Preparation of chemical reagents

I. Purpose of the Experiment

A reagent is any substance in a chemical reaction. Different reagents are used for laboratory experiments depending on the nature and type of experiment.

II. Introduction

Concentration of a solution is the number of moles of solute present per litre of the solution. It can be expressed in terms of Molarity.

Molarity:  The number of moles of  solute dissolved in one litre of solution

Molarity= mol (Moles of solute) / L (Litre of solution)

Mole(mol) =    mass (g) / Molar mass(g/mol)

Molar Mass (g/mol) : mass for one mole of any substance

III. Experimental

1. Chemicals: Sodium Hydroxide (NaOH) pellets, Sulphuric Acid solution

( H₂SO₄, 96%w/w, density 1.84 g/mL), Potassium Permanganate (KMnO4 crystals)

2 Equipment: Volumetric flask, Funnel, Watch glass, Spatula, Stirrer (Glass Rod), Polyethylene wash bottle, Reagent bottle, Measuring cylinder, Electronic Balance.

3 Procedure:

a. Preparation of approximately 0.1 M NaOH solution 1000mL.

-  The empty watch glass was weighed by using electronic balance.

-  Then approximately 4 g of NaOH added (poured) into watch glass which has the weighed

-  Small amount of water was added to 100mL volumetric flask & NaOH      pellets was poured through funnel into it.

-  Funnel was removed. The solution was then swirled  it until it became homogeneous. This will give a solution with approximately 0.1 M

b. Preparation of approximately 0.05 M H₂C₂O₄. 2H₂O solution 1000mL.

-  6.4g of H₂C₂O₄. 2H₂O  crystals was placed on a watch glass and weighed again.

-  Weighed H₂C₂O₄. 2H₂O   crystals were poured to a volumetric flask using a funnel and small amount of distilled water was add to a volumetric flask by using a funnel.

-  The glass stopper of the volumetric flask was placed and the mixture was then swirled thoroughly  until all H₂C₂O₄. 2H₂O   crystals were dissolved.

-  Distilled water was filled up to the marking and was mixed by shaking. This will give approximately 0.05 M.

c. Preparation of approximately 0.1 M H₂SO₄ solution 1000mL.

-  5.4  mL of H₂SO₄ was measured with a measuring cylinder.

-  H₂SO₄ was slowly poured through a funnel into the volumetric flask previously filled with 300mL of distilled water (made up the volume up to 1000mL and mixed it)

- A solution of H₂SO₄ will gave with approximately 0.1 M.

IV. Results and Discussions

(i) Molarity of NaOH solution......... 0.10M.

(ii) Molarity of H₂C₂O₄. 2H₂O   solution......... 0.05M.

(ii) Molarity of H2SO4 solution......... 0.10M.

Discussion

1. What will you do, if the solution becomes hot while preparing NaOH solution?

I will pour cold water on the outer surface of the volumetric flask to cool it off

2. What will happen if distilled water is poured to H₂SO₄?

Heat is produced because the reaction is exothermic

3. What will you do if KMnO₄ crystals are big and difficult to dissolve in distilled water?

Crush /grind them before adding in water to increase the surface area for dissolving.

V. Conclusion

Approximately 0.10 M NaOH solution, 0.05 M H₂C₂O₄. 2H₂O    solution and

0.10 M H2SO4 solutions were prepared for further laboratory use.