AL Chemistry Experiment Report Sheet

Experiment 23, 24: Investigating the Properties of s-Block Compounds

Name: ___________________ ( ) Form 7 S

Results Table 23a: Effect of heat on the s-block carbonates

Carbonate	Time to detect CO₂	Observations
Li₂CO₃
Na₂CO₃
K₂CO₃
MgCO₃
CaCO₃
SrCO₃
BaCO₃

Results Table 23b: Effect of heat on nitrates

Nitrates	Time to detect O₂ or NO₂	Observations	Effect of adding dilute HCl to cold residue
LiNO₃
NaNO₃
KNO₃
Mg(NO₃)₂
Ca(NO₃)₂
Sr(NO₃)₂
Ba(NO₃)₂

Results Table 24: Solubility of some salts of Group II elements

Cation solution	Number of drops of anion solution added to give a precipitates
Cation solution	OH^-	SO₄^2-	SO₃^2-	CO₃^2-
Mg²⁺
Ca²⁺
Sr²⁺
Ba²⁺

Questions:

1. Explain why many of these nitrates rapidly turn into colourless liquids on first heating, whilst on further heating become white solids again, before they decompose.

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2. Which of the Group I nitrates and carbonates most resemble those of Group II in their reaction to heat?

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3. Describe the trend in thermal stability of the nitrates and carbonates as each group is descended.

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4. Why are brown fumes produced when dilute HCl is added to the cold residue obtained when many of Group I nitrates are heated?

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5. For Group II, what are the trends in solubility of the salts listed below?

(a) hydroxides; (b) sulphates;

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The End