Question

a closed flask of air (0.250 L) contains 5.00 "puffs" of particles. The pressure probe on the flask reads 93 kPa. A student uses a syringe to add an additional 3.00 "puffs" of air through the stopper. Find a new pressure inside the flask.

Answer 1

Answer: New pressure inside the flask would be 148.8 kPa.

Explanation: The combined gas law equation is given by:

`PV=nRT`

As the flask is a closed flask, so the volume remains constant. Temperature is constant also.

So, the relation between pressure and number of moles becomes

`P=n\\or\\(P)/(n)=constant`

`(P_1)/(n_1)=(P_2)/(n_2)`

• Initial conditions:

`P_1=93kPa\\n_1=5\text{ puffs}`

• Final conditions: When additional 3 puffs of air is added

`P_2=?kPa\\n_2=8\text{ puffs}`

Putting the values, in above equation, we get

`(93)/(5)=(P_2)/(8)\\P_2=148.8kPa`