1.A solution is prepared by dissolving 0.25 g of sodium oxide in water to give 1

ID: 703938 • Letter: 1

Question

1.A solution is prepared by dissolving 0.25 g of sodium oxide in water to give 132.0 mL of solution.

Express the pH to two decimal places.

2.A solution is prepared by dissolving 1.29 g of pure nitric acid in water to give 0.495 L of solution.

Express the pH to three decimal places.

3.A solution is prepared by diluting 43.5 mL of 6.5×10?2M Ba(OH)2 to a volume of 270.5 mL .

Express the pH to two decimal places.

4.A solution is prepared by mixing equal volumes of 0.16 M HCl and 0.52 M HNO3. (Assume that volumes are additive.)

Express the pH to two decimal places.

Ans 1

Mass of NaOH = 0.25 g

Moles of NaOH = mass/molecular weight

= 0.25g / 40 g/mol

= 0.00625 mol

Concentration of NaOH = moles/Volume

= 0.00625 mol / (132 mL x 1L/1000 mL)

= 0.0473 M

Concentration of OH- = Concentration of NaOH

= 0.0473 M

pOH = - log [OH-] = - log (0.0473) = 1.325

pH = 14 - 1.325

= 12.68

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