You are Here: Home

# ammonia Watch

1. (ii) Explain with the aid of equations, why ammonia NH3 is considered a weak base while potassium hydroxide is a strong base under aqueous conditions. (3 marks)

not sure how to tackle this question for 3 marks
2. (Original post by otrivine)
(ii) Explain with the aid of equations, why ammonia NH3 is considered a weak base while potassium hydroxide is a strong base under aqueous conditions. (3 marks)

not sure how to tackle this question for 3 marks
NH3 partially ionizes whilst the NaOH completely dissociates. So for the question I would write out the equations to show this.

I would write it out the equations but it is kind of hard doing it on my phone
3. (Original post by otrivine)
(ii) Explain with the aid of equations, why ammonia NH3 is considered a weak base while potassium hydroxide is a strong base under aqueous conditions. (3 marks)

not sure how to tackle this question for 3 marks
weak bases are a bit like weak acids, there is only partial dissociation of the acid. In this example of NH3 it is dissolved in water. The acid is the H20

NH3+ H20 <---> NH4+ + OH-

Strong bases like KOH dissociate fully, like strong acids

KOH-----> K+ + OH-

Any questions?

EDIT: The weak base will produce significantly less OH- ions
4. (Original post by freetown)
NH3 partially dissociates whilst the NaOH completely dissociates. So for the question I would write out the equations to show this.

I would write it out the equations but it is kind of hard doing it on my phone
but the idea of partially and completely comes from weak and strong acids right?
5. (Original post by otrivine)
but the idea of partially and completely comes from weak and strong acids right?
You can apply that logic to bases too
6. (Original post by Booyah)
weak bases are a bit like weak acids, there is only partial dissociation of the acid. In this example of NH3 it is dissolved in water. The acid is the H20

NH3+ H20 <---> NH4+ + OH-

Strong bases like KOH dissociate fully, like strong acids

KOH-----> K+ + OH-

Any questions?

EDIT: The weak base will produce significantly less OH- ions
so for 3 marks

should i state NH3 is a weak base as it partially dissociates to give OH- and KOH is strong base because completely dissociates to form OH-

and for equations should i give the example with NH3 reacting with water to give NH4+ and OH-

and the KOH dissociating to give K+ + OH-
7. (Original post by James A)
You can apply that logic to bases too
Thank you, where have u been for so long
8. (Original post by otrivine)
Thank you, where have u been for so long
I've been around

But I got banned twice, loooooooool
9. Write the equation for a weak base as an equilibrium and for a strong base as going to completion.
10. (Original post by freetown)
NH3 partially dissociates whilst the NaOH completely dissociates. So for the question I would write out the equations to show this.

I would write it out the equations but it is kind of hard doing it on my phone
NH3 does not dissociate!! (Well it does, but there is one molecule of NH2- for every ~1035 molecules of NH3)

NH3 is a weak base because the equilibrium for the following equation lies towards the left.

NH3 + H2O <--> NH4+ + HO-

NaOH dissociates fully into Na+ ions and HO- ions

HO- is a strong base because the equilibrium for the following reaction is in the middle. (well I don't like this wording but I guess A levels want bases put into the context of formation of HO- ions rather than pKa)

HO- + H2O <--> H2O + HO-
11. (Original post by illusionz)
NH3 does not dissociate!! (Well it does, but there is one molecule of NH2- for every ~1035 molecules of NH3)

NH3 is a weak base because the equilibrium for the following equation lies towards the left.

NH3 + H2O <--> NH4+ + HO-
would it be more accurate to say "NH3 partially ionizes" instead?
12. (Original post by otrivine)
so for 3 marks

should i state NH3 is a weak base as it partially dissociates to give OH- and KOH is strong base because completely dissociates to form OH-

and for equations should i give the example with NH3 reacting with water to give NH4+ and OH-

and the KOH dissociating to give K+ + OH-
Sorry I meant to say that ammonia associates, but yeah pretty much all that

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: April 19, 2013
Today on TSR

### 'Entry requirements are a form of elitism'

What do you think?

### I fancy Donald Trump...

Discussions on TSR

• Latest
• ## See more of what you like on The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

• Poll
Discussions on TSR

• Latest
• ## See more of what you like on The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

• The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE