A chemist weighed out 1.36 g of mercury. Calculate the number of moles of mercury she weighed out.

Be sure your answer has the correct number of significant digits.

1 answer

To calculate the number of moles of mercury (Hg) weighed out, you can use the formula:

\[
\text{Number of moles} = \frac{\text{Mass}}{\text{Molar mass}}
\]

The molar mass of mercury (Hg) is approximately \( 200.59 \text{ g/mol} \).

Given:
- Mass of mercury = \( 1.36 \text{ g} \)
- Molar mass of mercury (Hg) = \( 200.59 \text{ g/mol} \)

Now, calculate the number of moles:

\[
\text{Number of moles} = \frac{1.36 \text{ g}}{200.59 \text{ g/mol}}
\]

\[
\text{Number of moles} \approx 0.006779 \text{ moles}
\]

Since the mass given \( (1.36 \text{ g}) \) has 3 significant digits, the final answer should also be reported with 3 significant digits:

\[
\text{Number of moles} \approx 0.00678 \text{ moles}
\]

Therefore, the number of moles of mercury she weighed out is approximately \( 0.00678 \text{ moles} \).