91Ó°ÊÓ

The pink dots in the given figure represents the$O$atom. So, the number of$O$atoms in citric acid is 7.

The black dot represents the $C$atom, thus the number of $C$atoms in citric acid is 6. And the blue dots represent the $\text{H}$atom, so the number of $\text{H}$atoms in citric acid is 8.

Therefore, the formula of citric acid is$C_6{H}_8{O}_7.$

The molar mass of = 12.01 g/mol

The molar mass of = 1.008 g/mol

The molar mass of = 16 g/mol

The molar mass of citric acid is calculated as:

$\begin{array}{rcl}molar mass of C_6{H}_8{O}_7& =& \left(6×molar mass of C\right)+\left(8×molar mass of H\right)+\left(7×molar mass of O\right)\\ & & \left(6×12.01 g/mol\right)+\left(8×1.008 g/mol\right)+\left(7×16 g/mol\right)\\ & & 192.124 g/mol\end{array}$

Since 1 qt is nearly equal to 946.35 mL.

The mass fraction of citric acid(W) = 6.82 %

The density of citric acid (d) = 1.09 g/mL

The volume of citric acid(V) = 1.50 qt

Thus, the mass of citric acid(m) is calculated as:

$\begin{array}{rcl}m& =& w d V\\ & =& 0.0682×1.09 g/mL×4.79×946.35 mL\\ & =& 336.98 g\end{array}$

The molar mass of citric acid = 192.124 g/mol

The mass of citric acid = 336.98 g

The number of moles of citric acid is calculated as:

$\begin{array}{rcl}& & \text{moles} \text{of} \text{citric} \text{acid=}\frac{\text{mass} \text{of} \text{citric} \text{acid}}{\text{Molar} \text{mass} \text{of} \text{citric} \text{acid}}\\ & & \text{=}\frac{\text{336.98} \text{g}}{\text{192.124} \text{g/mol}}\\ & & \text{=1.75} \text{mol}\end{array}$