Question

(5 pts) At 20°C, a 0.376 M aqueous solution of ammonium chloride has a density of 1.0045 g/mL. What is the mass % of ammonium chloride in the solution? The formula weight of NH4Cl is 53.50 g/mol. 5) (5 pts) At 20°C, an aqueous solution that is 24.0% by mass in ammonium chloride has a density of 1.0674 g/mL. What is the molarity of ammonium chloride in the solution? The formula weight of NH4Cl is 53.50 g/mol. i got 3.82 * 10^-4 on the first one and 5.44 on the second. can you tell me if it is right

Answer 1

1)

let volume of solution be 1 L

M = 0.376 M

so,

number of mol of NH4Cl = Molarity * volume

= 0.376 M * 1 L

= 0.376 mol

mass of of NH4Cl = number of mol of NH4Cl * molar mass of NH4Cl

= 0.376 mol * 53.50 g/mol

= 20.116 g

density of solution is 1.0045 g/mL

volume = 1 L = 1000 mL

So,

mass of solution = density * volume

= 1.0045 g/mL * 1000 mL

= 1004.5 g

mass % of NH4Cl = mass of NH4Cl * 100 / total mass

= 20.116 g * 100 / 1004.5 g

= 2.00 %

Answer: 2.00 %

2)

let volume of solution be 1 L

density of solution is 1.0674 g/mL

volume = 1 L = 1000 mL

So,

mass of solution = density * volume

= 1.0674 g/mL * 1000 mL

= 1067.4 g

mass % of NH4Cl = mass of NH4Cl * 100 / total mass

24.0= mass of NH4Cl * 100 / 1067.4 g

= 256.18 g

number of mol of NH4Cl = mass / molar mass

= 256.18 g / 53.50 g/mol

= 4.7883 mol

Since volume is 1 L,

Molarity = number of mol / volume

= 4.7883 mol / 1 L

= 4.7883 M

Answer: 4.7883 mol