(a) Explain briefly the observations in each of the following processes:
(i) when carbon (IV) oxide is bubbled through lime water, It turns milky but the milkiness disappears when the gas is bubbled for a long time.
(ii) A precipitate of calcium hydroxide is insoluble in excess sodium hydroxide solution whereas that of lead (ii) hydroxide is soluble
(b)(i) What is a primary standard solution?
(ii) Calculate the mass of sodium trioxocarbonate (V) required to prepare 250 cm\(^3\) of 0.15gmoldm\(^3\) solution hydroxide is soluble. [Na = 23.0; O = 16.0; C = 12.0]
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.
C and D are two aqueous solutions. Carry out the following exercises on C and D. Record your observations and identify any gas(es) evolved. State the conclusion you draw from the result of each test.
(a)(i) To about 2 cm\(^3\) portion of C, add NaOH\(_{(aq)}\) In drops until in excess. Warm the mixture
(ii) To another 2 cm\(^3\) portion of C, add HCl\(_{(aq)}\) followed by BaCl\(_{2(aq)}\)
(b)(i) (ii) To another 2 cm\(^3\) portion of D, add add NH\(_{3(aq)}\) drops and then in excess.
(ii) To about 2 cm\(^3\) portion of D, add AgNO\(_{3(aq)}\) followed by HNO\(_{3(aq)}\)
Burette readings (initial and final) must be given to two decimal places. Volume of pipette used must also be recorded but no account of experimental procedure is required. All calculations must be done in your answer book.
A solution containing 6.22 g of an acid H\(_2\)Y per dm\(^3\)
B contains 3.90 g of NaOH per dm\(^3\) of solution.
(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. Repeat the titration to obtain consistent titres. Tabulate your burette readings and calculate the average volume of acid A used. The equation for the reaction involved in the titration is:
