To get the answer you use the Law of Raoult.
Raoult's law states that the decrease of the vapor pressure of a liquid is proportional to the molar fraction of the solute.
ΔP = Pa * Xa
Here Pa = 0.038 atm
And Xa = N a / (Na + Nb), where Na is number of moles of A and Nb is number of moles of b
Na = mass of urea / molar mass of urea = 60 g / (molar mass of CH4N2O)
molar mass of CH4N2O = 12 g/mol + 4*1g/mol + 2*14 g/mol + 16 g/mol = 60 g/mol
Na = 60 g / 60 g/mol = 1 mol
Nb = mass of water / molar mass of water = 180g / 18g/mol = 10 mol
Xa = 1 mol / (10 mol + 1 mol) = 1/11 =0.09091
ΔP = Pb * Xa = 0.038 atm * 0.09091 = 0.0035 atm
Then, the final vapor pressure of water is Pb - ΔP = 0.038atm - 0.0035atm = 0.035 atm.
Answer: 0.035 atm
The equilibrium vapour pressure is typically the pressure exerted by a liquid .... it is A FUNCTION of temperature...
Explanation:
By way of example, chemists and physicists habitually use
P
saturated vapour pressure
...where
P
SVP
is the vapour pressure exerted by liquid water. At
100
∘
C
,
P
SVP
=
1
⋅
a
t
m
. Why?
Well, because this is the normal boiling point of water: i.e. the conditions of pressure (i.e. here
1
⋅
a
t
m
) and temperature, here
100
∘
C
, at which the VAPOUR PRESSURE of the liquid is ONE ATMOSPHERE...and bubbles of vapour form directly in the liquid. As an undergraduate you should commit this definition, or your text definition, to memory...
At lower temperatures, water exerts a much lower vapour pressure...but these should often be used in calculations...especially when a gas is collected by water displacement. Tables of
saturated vapour pressure
are available.
Answer:
Billions in the known universe!
Explanation:
Because there are approximately 100 billion galaxies in the observable universe.
Hope it helps!
