Comments on: O Levels Chemistry Tips Blog Marathon – Day 2

By: amna talaat

amna talaat — Mon, 14 Mar 2011 14:19:56 +0000

can sum one plz explain to me da precipation method for preparingg salt

By: Sherry Wheee

Sherry Wheee — Fri, 01 May 2009 13:45:38 +0000

Question 1:
The answer is C, Copper (II) oxide because it is a base. A base only reacts with acids to form salt and water but does not react with alkalis. Aluminium oxide and Zinc oxide are amphoteric oxides so they react with both acids and alkalis to form salt and water. Carbon dioxide is an acidic oxide, so it only reacts with alkalis but not acids. Thus, only Copper (II) oxide reacts with an acid to form a salt but does not react with an alkali.

Question 2:
The answer is B, Potassium carbonate neutralises sulfuric acid. When aqueous potassium carbonate is added to sulfuric acid, neutralisation takes place and a salt, potassium sulfate is formed. A salt is formed only during neutralisation.

Sir, are my answers correct?

By: hina

hina — Thu, 30 Apr 2009 10:18:54 +0000

the answer is “c” because aluminium oxide will not react beacus of the layer of oxygen above aluminium.
carbon dioxide is an acidic oxide so it definitely will react with alkali.zinc oxide
will react with both acids and alkalis since it is an amphoteric oxide.so the only option left
is “c”.
the answer of question 2 is “b” because the rest are wrong options because potassium
carbonate and potassium sulphte are slouble salts and potassium sulphate is not
a base,it is a salt.

By: Areeba

Areeba — Tue, 28 Apr 2009 10:23:34 +0000

a) Acids give hydrogen ions when dissolved in water while alkalis give hydroxide ions when dissolved in water. acids turn universal indicator from green to red. while alkalis turn universal indicators from green to blue.

Sir should I answer in the same prose or any other suggested answer?

By: SimpleChemConcepts | O Levels Chemistry Tips Blog Marathon - Day 4

SimpleChemConcepts | O Levels Chemistry Tips Blog Marathon - Day 4 — Mon, 27 Apr 2009 13:49:34 +0000

[...] the last few days, we have discussed on the topics of “Acids, Bases & Salts” (Day 2 & Day 3). Today we are going to discuss a very basic but Important Sec 3 Chemistry Topic on [...]