Question

A 1.50 liter flask at a temperature of 25°C contains a mixture of 0.158 moles of methane, 0.09 moles of ethane, and 0.044 moles of butane. What is the total pressure of the mixture inside the flask?

Answer 1

Answer: The pressure of the mixture inside the flask is 4.76 atm

Step-by-step explanation:

To calculate the pressure, we use the equation given by ideal gas equation:

PV = nRT

where,

P = Pressure of the flask = ?

V = Volume of the flask = 1.50 L

n = Total number of moles = 0.158 + 0.09 + 0.044 = 0.292 moles

R = Gas constant =
`0.0820\text{ L atm }mol^(-1)K^(-1)`

T = Temperature of the flask =
`25^oC=[25+273]K=298K`

Putting values in above equation, we get:

`P* 1.50L=0.292mol* 0.0820\text{ L atm }mol^(-1)K^(-1)* 298K\\\\P=(0.292* 0.0820* 298)/(1.50)=4.76atm`

Hence, the pressure of the mixture inside the flask is 4.76 atm

Answer 2

The total amount of moles inside the flask is
n = 0.158 + 0.09 + 0.044 = 0.292 mole

According to Boyle's Law, the total pressure of a mixture in a container does not depend on the identity of the gas and only on the amount of the number of moles. So, assuming the mixture behaves like an ideas gas:
P = nRT/V = 0.292 (0.08206) (25+273) / (1.50)
P = 4.76 atm