Answer:
[tex]\boxed{\text{378 mL}}[/tex]
Explanation:
The temperature and amount of gas are constant, so we can use Boyle’s Law.
[tex]p_{1}V_{1} = p_{2}V_{2}[/tex]
Data:
[tex]\begin{array}{rclrcl}p_{1}& =& \text{172 kPa}\qquad & V_{1} &= & \text{?} \\p_{2}& =& \text{85.0 kPa}\qquad & V_{2} &= & \text{765 mL}\\\end{array}[/tex]
Calculations:
[tex]\begin{array}{rcl}172V_{1} & =& 85.0 \times 765\\172V_{1} & = & 65 025\\V_{1} & = &\textbf{378 mL}\\\end{array}\\\text{The original volume was } \boxed{\textbf{378 mL}}[/tex]
