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.
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\(^{-2}\)]
(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].
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.
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.
