Question

1. calculate the number of molecules in 11.5 mol of water. (0.5 points) *

1.91 x 10⁻²³ molecules
5.78 x 10²² molecules
6.93 x 10²² molecules
6.93 x 10²⁴ molecules

Explanation:

Step1: Recall Avogadro's number

Avogadro's number is \( 6.022 \times 10^{23} \) molecules per mole. This means that 1 mole of any substance contains \( 6.022 \times 10^{23} \) particles (in this case, molecules of water).

Step2: Use the formula to calculate number of molecules

The formula to find the number of molecules (\( N \)) is \( N = n \times N_A \), where \( n \) is the number of moles and \( N_A \) is Avogadro's number. Here, \( n = 11.5 \) mol and \( N_A = 6.022 \times 10^{23} \) molecules/mol.
So, \( N = 11.5 \times 6.022 \times 10^{23} \)
First, calculate \( 11.5 \times 6.022 = 69.253 \)
Then, \( N = 69.253 \times 10^{23} = 6.9253 \times 10^{24} \approx 6.93 \times 10^{24} \) molecules.

Answer:

D. \( 6.93 \times 10^{24} \) molecules