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IGCSE CHEMISTRY DOUBTS HERE !!!!

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elemis:
http://www.echeat.com/essay.php?t=30794

Read it.

Got questions post here ;)

Ivo:
Ammonium sulfate was prepared by adding ammonia solution to 25 cm3 of 2.0 mol dm-3 sulfuric acid.

2NH3(aq) + H2SO4(aq) --> (NH4)2SO4(aq)

Question:

i) What volume of 2.0 mol dm-3 ammonia solution will just neutralise the sulfuric acid?  I got 50 cm3.

ii) How could you test to check that enough ammonia has been added to neutralise the sulfuric acid?

Thanks in advance!

ashish:

--- Quote from: Ivo on October 17, 2010, 12:27:00 am ---Ammonium sulfate was prepared by adding ammonia solution to 25 cm3 of 2.0 mol dm-3 sulfuric acid.

2NH3(aq) + H2SO4(aq) --> (NH4)2SO4(aq)

Question:

i) What volume of 2.0 mol dm-3 ammonia solution will just neutralise the sulfuric acid?  I got 50 cm3.

ii) How could you test to check that enough ammonia has been added to neutralise the sulfuric acid?

Thanks in advance!

--- End quote ---

i got 50 cm3 too

ii)test with and indicator such as methyl orange,  if is acidic it turns red and in alkaline medium it turns yellow .. the solution should be neutral so it should remains orange

or use universal indicator, which turns green

nid404:
First answer is right.

Use an indicator...say phenolphthalein. It is colorless in acids. To ensure that the sulfuric acid is completely neutralized, add ammonia until the solution just turns pink.  

Arthur Bon Zavi:

--- Quote from: Garfield on October 17, 2010, 06:30:07 am ---First answer is right.

Use an indicator...say phenolphthalein. It is colorless in acids. To ensure that the sulfuric acid is completely neutralized, add ammonia until the solution just turns pink.  

--- End quote ---

Phenolphthalein is used in strong acid - strong base titration!

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