A series of free IGCSE Chemistry Activities and Experiments (Cambridge IGCSE Chemistry).
Solid E was analysed. E was an aluminium salt. Some of the observations are shown below.
Appearance of solid E - white crystalline solid.
A little of solid E was heated in a test-tube - colourless drops of liquid formed at the top of the tube.
(a) A little of solid E was dissolved in distilled water.
The solution was divided into four test-tubes and the following tests were carried out.
Complete the observations for tests 2 and 3.
(i) Test 2:
Drops of aqueous sodium hydroxide were added to the first test-tube.
(ii) Excess sodium hydroxide was then added.
(iii) Test 3:
Drops of aqueous ammonia solution were added to the second test-tube. Excess ammonia solution was then added.
observations ______________ 
Two further tests are carried out and the following observations made.
tests on solution of E observations
To the third test-tube of solution, dilute hydrochloric acid was added, followed by barium nitrate solution - no reaction
To the fourth test-tube of solution, aqueous sodium hydroxide and aluminium foil were added.
The mixture was warmed carefully - effervescence, pungent gas given off, gas turned damp litmus paper blue
(b) What does test 1 tell you about solid E? __________
(c) Identify the gas given off in test 5. __________ 
(d) What conclusions can you draw about solid E? __________ 
(e) Test 5 states that the mixture should be warmed carefully.
In terms of safety, explain why it is necessary to warm carefully _________ 
(a) (i) white precipitate 
(ii) precipitate dissolves in excess; 
(iii) white precipitate; 
no change / precipitate remains; 
(b) contains water / hydrated 
(c) ammonia, not: ammonium 
(d) Any two from:
hydrated salt / contains water;
it is not a sulfate; 
(e) sodium hydroxide is hazardous / irritant / caustic; 
boiling causes mixture to spit / blow-out; 
E-numbers identify chemicals which are added to foods.
(a) E210 is benzoic acid. How could you show that a solution of benzoic acid is a weak acid?
result __________ 
(b) E110 is Sunset Yellow.
Outline a method you could use to show the presence of E110 in a food colouring.
You may draw a diagram to help answer the question. 
(a) Universal indicator / pH paper; 
pH of 4–6 / yellow / orange; 
note: any suitable test with appropriate result
(b) Any four from:
description of applying food colouring to paper;
use of solvent;
results / number of spots;
compare results to known sample / reference to Rf value; 
marks can be obtained from a labelled diagram
Try the free Mathway calculator and
problem solver below to practice various math topics. Try the given examples, or type in your own
problem and check your answer with the step-by-step explanations.
We welcome your feedback, comments and questions about this site or page. Please submit your feedback or enquiries via our Feedback page.