How many grams of hydrogen are present in 2 moles of H_2O?

• A. 4.0 g
• B. 18.0 g
• C. 2.0 g
• D. 8.0 g

Answer: (D)

Verified step by step guidance

1. Identify the chemical formula of water, which is \(\mathrm{H_2O}\), meaning each molecule contains 2 hydrogen atoms and 1 oxygen atom.
2. Determine the molar mass of hydrogen atoms in one mole of water. Since each water molecule has 2 hydrogen atoms, the total moles of hydrogen in 1 mole of \(\mathrm{H_2O}\) is 2 moles of hydrogen atoms.
3. Calculate the mass of hydrogen in 1 mole of water by multiplying the number of moles of hydrogen atoms (2 moles) by the molar mass of hydrogen (approximately 1.0 g/mol): \$2 \times 1.0 \ \mathrm{g/mol}$.
4. Since the problem asks for the mass of hydrogen in 2 moles of water, multiply the mass of hydrogen in 1 mole of water by 2: \$2 \times (\text{mass of hydrogen in 1 mole of } \mathrm{H_2O})$.
5. The result from step 4 gives the total grams of hydrogen present in 2 moles of water.