Question

The mole fraction of CO2 in a certain solution with H2O as the solvent is 3.6 × 10−4. What is the approximate molality of CO2 in this solution? A.0.00036 m.B.0.0065 m.C.0.020 m.D.2.0 × 10−5 m.E.6.5 m

Answer 1

Answer: C) 0.020 m

Step-by-step explanation:

Molality of a solution is defined as the number of moles of solute dissolved per kg of the solvent.

`Molality=(n* 1000)/(W_s)`

where,

n = moles of solute

`W_s` = weight of solvent in g

Mole fraction of
`CO_2` is =
`3.6* 10^(-4)` i.e.
`3.6* 10^(-4)` moles of
`CO_2` is present in 1 mole of solution.

Moles of solute
`(CO_2)` =
`3.6* 10^(-4)`

moles of solvent (water) = 1 -
`3.6* 10^(-4)` = 0.99

weight of solvent =
`moles* {\text {Molar mass}}=0.99* 18=17.82g`

Molality =
`(3.6* 10^(-4)* 1000)/(17.82g)=0.020`

Thus approximate molality of
`CO_2` in this solution is 0.020 m