Respuesta :
Answer:
The molality of HCl solution is 16.24 mol/kg.
The molality of [tex]HC_2H_3O_2[/tex] solution is 82,500 mol/kg.
The molality of [tex]NH_3[/tex] solution is 27.78 mol/kg.
Explanation:
formula used:
[tex]Molality=\frac{Moles}{\text{Mass of solvent(kg)}}[/tex]
1) Mass percentage of the HCl solution = 37.2%
This means that in 100 grams of solution 37.2 grams of HCl is present.
Mass of HCl (solute)= 37.2 g
Mass of water(solvent) = 100 g - 37.2 g = 62.8 g = 0.0628 kg (1g = 0.001 kg)
Mole of HCl = [tex]\frac{37.2 g}{36.465 g/mol}=1.020 mol[/tex]
[tex]Molality=\frac{Moles}{\text{Mass of solvent(kg)}}[/tex]
[tex]m=\frac{1.020 mol}{0.0628 kg}=16.24 mol/kg[/tex]
The molality of HCl solution is 16.24 mol/kg.
2) Mass percentage of the [tex]HC_2H_3O_2[/tex] solution = 99,8%
This means that in 100 grams of solution 99.8 grams of [tex]HC_2H_3O_2[/tex] is present.
Mass of [tex]HC_2H_3O_2[/tex](solute)= 99.8 g
Mass of water(solvent) = 100 g - 99.8 g = 0.2 g = 0.0002 kg (1g = 0.001 kg)
Mole of [tex]HC_2H_3O_2[/tex] = [tex]\frac{99.8 g}{60.05g/mol}=16.50 mol[/tex]
[tex]Molality=\frac{Moles}{\text{Mass of solvent(kg)}}[/tex]
[tex]m=\frac{16.50 mol}{0.0002 kg}=82,500 mol/kg[/tex]
The molality of [tex]HC_2H_3O_2[/tex] solution is 82,500 mol/kg.
3) Mass percentage of the [tex]NH_3[/tex] solution = 28.0%
This means that in 100 grams of solution 28.0 grams of [tex]NH_3[/tex] is present.
Mass of [tex]NH_3[/tex](solute)= 37.2 g
Mass of water(solvent) = 100 g - 28.0 g = 72.0 g = 0.072 kg (1g = 0.001 kg)
Mole of [tex]NH_3[/tex]= [tex]\frac{28.0g}{17 g/mol}=2mol[/tex]
[tex]Molality=\frac{Moles}{\text{Mass of solvent(kg)}}[/tex]
[tex]m=\frac{2 mol}{0.072kg}=27.78 mol/kg[/tex]
The molality of [tex]NH_3[/tex] solution is 27.78 mol/kg.
