Question

14. A child's lungs can hold 2.20 L. How many grams of air do her lungs hold at a pressure of

102 kPa and a body temperature of 37°C? Use a molar mass of 29 g/mol for air, which is about 20% O2 and 80% N2.

Answer 1

Step-by-step explanation:

Use the gas equation: PV=nRT

P=pressure

V=Volume

R= gas constant of around 8.31 J/K/mol

T=temperature

n= number of moles

To find n, Rearrange:

n=PV/RT

102kPa= 102,000 kilo pascals which standard form is 102 x 10^3

Convert Celsius to kelvin, which you just add 273.15. So:

37+273.15=310.15 K round to a whole number is 310 K

Sub in all numbers to calculate the mol

n= 102 x 10^3 x 2.20 x 10^3/ 8.31 x 310 (cross out 10^3 as this will make a big number)

n=102 x 2.2/8.31 x 310 =0.087 mol

We know 1 g=29 moles

Multiply 29 moles with 0.087 to find the grams

29*0.087=2.523, which to one d.p is 2.5 g

Hence, the child's lung will hold 2.5 g of air.

Hope this helps you :)

Have a nice day!!

Answer 2

The mass of air is 2.53 grams

Step-by-step explanation:

Step 1: Data given

Volume of the lungs = 2.20 L

Pressure = 102 kPa = 1.00666 atm

Body temperature = 37.0 °C = 310 K

Molar mass of air = 29 g/mol

Step 2: Calculate number of moles

p*V = n*R*T

⇒with p = the pressure = 1.00666 atm

⇒with V = the volume of the lungs = 2.20 L

⇒with n = the number of moles air = TO BE DETERMINED

⇒with R = the gas constant = 0.08206 L*atm/mol*K

⇒with T = the temperature = 310 K

n = (p*V)/(R*T)

n = (1.00666 * 2.20) / (0.08206* 310)

n = 0.0871 moles

Step 3: Calculate mass of air

Mass air = moles of air * molar mass

Mass air = 0.0871 moles * 29 g/mol

Mass air = 2.53 grams

The mass of air is 2.53 grams