Question

Ross (he was on break) pours water at 6.0 c into a container with a pressure of 23. torr. he then boils the water to a temperature of 34
c. the volume changes to 18. ml and pressure to 78. torr. what was the initial volume of the water?

Answer 1

For this question, since the parameters volume, pressure and temperature changes, we can use the combined gas law equation.
It states that PV/T = constant 
Therefore,
$\frac{P1V1}{T1} = \frac{P2V2}{T2}$
Where parameters for the first instance are given on the left side and parameters for the second instance are given on the right side of the equation
Temperature in K - T1 = 6 °C + 273 = 279 K
                               T2 = 34 °C + 273 = 307 K
substituting the values in the equation
$\frac{23.0 torr*V}{279K} = \frac{78 torr*18 mL }{307 K}$
V = 55.5 mL