Conversion of Orthophosphoric acid to Pyro and Meta Phosphoric acid

[Physics lover]

Homework Statement

Question pic is in My attempt.

Relevant Equations

Melting point of Pyrophosphoric acid
Melting point of Metaphosphoric acid

I know that both Pyro and Meta phosphoric acid exists in solid form.But the temperature mentioned here are more than melting points of both.
So the acids will be obtained in liquid state.But the answer was given as b).
I can't make out the reason.Please explain.

 

[Physics lover]

Homework Statement:: Question pic is in My attempt.
Relevant Equations:: Melting point of Pyrophosphoric acid
Melting point of Metaphosphoric acid

View attachment 260752

I know that both Pyro and Meta phosphoric acid exists in solid form.But the temperature mentioned here are more than melting points of both.
So the acids will be obtained in liquid state.But the answer was given as b).
I can't make out the reason.Please explain.

I think the answer given is wrong.Please confirm it.

 

[Borek]

The question doesn't say anything about the temperature of the final state, it just lists temperature at which conversion takes place.

 

[Physics lover]

The question doesn't say anything about the temperature of the final state, it just lists temperature at which conversion takes place.

I cannot understand that.How can final temperature be lower than supplied temperature.Please explain a little bit.

 

[Borek]

You heat up the acid to convert it, you leave it to cool down, you report state of the product at the room temperature.

 

[Physics lover]

You heat up the acid to convert it, you leave it to cool down, you report state of the product at the room temperature.

Ok so the answer would be both solid?