Question

How do you work out the concentration of HCl after mixing?

Part 1b: Effect of Hydrogen lon Concentration on Reaction Rate (1 mark) You are supplied with stock solutions of: • sodium thiosulfate (0.25 mol L-1) · hydrochloric acid (1 mol L.) Volume of Na2S2O3 Volume of water Volume of HCI Total volume Concentration of HCI after mixing (mL) (mL) (mL) (mol L) (mL) 0 45 45 1 45 45 3

Answer 1

Molarity = No of moles of HC1 Volume of solution (in L) Also, No of moles of HCl = Molarity of HCl stock x Volume of HCI (in L) Now, Molarity of HCl stock = 1 mol/L 1L And, Volume of solution = 50 mL = 50 mLx -= 0.05 L 1000 mL 1 mol/L < Volume of HC1 (in L) Hence, Molarity = 2 -= (20 x Volume of HCl) mol/L 0.05 L Volume of HCl (in ml) 5 4 3 Volume of HCl (in L) (v/1000) 0.005 0.004 0.003 0.002 0.001 Concentration of HCl (mol/L) (20)x(v/1000) 0.1 0.08 0.06 0.04 0.02