Volumetric Analysis

CONTENT

• Calculation Based on Percentage Purity and Impurity of substances.
• Percentage/amount of water of crystallization,
• Molar mass of the acidic base
• Solubility of substances
• Volume of gases
• Mole ratio of acid to base

Volumetric Analysis

Volumetric analysis involves acid base titration.

Mole Ratio

Mole ratio is the ratio of the reacting species.  This determines the ratio of the acid that would react with the base.

Examples are

1.          H₂SO₄  +  2NaOH         →               Na₂SO₄ + 2H₂O

CaVa   =  ½

CbVb

2.         2HCl +  Na₂CO₃         →     2NaCl +H₂O + CO₂

            CaVa / CbVb =    2/1

EVALUATION

1. What is volumetric analysis
2. Give the ratio of the reaction species in the following chemical reactions

a.   CaCO₃ + 2 HCl →        CaCl₂     +   H₂O    +   CO₂

b.  KHCO₃ + 2HCl          →    KCl +      H₂O    +    CO₂

Calculation Involving Titration

PERCENTAGE PURITY AND IMPURITY

During the titration process of an impure acid or base is titrated only the pure part of either acid or base react with the base or acid.  Therefore, the percentage (%) purity or impurity can be calculated.

READING ASSIGNMENT

Practical Chemistry by Makanjuola pages 1-15.

New School Chemistry by Osei Yaw Ababio pages 165 – 183

Practical Chemistry for Schools and Colleges pages 100 – 170

GENERAL EVALUATION

1. What is volumetric analysis
2. Name five  apparatus used in volumeric analysis.
3. Define the following terms;   a. Indicator  b. Buffers  c. pH scale

WEEKEND ASSIGNMENT

1. C + water give colourless solution (a) c is a soluble salt (b) c is partially dissolve in water (c) c is a filterate (d) c is a residue
2. ____ is the apparatus use to convert vapor into liquid during distillation. (a) conical flask (b) distillation column   (c) lie-big condenser (d) round bottom flask
3. X which fumes in most air can be suitably stored (a) under paraffin or naphtha (b) In a white bottle (c) inside a corked conical flask (d) inside a burette.
4. The observation in bubbling SO₂ into acidified KMnO₄ solution is (a) The solution turns to green   (b) the solution becomes decolourized  (c) no visible reaction (d) the solution turns steam
5. The two substances that can give both H₂ and ZnSO₄ when added to H₂SO₄ are: (a) Magnesium and Zinc (b) Magnesium and CuO (c) Sodium and NaOH (d) iron and copper

THEORY

1. State what would observe on
2. mixing Zinc dust with CuSO₄ solution
3. adding concentrated HNO₃ to freshly prepared FeSO₄ solution
4. A salt sample was suspected to be either Na₂CO₃ or NaHCO₃. A student who was required to identify it, tested a portion for solubility in water and for effects on litmus paper.
5. What was the observation in each case?
6. State the reason why the student’s procedure was unsuitable.
7. Describe briefly how you would have identified the salt.