Question

What is the pH of a solution made by mixing 500 mL of 1.00 M HCN and 1.50 L of 0.250 M NaOH, and then diluting the entire solution to a volume of 3.00 L? (Ka HCN = 4.0 x 10^-10)

• A.

  8.92

• B. 6.52

• C.

  9.88

• D.

  9.27

• E.

  5.08

To obtain one litre of a solution of pH = 7, you should dissolve in water

• A.

  Two mol of HI + two mol of CH₃NH₂

• B.

  One mol of H₂SO₄ + two mol of NH₃

• C.

  One mol of HF + one mole of KOH

• D.

  Two mol of H₂SO₄ + four mol of NaOH

• E.

  Two mol of H₃PO₄ + three mol of Ca(OH)₂

Answer 1

1.

2.

D. Two mol of H₂SO₄ + four mol of NaOH

The neutralization reaction b/w strong acid and strong base will produce neutral salt .

the balanced equation is

H2SO4 + 2 NaOH -------> Na2SO4   + 2 H2O

from the above reaction

1 mol of H2SO4 needs two moles NaOH

so 2 mol of H2SO4 needs 4 moles of NaOH

so answer is

D. Two mol of H₂SO₄ + four mol of NaOH