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 of tetraoxosulphate (VI) acid. B is a solution containing 1.4g of potassium hydroxide per 250cm\(^3\)
(a) Put A into burette and titrate with 20.0cm\(^3\) or 25.0cm\(^3\) portions of B using methyl orange or screened methyl orange as 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) concentration of A in mol dm\(^{-3}\)
(iii) number of hydrogen ions in 1.0dm\(^{-3}\) of A. The equation for the reaction is: H\(_2\)SO\(_4\) + 2KOH \(\to\) K\(-2\)SO\(_4\) + 2H\(_2\)O. [H= 1, O = 16; K = 39. Avogadro constant = 6.0 x 10\(^{23}\)]
(c) State whether the pH of the following would be equal to 7, greater than 7 or less than 7
(i) Solution A:
(ii) Titration mixture of A and B before the endpoint
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 and D are samples of two 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) Put all of C in a test tube and heat strongly for about 3 to 5 minutes. Allow the residue to cool.
(b) Add about 5cm\(^3\) of distilled water to the residue from (a) above. Shake and test with litmus paper.
Mention one suitable laboratory procedure for
(i) removing carbon (IV) oxide from a sample of air
(ii) determining whether a given sample of water is pure or not;
(iii) concentrating a dilute solution of sodium chloride.
(b) Use the information provided in the table below to outline a suitable procedure for separating a mixture containing P, Q and R into its Components.
| Component | Solubility in tetrachloromethane | Solubility in water |
|
P Q R |
Insoluble Soluble Insoluble |
Insoluble Slightly soluble soluble |
(c)(i) Draw a labelled sketch to illustrate the collection of gases by upward displacement of air.
(ii) A gas S, with a rotten egg smell, was evolved when dilute hydrochloric acid was added to T which is a salt of iron (II). S decolorized acidified potassium tetraoxomanganate (VIl) solution and a yellow precipitate V was also obtained. Identify S, T and V.
(iii) State what would be observed on bubbling chlorine through a solution of potassium bromide.
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.
A is 0.50 mol dm\(^{-3}\) hydrochloric acid. B is 0.025 mol dm\(^{-3}\) of a trioxocarbonate (IV) salt.
(a) Put A into the burette and titrate with 20.0cm\(^{-3}\) or 25.0 cm\(^{-3}\) portions of B using methyl orange or screened methyl Orange indicator. Record the volume of your pipette. Tabulate your burette readings and calculate the average of A used.
(b) From your results, calculate the mole ratio of acid to trioxocarbonate (IV) in the reaction, expressing your answer as a whole number ratio of one.
(c) Given that B contains 7.2g dm\(^{-3}\) of the hydrated trioxocarbonate (IV) salt, calculate the:
(i) concentration of anhydrous salt in B in g dm\(^{-3}\) [Molar mass of anhydrous salt in B = 106g]
(ii) percentage of water of crystallization in the hydrated salt.
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 and D are samples of two simple salts. Carry out the following exercises on them. Record your observations and state the conclusion you draw from the result of each test.
(a)(i) Put half of C in a test tube and add about 5cm\(^3\) of distilled water. Test with litmus.
(ii) Put the rest of C in a test tube and add about 5cm\(^3\) of dilute hydrochloric acid. Identify any gases evolved.
(b)(i) Put half of D in a test tube. Add about 5cm\(^3\) of sodium hydroxide solution and warm. Identify any gases evolved.
(ii) Put the rest of D in a test tube and add about 5cm\(^3\) of distilled water. Mix thoroughly. Add about 2cm\(^3\) of barium chloride solution, followed by dilute hydrochloric acid in excess.
(a) Name one laboratory apparatus/set-up for:
(i) determining the heat of neutralization:
(ii) decomposing water into hydrogen and oxygen.
(b) Outline a suitable procedure for distinguishing between glucose and cellulose using
(i) one physical test apart from tasting.
(ii) one chemical test.
(c) Draw a labelled sketch to illustrate the separation of a mixture by sublimation.
(ii) Give two examples of substances that are sublime.
