unit 1 chemistry - reactions questions. pls help! Watch

ash213
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some reactions of solid and aqueous calcium bromide are given below.

CaBr2(aq) + 2AgNO3(aq) ---------> Ca(NO3)2(aq) + 2AgBr(s) eq. 2.1

CaBr2(s) + H2SO4(l) ------------> CaSO4(s) + 2HBr(g) eq.2.2a

followed by:2HBr(g) + H2SO4(l) ----------> Br2(l) + SO2(g) + 2H20(l) eq2.2b

Cl2(g) + CaBr2(aq) ---------> CaCl2(aq) + Br2(aq) eq2.3

1) from the equations identify a precipitation reaction and write an ionic eqquation to represent it (including state symbols)

2)from the equations identify a redox reaction and state what is being oxidised

3) aqueous calcium bromide can be electrolysed. write the half equation for the reaction in which bromide ions are turned into the element brominde.

and finally.......

4) using eqquations 2.2 (a and b), 2.3 and your answer to q3, suggest with a reason which process would be the best for the industrial production of pure bromine from calcium bromide

state for each of the other two processes, why you rejected them.
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tamala
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AgBr is a precipitate. The first reaction is precipitations reaction as we get a solid AgBr from two aqueous mixtures. Ions equation is: Ag+(aq) + Br-(aq) = AgBr(s)

A redox reaction is the thirs reaction: Cl2(g) + CaBr2(aq) ---------> CaCl2(aq) + Br2(aq).
Reactions taking place are as follows: Cl2 + 2e- = 2Cl- and 2Br- - 2e-= Br2. Oxidation is loss of electrons. Therefore, bromine is oxidised.
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Manifest
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(Original post by ash213)
some reactions of solid and aqueous calcium bromide are given below.

CaBr2(aq) + 2AgNO3(aq) ---------> Ca(NO3)2(aq) + 2AgBr(s) eq. 2.1

CaBr2(s) + H2SO4(l) ------------> CaSO4(s) + 2HBr(g) eq.2.2a

followed by:2HBr(g) + H2SO4(l) ----------> Br2(l) + SO2(g) + 2H20(l) eq2.2b

Cl2(g) + CaBr2(aq) ---------> CaCl2(aq) + Br2(aq) eq2.3

1) from the equations identify a precipitation reaction and write an ionic eqquation to represent it (including state symbols)

2)from the equations identify a redox reaction and state what is being oxidised

3) aqueous calcium bromide can be electrolysed. write the half equation for the reaction in which bromide ions are turned into the element brominde.

and finally.......

4) using eqquations 2.2 (a and b), 2.3 and your answer to q3, suggest with a reason which process would be the best for the industrial production of pure bromine from calcium bromide

state for each of the other two processes, why you rejected them.
3) Br- + 2e- = Br

4) Q3 Because a) Pure Bromine is formed b) It says industrially, so you can't start making bromine in the laboratory all along. Electrolysis is used to produce Compound/element/substance in large/massive production. It is a continuous process although it might be expensive.

2.2 contained HBr which needs extra processing.
2.3 It says pure bromine but CaCl2 is present which I presume will no longer be pure bromine
.


Hope that helps.
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silent ninja
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Group 1 elements tend to be produced by electrolysis as they are very strong reducing agents, so trying to separate them (by adding carbon or other reagents for example) doesn't work. They're not easily displaced.
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silent ninja
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I would have thought electrolysis would be the best method. 2.2a & b would cost too much. 2.3 would require use of chlorine, of which you will lose as CaCl2 and to get chlorine in the first place can be expensive in itself, so why lose chlorine when you already have the pure substance?
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