(a) A mixture consist of sodium chloride, ammonium chloride and lead (II) tetraoxosulphate (VI). Describe how you would obtain each component in a pure state.
(b) You are required to determine the concentration of a solution of tetraoxosulphate (VI) acid by titrating it against sodium trioxocarbonate (IV) solution of known concentration.
(i) Name the indicator you would use
(ii) List two precautions you would take to ensure accurate readins
(iii) State the colour of the sodium trioxocarbonate (IV) solution after adding the named indicator and then at the end point.
Credit will be given for strict adherence to instructions, for observations precisely recorded, and for accurate inferences. All tests, observations, and inferences must be clearly entered in your answer book, in ink, at the time they are made.
Carry out the following exercises on sample F. Record your observations and identify any gases evolved. State the conclusion you draw from the result of each test.
(a) Put all of F into a beaker and add about 10cm\(^3) of water. Stir the mixture and filter. Keep both the residue and the filtrate.
(b)(i) Test the filtrate with litmus paper.
(ii) Add a few drops of the fehling’s solution provided to about 2cm\(^3\) of the filtrate in a test tube. Boil the mixture.
(c) Put the residue from (a) above into a test tube and add about 5cm\(3\) of hydrochloric acid. Identify the gas evolved.
(d) To about 2cm\(^3\) of the clear solution from (c) above add dilute sodium into hydroxide solution dropwise and then in excess.
(e) From your results deduce what F is and its constituent
D is 2.00M ethanoic acid. E is 2.00M potassium hydroxide solution.
(a) Using a 50cm\(^3\) measuring cylinder, measure 50cm\(^3\) of D and transfer the solution into plastic cup.Record the temperature T\(_1\) of the solution. Rinse the cylinder distilled water and allow to dry.
(b) Using the dry measuring cylinder from (a) above, measure 50cm of E. Record the temperature, T\(_2\) of the solution.
(c) Find the average temperature T\(_3\) of the two solutions and record the value.
(d) Pour the measured quantity of solution E quickly from the measuring cylinder into the plastic cup containing solution D. Stir the mixture with the thermometer. Record the highest temperature T\(_4\) attained.
(e)(i) Find the rise in temperature (T\(_4\) – T\(_3\) ad record the value
(ii) Calculate the mass of the reaction mixture, given that during the reaction 1cm\(^3\) of the mixture weighs 1g
(f) From your results in (a) to (e) above, calculate the;
(i) Heat evolved during the reaction, giving that the specific heat capacity of water is 4.2Jg\(^{-1}\)C \(^{-1}\) and using the formula; heat evolved = mass x specific heat capacity x rise in temperature
(ii) Heat of neutralization of one mole of ethanoic acid by potassium hydroxide
(g) List two sources of error in the method used for determining the heat of neutrailzation and suggest how their effect can be minimized.
(a)(i) Give one laboratory use of activated charcoal
(ii) A piece of phosphorus and some magnesium ribbon were burnt in two separate jars of oxygen. Water was then added to dissolve the product. State the action of litmus on each of the resulting solutions
(b) Give one chemical test to distinguish between CH\(_3\)CH\(_2\)OH and CH\(_3\)COOH.
(c) Describe how you would dilute accurately a solution containing 0.10 mole of the solute per dm\(^3\) of solution to 0.010M.
Credit will be given for strict adherence to the instructions, for observations precisely recorded, and for accurate inferences. All tests, Observations, and inferences must be clearly entered in your answer book, in ink, at the time they are made. Carry out the following exercises on sample C.
Record your observations and identify any gases evolved
(a) Put all of C into a test tube and add about 5cm\(^3\) of water. Shake the mixture and filter. Keep both the residue and the filtrate
(b) Divide the filtrate into two portions;
(i) To the first portion, add a few drops of dilute trioxonitrate (V) acid followed by about 1cm\(^3\) of silver trioxonitrate (V) solution
(ii) Add excess aqueous ammonia to the mixture in (i) above
(iii) To the second portion, add about 2cm\(^3\) of dilute sodium hydroxide solution and warm gently
(c) Add about 2cm\(^3\) of dilute hydrochloric acid to the residue from (a) above and warm gently. Filter if necessary and divide the resulting solutio into two portions.
