Question

a 35.0 ml sample of 0.225 m hbr was titrated with 42.3 ml of koh. what is the concentration of the koh?
0 0.303 m
0 0.157 m
0 0.186 m
0 0.272 m
0 none of the above

Explanation:

Step1: Recall titration formula

$M_1V_1 = M_2V_2$ (1:1 reaction HBr+KOH)

Step2: Plug in values

$M_2 = \frac{M_1V_1}{V_2} = \frac{0.225\,\text{M} \times 35.0\,\text{mL}}{42.3\,\text{mL}}$

Step3: Calculate concentration

$M_2 = \frac{7.875}{42.3} \approx 0.186\,\text{M}$

Answer:

C. 0.186 M