chem 不明

2011-05-30 5:56 am
ce86年18題
which of the following compounds would produce a gas heated with concentrated sulphuric acid??

A:sodium sulphate
B:calcium chloride
C:magnesium oxide
D:aluminium hydroxide

點解答案是B不是C
更新1:

sorry,是86年50題

更新2:

sorry,都是86年18題

回答 (2)

2011-05-30 8:58 am
✔ 最佳答案
Which of the following compounds would produce a gaswhen heatedwith concentrated sulphuric acid ?
A: sodiumsulphate
B: calciumchloride
C: magnesiumoxide
D: aluminiumhydroxide


The answer is B: calcium chloride.

A: No gas is formed.
There is no reaction between sodium sulphate and concentrated sulphuric acid.

B. Hydrogen chloride gas is formed.
When heated, calcium chloride reacts with concentrated sulphuric acid to givehydrogen chloride gas.
CaCl2(s) + 2H2SO4(aq) → Ca(HSO4)2(aq) + 2HCl(g) .. [gentle heating]
CaCl2(s) + H2SO4(aq) → CaSO4(s) + HCl(g) .. [strong heating]

C. No gas is formed.
Neutralization occurs between magnesium oxide and concentrated sulphuric acidto give magnesium sulphate and water.
MgO(s) + H2SO4(aq) → MgSO4(aq) + H2O(l)

D. No gas is formed.
Neutralization occurs between aluminium hydroxide and concentrated sulphuricacid to give aluminium hydroxide and water.
2Al(OH)3(s) + 3H2SO4(aq) → Al2(SO4)3(aq)+ 3H2O(l)
參考: miraco
2011-05-31 1:21 am
Concentrated sulphuric acid is H2SO4(l), not H2SO4(aq)


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