AP chem help, reactants and products!

[MattY]

For my summer AP Chemistry assignement, I have been given 10 different questions each involving 2 reactants. I am to write them in molecular form. Here are the directions exatly (as it might help for you to know, they are only increasing my confusion)

"Assignment: Write the fomulas to show the reactants and the products for the laboratory situations described below. In all cases, a reaction occurs. Assume that solutions are aqueous (this means they're all water based, right? What the hell good does that do me?) unless otherwise indicated. Represent substances in solutions as ions if the substances are extensively ionized (whatever that means). Omit formulas for any ions or molecules that are unchanged by the reactions (understand that). You need not balance the equations". Firstly, it would be great if you could help me understand the directions, and how they will effect me solving these problems.

It has been 2 years since I have taken chemistry, and I forget alot (I do know the types of reactions, I just don't understand how I decide whether this is a synthesis, decomposition, double replacement etc...)

2) Liquid Bromide is mixed with a solution of potassium iodide.

Here's what I did, which is most likely wrong. I wrote.

Br2 + IK =YIELDS= I2 + BrK (the numbers are the quantities, under the name, or whatever)

I just thought it looked like a single replacement, and chose to replace the bromide with the potassium. I am really really baffled, and I have no idea how I predict what the product will be. Any and all help would be appreciated, because as you can see, I'm absoultely stumped on everything!

[sdekivit]

this is a simple redox reaction between Br2 and I(-). The reaction is correct, but you should write it as following:

Br2 + 2 I(-) --> 2 Br(-) + I2

The potassium ions are the so called spectator ions.

[MattY]

So I don't need to show potassium at all?

And how did you know it's an redox reaction (and what is that??)

Also, I researched liquid bromide a little more, and found out it isn't Br2. Is it just Br(l)?

[susanlucas123]

you don't need to show the potassium b/c as the first person said they are just "spectator ions" and all the teacher wants to know is the NET IONIC EQUATION

i'm taking AP Chem too. i have to do a summer assignment as well (i wonder if we have similar packets)

[adrian]

Additional: If you have an excedent of KI, another reaction can occur:
KI+I2--->KI3 (and iodine is solubilized into the water)
Of course, this reaction is not redox.