WAEC Chemistry Practical Specimen 2024 Answers Out

WAEC Chemistry Practical Answers 2024 Released – See Chemistry Specimen Here.

The Waec chemistry practical 2024 specimen paper for SSCE will now be written on Thursday, 16th May 2024 from 09:30 hrs. to 11:30 hrs. for the first set and from 12:00 hrs. to 14:00 hrs. for the second set. The paper is Waec Chemistry Practical Alternative A.

We made this post to show apparatus, Waec chemistry practical specimens, graphs, and calculations that are used in the Chemistry Practical Examination questions and syllabus.

Here, we will be providing you with the Waec Chemistry practical 2024 specimen questions and materials that will be used for Examination preparation. Read the answers below.

WAEC Chemistry Practical Specimen 2024.

The following apparatus and materials will be required by each candidate for Waec Chemistry Practical 2024;
(a) one burette of 50cm³ capacity.
(b) one pipette, either 20cm³ or 25cm³.
(c) the usual apparatus for titration.

(d) the usual apparatus and reagents for qualitative work including the following with all reagents appropriately labelled;
(i) dilute sodium hydroxide solution.
(ii) dilute hydrochloric acid.
(iii) dilute trioxonitrate(v) acid
(iv) silver trioxonitrate(v) solution.
(v) acidified potassium dichromate solution.
(vi) aqueous ammonia.
(vii) lime water.
(viii) red and blue litmus paper.
(ix) dilute tetraoxosulphate(vi) acid.

(e) Spatula
(f) filtration apparatus.
(g) one beaker
(h) one boiling tube
(i) four test tubes.
(j) Methyl orange as an indicator.
(k) mathematical table/calculator
(l) wash bottle containing distilled/deionized water.
(m) a burning splint
(n) watch glass
(o) bunsen burner/source of heat
(p) droppers.

Each candidate should be supplied with the following where n is the candidate’s serial number.
(a) 150cm₃ of a solution of HCL in a corked flask or bottle labeled ‘An’. These should all be the same containing 8.5cm³ of conc HCL per dm₃ solution.
(b) 150cm₃ of Na²Co³. 10 H2O in a corked flask or bottle labeled ‘Bn’. These should all be the same containing 5g of hydrated salt per dm₃ of solution.
(c) One spatulaful of glucose in a specimen bottle labelled ‘Cn’. This must be the same for all candidates.

WAEC Chemistry Practical Questions & Answers.

1. A is 0.100 mol dm-3 solution of an acid. B is a solution NaOH containing 2.8 g per 500 cm3.
(a) Put A into the burette and titrate it against 25.0 cm3 portions B using methyl orange as an indicator. Repeat the titration to obtain consistent titres.  Tabulate your readings and calculate the average volume of A used.

(b) From your results and the information provided above, calculate the:
(i) number of moles of acid in the average titre;
(ii) number of moles of NaOH in the volume of B pipetted;
(iii) mole ratio of acid to base in the reaction
[H = 1.00, O = 16.0, K = 39.0]

ANS: (a) titration answer soon.

(b) (i) number of moles of acid = 0.100 x VA 
                                                                1000    
                                    =   X mole(s) [3sig. Fig to score]

                        1000cm3 contains 0.100 mole(s)
                    VA will contain 0.100 x VA 
                                                     1000
                                    =   X moles [3 Sig. Fig. to score]       

(ii) Number of moles of NaOH in B
                             500cm3 of B contains 2.8g of NaOH
                       1000cm3 of B will contain 2.8 x 1000 = 5.6 NaOH
                                                                           500  
                             Molar mass of NaOH = 39 + 16 + 1 or 56 gmol-1 

      Conc of B = 5.6  = 0.100 mol dm-3
                           56

(iii) Mole ratio of acid to base = X: Y to nearest whole number ratio.

2. C is a mixture of two salts. Carry out the following exercises on C. Record your observations and identify any gas(es) evolved. State the conclusion drawn from the result of each test.

(a) Put all of C into a boiling tube and add about 5cm3 of distilled water.  Stir thoroughly and filter. Keep both the residue and the filtrate. 

(b) To about 2 cm3 of the filtrate, add few drops of K2Cr2O7/H+. Boil the mixture and then allow to cool as (D).

(c) (i) Put the residue in a test tube and add dilute NaOH(aq). Shake the mixture and divide the solution into two portions.
(ii) To the first portion from (c)(i), add NaOH(aq) in drops and then in excess.
(d) What organic class does C belong to?

ANS:

3. (a) Explain briefly the observations in each of the following processes:
(i) when carbon(IV) oxide is bubbled through lime water, it turns milky but the milkiness disappears when the gas is bubbled for a long time;
(ii) a precipitate of calcium hydroxide is insoluble in excess sodium hydroxide solution whereas that of lead (II) hydroxide is soluble.

(b) (i) What is a primary standard solution?
(ii) Calculate the mass of sodium trioxocarbonate(V) required to prepare 250 cm3 of 0.15 mol dm-3 solution.
[Na = 23.0; O = 16.0; C = 12.0]

(c) Name one gas that can be collected by:
(i) upward displacement of air;
(ii) downward displacement of air. 

ANS: (a) (i): Insoluble CaCO3 formation is responsible for the milkiness produce when CO2 is bubbled through lime water while the disappearance of milkiness is due to the formation of soluble Ca(HCO3)2.
Lime water turns milky with CO2 because  CaCO3/ CaCO3(s)  is formed. Milkiness disappear when excess CO2 reacts with CaCO3 in water medium forming the soluble Ca(HCO3)2/ Ca(HCO3)2 (aq).
(ii) Calcium hydroxide is not amphoteric. Does not react with an alkali NaOH whereas lead (II) hydroxide is amphoteric so reacts with excess NaOH.

(b) (i) Primary standard solution is one whose concentration is known and can be used to standardize another solution.
(ii)    M (Na2CO3)    =  106 gmol-1 
         m(Na2CO3)     =  C x M x V
                                   =   0. 15 x 106 x 0. 25 
                                   =   3. 98 g                                 

 (c) (i) Carbon(IV) oxide, sulphur (IV) oxide, hydrogen chloride, oxygen, nitrogen (IV) oxide, chlorine, hydrogen sulphide.
(ii) Ammonia, oxygen, hydrogen, methane.  

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