1) A solid mixture consists of one mole of sodium carbonate and one mole of sodium hydrogencarbonate.What is the least number of moles of sulphuric acid required to liberated all the available carbon dioxide from the mixture?
2) Which of the following solids gives different observations when added separately to sulphuric acid and hydrochloric acid?
a)NaCO3
b)Zn(NO3)2
c)Zn
d)CaCO3
3) Which of the following solutions can exist in room temperature and perssure?
a)70% hydrochloric acid
b)70% nitric acid
c)70% sulphuric acid
4) Which of the following methods can be used to prepare CuSO4?
a) Cu(s) + H2SO4(aq)
b)CuO(s) + H2SO4(aq)
c)CuCO3(s) + H2SO4(aq)
d)CuCO3(s) + NaSO4(aq)
chem acid & alkali
2010-10-29 2:41 am
回答 (1)
2010-10-31 3:04 am
✔ 最佳答案
b. 1. NaHCO3 + (1/2)H2SO4 ------> (1/2)Na2SO4 + H2O + CO2
Na2CO3 + H2SO4 ------> NasSO4 + H2O + CO2
per mole of sodium hydrogencarbonate, half a mole of sulphuric acid is needed;
per mole of sodium carbonate, onemole of sulphuric acid is needed.
thus 1.5 mole of sulphuric acid is needed
2. D
A is Na2CO3? both acid reacts to give colorless solution and carbon dioxide, a colorless gas.
B has no reactions with acids.
C reacts with both acid to give colorless solution and hydrogen gas, a colorless gas.
(assuming sulphuric acid is diluted. if sulphuric acid is concentrated, colorless sulphur dioxide gas is produced instead --- though observation is still the same.)
D reacts with both acids to give colorless solution and carbon dioxide, a colorless gas. HOWEVER, calcium ion reacts with sulphate ion to give white precipitate of calcium sulphate, while hydrochloric acid has no such observation.
3. C
maximum concentration of hydrochloric acid at normal conditions is 35%; nitric acid is 65%; sulphuric acid is be up to 98%.
hydrochloric acid will just fume; nitric acid decompose to give nitrogen dioxide.
4. B & C.
both copper(II) oxide and copper(II) carbonate are insoluble in water but reacts with sulphuric acid. addition of excess solid into acid, followed by filtration gives copper(II) sulphate solution.
A: copper cannot react with diluted sulphuric acid (aq ---- diluted).
D: Na2SO4 is not acidic.
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