Halogen boiling point qn

Laboromniavincit

17

Could someone explain the answer it’s from aqa specimen 2018 the ans is +30 to +120

OP

OP

the question was predict the boiling point of bromine the MS says+30 to +120 I wrote 149 ( wrong answer) How do i do the calculation?

Reply 3

cpocha1

11

Original post by Laboromniavincit

the question was predict the boiling point of bromine the MS says+30 to +120 I wrote 149 ( wrong answer) How do i do the calculation?

Hello,
The question is about predicting, so there is no method to arrive at the final answer. You have to see the trend of the halogens down the group. in this case it is increasing. See the depth of the increase and then use the difference to find the value for bromine. From F to Cl it is approximately 150. Add 150 to Cl value you should get 115 which is in the range of 30 to 120. But I would also suggest you to use a lower value since the depth of increase is decreasing slowly. Iodine has 184. Here the difference is so small, so decrease the value of Br at least to 30. You should get 85 which is the perfect answer

Reply 4

Laboromniavincit

OP

17

Original post by cpocha1

Hello,
The question is about predicting, so there is no method to arrive at the final answer. You have to see the trend of the halogens down the group. in this case it is increasing. See the depth of the increase and then use the difference to find the value for bromine. From F to Cl it is approximately 150. Add 150 to Cl value you should get 115 which is in the range of 30 to 120. But I would also suggest you to use a lower value since the depth of increase is decreasing slowly. Iodine has 184. Here the difference is so small, so decrease the value of Br at least to 30. You should get 85 which is the perfect answer