Question

P
Calculate the number of molecules in a deep breath of air whose volume is 2 35 L at body temperature 36 C and a presyre of 740 torr
Express the answer in molecules to three significant figures

Answer 1

5.426 x $10^{22}$ molecules are there in a deep breath of air whose volume is 2. 35 L at body temperature 36 C and a pressure of 740 torr.

Explanation:

Data given:

volume V = 2.35 L

Temperature T = 36 Degrees or 273.15 + 36 = 309.15 K

pressure P = 740 torr OR 0.973 Atm

R = 0.08205 L atm / mole K

n (number of molecules of gas)= ?

The formula used will be

PV = nRT

Putting the value of given variables in above equation:

n = $\frac{PV}{RT}$

 = $\frac{0.973 x 2.35}{0.08205 x 309.15}$

 = 0.0901 moles

According to Avagadro' s law that gases at equal volume, temperature and pressure contains same molecules.

number of molecules:

number of moles x avagadro number

0.0901 x 6.02 x $10^{23}$

= 0.54 x $10^{23}$

= 5.426 x $10^{22}$ molecules.