Question

Determine the molality of each of the following solutions

a. 2.34 mol KCI in 2.300 L of solution

b. 0.56 H2SO4 in 2 L of solution

c. 20.45 g AI (NO3)3 in 2000 mL of solution

Answer 1

Molality is a concentration in mole/1000g.

Let dencity of solutions eaual 1 g/ml

a.c=2.34 /2,3=1.02 mol/kg

b. Let it be 0.56 mol ( it is not mentioned in task) of $H_2SO_4$ .

c=0.56/2=0.28 mol/kg

c.$M(Al(NO_3)_3)=27+3(14+16x3)=213 g/mol$

$n(Al(NO_3)_3)=20.45/213=0.096 mol$

$c(Al(NO_3)_3)=0.096/2=0.048 mol/kg$