Can someone explain how reagents work?

[wonders]

And what are the purposes of doing tests with reagents?

[Country Boy]

If you have no idea what reagents ARE, look up the definition. That should make it clear how they "work"! If you d0 know what reagents are, I can see no reason for your question.

[wonders]

Yes, I do know what reagents are. But I don't know how to conduct an experiment with them. The teacher gave us KOH (aq) and H2SO4 (aq) and asked us to use them to identify unknown substances. I have no idea what I should do.

 

Sorry if that doesn't make any sense to you.

[hotcommodity]

Yes, I do know what reagents are. But I don't know how to conduct an experiment with them. The teacher gave us KOH (aq) and H2SO4 (aq) and asked us to use them to identify unknown substances. I have no idea what I should do.

 

Sorry if that doesn't make any sense to you.

 

I assume your teacher is talking about titrating H2SO4 with KOH. Lets say you have plenty of KOH, but only a limited amount of of H2SO4, and lets say you don't know how much H2SO4 you're dealing with. The idea is to react just enough KOH with H2SO4. When this happens, your indicator in the titrated H2SO4 will change color. You want to look at how much KOH you used to titrate the H2SO4. Seeing as you have only a limited amount of H2SO4, you know that will be your limiting reagent. And by looking at the reation equation for KOH and H2SO4, you'll be able to determine the amount of H2SO4 you were initially given. Does this make sense?

[wonders]

I don't know if that's the same thing my teacher meant. How do you use that method to identify unknown substances (aq) though?

 

The example she gave us is:

 

suppose

NaBr (s) --> Na+ (aq) + Br- (aq)

AgNO3 (s) --> Ag+ (aq) + NO6- (aq)

 

If the solutions are mixed,

Na+ (aq) + Br- (aq) + Ar+ (aq) + NO3- (aq) --> AgBr (s)

 

AgBr (s) is the precipitate, so what is in the mixture will be:

 

AgBr (s) + Na+ (aq) + NO3-(aq)

 

 

 

So now for the experiment we are given reagents KOH and H2SO4 to identify unknown substances. How do you apply her example in this case?

[hotcommodity]

Hmm...How is your teacher telling you to approach the problem with the KOH and H2SO4? If it's written down somewhere, type out the entire problem. This will give me a better grasp on what's being asked for.

[wonders]

My teachers wants us to design the lab ourselves. She gave us the materials and purpose, and we plan it.

 

-sigh-