Question

Calculate the molality of a solution containing 14.3 g of nacl in 42.2 g of water.

a. 2.45 ï´ 10â4 m
b. 5.80 ï´ 10â4 m
c. 2.45 ï´ 10â1 m
d. 103 m
e. 5.80 m

Answer 1

Answer: e) 5.80 m

Step-by-step explanation:

Molality : It is defined as the number of moles of solute present per kg of solvent

Formula used :

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

where,

n= moles of solute

To calculate the moles, we use the equation:

`\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}=(14.3g)/(58.5)=0.24moles`

`W_s` = weight of solvent in g= 42.2 g

Now put all the given values in the formula of molarity, we get

`Molarity=(0.24moles* 1000)/(42.2g)=5.80mole/kg`

Therefore, the molality of solution will be 5.80 m

Answer 2

molarity =Number of moles of compound*1000/(mass of solvent)

Number of moles of NaCl=Given mass/molar mass

Given mass of NaCl=14.3 g

molar mass of NaCl=58.44g

Number of moles of NaCl= 14.3/58.44

=0.244

Mass of solvent (Water)=42.2 g

Molarity=0.244*1000/(42.2)

= 5.80m