Question

Label them 25,26,27,28,29

25) Use this volume of 0.1 M NaCl stock solution to make 20 mls of 1 mM final concentration

26) Use this volume of 10 mM NaCl stock solution to make 1 L of 5 mM final concentration

27) Use this volume of 5 M NaCl stock solution to make 100 mls of 0.35 M final concentration

28) Use this volume of 5 M NaCl stock solution to make 100 mls of 1% final concentration

29) Use this volume of 5 mM NaCl stock solution to make 10 mls of 1 mM final concentration

Answer 1

25: To make 1 mM working solution from 0.1 M stock solution,

M1V1 = M2V2

(0.1 × 10³) mM × V1 = 1 mM × 20 ml

V1 = 1 × 20/  (0.1 × 10³)

V1 = 0.2 ml

0.2 ml from 1 M stock should be added to 19.8 ml of distilled water to make 20 ml of 1 mM working solution.

26: To make 5 mM working solution from 10 mM stock solution,

M1V1 = M2V2

10 mM × V1 = 5 mM × 1000 ml

V1 = 5 × 1000/ 10

V1 = 500 ml

500 ml from 10 mM stock should be added to 500 ml of distilled water to make 1L of 5 mM working solution.

27: To make 0.35 M working solution from 5 M stock solution,

                       M1V1 = M2V2

5 M × V1 = 0.35 M × 100 ml

V1 = 0.35 × 100/ 5

V1 = 7 ml

7 ml from 5 M stock should be added to 93 ml of distilled water to make 100 ml of 0.35 M working solution.

28: To make 1% working solution from 5 M stock solution:

1 % NaCl solution means 1 g of NaCl in 100 ml of water, or 10 g in 1000 ml (1L). From this molarity of working solution can be calculated by:

M = 10/ 58.4 × 1

M = 0.17

now, M1V1 = M2V2

5 M × V1 = 0.17 mM × 100 ml

V1 = 0.17 × 100/ 5

V1 = 3.42 ml

3.42 ml from 5 M stock should be added to 96.58 ml of distilled water to make 100 ml of 1 % working solution.

29: To make 1 mM working solution from 5 mM stock solution,

M1V1 = M2V2

5 mM × V1 = 1 mM × 10 ml

V1 = 1 × 10/ 5

V1 = 2 ml

2 ml from 5 mM stock should be added to 8 ml of distilled water to make 10 ml of 1 mM working solution.