total number of hydrogen atoms present in the solution is $10.26\times 10^{25}$ atoms.