All your burette readings (initial and final), as well as the size of your pipette, must be recorded but no account of the experimental procedure is required. All calculations must be done in your answer booklet.
A is a solution containing 5.00 g of HNO\(_3\) in 500 cm\(^3) of solution. B is a solution of NaOH of unknown concentration.
(a) Put A into the burette and titrate it with 20.0 cm\(^3\) or 25.0 cm\(^3\) portions of B using methyl orange as an indicator. Repeat the titration to obtain concordant titre values. Tabulate your results and calculate the average volume of acid used. Equation of the reaction is HNO\(_{3(aq)}\) + NaOH\(_{(aq)}\) \(\to\) NaNO\(_{3(aq)}\) + H\(_2\)O\(_{(l)}\)
(b) From your results and the information provided. calculate the: (i) concentration ot A In mol dm\(^{-3}\)
(ii) concentration of B in mol dm\(^{-3}\).
(iii) concentration of B in gdm\(^{-3}\)
(iv) mass of NaNO\(_3\) formed. If 250 cm\(^3\) of NaOH were neutralised. [Molar mass of NaOH = 40g mol\(^{-1}\), NaNO\(_3\) = 85 gmol\(^{-1}\). 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 this booklet, in ink, at the time they are made.
C is an organic compound. Carry out the following exercises on C. Record your observations and identity any gas(es) evolved. State the conclusions you draw from the results of each test.
(a) Put about 10 drops of C on a watch glass and ignite it using a burning splint.
(b)(i) Put about 1 cm\(^3\) of C in a test tube and add about 1 cm\(^3\) of distilled water. Shake the test tube.
(ii) Put about 1 cm\(^3\) of C in a test tube and add about 2 cm\(^3\) of acidified K\(_2\)Cr\(_2\)O\(_7\) solution. Warm the mixture gently and leave to stand for 5 minutes.
(c) Put few crystals of specimen D in a test tube and add about 2cm\(^3\) of C followed by about 2 cm\(^3\) of 10 % NaOH\(_{(aq)}\) Shake the test tube vigorously.
(d) State the class of compounds to which C belongs.
(a) A zinc salt, E when heated strongly, produced a brown gas with pungent smell, a colourless gas that rekindled a glowing splint, and a residue that was allowed to cool.
(i) identify the salt E.
(ii) Write an equation for the decomposition of E.
(iii) State what would be observed when the residue was allowed to cool.
(b) Describe how 250cm\(^3\) of 0.2 mol dm\(^3\) H\(_2\)SO\(_4\) could be prepared from 150 cm\(^3\) of a 1.0 mol dm\(^{3}\) stock solution of the acid.
(c) State the effect of aqueous solution of Al\(_2(SO_4)_3\) on litmus paper.
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 is a solution containing 15.8 g dm\(^3\) of Na\(_2\)S\(_2\)O\(_3\). B was obtained by dissolving 9.0 g of an impure sample of I\(_2\) in aqueous Kl and the solution made up to 1 dm\(^3\).
(a) Put A into the burette and titrate it against 20.0 cm\(^3\) or 25.0 cm\(^3\) portions of B. Use starch solution as indicator. Repeat the titration to obtain concordant titre values. Tabulate your results and calculate the average volume of A used. The equation for the reaction involved in the titration is I\(_2\) + 2S\(_2\)O\(_3\) \(\to\) 2I\(^-\) + S\(_4\)O\(_6^{2-}\).
(b) From your results and the information provided, calculate the:
(i) concentration of A in mol dm\(^{-3}\)
(ii) concentration of I\(_2\) in B in mol dm\(^{-3}\);
(iii) percentage by mass of I\(_2\) in the sample
(c) Give reasons why the starch indicator was not added to the titration mixture at the beginning of the titration. [O = 16.0, Na = 23.0, S = 32.0, 1 = 127.0] Credit will be given for strict adherence to the instructions for observations precisely recorded and for accurate inferences. AIl tests, observations and inferences must be clearly entered in the booklet in ink at the time they are made.
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 mixture of two inorganic compounds. Carry out the following exercises on C. Record your observations and identify any gas(es) evolved. State the conclusions you draw from the result of each test.
(a) Put all of C in a boiling tube and add about 10 cm\(^3\) of distilled water. Shake thoroughly and filter. Keep both the residue and the filtrate.
(b)(i) To about 2 cm\(^3\) of the filtrate add a few drops of Silver trioxoitrate (V) followed by dilute HNO\(_{3}\)
(ii) Add excess NH\(_3\) solution to the resulting mixture in (b)(i).
(C)(i) Put the residue in a test tube, add about 2 cm\(^3\) of dilute HCl and shake.
(ii) Add NH\(_3\) Solution in drops to the mixture from (c)(i) and then in excess.