(d)(i) Mention one salt which produces brown fumes on being heated strongly
(ii) What is the action of the brown fumes mentioned in (i) above on litmus.
(iii) Give one reason why it is not advisable to collect nitrogen by displacement of air [N – 14].
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 14.0gdm\(^{-3}\) of potassium hydrogen tetraoxosulphate (VI). B is a solution of sodium hydroxide.
(a) Put A into the burette and titrate with 20.0cm\(^{-3}\) or 25.0 cm\(^{-3}\) portion of B using methyl orange, as 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 A in mol dm\(^{3}\)
(ii) concentration of B in g dm\(^3\)
(iii) volume of A (in dm\(^{-3}\)) that would produce one mole of Sodium tetraoxosulphate (VI) in solution. The equation for the reaction is:
2KHSO\(_{4(aq)}\) + 2NaOH\(_{(aq}\) \(\to\) K\(_2\)SO\(_{4(aq)}\) + NaSO\(_{4(aq)}\) + 2H\(_2\)O\(_{(l)}\) [H = 1; O = 16, Na = 23, KHSO\(_4\) = 136gmol\(^{-2}\)]
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, a 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 of each test.
(a) Add about 10cm\(^3\) of distilled water to all of C in a boiling tube. Shake the mixture and filter: Keep both the filtrate and the residue.
(b) Divide the filtrate into two portions.
(i) To the first portion, add about 2cm\(^3\) of barium chloride solution, followed by dilute hydrochloric acid in excess. Warm the mixture and identify any gas evolved.
(ii) To the second portion, add few drops of acidified potassium tetraoxomanganate (VIl) solution and shake.
(C) Put the residue in a test tube and add about 3cm\(^3\) of dilute hydrochloric acid Warm gently and identify any gas evolved. Keep the mixture.
(d) Divide the clear solution from (c) above into two portions
(i) To the first portion, add sodium hydroxide solution in drops and then in excess.
(ii) To the second, add aqueous ammonia in drops and then in excess.
(a) A soluble chloride X reacted with a liquid Y on heating, to give gas Z which turned moist blue litmus paper red and fumed in moist air.
(i) Identity Y and Z
(ii) Give one chemical test to confirm that X is a chloride
(b)(i) State one laboratory use of calcium chloride.
(ii) Name one laboratory technique suitable for separating a mixture of iron filings and ammonium chloride without applying heat.
(iii) State the action of solutions of the following salts on litmus respectively: K\(_2\)CO\(_3\); NaNO\(_3\), AICl\(_3\), (NH\(_4\))\(_2\)SO\(_4\).
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.
(a) Put A into the burette and titrate it against 20.0 cm\(^3\) or 25.0 cm\(^3\) portion of B using methyl orange as indicator. Record the volume of your pipette. Tabulate your burette readings and calculate the average volume of A used. The equation for the reaction is 2NaOH\(_{(aq)}\) + H\(_2\)X\(_{(aq)}\) \(\to\) 2H\(_2\)O\(_{(l)}\)
(b) From your results and the information provided, calculate the;
(i) Concentration of solution B in mol dm\(^{-3}\)
(ii) concentration of solution A in mol dm\(^{-3}\)
(iii) molar mass of the acid H\(_2\)X. [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.
C is a mixture of two inorganic compounds. Carry out the following exercises on C. Record your observations and identify any gases evolved. State the conclusion you draw from the result of each test.
(a) put all of C into a beaker and add about 10cm\(^3\) of distilled water. Stir thoroughly and filter. Keep both the residue and the filtrate
(b) Divide the filtrate into three portions.
(i) To the first portion, add sodium hydroxide solution in drops until ít is in excess.
(ii) To the second portion, add aqueous ammonia in drops until it is in excess.
(iii) To the third portion, add about 2cm\(^3\) of barium chloride solution, followed dilute hydrochloric acid in excess.
(c) Put the residue in a test tube and add about 2cm\(^3\) of dilute tetraoxosulphate (VI) acid. Shake the mixture and warm.
(i) Add aqueous ammonia in drops to the mixture from (c) (i) above until it is in excess.
