Volumetric analysis questions | form three Chemistry

The PH value of a solution of sulfuric acid could be increased by adding an equal volume of

• Water
• The same sulfuric acid solution
• Sodium hydroxide solution
• Potassium hydroxide

What volume of 0.2M H₂SO₄ will be required to neutralize completely 25.0 cm³ of 0.05 M KOH?

1. 0.626 cm³
2. 6.125 cm³
3. 6.315 cm³
4. 3.125 cm³

You are required to determine the purity of an impure NaOH solution contaminated with NaCl by using pure HCl. Given the following soultion:

AA: 1.1g of the impure NaOH dissolved in a 0.25 dm³ of a solution and

BB: 0.73g of a pure HCl present in a 0.2dm³ of a solution.

Proceed as follow:

Titrate the acid( in a burette) against the impure NaOH( in a conical flask) using two drops of methyl orange (MO) as ana indicator . Record the volume of an acid used. Repaeat the titration to obtain three more titre values and record your results in a tabular form.

Questions

1. How much volume of the acid required to neutralize completely 20cm³ or 25cm³ of the base?
2. Write a balanced chemical equation for this reaction.
3. Calculate the molarity of the acid and that of the base.
4. Calculate the percentage purity of the base (NaOH).
5. What is the percentage by mass of NaCl?

You are required to standardize dilute hydrochloric acid using standard aqueous sodium carbonate of 0.1M concentration. Proceed as follows:

1. Pour a small amount (about 2cm³) of solutions AX andAY into separate test tubes and add two drops of phenolphthalein (POP) or methyl orange (MO) indicators to identify the dilute hydrochloric acid and 0.1 M sodium carbonate solution given.
2. Fill the burette with the acid solution.
3. Using a pipette, measure out 20cm³ or 25cm³ of the base solution and put it into a clean titration or conical flask.
4. Titrate the acid ( in the burette) against the base using two drops of methyl orange (MO) as an indicator and obtain three titre volumes. REcord your results in a tabular form.

Questions

(a) which is an acid or base between AX and AY?

(b) What is the mean titre volume of the acid>

(c )Write a balanced chemical equation for this reaction.

(d) Calculate molarity of the acid.

(e ) Calculate the mass of the acid dissolved in one litre of the solution.

You are provided with the following solutions

X: A 0.5 M Sulphuric acid solution

Y: A monovalent metal hydroxide made by dissolving 4.00 g of MOH in distilled water to make up to 1000 cm³ of solution.

MO: Methyl orange indicator.

Procedure

(i) MEasure exactly 20cm³ of X by using 100cm³ measuring cylinder. Carefully add distilled water to 100cm³ mark then stir, Call this solution X₁. Fill X₁ into a burette.

(ii) Titrate X₁ against 20.00 cm³ or 25.00 cm³ of Y using two drops of the indicator, obtain three accurate values. Record your results in a tabular form.

Questions.

(a) (i) The color change at the end point was from ___ to ____.

     (ii) ___ cm³ of Y required  ___ cm³ of X₁ for complete reaction.

(b) Write a balanced chemical equation for the reaction between X₁ and Y

(c ) Calculate the following

1. Molarity of X₁ and of Y
2. Molar mass of Y
3. Atomic mass of M

(d) Identify metal M and write its electronic configuration

(e ) State two properties of each X and Y.