Asked by Chem master

A 25.0 mL sample of NaHSO4(aq) was titrated with 0.500 mol/L NaOH(aq) using phenolphthalein indicator. At the endpoint, one drop of NaOH(aq) was sufficient to change the phenolphthalein indicator from colourless to pink. To reach this point, 10.2 mL of NaOH(aq) had been added. What is the concentration of the NaHSO4(aq)?
Answered by Chem master
Please show all work. I’m very confused with this question
Answered by DrBob222
No need to be confused. Reactions reach the end point when mols of one = mol equivalent of the other. So how many millimoles (1000*mols) NaOH were added. That's mL x M = millimols = 10.2 mL x 0.500 = 5.1
So you have 5.1 millimols NaHSO4 in that sample. It was in 25.0 mL so the concentration in millimols/mL = mols/L = M = 5.1 mmols/25.0 mL = ?
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