(a) List two gases in each case which;
(i) can be used to demonstrate the fountain experiment;
(ii) decolourize acidified potassium tetraoxomanganate (VII).
(b) State briefly how you would distinguish between
(i) crystals of PbCO\(_3\) and Pb(NO\(_3\)) using heat;
(ii) solutions of NH\(_4\)CI and NaCl using litmus paper.
(c) Mention two changes that would be observed on adding moderately concentrated hydrochloric acid to iron filings
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.
A is solution of trioxonitrate (V) acid, B is a solution containing 6.90 g of potassium trioxocarbonate (IV) per dm\(^3\)
(a) Put A into the buret and titrate it against 20.0 cm\(^3\) or 25.0 cm\(^3\) portions of B using methy orange or screened methyl orange as indicater. Record the volume of your pipette. Tabulate your burette readings and calculate the average volume A used. The equation for the reaction is K\(_2\)CO\(_{3(aq)}\) + 2HNO\(_{3(aq)}\) \(\to\) 2KNO\(_{3(aq)}\) + CO\(_{2(g)}\) + H\(_2\)O\(_{(l)}\)
(b) From your results and the information provided calculate;
(i) concentration of solution B in mol dm\(^{-3}\)
(ii) number of potassium ions in 1.00 dm\(^3\) of B [C = 12.0, O = 16.0, K = 39.0, Avogadro constant = 6.02 x 10\(^{23}\) mol \(^{-1}\)]
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. Sate the conclusion you draw from the result of each test.
(a) Put all of C into a beaker of boiling tube and add about 10cm\(^3\) of distilled water. Stir well and filter. Keep the residue and keep the residue and the filtrate. Test the filtrate with litmus
(b) Add about 1 cm\(^3\) of dilute hydrochloric acid to the residue in a test tube and warm gently Divide the reaction mixture into two portions.
(c)(i) To the first portion from (b) add saturated sodium trioxocarbonate (V) solution in excess.
(d) To about 2cm\(^3\) of the filtrate from (a) add a few drops of barium chloride solution followed by excess dilute hydrochloric acid.
(a) Name one laboratory equipment used for
(i) keeping salts dry:
(ii) converting vapour to liquid during distillation
(ii) bubbling a gas into a liquid
(b) (i) What technique would you use to purify a sample of sodium chloride contaminated with ammonium chloride?
(ii) Given sodium hydroxide solution, outline the procedure you would use to determine whether or not all the ammonium chloride in (b)(i) above had been removed.
(c) State what is observed on carrying out each of the following exercises.
(i) Adding few drops of methyl orange indicator to lime juice:
(ii) Adding few drops of concentrated HNO\(_3\) to acidified FeSO\(_4\) solution
(iii) Exposing a fresh precipitate of silver chloride to sunlight for 30 minutes
(iv) Adding zinc dust to dilute CuCl\(_2\) solution;
(v) Adding dilute H\(_2\)SO\(_4\), to Pb(NO\(_3\))\(_2\) solution
(a) If you were provided with anhydrous Na\(_2\)CO\(_3\), spatula and stirrer;
(i) list three other materials you would require to prepare a standard solution of Na\(_2\)CO\(_3\)
(ii) state what you would observe on adding diluted H\(_2\)SO\(_4\) to a portion of the Na\(_2\)CO\(_3\)
(b)(i) Describe briefly one chemical test you would perform to distinguish between zinc ions and aluminium ions in solution.
(ii) Mention one laboratory reagent you would use to;
I. produce ammonia from (NH\(_4\))\(_2\)SO\(_4\)
II. differentiate between precipitates of AgCl and Agl
lll. dehydrate ethanol
(c) Give the reason for each of the following laboratory practices
(i) Aqueous solutions of FeSO\(_4\) are freshly prepared when required for use.
(ii) The first jar of hydrogen collected during its preparation is discarded
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 one of the following substances; starch or sucrose or glucose D is a simple salt. Carry out the following exercises on C and D. Record your observations and identify any gases evolved. State the conclusion you draw from the result of each test.
