Experiment 112

Objective

To prepare a 250 mL solution of 0.1 M sodium hydroxide (NaOH).

Introduction

Sodium hydroxide, a primary standard, is a solid substance that can be used to prepare a standard solution by dissolving a fixed amount in distilled water. The molecular weight of sodium hydroxide (NaOH) is 40 g/mol. For a 1 M solution, 40 g of NaOH is required per liter. Therefore, to prepare a 0.1 M solution in 250 mL, the required amount of NaOH is:

Materials

Chemicals

·       Sodium hydroxide (NaOH)

·       Distilled water

Apparatus

·       250 mL volumetric flask

·       Weighing bottle

·       Analytical balance

Procedure

1.    Wash the 250 mL flask thoroughly and dry it in an oven.

2.    Measure 1 g of sodium hydroxide using the weighing bottle and balance.

3.    Carefully transfer the NaOH into the flask.

4.    Add distilled water gradually to dissolve the NaOH, swirling to aid dissolution.

5.    Add distilled water up to the 250 mL mark on the flask.

6.    Mix the solution thoroughly to ensure even distribution of NaOH.

Observation

The weight of NaOH used is 1.0 g, and the final volume of the solution is 250 mL. The resulting solution appears clear, indicating complete dissolution of NaOH.

Questions

1.    What is a primary standard substance?

2.    What is a primary standard solution?

3.    What defines a 0.1 M NaOH solution?

4.    What is the molecular weight of NaOH?

5.    What is the solute in this experiment?

6.    What is the solvent in this experiment?

7.    Define a solution.