A beaker contains 9 g of water. The number of hydrogen atoms are:
Correct answer: A. 6.02 x 10^23
- A. 6.02 x 10^23
- B. 3.01 x 10^23
- C. 6.02 x 10^24
- D. 3.01 x 10^24
Explanation
Calculate the moles of H₂O in 9 g. moles (n) = mass (m)/molar mass (M) M(H₂O) = (2 × 1 g/mol H) + 16 g/mol O = 18 g H₂O/mol H₂O n(H₂O) = 9 g H₂O/18 g H₂O/mol H₂O = 0.5 mol H₂O In one mole of H₂O, there are two moles of H atoms. Calculate the moles of H atoms in 0.5 mol H₂O. 0.5 mol H₂O × 2 mol H atoms/1 mol H₂O = 1 mol H atoms Calculate the number of H atoms in 1 mole. 1 mole = 6.02 × 10²³ atoms 1 mole H atoms = 6.02 × 10²³ H atoms There are 6.022 × 10²³ atoms of hydrogen in 9 g of water.
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