What is the mass of 1.20 × 10^{24} atoms of potassium (K)? (Atomic mass of K = 39.1 g/mol)

• A. 46.8 g
• B. 78.2 g
• C. 39.1 g
• D. 78.1 g

Answer: (B)

Verified step by step guidance

1. Identify the given information: the number of potassium atoms is \$1.20 \times 10^{24}$ atoms, and the atomic mass of potassium (K) is 39.1 g/mol.
2. Recall that 1 mole of any element contains Avogadro's number of atoms, which is \$6.022 \times 10^{23}$ atoms/mol.
3. Calculate the number of moles of potassium atoms by dividing the given number of atoms by Avogadro's number using the formula: \(\text{moles} = \frac{\text{number of atoms}}{6.022 \times 10^{23}}\).
4. Use the atomic mass to convert moles to mass with the formula: \(\text{mass} = \text{moles} \times 39.1 \text{ g/mol}\).
5. Multiply the number of moles by the atomic mass to find the mass of potassium corresponding to \$1.20 \times 10^{24}$ atoms.