(a)(i) Add about 5 cm\(^3\) of distilled water to a portion of C in a test tube. Stir thoroughly and test with litmus
(ii) Add about 2cm\(^2\) of Fehling’s solution to the resulting mixture from (a)(i) above the heat.
(b)(i) Heat a portion of D strongly in a test tube
(ii) Put the rest of D in a boiling tube and add about 10 cm\(^3\) of distilled water. Shake the mixture
(iii) Put about 2 cm\(^3\) of the mixture from (b)(ii)) in a test tube. Add aqueous ammonia in drops and then in excess
All your burette readings (initial and final), as well as the size of your pipette, must be recorded but on no account of experiment procedure is required. All calculations must be done in your answer book.
A is mol dm HCI. B is a solution containing 15.0 g dm of a mixture of NaCl and KHCO\(_3\).
(a) Put A burette and titrate it against 20.0cm\(^3\) or 25.0cm\(^3\) portions of B using methyl orange as indicator. Record the volume of your pipette. Tabulate your burette readings and calculate the average volume of A used. The equation for the reaction involved in the titration is: HCl\(_{aq}\) + KHCO\(_{3(aq)}\) \(\to\) KCl\(_{(aq)}\) +CO\(_{2(g)}\)
(b) From your results and the information provided above, calculate the:
(i) concentration of KHCO\(_3\), in mol dm\(^{-3}\) in B;
(ii) mass of KHCO\(_3\), in g dm\(^{-3}\) in B
(ii) Percentage by mass of KHCO\(_{3}\) in the mixture, [H=1; C = 12; O = 16; K = 39]
(iv) mass of NaCl in the mixture.
(a) Suggest how the following liquid reagents can be suitably stored in the laboratory
(i) X which fumes in moist air;
(ii) Y which is slowly decomposed by sunlight in ordinary reagent bottles.
(b) State what is observed when aqueous ammonia is added to:
(i) litmus paper;
(ii) Pb(NO\(_3\))\(_2\) solution in drops until in excess
(iii) freshly precipitated AgCI in excess.
(c) A salt sample was suspected to be either Na\(_2\)CO\(_2\) or NaHCO\(_3\). A student who was required to identify it tested a portion for solubility in water and then for effect on litmus paper.
(i) What was observed in each case?
(ii) Give the reason why the student’s procedure was unsuitable
(iii) Describe briefly how you would have identified the salt.
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 i.itne time they are made.
C is a sample of copper (II) tetraoxosulphate (VI) crystals. Carry out the following exercises on C. Record your observations and identify any gases evolved. State the conclusion you draw from the result of each test.
(a) Put half of C in a test tube and heat strongly
(b) Make solution of about 10 cm\(^{-3}\) with the sécond half of C and divide it into three portions
(i) To the first portion, add Sodium hydroxide solution in drops and then in excess. Heat the mixture
(ii) To the second portion, add aqueous ammonia in drops and then in excess followed by few drops of moderately concentrated HCI.
(iii) To the third portion, add all the zinc dust provided and stir thoroughly until there is a visible change.
All your burette readings (initial and final), as well as the size of your pipette, must be recorded but no account or expeimental procedure is required. All calculations must be done in your answer book.
A is 0.125 mol dm\(^3\) H\(_2\)SO\(_4\). B is a solution containing X g dm\(^{-3}\) of NaOH.
(a) Put A into the burette and titrate it against 20.0 cm\(^3\) or 25.0 cm\(^3\) portions of B using methyl orange as indicator. Record the volume of your pipette. Tabulate your burette readings and calculate the average volume of A used. The equation for the reaction involved in the titration is H\(_2\)SO\(_4\) +2NaOH\(_{(aq)}\) \(\to\) Na\(_2\)SO\(_4\) + 2H\(_2\)O\(_{(l)}\)
(b) From your results and the information provided above, calculate the;
(i) amount of H\(_2\)SO\(_4\) in the average volume of A used
(ii) Concentration of B in mol dm\(^{-3}\)
(iii) value of X.
[H = 1: O = 16; Na = 23]
(c) Describe briefly a suitable laboratory procedure for obtaining pure water from the titration mixture. (No diagram is required)