(i) To the first portion add dilute sodium hydroxide solution in drops until it is in excess
(ii) To the second portion, add aqueus ammonia in drops until it is in excess.
All your burette readings (initial and final) as well as the size size of your pipette, must be recorded but no account of experimental procedure is required. All calculations must be done in your answer book.
Xg of pure potassium trioxocarbonate (IV) was treated with 1dm\(^3\) of 0. 25M tetraoxosulphate (VI) acid to obtain solution A which contains excess acid. B is a solution containing 2.8g of potassium hydroxIde per 250cm\(^3\) solution.
(a) Put A into the burette and titrate with 20cm\(^3\) or 25cm\(^3\) portions of B. using methyl orange as indicator. Record the volume of your pipette. Tabulate your burette readings and calculate the average volume of acid used.
(b) From your results and the information given. Calculate the;
(i) concentration of the excess acid in A in mol dm\(^3\)
(iii) value of X. The equation for the reaction between the excess acid the potassium hydroxide is H\(_2\)SO\(_4\) + 2KOH \(\to\) K\(_2\)SO\(_4\) [H = 1. C = 12, O = 16. S = 32, K = 39]
C is a mixture of an organic and an inorganic salt. The test recorded in the table below were performed as indicated,
(a)Copy and complete the table as appropriate.
| Test | Observation | Inference |
| (i) C + water mixed thoroughly and filtered | Partially soluble, colourless filtrate, white residue | |
|
(ii) Portion of filtrate from (i) + NH\(_{3(aq)}\) in drops, then in excess |
White precipitate which dissolves in excess to give a colourless solution | |
| (iii) Portion of filtrate from (i) + NH\(_3\) in drops, then in excess | White precipitate insoluble in excess | |
| (iv) Portion of filtrate from (i) + conc. HCl + heat | White precipitate which dissolves on warming and reappears on cooling | |
| (v) Portion of filtrate from (i) + conc. H\(_2\)SO\(_4\) + gentle warming | Brown fumes produced on warming | |
| (vi) Residue from (i) + iodine solution | Blue-black colouration | |
| (vii) Residue from (i) + Fehling’s solution + heat | ||
| (vii) Residue from (i) + dil HCl solution + heat + Fehling’s solution |
(b) From the information provided and your inference, identify the compounds of C
(c) Describe the action of heat on a solid sample of the inorganic component Write an equation for the reaction.
(d) State what would be observed if an aqueous suspension of the organic component were heated to boiling
A is a solution containing 0.50 mole of barium chloride per dm\(^3\). Solution B contains 1.0 mole of tricxocarbonate (IV) salt per dm\(^3\)
(a) State what would be observed and give the confirmatory test for any gases evolved if the following tests were performed
(i) mixing 2cm\(^3\) each of solutions A and B in a test tube
(ii) adding excess dilute hydrochloric acid to the mixture from (a)(i) above
(b) 10cm\(^3\) of solution A were measured into each of seven boiling tubes of uniform bore and various quantities of solution B were added respectively to the boiling tubes, The tubes were immersed in hot water. After the reaction, the height of the product in each of the tubes was measured. The results were as tabulated below.
| Test tube | I | II | III | IV | V | VI | VII |
| Volume of sodium B added (cm\(^3\)) | 2.0 | 3.0 | 4.0 | 5.0 | 6.0 | 7.0 | 8.0 |
| Height of the product (to the nearest m) | 12 | 18 | 24 | 30 | 30 | 30 | 30 |
(i) Plot a graph of the height of the product against the volume of solution B added to each test tube. Explain the shape of the graph
(ii) Calculate the amount (in mole) of the trioxocarbonate (IV) salt contained in the volume of solution B added to tube lV
(iii) Calculate the amount (in mole) of barium chloride contained in 10cm\(^3\) of solution A. Hence, determine the mole ratio of barium chloride and the trioxocarbonate (IV) Salt in the reaction
(a) Name the apparatus used in the laboratory to (i) Convert vapour into liquid during distillation
(ii) determine the volumetric composition of water
(ii) produce an intermittent supply of any gas which can be evolved by the action of a liquid on a solid without heating.
