Question

QUESTION 7

What is the pH of a solution made by mixing 30.00 mL of 0.10 M HCl with 40.00 mL of 0.10 M KOH? Assume that the volumes of the solutions are additive.

		0.85
		1.85
		12.15
		13.15

1 points (Extra Credit)   

QUESTION 8

Which of the following titrations result in a basic solution at the equivalence point?

		HI titrated with NaCH3CO2
		HOCl titrated with NaOH
		HBr titrated with KOH
		HNO3 titrated with NH3

Answer 1

7)

we have:

Molarity of HCl = 0.1 M

Volume of HCl = 30 mL

Molarity of KOH = 0.1 M

Volume of KOH = 40 mL

mol of HCl = Molarity of HCl * Volume of HCl

mol of HCl = 0.1 M * 30 mL = 3 mmol

mol of KOH = Molarity of KOH * Volume of KOH

mol of KOH = 0.1 M * 40 mL = 4 mmol

We have:

mol(HCl) = 3 mmol

mol(KOH) = 4 mmol

3 mmol of both will react

remaining mol of KOH = 1 mmol

Total volume = 70.0 mL

[OH-]= mol of base remaining / volume

[OH-] = 1 mmol/70.0 mL

= 0.0143 M

we have below equation to be used:

pOH = -log [OH-]

= -log (1.429*10^-2)

= 1.85

we have below equation to be used:

PH = 14 - pOH

= 14 - 1.85

= 12.15

Answer: 12.15

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