Tuesday, 5 June 2012

NECO 2012, CHEMISTRY PRACTICAL, QUESTIONS AND ANSWER

1(i) A contains ......cm3 of concentrated HCl per dm3 of solution.
(ii) B contains ......g of anhydrous Na2CO3 per dm3 of solution.
=>State the volume of A required to neutralize 20cm3 or 25cm3 of B with indicator.
(a) 150cm3 of hydrochloric acid solution in a beaker labelled"A".
The acid solution which should be the same for all Candidates will contain 9.0cm3 of concentrated hydrochloric acid per dm3 of solution.
(b) 150cm3 of Sodium trioxocarbonate (IV) solution in a beaker labelled"B".
The solution which should be the same for all candidates will contain 5.00g of Sodium trioxocarbonate(IV) in per dm3 of solution.
(c) One spatula full of sodium trioxocarbonate(IV) in a corked specimen bottle labelled"C".
(d) One spatula full of calcium chloride in a corked specimen bottle labelled"D".
REGISTER TO BE NOTIFIED OF LATEST UPDATE ON NECO EXAMINATION

2. QUANTITATIVE ANALYSIS ( SALT ANALYSIS)
=> Candidates are advised to adhere strictly to the instructions given.
All observations and inference must be clearly recorded in the table below.
Identify any gas(es) evolved.
N/B: The table is stated as thus:
TEST - OBSERVATION - INFERENCES. Under TEST:
(a.) Put all of C in a boiling tube and add about 5cm3 of distilled water.
Divide the resulting solution into two portions.
(i) To the first portion add about 2cm3 of BaCl2 solution.
Then dilute HCl in excess.
(ii) To the second portion of the solution add two drops of phenolphthalein indicator.
(b.) Dissolve all of D in a boiling tube with about 5cm3 of distilled water.
Divide the resulting solution into two equal parts.
(i) To the first portion add Ammonia solution.
(ii) To the second portion add NaOH solution in drops.
Then in excess.
(c.) A white solid X when heated strongly, gave off a gas Y which turns lime water milky and, a white powdery residue Z.
When water was added to Z, it formed an alkaline solution.
(i) From the information provided, name:
[I] The white solid X. (1 mark)
[II] The gas Y given off (1 mark)
[III] The white residue Z ( 1 mark)
(ii) Write the equation for the reaction between Z and water. (2 marks)
REGISTER TO BE NOTIFIED OF LATEST UPDATE ON NECO EXAMINATION

(3a) State what would be observed if hydrogen sulphide gas was:
(i) Bubbled into a solution of lead (II)ethanoate.
(1 mark) (ii) Mixed with Sulphur (IV)oxide in a gas jar in the presence of moisture.
(1 mark) (b) Q is a solid sample of zinc trioxocarbonate(IV).
Record in a tabular form what would be observed and the appropriate inferences if the following tests were performed on Q.
N/B: The table is stated as thus: TEST - OBSERVATION - INFERENCES.
Under TEST:
(i) Q + water
(ii) Q + dil HCl
(iii) Solution from
(ii) above + NH3(aq) in drops, then in excess.

0 comments :

Disclaimer: Note that we make every effort to verify the authenticity of our daily posts, we encourage our readers to also confirm before application. Our advice for you is never to pay any amount of money to any recruiter for job aid or educational consultant for admission aid.
Related Posts Plugin for WordPress, Blogger...
Loading...

Get Exclusive Job Alert And Educational News From Us!

Join Over 100,000 Registered Subscribers Today.


Enter your email address:

Delivered by FeedBurner | Follow Us On Twitter | Like Our Facebook Fan Page


Register Now To Get Quality Job Vacancies, Educational News, And Articles Update.