IB-Adam Posted April 9, 2011 Report Share Posted April 9, 2011 (edited) Hi, I would like to know a method to measure the rate of reaction of each of the following reactants; AgCl, AgBr, and AgI. The reactions has to be unimolecular, that is in this case, when these reactants are exposed to light forming Ag+Cl/Br/I. I had the idea that for each measurement, I give the silver halide light for a fixed amount of time. Then I separate the silver formed from the unused silver halide and measure the weight. But then I would not would not be measuring the rate of reaction that accurately, or not even at all. Do you have any good methods to share? It would be best if concentration or mass vs. time graphs could be made. In school we have those programs and tools to measure mass per time graphs. I have been thinking about this for weeks now, and I guess I am too unexperienced to come up with any good methods. I have tried to google regarding this matter but without any further success. This is not a design lab The reactions: 2AgCl(s) --> 2Ag(s) + Cl2(g) 2AgBr(s) --> 2Ag(s) + Br2(l) 2AgI(s) --> 2Ag(s) + I2(s) Edited April 10, 2011 by IB-Adam Reply Link to post Share on other sites More sharing options...
Drake Glau Posted April 10, 2011 Report Share Posted April 10, 2011 Measuring the silver at the end will give you a single rate and chemical reactions are not linear rates sadly =/ (collision theory won't allow for this)The Cl for your AgCl trial would end up making Cl2 if i'm not mistaken so that one you could literally put the beaker or whatever on a scale and watch the mass drop as the gas escapes the system.The other two I'm unsure of. The iodine under stp will give you a solid and the bromine will just give you a liquid. So for both of those all i can think of is what you mentioned. Reply Link to post Share on other sites More sharing options...
Keel Posted April 10, 2011 Report Share Posted April 10, 2011 Hi,I dont know much about this and I've never seen such an experiment before but having looked at this which I'm more familiar with; is it not the case that the precipitate will disappear when exposed to light? Silver halides are insoluble in water, hence the precipitate, but if, as you describe, the compound splits into Ag+ + I-/Br-/Cl- these individual ions should be soluble in water and hence the 'solution' should become colourless/ more seethrough. So you could measure the time taken for the observer to see an 'x' on the other side of the test tube/beaker and hence find the rate. Would that work? Reply Link to post Share on other sites More sharing options...
Drake Glau Posted April 10, 2011 Report Share Posted April 10, 2011 Hi,I dont know much about this and I've never seen such an experiment before but having looked at this which I'm more familiar with is it not the case that the precipitate will disappear when exposed to light? Silver halides are insoluble in water, hence the precipitate, but if, as you describe, the compound splits into Ag+ + I-/Br-/Cl- these individual ions should be soluble in water and hence the 'solution' should become colourless/ more seethrough. So you could measure the time taken for the observer to see an 'x' on the other side of the test tube/beaker and hence find the rate. Would that work?The water+Halide would be colorless. Releasing the ions would make the solution their corresponding color. Bromine would be a deep red/brown, Iodine will be black/purple and Cl should be a weird green/yellow color. And this works too. I just hate qualitative stuff like this =/ Reply Link to post Share on other sites More sharing options...
Keel Posted April 10, 2011 Report Share Posted April 10, 2011 Yea I sorta agree but its not purely qualitative, you're still measuring the time taken for 'something' to happen. Reply Link to post Share on other sites More sharing options...
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