# CHEMISTRY

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Calculate ΔSfus and ΔSvap for HF.
Determine the entropy change when 7.60 mol of HF(l) freezes at atmospheric pressure.

I already calculated ΔSfus as 24.103 J/k*mol and ΔSvap as 86.07 J/K*mol....These are correct (I checked them already). I need help with this part of the question:
Determine the entropy change when 7.60 mol of HF(l) freezes at atmospheric pressure.

I got an answer of 183.18 J/K and it marked me wrong and said "The value of ΔSfus above is for 1.00 mol of HF. You need to scale that value up for 7.60 mol of HF. Also, consider the sign of your answer. Does freezing result in an increase or decrease in entropy?"

• CHEMISTRY - ,

The problem here may be that you need to add a negative sign to your 183.18 AND you need to watch the significant figures. These data bases are notorious for counting off for the wrong number of s.f.

• CHEMISTRY - ,

Yeah but it also said that I need to calculate for 7.60 mol of HF. The answer I got, 183.18 is only for 1.00 mole of HF. It says I need to scale that value up for 7.60 mol of HF. How would I do that????

• CHEMISTRY - ,

Didn't you scale it up? You had 24.103 J/mol and you multiplied by 7.60 moles. That looks like scaling it up to me.

• CHEMISTRY - ,

So the answer would just be -183.18 ?

• CHEMISTRY - ,

• CHEMISTRY - ,

And also make sure that -183.18 is correct....I have one more attempt thanks!

• CHMISTRY - ,

Hallo

• CHEMISTRY - ,

indeed