1.What should be the pressure of a gas if the volume of the gas at STP condition is
reduced by 80% keeping the temperature constant.?
2.At what initial pressure should have been a gas of 50 mL at 300 K if the pressure after
expansion by 10 times becomes 100 mm ?
class 11 chapter 5
please solve these
Answers
1. What should be the pressure of a gas if the volume of the gas at STP condition is reduced by 80% keeping the temperature constant ?
answer : initial volume of gas, V = 22.4 L ( at STP)
initial pressure , P = 1 atm
final volume, V' = V - 80% of V = 0.2V = 0.2 × 22.4 = 4.48 L
final pressure , P' = ?
when temperature remains constant.
PV = constant,
⇒PV = P'V'
⇒22.4 × 1 = 4.48 × P'
⇒P' = 22.4/4.48 = 5 atm
2. At what initial pressure should have been a gas of 50 mL at 300 K if the pressure after expansion by 10 times becomes 100 mm ?
answer : initial volume, V = 50 ml
final volume, V' = 10V = 500 ml
initial pressure, P = ?
final pressure , P' = 100 mm
temperature remains constant,
PV = P'V'
⇒50 × P = 500 × 100
⇒P = 1000 mm
Therefore the initial pressure is 1000 mm