catalyst (1 Viewer)

[fullonoob]

A catalyst (conc. H2SO4) is essential to allow the rxn to take place at low temps. Why low temps?

 

[ilikebeeef]

A catalyst (conc. H2SO4) is essential to allow the rxn to take place at low temps. Why low temps?

Catalysts provide an alternate chemical pathway, lowering activation energy. Some reactions have high activation energy, and so would not happen at low temperatures without a catalyst.

 

[fullonoob]

thx and what is the diff between equivalence point and end point.

 

[js992]

The end point is the point at which there is a permanent colour change in the indicator.

The equivalence point is where the exact amount of titrant has been added to your aliquot to completely neutralise each other.

 

[fullonoob]

The end point is the point at which there is a permanent colour change in the indicator.

The equivalence point is where the exact amount of titrant has been added to your aliquot to completely neutralise each other.

so end point = change in colour?
equivalence point = neutral substance? (isn't that change in colour as well)

My teacher said equivalence point = theoretical and end point = experimental. Is this true?

 

[mtsmahia]

so end point = change in colour?
equivalence point = neutral substance? (isn't that change in colour as well)

My teacher said equivalence point = theoretical and end point = experimental. Is this true?

yes ur teacher is right..

The end point is in regards to the experimental evidence & Equivalence point refers to ur calculations (theory).
They are different because, end point depends on what u perceive to be as a colour change, and it may not correspond to the num of moles added from burete to neutralize the unknown solution. So in reality they wont be the same value

 

[js992]

Your end point will depend on what indicator you choose and will certainly not always reflect your equivalence point all the time.
Eg. When a strong base is neutralised with strong base, the salt produced is neutral hence has a pH of 7. The equivalence point is therefore at about a pH of 7.

Choosing phenophthaelein as your indicator will give you an end point of pH approximately ~9. Hence it is not at the equivalence point

However if you choose bromothymol blue which changes colour from 6.0-7.6, the end point will be quite close to your equivalences point.

And also, when two substances neutralise, they dont necessarily form a neutral salt.

 

[ilikebeeef]

thx and what is the diff between equivalence point and end point.

Equivalence point is the point at which the neutralisation reaction is complete.
End point is the point at which the indicator permanently changes colour.