# TEST OF PRACTICAL KNOWLEDGE QUESTION All your burette readings (initials and final), as well as the size of your pipette, must be recorded but no account of...

Question 1

TEST OF PRACTICAL KNOWLEDGE QUESTION

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 0.200 moldm$$^3$$ of HCl. C is a solution containing 14.3g of Na2CO$$_{3}$$.xH$$_2$$O in 500 cm$$^3$$ of solution.

a) Put A into the burette and titrate it against 20.0 cm$$^3$$ or 25.0cm$$^3$$ portions of C using methyl orange as indicator. Repeat the titration to obtain Consistent titre values. Tabulate vour results and calculate the average volume of A used. The equation for the reaction is;

Na$$_2$$CO$$_3$$ . xH$$_2$$O + 2HCl$$_{(aq)}$$ $$\to$$ 2NaCl$$_{(aq)}$$ + CO$$_{2(g)}$$ + (x + 1)$$_3$$H$$_2$$O$$_{(l)}$$

(b) From your results and the information provided. calculate the:

(i) concentration of C in moldm$$^{-3}$$

(ii) concentration of C in gdm$$^{-3}$$

(iii) molar mass of Na$$_2$$CO$$_3$$ . xH$$_2$$O

(iv) the value of x in Na$$_2$$CO$$_3$$ . xH$$_2$$O. [H =1.0; C = 12.0; O = 16.0; Na = 23.0]

Credit will be given for strict adherence to the instruction, for observations precisely recorded and for accurale references. All tests. obsenations and influences must be cleary entered in the booklet in ink at the same time they are made.