Question

Calculate the molarity of the following solutions.

A.Calculate the molarity of 0.900 mol of glucose in 0.150 L of a glucose solution.

Express your answer with the appropriate units.

B.Calculate the molarity of 77.5 g of HCl in 2.50 L of an HCl solution.

Express your answer with the appropriate units.

C.Calculate the molarity of 21.5 g of NaOH in 400. mL of an NaOH solution.

Express your answer with the appropriate units.

Answer 1

A)

volume , V = 0.15 L

use:

Molarity,

M = number of mol / volume in L

= 0.9/0.15

= 6 M

Answer: 6.00 M

B)

Molar mass of HCl,

MM = 1*MM(H) + 1*MM(Cl)

= 1*1.008 + 1*35.45

= 36.458 g/mol

mass(HCl)= 77.5 g

use:

number of mol of HCl,

n = mass of HCl/molar mass of HCl

=(77.5 g)/(36.46 g/mol)

= 2.126 mol

volume , V = 2.5 L

use:

Molarity,

M = number of mol / volume in L

= 2.126/2.5

= 0.8503 M

Answer: 0.850 M

C)

Molar mass of NaOH,

MM = 1*MM(Na) + 1*MM(O) + 1*MM(H)

= 1*22.99 + 1*16.0 + 1*1.008

= 39.998 g/mol

mass(NaOH)= 21.5 g

use:

number of mol of NaOH,

n = mass of NaOH/molar mass of NaOH

=(21.5 g)/(40 g/mol)

= 0.5375 mol

volume , V = 4*10^2 mL

= 0.4 L

use:

Molarity,

M = number of mol / volume in L

= 0.5375/0.4

= 1.344 M

Answer: 1.34 M