# Homework Help: Conjugate bases

1. Mar 24, 2010

### Amy-Lee

1. The problem statement, all variables and given/known data
Indicate the conjugate bases of the following:

NH2-
NH2-

2. Relevant equations

3. The attempt at a solution
This is the only information given. Can I assume that these species react with water? The ionic signs indicate that they are bases, but are they the conjugate bases?

2. Mar 25, 2010

### Staff: Mentor

What are the definitions of acid and conjuagte base? Can you write acid-base reaction equation involving one of given ions as a reactant and the other as a product?

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methods

3. Mar 28, 2010

### Amy-Lee

When species donates a proton, it becomes the conjugate base; when a species gains a proton, it becomes a conjugate acid...

NH2- + H2O -> NH3 + OH-

NH2- becomes a conjugate acid

4. Mar 28, 2010

### PhaseShifter

What does $$NH{_2}{^-}$$ become when it donates a proton?

5. Mar 28, 2010

### Amy-Lee

nh ?

6. Mar 28, 2010

### PhaseShifter

Close, but still missing something.

What will the charge be?

7. Mar 28, 2010

### Amy-Lee

negative

8. Mar 28, 2010

### Amy-Lee

So is the conjugate base of NH2- N3-?

9. Mar 28, 2010

### Staff: Mentor

No, acid and conjugate base must differ by exactly one proton. And PhseShifter didn't ask about positive/negative, but about exact value. You wrote nh (meaning NH) - but what is the exact charge?

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methods

10. Mar 28, 2010

### Amy-Lee

11. Mar 28, 2010

### Staff: Mentor

Oops, sorry, somehow I missed track of hydrogens and charge

That was right. I misread it as NH2-, not NH2-.

Still, nh was wrong - should be NH2-. Treat my mistake as a warning why you should never ignore capitalization and charge - it adds to the confusion.

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12. Mar 28, 2010

### Amy-Lee

I will, thank you so much for all your help and patience.