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6. a) If concentrated hydrochloric acid is 12 M.. explain how you would prepare

ID: 875596 • Letter: 6

Question

6. a) If concentrated hydrochloric acid is 12 M.. explain how you would prepare 80 ml of a 1.5 M solution. (i.e. What volumes would you use?) Also record your answer on the data page for Part I. b) If sodium hydroxide pellets are used, explain how you would prepare 80 ml of a 1.5 M sodium hydroxide solution. (i.e. What mass and volumes would you use?) Also record your answer on the data page for Part 1. c) If concentrated hydrochloric acid is 12 M, explain how you would prepare 100 ml of a 0.5 M solution. What volumes would you use?) Also record your answer on the data page for Part III.

Explanation / Answer

6)

a) Since the moles of HCl must be same at the left hand side and right hand side

M1V1 = M2V2

V1 * 12 = 80 * 1.5

V1 = 10 ml

Hence dilute acid will contain, 10mL of concentrated acid in 70mL of water to get 80 mL of HCl solution with concentration equal to 1.5 M

b) Number of moles of Sodium Hydroxide = M * V = 80/1000 * 1.50 = 0.120 moles

Hence amount of NaOH pellets required = 0.120 * (Molecular weight of NaOH)

Molecular weight of NaOH = 23 + 16 + 1 = 40 gm/mol

Amount of NaOH pellets required = 0.120 * 40 = 4.8 gms

c) Since the moles of HCl must be same at the left hand side and right hand side

M1V1 = M2V2

V1 * 12 = 100 * 0.5

V1 = 4.1667 ml

Hence dilute acid will contain, 4.1667 mL of concentrated acid in 95.8333mL of water to get 100 mL of HCl solution with concentration equal to 0.5 M