During a titration it was determined that 30.00 mL of a 0.100 M Ce4+ solution wa

[bnleong]

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During a titration it was determined that
30.00 mL of a 0.100 M Ce4+ solution was
required to react completely with 20.00
mL of a 0.150 M Fe2+ solution. Which
reaction occurred?
A. Ce4+ + 3Fe2+ + H2O ---->3Fe3+
+ CeO- + 2H+
B. 2Ce4+ + Fe2+ --->Fe4+ + 2Ce3+
C. Ce4+ + Fe2+ --->Fe3+ + Ce3+
D. Ce4+ + 2Fe2+ ---->2Fe3+ + Ce2+
E. Ce4+ + 2Fe2+----> 2Fe4+ + Cs2+ 2e-

So the answer is C. Any ideas on how to solve this? I dont even know where to start... 😱😱😱
Sorry I forgot to put the arrows in there. I dont understand this because I thought a titration is done as neutralization reaction. THese are two positive metals. How are they even reacting. This is from the 2007 sample DAT

 

[silveryhair]

Are u sure the answer is C? and not B?

What practice material is this from? It looks familiar.

I would have thought it was B, but anyways, the only way I can see that it is C is that in the reaction you know that Ce4+ reacts with Fe2+ right?

The next step after that would be to find out the number of moles present on both sides, so 30ml(.1) Ce4+ and 20ml(.15) Fe2+

From that you see that there are 3 moles of each and you can divide them therefore it is Ce4+ + Fe3+ --> Fe4+ + Ce3+

That why its C, I suppose.

 

[bnleong]

Yep I'm sure the answer is C. Unless it is a mistake on the answer key.I added arrows into the equations. HOpe this helps.

 

[bnleong]

anyone?

 

[DoCt0rPeTe]

Just because they are positively charged doesn't mean they don't interact. It is showing a net ionic equation, where the spectator ions (the negatively charged things) are cancelled out.

Honestly, if I got this on my DAT I'd probably get really worried.

But I would have to guess that the only way to figure this out is to realize that both species are in a 1:1 mol ratio, so C is the only possible choice.

0.3L x .1 mol/L = 0.03

and 0.2 x 0.15 = 0.03

since they have an equal number of moles and are reacting with one another, the only logical choice is C.
And if you look at the answer choices, most of the other ones don't make sense.
I agree in that its a Redox rxn, so one thing must gain e- and the other must lose. Most answer choices don't even have that- their charges are the same on both sides of the equation.