Comments on: O Level Chemistry: Mole Concepts / Qualitative Analysis

By: Natalie

Natalie — Wed, 13 Oct 2010 16:04:10 +0000

Hi, Na2CO3 and Na2SO4 are colourless solution is it because Na is a group 1 element. and all group 1 salts and ammonium salts are colourless? thanks.

By: Wawan Carls

Wawan Carls — Thu, 24 Jun 2010 08:06:07 +0000

Sir, i thought only iron two plus (Fe2+) will give you green ppt, insted of blue ppt.

I’mma bit confuse here.

By: Wasiq

Wasiq — Mon, 11 Jan 2010 15:26:47 +0000

Hey how did you came to know that CUSO4 is the limiting reactant pls reply

By: sean

sean — Tue, 28 Oct 2008 03:21:54 +0000

% Yield = Actual Yield/Theoretical Yield x 100%

whereas

% Purity = Amt of Pure Substance/Amt of Substance used in Rxn x 100%

Hope this helps.

Cheers
Sean
Master Trainer
SimpleChemConcepts.com

By: TEC

TEC — Tue, 21 Oct 2008 06:00:39 +0000

20cm3 of a gaseous hydrocarbon was mixed with 100cm3 of oxygen and the mixture sparked so that the hydrocarbon was completely burnt. The volume of gas remaining at the end of the combustion was 70cm3. After passing over soda lime, this volume was reduced to 10cm3. All gases were measured at 25C and at the same pressure.

(a) What volume of oxygen gas remained unburnt at the end?
(b) What volume of oxygen gas was used in the combustion?
(c) What volume of carbon dioxide was produced in the combustion?
(d) Deduce the formula of hydrocarbon.