Neco 2019 Chemistry Question 4

Practice practical question 4 from the 2019 Neco Chemistry examination. This question covers Mole Concept .

Neco 2019 Chemistry Practical

Topic: Mole Concept

Question 4 NECO • 2019 • CHEMISTRY • practical

A student carried out a titration to determine the molar mass of an unknown monoprotic acid (solid). The procedure and data are as follows: 1. The NaOH solution used in the titration was standardised using 0.2000 g of potassium hydrogen phthalate (KHP, molar mass = 204.22 g mol⁻¹). The volume of NaOH required to reach the phenolphthalein endpoint was 21.80 mL. 2. A sample of the unknown acid weighing 0.542 g was dissolved in distilled water and titrated with the same NaOH solution. The volume of NaOH used to reach the endpoint was 23.45 mL. 3. The theoretical molar mass of the pure acid is known to be 120.1 g mol⁻¹. Using the data above, answer the following questions:

( a )

Calculate the actual concentration (M) of the NaOH solution after standardisation with KHP.

( b )

Using the concentration obtained in part (a), determine the molar mass of the unknown acid.

( c )

Calculate the percent purity of the sample, assuming the impurity is inert and the theoretical molar mass of the pure acid is 120.1 g mol⁻¹.

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This is Neco 2019 Chemistry Question 4. It is one of the practical questions from the 2019 Neco Chemistry examination.

The question covers Mole Concept .

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