Question

1)a solution of ammonia has a concetration of 7.42M. How much of thus solution will be needed to get 0.0491 mol of ammonia? 2) a concentrated solution of ammonia has a concentration of 15.0M. How much of this solution is needed to make 250mL of 1.65M ammonia solution? 3) You take 150mL of 18.0 M H2So4 solution and dilute it to a total volume of 3.75 L. what is the concentration of the dilute solution?

Answer 1

1) Molarity of NH3 = 7.42M

Volume of 7.42 M solution required for 0.0491mol is given by

Molarity, M= no. of moles/Volume

Volume = 0.0491/7.42 = 6.61*10^-3 mL

2) Dilution law is given by, M1V1=M2V2

M1=molarity of ammonia given = 15.0M

V1= Volume of NH3 to be taken=?

M2= molarity of NH3 needed = 1.65M

V2=Volume of NH3 needded= 250mL

V1 = M2V2/M1 = 1.65*250/15.0 = 27.5mL

Therefore the volume of 15.0M NH3 to be taken to prepare 1.65M of 250mL NH3 is 27.5mL

3) M1V1=M2V2

M1=molarity of H2SO4 given = 18.0M

V1= Volume of H2SO4 given=150mL

M2= molarity of H2SO4 after dilution=?

V2= Volume of H2SO4 after dilution= 3.75L = 3750mL

M2 = M1V1/V2 = 18.0*150/3750 =0.72M

Therefore the molarity of the 18.0M of 150mL of H2SO4 solution after dilution to 3.75L is 0.72M