Gen chem formulae error in kaplan?

[Dental2000]

Suppose we have the mass of a compound say x grms
and they have given us delta Heat = 90kcal/g( fr example)

would the q= m X 90 or

q= moles of the compound(x/mm) X 90

Chad says u gota convert grams to moles if ur givin heat of fusion, vap etc

but kaplan just does mass X delta H

which one is right?

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[KyoPhan]

Both are correct.

It depends on the units of the constant.

If your constant(Delta Hvaporization) is in grams, then you can go directly into m x delta H.

If your constant is in mols(Ex: Delta Hvaporization=41KJ/mol), then you have to convert your mass into amounts of mols.

In your example, the constant is in grams. So you can just do mass x delta H to calculate for q.

Dat destroyer General chemistry #90 has a good example on that if you have it.

 

[Dental2000]

oh yeah...duh, im ******ed...thanks dude

and are u sure its #90 in the destroyer? i have the 2010 edition
mine is just a multiple choice question

 

[KyoPhan]

oh yeah...duh, im ******ed...thanks dude

and are u sure its #90 in the destroyer? i have the 2010 edition
mine is just a multiple choice question

I have the 2011 edition.

Answer is B.