(b) Give the reason for the following;
(i) the edge of the lid of a desiccator should be greased
(ii) a standard solution of sodium hydroxide is not prepared by weighing out accurately a given mass of the solid and making it up to the required volume.
iii) after the reduction of copper (II) oxide by a a stream of hydrogen gas passed overs the heated oxide in a combustion tube, it is necessary to continue passing the gas over the residue until the residue cools.
(c) An acid-base indicator turns orange in an acidic solution, green in a neutral solution and blue in an alkaline solution. The table shows the results obtained when a few drops of the indicator were added to samples of some liquids.
| Liquid | Colour of the indicator in the liquid |
|
Glucose solution Rainwater Lime water Vinegar Stomach powder solution |
Green Pale orange Blue Orange Pale blue |
(i) Arrange the liquids in increasing order of their expected pH values.
(ii) Explain why the colour of the indicator in the sample of rainwater is pale orange whereas in pure water it is green.
(iii) A given crystalline solid is suspected to be either sodium chloride or ammonium tetraoxosulphate (VI). Describe how you would use the indicator to identify the solid.
(iv) State with reason whether or not phenolphthalein indicator can be used to distinguish between the samples of glucose solution and vinegar.
(v) What would be the colour of methyl orange indicator in the lime water sample?
All your burette readings (initial and final), as well as the size of your pipette, must be recorded but on no account of experimental procedure is required. All calculations must be done in your answer book.
F is a solution, O a dibasic acid H\(_2\)X. G is a solution containing 1.00g of sodium hydroxide in 250cm\(^3\) of solution.
(a) Put F in the burette and titrate with 20cm\(^3\) or 25cm\(^3\) portion of G using methyl orange as indicator. Record the volume of your pipette. Tabulate your burette readings and calculate the average volume of F used
(b) From your results and the information provided, calculate the;
(i) concentration of G in mol. dm\(^3\)
(ii) concentration of F in mol. dm\(^{-3}\)
(iii) molar mass of the acid H\(_2\)X, given that 100cm\(^3\) of solution F contained 0.4850 the acid.
The equation for the reaction is H\(_2\)X\(_{(aq)}\) + 2NaOH\(_{(aq)}\) \(\to\) Na\(_2\)X\(_{(aq)}\) + 2H\(_2\)O [H = 1; O = 16; Na = 23]
Credit will be given for strict adherence to instructions, for observations precisely recorded and for accurate inferences. All tests observations and inferences must be clearly entered in your answer book. in ink, at the time they are made.
H is a mixture of an element and an organic compound. Carry out the following exercises on H. Record your observations and identify any gases evolved. State the conclusion you draw from the result of each test
(a) Put all of H in a beaker and add about 10cm\(^3\) of distilled water. Stir the mixture thoroughly and filter Keep both the filtrate and the residue. Test the filtrate with litmus paper.
(b) Divide the filtrate into two portions
(i) To the first portion add two to three drops of acidified potassium tetraoxomanganate (VII) and warm
(ii) To the second portion. add a few drops of a saturated solution of sodium hydrogentrioxocarbonate (IV)
(c)(i) Put all the residue in a test tube and add 5cm\(^3\) of dilute hydrochloric acid
(ii) To the resulting solution from (C)(i) above add aqueous sodium hydroxide in drops until it is in excess
(iii) From your inferences in (c)(i) and (c)(i) state what would be observed if 5cm\(^3\) of dilute trioxonitrate (V) acid were added to a portion of the residue and the mixture was warmed.
(a)(i) Define a standard solution
(ii) Give the reason why a standard solution of sodium hydroxide cannot be made by weighing out accurately a given mass of the solid and making it up to the required volume of solution
(b) Give two ways by which a solid solute can be made to dissolve more quickly in a liquid Solvent
(i) Draw a labelled diagram of the apparatus used for drying solids in the laboratory
(c) State what would be observed if a fresh precipitate of silver chloride was;
(i) Exposed to light.
