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Topic: Writing ionic equations, do I assume they always react?  (Read 2056 times)

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Offline chedoxychris

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Writing ionic equations, do I assume they always react?
« on: May 21, 2012, 09:06:26 AM »
Hello everyone. Hope your having a good day ;).

I'm currently finishing my A-Level salters chemistry course which is year12/13 here in the uk. If it helps with giving you an idea of my understanding/experience.

I have a simple-ish question: Zinc is added to copper(II) sulfate solution.
A) Write an ionic equation for the reaction.
Answer: Cu2+ + Zn -> Cu + Zn2+

My question is, how would I know these would react? Do I assume so because it's 'asking' in the question?

Offline Borek

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Re: Writing ionic equations, do I assume they always react?
« Reply #1 on: May 21, 2012, 09:12:15 AM »
In this particular case it is about reactivity series.

But in general, unless your teacher asks tricky questions, and you are not asked to predict if the reaction occurs, just to balance the equation, you can safely assume reaction goes as you are told.

You can input correctly formatted charges (Cu2+) using clickable symbols above the edit field.
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Offline chedoxychris

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Re: Writing ionic equations, do I assume they always react?
« Reply #2 on: May 21, 2012, 09:14:47 AM »
In this particular case it is about reactivity series.

But in general, unless your teacher asks tricky questions, and you are not asked to predict if the reaction occurs, just to balance the equation, you can safely assume reaction goes as you are told.

You can input correctly formatted charges (Cu2+) using clickable symbols above the edit field.

Right, I'm guessing the reactivity of transition metals is what I should look into? Although we didn't really cover the 'reactivity' of them in the first part of the year, so I'm assuming I just do the assuming thing uh. (doing a resit of the first year)

Thank you for your quick reply :)

Offline fledarmus

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Re: Writing ionic equations, do I assume they always react?
« Reply #3 on: May 21, 2012, 10:13:10 AM »
The reaction that you wrote is actually telling you where the electrons are going. The only difference between your starting materials and your products is that two electrons have moved.

There are tables of electrode potentials which compare the ability of different species to gain or lose electrons. Here is one...

http://en.wikipedia.org/wiki/Standard_electrode_potential_(data_page)

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