Concept:When calculating total constituent atoms in a compound, you must multiply the total number of moles by Avogadro's number, and then multiply by the total atomicity (atoms per molecule) of the compound.
Formula:$$ \text{Total Atoms} = n \times \text{Atomicity} \times N_A $$
Solution:- A single water molecule (\( \text{H}_2\text{O} \)) contains exactly 3 atoms (2 Hydrogens + 1 Oxygen). Its atomicity is 3.
- We are given 2 moles of water.
- Total moles of atoms = \( 2 \text{ moles of molecules} \times 3 \text{ atoms/molecule} = 6 \text{ moles of atoms} \).
- Multiply by Avogadro's constant: \( 6 \times (6.022 \times 10^{23}) \).
- \( 6 \times 6.022 = 36.132 \).
- In standard scientific notation: \( 3.61 \times 10^{24} \text{ atoms} \).
Why other options are incorrect:- \( 6.02 \times 10^{23} \): This is the number of molecules in 1 mole of water, completely ignoring both the 2 moles and the atomicity of 3.
- \( 1.24 \times 10^{24} \): This calculates the number of molecules in 2 moles of water, but fails to multiply by 3 to find the number of atoms.
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