Neco GCE Chemistry to Alternative Practical 2022:
QUESTION 1: In an experiment, 20.0cm3 portions of 0.065 mol dm-3 NaOH were titrated against dilute HCl. The table below shows the results of the titration;
| Burette readings {cmt] | 1st | 2nd | 3rd |
| Final reading [cm-] | 23.50 | 46.60 | 47.40 |
| Initial reading [cmt) | 0.00 | 23.50 | 24.00 |
| Volume of acid used | 23.50 | 23.10 | 23.40 |
(a) (i) Name a suitable indicator for the titration. Give a reason for your answer.
(ii) Give the colour of the indicator in the base and at the end point.
(iii) What type of reaction is demonstrated by the experiment?
(b) (i) Write a balanced equation for the reaction
(ii) Determine the average volume of acid used.
(c) Calculate the (i) concentration of the acid in mol dm-3
(ii) concentration of the acid in g dm-3
(iii) mass of HCl in 20cm3 of solution [H = 1.00, Cl = 35.5 ]
QUESTION 2: C was a mixture of an inorganic salt and organic compound. Tests were carried out on C.
Copy and complete the table and hence state what C could be.
| Test | Observation | Inference | ||
| (a) (i) | C + 10cm3 of distilled | C partially dissolved | ||
| water, stirred and filtered | to give colourless | |||
| filtrate and a white | ||||
| residue | ||||
(in | Filtrate + Litmus paper | Neutral filtrate | ||
(b) | (i) | First portion of filtrate + | ||
| AgN03(aq) | ||||
| +HN03(aq) | ||||
| +NH3(aq) | Cl- confirmed | |||
(ii) | Second portion of filtrate | White gelatinous | ||
| + NaOH(aq) in drops | precipitate | |||
| then in excess | Precipitate dissolved | |||
(iii) | Third portion of filtrate | White gelatinous | ||
| + NH3(aq) in drops | precipitate | |||
| then in excess | Precipitate dissolved | |||
(c) | (i) | Portion of residue + | Starch present | |
| Iodine solution | ||||
(ii) | Portion of residue + | Starch | ||
| HCl(aq) and boil | hydrolysed | |||
| cool and add iodine | ||||
| solution | ||||
QUESTION 3: (a) Outline how a mixture of ammonium chloride, potassium chloride and lead (II) chloride could be separated in the laboratory.
(b) Name one drying agent that is
(i) solid,
(ii) liquid
(c) Mention one laboratory apparatus used for:
(i) preparing a standard solution;
(ii) converting vapour to liquid;
(iii) keeping solid samples dry;
(iv) generating gases intermittently;
(v) determining the pH of a solution. [5 marks]
(d) (i) Describe a chemical test that could be used to distinguish between pure water and sodium tetraoxosulphate(VI)solution
(ii) Zn(OH)2 and Ca(OH)2 are white substances What reagent would be suitable to distinguish between the two substances?
**Older*** Practical for June/July NECO
1. 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.
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. To about 2 cm3 of the filtrate, add few drops of Pb(NO3)2(aq)‑Boil the mixture and then allow to cool.
(i) Put the residue in a test tube and add dilute HNO3. 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.
(iii) To the second portion from (c)(i), add aqueous ammonia in drops and in excess.
2. F is a mixture of two compounds. Carry out the following exercises on F. Record your observations and identify any gas(es) evolved. State the conclusion drawn from the results of each test. Put all of F into a beaker or a boiling tube and add about 10 cm3 of distilled water. Stir the mixture thoroughly and filter. Keep both the filtrate and the residue.
(i) Divide the filtrate into two portions.
(a) To the first portion, add dilute HNO3 followed byAgNO3(aq).
(b) Add excess NH3(aq) to the resulting mixture.
(ii) To the second portion, add NH3(aq) in drops and then in excess.
Add about 5 cm3 of distilled water to the residue in a test tube. Boil and allow to cool. Add few drops of iodine solution.
ANS:
| TEST | OBSERVATION | INFERENCE | |
| a) | F + water, stirred mixture and filtered | Partly dissoves/soluble Colourless filtrate White residue | F contains soluble and insoluble salts |
| b) (i) I II | Filtrate + dil HNO3+ Ag NO3(aq) Mixture in (b)(i) + | No visible reactionWhite precipitate formed
Precipitate dissovles | Cl- present
Cl- confirmed |
| b)(ii) | Filtrate + HN3(aq) in drops then in excess | White gelatinous precipitate Precipitate dissovles | Zn+2 or A13+ may be presentZn2+ confirmed |
| c) | Residue + water + heatallow to cool + iodine solution | Jelly-like paste is formedDark/deep blue/blue black colouration is obtained | Starch is confirmed |
Regular Specimen Apparatus for Titration in Chemistry:
This is a complete list of the normal apparatus and reagents for qualitative work including the following with all reagents appropriately labelled to avoid mistake.
- Four test tubes
- Wash bottle containing distilled/ deionized water
- Mathematical table /calculator.
- Dilute sodium hydroxide solution
- Barium chloride solution
- Dilute trioxonitrate (V) acid
- Glass rod
- Aqueous ammonia
- Dilute hydrochloric acid
- Silver trioxonitrate (V) solution
- Dilute tetraoxosulphate (VI) acid
- Filtration apparatus
- Spatula
- Two boiling tubes.
During NECO Chemistry Practical exam, each candidate should be supplied with the following, where ‘n’ is the candidate’s serial number.
- 150cm3 of ethanedioic acid (H2C204) solution in a corked flask or bottled labelled ‘An’. These should all be the same containing 4.50g of H2C204 per dm3 of solution.
- 150cm3 of potassium tetraoxomanganate (VII) solution in a corked flask or bottle labelled ‘Bn’. These should all be the same containing 3.16g of KMnO4 per dm3 of solution.
- One spatulaful of a uniform mixture of NaCl and ZnCO3 in a specimen bottle labelled ‘Cn’. The components of the mixture should be in the ratio 1:1 by mass.
The details of the 2022 NECO Chemistry practical titration and calculations will be made available to you candidates as soon as it is released. Keep following this page and make sure you bookmark this site for reference purposes.
If you have any questions, endeavour to use the comment box below.