Explore BrainMass

Molarity, Mole, Dilution

See the attached file.

1. A sample of concetrated nitric acid has density of 1.41g/ml and contains 70% HNO3, by mass.
a. What mass of HNO3 is present per litre of solution?(in g/l)
b. What is the molarity of the solution?

2. Calculate each of the following quantities.

a. molarity of a solution prepared by diluting 32.14ml of 0.238M potassium chloride to 150.00ml

b. molarity of a solution prepared by diluting 27.83ml of 0.0682M ammonium sulfate to 500.00ml

c. molarity of sodium ion in a solution made by mixing 3.79ml of0.284M sodium chloride with 500.00ml of 6.51 x 10-3M sodium sulfate(assume volumes are additive)

(Write answers in standard form).


Solution Preview

The solution is attached.

Density of concetrated HNO3 = 1.47g/ml

a) Mass of HNO3 = 70% of 1.47g
= 70/100 x 1.47g = 0.987g
Mass of water = Mass of conc. HNO3 solution - Mass of HNO3
= (1.41 - 0.987)g
= 0.423g
1ml of water weighs approximately 1g
Therefore, 0.423g water has volume of 0.423ml
HNO3 was prepared by dissolving 0.987g HNO3 in 0.423ml of water.
0.423ml of water contained 0.987g HNO3
1ml water =( 0.987/0.423)g
1000ml water = (0.987/0.423)g x 1000
= 2.3333 x 103g/l

Alternatively, Mass Conc.(g/l) = mass in g/volume(l)
= 0.987g

Solution Summary

The solution assists with calculating the molarity, mole and dilution in the given problem.