Question

A titration is done using 1 M NaOH in the buret and 15mL of 1.8M HCL in the Erlenmeyer flask. How many moles of HCl are left in the flask after a total of 5mL of the 1M NaOH solution were added to the flask

Answer 1

given

Molarity of NaOH M1 = 1 M = 1 mol/L

Volume of NaOH added V1 = 5 ml = 0.005 L

Molarity of HCl M2 = 1.8 M = 1.8 mol/L

Volume of HCl nuetralized by 5 ml of 1 M NaOH = V2

M1 * V1 = M2 * V2

1 mol/L * 0.005 L = 1.8 mol/L * V2

V2 = 0.002778 L = 2.778 ml

No. of moles of HCl consumed = Volume of HCl Consumed * Molarity of HCl = 0.002778 L * 1.8 mol/L = 0.005 moles

Volume of HCl present in flask intially = 15 ml = 0.015 L

No. of moles of HCl present in flask intially = intial HCl Volume * Molarity of HCl = 0.015 L * 1.8 mol/L = 0.027 moles

No. of moles of HCl left in flask = 0.027 moles - 0.005 moles = 0.022 moles answer