Question

What volume (in mL) of 0.0149 M HBr solution is required to titrate 125 mL of a 0.0132 M Ca(OH)2 solution?
Ca(OH)2(aq) + 2 HBr(aq) → CaBr2(aq) + 2 H2O(l)

Answer 1

$Ca(OH)_2(aq) + 2 HBr(aq) → CaBr_2(aq) + 2 H_2O(l)$

From the equation, we can see that 1 mole of Ca(OH)2 requires 2 moles of HBr.

Let the volume of HBr solution = x mL

millimoles of HBr in x mL = 0.0149x

millimoles of Ca(OH)2 in 125 mL = 125×0.0132

Thus,

$0.0149x = 2 \times 125 \times 0.0132 \\ \\ x = \frac{2 \times 125 \times 0.0132}{0.0149} \\ \\ x = 221.48 \: ml$


So you need 221.48 mL of HBr for titration.

Answer 2

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$Ca(OH)_2(aq) + 2 HBr(aq) → CaBr_2(aq) + 2 H_2O(l)$

From the equation, we can see that 1 mole of Ca(OH)2 requires 2 moles of HBr.

Let the volume of HBr solution = x mL

millimoles of HBr in x mL = 0.0149x

millimoles of Ca(OH)2 in 125 mL = 125×0.0132

Thus,

$0.0149x = 2 \times 125 \times 0.0132 \\ \\ x = \frac{2 \times 125 \times 0.0132}{0.0149} \\ \\ x = 221.48 \: ml$

So you need 221.48 mL of HBr for titration.