ecieee Posted August 27, 2011 Report Share Posted August 27, 2011 (edited) I was going through some past papers, and I got stuck on a question. Which list represents the halogens in increasing order of oxidizing strength (weakest oxidizing agent first)? A. Cl2 I2 Br2 B. I2 Br2 Cl2 C. I2 Cl2 Br2 D. Cl2 Br2 I2 I'm really confused about what this question is asking. It says 'increasing order of oxidising strength' but then 'weakest oxidising agent first'! From what I know, these two contradict each other ,no? what oxidises loses electrons, and what reduces (oxidising agent) gains electrons. So does this question want me to list halogens that are least likely to oxidise -> most likely? or most likely (weak oxidising agent) -> least likely (strong oxidising agent) ? I'm so confused. They seem to contradict each other Edited August 27, 2011 by ecieee Reply Link to post Share on other sites More sharing options...
dessskris Posted August 27, 2011 Report Share Posted August 27, 2011 (edited) no... increasing order is from the smallest to the largest so they're right when they mentioned the weakest comes first. what oxidises loses electrons, and what reduces (oxidising agent) gains electrons. wrong... what IS OXIDISED loses electron. it's called reducing agent. it reduces another substance. what IS REDUCED gains electron. it's called oxidising agent. it oxidises another substance. so the answer is B. Edited August 27, 2011 by Desy Glau Reply Link to post Share on other sites More sharing options...
caveat emptor Posted August 27, 2011 Report Share Posted August 27, 2011 (edited) ummm...i do chem SL but i would give it a try...i think its 'B' Due to the fact that Chlorine is more electronegative than the rest of the halogens. i guess so Edited August 27, 2011 by Saig Reply Link to post Share on other sites More sharing options...
Drake Glau Posted August 27, 2011 Report Share Posted August 27, 2011 ummm...i do chem SL but i would give it a try...i think its 'B' Due to the fact that Chlorine is more electronegative than the rest of the halogens. i guess soThat would be the easiest way to remember it. The reactivity for the halogens are in decreasing order if you follow them down. The strongest is F and the weakest is...w/e is at the bottom, i forget. The strength of an OXIDIZING agent would be directly related to this, for a reducing agent it would be flipped. Reply Link to post Share on other sites More sharing options...
ecieee Posted August 27, 2011 Author Report Share Posted August 27, 2011 (edited) no... increasing order is from the smallest to the largest so they're right when they mentioned the weakest comes first. what oxidises loses electrons, and what reduces (oxidising agent) gains electrons. wrong... what IS OXIDISED loses electron. it's called reducing agent. it reduces another substance. what IS REDUCED gains electron. it's called oxidising agent. it oxidises another substance. so the answer is B. Hey Desy, thanks for your clarification! I'm a bit confused though. When I said what oxidises loses electrons, and what reduces (oxidising agent) gains electrons. isn't that exactly same as what you wrote? or is their a difference between what 'oxidises' and what 'oxidised'. I always said something like "in a zinc copper voltaic cell, zinc oxidises and copper reduces". Is this not the correct way to say then? should I say "in a zinc copper voltaic cell, zinc is oxidised and copper is reduced"? I'm so confused! I think this is a matter of english Edited August 27, 2011 by ecieee Reply Link to post Share on other sites More sharing options...
ChikkyD Posted August 27, 2011 Report Share Posted August 27, 2011 When you say reduced, it means it is the substance GETTING reduced. When you say reduces, it means it is the substance DOING the reducing. I always said something like "in a zinc copper voltaic cell, zinc oxidises and copper reduces". Is this not the correct way to say then? should I say "in a zinc copper voltaic cell, zinc is oxidised and copper is reduced"? You've just said that they do two different things, so the two statements don't mean the same thing 1 Reply Link to post Share on other sites More sharing options...
ecieee Posted August 28, 2011 Author Report Share Posted August 28, 2011 When you say reduced, it means it is the substance GETTING reduced. When you say reduces, it means it is the substance DOING the reducing. I always said something like "in a zinc copper voltaic cell, zinc oxidises and copper reduces". Is this not the correct way to say then? should I say "in a zinc copper voltaic cell, zinc is oxidised and copper is reduced"? You've just said that they do two different things, so the two statements don't mean the same thing Thanks Chikky! :-) I've got another question, I came across this question Which describes the visible emission spectrum of hydrogen? A. A series of lines converging at longer wavelength B. A series of regularly spaced lines C. A series of lines converging at lower energy D. A series of lines converging at higher frequency and I'm confused here. I know that lines converge as energy level increases, but I'm confused because the answer seems to contradict what I know? The answer from the mark scheme is D - converge at higher frequency. Now, higher frequency means shorter wavelength which means lower energy levels.............. So how can this be the answer? Reply Link to post Share on other sites More sharing options...
ILM Posted August 28, 2011 Report Share Posted August 28, 2011 Now an electron has absorbed energy and moved to the 7th energy level. When that electron is coming back it will move from 7th to 6th and then from 6th to 5th and so on. the distance between the 3rd and the 2nd is less than the distance between 2nd and the 1st, this mean that there will be higher energy emitted at the end of the spectrum. Higher energy= higher frequency, so D is the right answer. Hope that this is clear Reply Link to post Share on other sites More sharing options...
ecieee Posted August 28, 2011 Author Report Share Posted August 28, 2011 Now an electron has absorbed energy and moved to the 7th energy level. When that electron is coming back it will move from 7th to 6th and then from 6th to 5th and so on. the distance between the 3rd and the 2nd is less than the distance between 2nd and the 1st, this mean that there will be higher energy emitted at the end of the spectrum. Higher energy= higher frequency, so D is the right answer. Hope that this is clear Eek.... I didn't quite get that...... Reply Link to post Share on other sites More sharing options...
Ezeh Posted August 28, 2011 Report Share Posted August 28, 2011 Now an electron has absorbed energy and moved to the 7th energy level. When that electron is coming back it will move from 7th to 6th and then from 6th to 5th and so on. the distance between the 3rd and the 2nd is less than the distance between 2nd and the 1st, this mean that there will be higher energy emitted at the end of the spectrum. Higher energy= higher frequency, so D is the right answer. Hope that this is clear Eek.... I didn't quite get that...... think of it like the hydrogen's energy levels are on their side. for example this: is like the right hand side of this (forget the left hand side): basically, the energy levels are more condensed at the top (so to speak), and these are the energy levels that produce the highest frequency photons. that's probably not the best way to think of it, but it should help you remember Reply Link to post Share on other sites More sharing options...
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