Question

please do prelab assignment

WEEK 2 PRE-LABORATORY ASSIGNMENT: Before you come to lab, clearly write out in your notebook all calculations necessary for the preparation of the three solutions listed in Part C. Be sure to pay close attention to units! Part C: Preparation of Sodium Sulfate Dilutions An X-fold dilution divides the concentration of a solution by a factor of X. For example: A 5-fold dilution of a 0.25 M stock solution would result in a 0.050 M final solution. A 2.5-fold dilution of a 0.25 M stock solution would result in a 0.10 M final solution.

Answer 1

Molar mass of sodium sulphate(Na2SO4) is 142.04 g/mol. Let the volume of the 0.25 M of stock solution is V ml. Amount of Na2SO4 required to make V ml of 0.25 M stock solution =( 142 Let V1 ml of 0.050 M Na2SO4 has to be prepared from the 0.25 M stock solution, therefore, (142.04xVx0.25) gm. 1000 g m. 0.050 x V1 = 0.25 x x 0.050 V1 0.25 x= 0.2 V1 V = 5 x x Let V2 ml of 0.10 M Na2SO4 has to be prepared from the 0.25 M stock solution, therefore, 0.100 x V2 = 0.25 x x 0.10 X V2 0.25 = 0.4 x V1 x = x V2 V2 = 3 x x NIGN x is the amount of 0.25 M stock solution originally taken before it is diluted.