(ii) Shaken will excess aqueous ammonia
A solution containing 0.095 mol. dm\(^{-3}\) of trioxonitrate (V) acid. Solution B contains 13.50g of X\(_2\)CO\(_3\).10H\(_2\)O per dm\(^3\)
(a) Put A in the burette and titrate with 20cm\(^3\) or 25cm\(^3\) portions of B using methyl orange as an indicator. Record the volume of your pipette. Tabulate your burette readings and calculate the average volume of A used.
(b) From your results and the information provided, calculate the;
(i) Concentration of B in mol. dm\(^3\)
(ii) molar mass of X\(_2\)CO\(_3\).10H\(_2\)O
(iii) percentage by mass of X in X\(_2\)CO\(_3\).10H\(_3\)O. The equation for the reaction is X\(_2\)CO\(_3\) + 2HNO\(_3{(aq)}\) \(\to\) 2XNO\(_{3(aq)}\) + CO\(_{2(g)}\) + 11H\(_2\)O\(_{(l)}\) [H = 1, C = 12, O = 16]
(c) Give the reason for the following:
(i) using just a small quantity of the indicator during acid-base titrations.
(ii) obtaining at least two sets of readings for titration experiment.
You are provided with two aqueous solutions labelled C and D. Carry out the following exercises on them. Record your observations and identify any gases evolved. State the condition you draw from the result of each test.
(a)(i) Mix C and D in a beaker thoroughly.
(ii) Filter the mixture. Keep both the residue and the filtrate.
(b)(i) To about 5cm\(^3\) of the filtrate, add barium chloride solution, followed by excess dilute hydrochloric acid in a boiling tube. Divide the resulting solution into two portions.
(c)(i) To the first portion of the solution from (b)(ii) above, add sodium hydroxide solution in excess.
(ii) To the second portion of the solution from (b)(ii) above, add aqueous ammonia in drops until it is in excess.
(a) State;
(i) One advantage:
(ii) One disadvantage of evaporation of salt solutions to dryness over crystallization.
(b)(i) List two normal salts which when dissolved in pure water are acidic to litmus
(ii) Mention the phenomenon that accounts for the behaviour of the salts in (b)(i) above.
(c)(i) Outline a suitable laboratory method for separating a mixture of glucose and starch.
(i) Give two chemical tests that would enable you to identify three solids suspected to be glucose, sucrose and starch.
A is a solution containing 0.050 mol. dm of tetraoxosulphate (VI) acid. B is a solution of anhydrous trioxocarbonate (IV).
(a) Put A into the burette and titrate with 20cm\(^3\) or 25cm\(^3\) portions of B using methyl orange as an indicator. Record the volume of your pipette. Tabulate your burette readings and calculate the average volume of A used
(b) From your results and the information provided, calculate the:
(i) Concentration of solution B in mol. dm\(^{-3}\)
(ii) mass of sodium tetraoxosulphate (VI) that would be formed in solution of 1dm\(^3\) of solution B were neutralized by solution A
(iii) volume of carbon (IV) oxide at s.t.p. that would be liberated in (b)(ii) above. The equation for the reaction is: N\(_2\)CO\(_{3(aq)}\) + H\(_2\)SO\(_{4(aq)}\) \(\to\) Na\(_2\)SO\(_{4(aq)}\) + H\(_2\)O\(_{(l)}\) + CO\(_{2(g)}\) [O = 16; Na = 23, S = 32; molar volume of gases of s.t.p. = 22.4dm\(^3\)
C and D are samples of two different simple salts. Carry out the following exercises on them. Record your observations and identify any gases evolved. State the conclusion you draw from the result of each test.
a) Heat about one-half of C in a dry test tube until no further change is observed. Allow to cool.
(b)(i) To the cooled residue from (a) above, add about 5cm\(^3\) of dilute hydrochloric acid and warm.
(ii) To about 2cm\(^3\) of the clear solution from (b)(i) above add aqueous ammonia in drops until it is in excess.
