Question

A chemist needs to determine the concentration of a solution of nitric acid, HNO3. She puts 905 mL of the acid in a flask along with a few drops of indicator. She then slowly adds 0.600 M Ba(OH)2 to the flask until the solution turns pink, indicating the equivalence point of the titration. She notes that 205 mL of Ba(OH)2 was needed to reach the equivalence point.

a) How many moles of Ba(OH)2 are present in 205 mL of 0.600 M Ba(OH)2?

Express your answer with the appropriate units.

Answer 1

Answer:

The balanced reaction between Nitric acid and Barium Hydroxide can be written as;

2HNO₃+ Ba(OH)₂ => Ba(NO₃)₂ + 2H₂O

Hence 2 moles of nitric acid requires 1 mole of barium hydroxide. As equivalence point and volume is already given;

205 mL of Ba(OH)₂ requires at the equivalence point.

The molarity of barium hydroxide given = 0.600 M (or moles/L)

From Molarity relation;

0.6 moles in = 1 Litre of solution or 1000 mL of solution

Hence, 205 mL of solution will contains = (0.6 moles/1000 mL) x 205 mL = 0.123 moles

0.123 moles of Ba(OH)₂ are present in 205 mL of solution.

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