Question

HBr(aq) + NaOH(aq) → H2O(l) + NaBr(aq) 25.00 mL of an HBr solution of unknown molarity reacts with 28.41 mL of 0.1500 M NaOH. What is the Molarity of the HBr solution?

Answer 1

Volume of NaOH, V = 28.41mL = 28.41/1000 = 0.02841L

Molarity of NaOH, M = 0.1500M

Moles of NaOH, n = molarity(mol/L) X Volume (L)

= (0.1500 mol/L) X 0.02841L

= 0.00426 mol

from the reaction it is clear that 1 mol of NaOH reacts with 1 mol of HBr , so 0.00426 mol of NaOH will react with 0.00426mol of HBr.

Moles of HBr =0.00426

Volume of HBr = 25mL = 25/1000 = 0.025 L

molarity of HBr = moles of HBr / Volume of HBr

= 0.00426/0.025 = 0.17 M

so,  Molarity of the HBr solution is 0.17M