(c) Put all of D in a boiling tube and add about 10cm\(^3\) of distilled water. Shake thoroughly and divide into two portions.
(d)(i) To the first portion from (c) above, add about 2cm\(^3\) of barium chloride solution, followed by dilute hydrochloric acid in excess. Warm the mixture.
(ii) To the second portion from (c) above, add 2 or 3 of acidified potassium tetraoxomanganate (VII) solution and shake.
(a) Draw a labelled sketch of the laboratory set-up for dissolving hydrogen chloride acid.
(ii) Give one chemical test to distinguish between hydrochloric acid and ethanoic acid
(b) Outline a suitable laboratory procedure for obtaining a fairly pure sample of sodium chloride crystals from a solution of it that is contaminated with some methyl orange:
(c) Name one substance used in the laboratory for:
(i) drying ammonia gas,
(ii) testing for the presence of water;
(iii) converting copper (I) oxide to copper.
All your burette readings (initial and final), as well as the size of your pipette, must be recorded but no account of experimental procedure is required. All calculations must be done in your answer book.
A is a solution containing 6.3g dm\(^{-3}\) of impure ethanoic acid. B is 0.10mol. dm\(^{-3}\) sodium hydroxide sodium hydroxide solution.
(a) Put A into the burette and titrate with 20.0cm\(^3\) or 25.0cm\(^3\) portions of B using phenolphthalein as indicator. Record the volume of your pipette Record the volume of your pipette. Tabulate your burette readings and calculate the volume of A used.
(b) From your result and the information provided, calculate the
(i) concentration of solution A in mol.dm\(^{-3}\)
(ii) Concentration of solution A in dm\(^{-3}\) and hence the percentage purity of the ethanoic acid,
(iii) Volume of solution A that would neutralize a solution containing 0.005 mole of sodium hydroxide. The equation for the reaction is;
H\(_2\)C\(_2\)O\(_{4(aq)}\) + 2NaOH\(_{(aq)}\) \(\to\) Na\(_2\)C\(_2\)O\(_{(aq)}\) + 2H\(_2\)O\(_{(l)}\) [H = 1; C = 12. O = 16]
(c)(i) What would be the colour of methylorange indicator in solution B?
(ii) Give the reason why methylorange is not a suitable indicator for titration.
Credit will be given for strict adherence to instructions, for observations precisely recorded, and for accurate inferences. All tests, observations, and inferences must be clearly entered in your answer book, in ink at the time they are made.
C is a mixture of two simple salts. Carry out the following exercises on C. Record your observations and identify any gases evolved. State the conclusion you draw from the result
(a)(i) Put all C in a boiling tube or beaker and add about 10cm\(^{3}\) of distilled water Stir the mixture thoroughly and tilter Keep both the residue and the filtrate
(ii) Test the filtrate with litmus paper.
(b) Divide the filtrate of two portions
(i) To the first portion of the filtrate. add about 2cm\(^3\) of dilute trioxonitrate (v) acid and then silver trioxonitrate (v) solution
(ii) To the second portion of the filtrate, add sodium hydroxide solution in drops until it is in excess.
(c) Put half of the residue in a test tube and heat strongly. Allow to cool
(d)(i) Put the remaining half of the residue in a test tube and add about 2cm\(^3\) of dilute hydrochloric acid.
(ii) To the resulting solution from (d(i)) above, add aqueous ammonia in drops until it is in excess.
(a) Use the following reaction scheme to answer Questions;(i) – (iii) below;
(i) Give one suitable procedure for carrying out each of reactions 1, 2, and 3 separately in the laboratory
(ii) State the gases produced along with lead (lI) Oxide in reaction 1.
(iii) What is the colour of lead (II) tetraoxosulphate (VI)?
(b) When a drop of concentrated trioxonitrate (V) acid was added to potassium iodide solution, a violet-colored gas was evolved?
(i) What is the name of the gas evolved?
(ii) State the functions of concentrated trioxonitrate (V) acid in the reaction.
(iii) What would be observed if starch solution were added to the reaction mixture?