How many molecules of water are present in 7.8 moles of water? (1 point)

Question

Responses

4.7 x 1024 molecules
4.7 x 1024 molecules

6.022×1023 molecules
6.022×1023 molecules

4.69 molcules
4.69 molcules

7.8 x 1023 molecules

Answer 1

To calculate the number of molecules present in 7.8 moles of water, you can use Avogadro's number, which is \(6.022 \times 10^{23}\) molecules/mole.

Now, multiply the number of moles by Avogadro's number:

\[ \text{Number of molecules} = 7.8 , \text{moles} \times 6.022 \times 10^{23} , \text{molecules/mole} \]

Calculating this gives:

\[ 7.8 \times 6.022 \approx 46.94 \]

Now multiply by \(10^{23}\):

\[ 46.94 \times 10^{23} = 4.694 \times 10^{24} , \text{molecules} \]

So, rounding this to two significant figures gives approximately:

\[ 4.7 \times 10^{24} , \text{molecules} \]

Thus, the correct response is:

4.7 x 10²⁴ molecules.