All your burette readings (initials 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 booklet
(a) What difference in physical properties enable the separation of mixtures by:
(i) simple distillation,
(ii) paper chromatography;
(iii) fractional distillation.
(b) Give a reason for each of the following practices during titration in the laboratory.
(i) White tile is placed under the conical flask.
(ii) Burette readings are always recorded to two decimal places.
(iii) Calculate the volume of 2.5 moldm\(^{-3}\) stock HČI required to prepare 500 cm\(^3\) of 0.20 moldm HCI.
All your burette readings (initials 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 booklet
C is a mıxture of two salts, containing one cation and two anions. Carry out the following exercises on C. Record your observations and identify any gas(es) evolved. State the conclusion you draw from the result of each test.
(a) Put all of C in a beaker and add about 10 cm\(^3\) of distilled water. Stir well and filter. Keep the filtrate and the residue.
(b) To about 2 cm\(^3\) of the filtrate, add few drops of AgNO\(_{(aq)}\), followed by HNO\(_{3(g)}\). Add excess NH\(_{3(aq)}\) to the resulting mixture.
(c)(i) Put all of the residue into a clean test tube and add about 5 cm of HNO\(_{3(aq)}\)
(ii) To about 2 cm\(^3\) of the solution from 2(c)(i), add NaOH\(_{(aq)}\) in drops and then in excess
(iii) To another 2 cm\(^3\) of the solution from 2(c)(i), add NH\(_{3(aq)}\) in drops and then in excess.
All your burette readings (initials 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 booklet
A solution of 0.050 moldm\(^3\) H\(_2\)C\(_2\)O\(_4\) (ethanedioic acid). B is a solution of KMnO\(_4\), (potassium tetraoxomanganate (VII), of unknown concentration.
(a) Put B into the burette. Pipette 20.0 cm\(^3\) or 25.0 cm\(^3\) of A into a Conical flask and add about 10.0 cm\(^3\) of dilute H\(_2\)SO\(_4\), Heat the mixture to about 40°C - 50°C and titrate it while still hot with B. Repeat the titration to obtain consistent titre values. Tabulate your results and calculate the average volume of B used. The equation of reaction is;
2MnO\(_{4(aq)}^-\) + 5C\(_2\)O\(_{4(aq)}^{2-}\) + 16H\(^+_{(aq)}\) \(\to\) 2MnH\(^{2+}_{(aq)}\) + 8H\(_2\)O\(_{(l)}\) + 10CO\(_{2(g)}\)
(b) From your results and the information provided, calculate the:
(i) concentration of MnO\(_2^-\) in B in moldm\(^{-1}\)
(ii) concentration of KMnO\(_4^-\) in B in gdm\(^{-3}\)
(iii) volume of CO\(_2\) evolved at s.t.p when 25.0 cm\(^3\) of H\(_2\)C\(_2\)O\(_4\) reacted completely. [0 = 16.0, K= 39.0, Mn = 55.0, Molar volume of gas at s.t.p.= 22.4 dm\(^3\) mol\(^{-1}\)]
Credit will be given for strict adherence to the instructions. for observations precisely recorded and jor accurate inferences. All tests, observations and inferences must be clearly entered in your answer book in ink, at the time they are made
