On a humid day in summer, the mole fraction of gaseous H2O (water vapour) in the air at 25° C can be as high as 0.0287 . Assuming a total pressure of 0.977 atm. What is the partial pressure of dry air?

Question

On a humid day in summer, the mole fraction of gaseous H2O (water vapour) in the air at 25° C can be as high as 0.0287 . Assuming a total pressure of 0.977 atm. What is the partial pressure of dry air? (A) 94.9 atm (B) 0.949 atm (C) 949 atm (D) 0.648 atm

Tardigrade Admin · Accepted Answer

PH2O=XH2OPtotal =0.0287× 0.977 =0.028 text atm Ptotal=Pdry air+PH2O Pdry air=Ptotal-PH2O =0.977-0.028=0.949 text atm

Q. On a humid day in summer, the mole fraction of gaseous $H_{2} O$ (water vapour) in the air at $25^{\circ} C$ can be as high as $0.0287$ . Assuming a total pressure of $0.977$ atm. What is the partial pressure of dry air?

94.9 atm

0.949 atm

949 atm

0.648 atm

1.248 atm

$P_{H_{2} O} = X_{H_{2} O} P_{t o t a l}$
$= 0.0287 \times 0.977$ $= 0.028 a t m$
$P_{t o t a l} = P_{d ry ai r} + P_{H_{2} O}$
$P_{d ry ai r} = P_{t o t a l} - P_{H_{2} O}$
$= 0.977 - 0.028 = 0.949 a t m$

Q. On a humid day in summer, the mole fraction of gaseous H2​O (water vapour) in the air at 25∘C can be as high as 0.0287 . Assuming a total pressure of 0.977 atm. What is the partial pressure of dry air?