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Air in an internal combustion engine is at 440°F and 150 psia, with a volume of 10 in3 What is the mass of air (in lbm)?

1 Answer

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Answer: The mass of air is 0.00260 lbs.

Step-by-step explanation:

To calculate the number of moles, we use the equation given by ideal gas equation:

PV = nRT

Or,


PV=(m)/(M)RT

where,

P = pressure of the gas = 150 psia = 10.2 atm (Conversion factor: 1 psia = 0.068 atm)

V = Volume of gas =
10in^3=0.164L (Conversion factor:
1in^3=0.0164L )

m = mass of air = ?

M = Average molar mass of air = 28.97 g/mol

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

T = temperature of the gas =
440^oF=499.817K (Conversion factor:
(T(K)-273.15)=(T(^oF)-32)* (5)/(9) )

Putting values in above equation, we get:


10.2atm* 0.164L=(m)/(28.97g/mol)* 0.0820\text{ L atm }mol^(-1)K^(-1)* 499.817K\\\\m=1.18g

Converting this mass into lbs, we use the conversion factor:

1 lbs = 454 g

So,
1.18g* (1lbs)/(454g)=0.00260lbs

Hence, the mass of air is 0.00260 lbs.

User Milushov
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