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Non Life Sciences => Chemistry => Topic started by: portugal on 22/08/2007 09:06:31

Title: electrochemistry
Post by: portugal on 22/08/2007 09:06:31

When KBr reacts with conc. H2SO4 some bromine and SO2 are evident as well as the main product (HBr). The number of moles of KBr which reacts with one mole of conc. H2SO4?

Title: electrochemistry
Post by: lightarrow on 22/08/2007 12:07:16

Quote from: portugal on 22/08/2007 09:06:31

When KBr reacts with conc. H2SO4 some bromine and SO2 are evident as well as the main product (HBr). The number of moles of KBr which reacts with one mole of conc. H2SO4?

In which reaction?

2KBr + H₂SO₄ --> K₂SO₄ + 2HBr↑   or:

2KBr + 2H₂SO₄ --> SO₂↑ + Br₂↑ + K₂SO₄ + 2H₂O?

Title: electrochemistry
Post by: portugal on 22/08/2007 13:14:57

i will post the full question up ok unchanged:
1. When KBr reacts with conc. H2SO4 some bromine and SO2 are evident as well as the main product (HBr). The number of moles of KBr which reacts with one mole of conc. H2SO4 in this side reaction is:

 a. 1.33 mol

 b. 0.75 mol

 c. 1.00 mol

 d. 2.00 mol

 e. 0.50 mol

Title: electrochemistry
Post by: eric l on 22/08/2007 14:06:08

With the first reaction (only HBr) you have a molar ratio of 2/1
With the second (Br₂ and SO₂) you have a molar ratio of 1/1
You have both, so the only valid answer is with a value in between or answer A

Title: electrochemistry
Post by: lightarrow on 22/08/2007 19:16:24

Quote from: portugal on 22/08/2007 13:14:57

i will post the full question up ok unchanged:
1. When KBr reacts with conc. H2SO4 some bromine and SO2 are evident as well as the main product (HBr). The number of moles of KBr which reacts with one mole of conc. H2SO4 in this side reaction is:

 a. 1.33 mol

 b. 0.75 mol

 c. 1.00 mol

 d. 2.00 mol

 e. 0.50 mol

With "this side reaction" it means: the one which forms SO₂ and Br₂. So you can see from the balanced reaction I wrote that it's 2 moles of KBr and 2 of H₂SO₄, that means 1 and 1. So the answer is 1 (c.)