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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: deltamoles on December 04, 2005, 03:08:24 AM

Title: How to find delta H when molar mass is unknown
Post by: deltamoles on December 04, 2005, 03:08:24 AM

I am doing lab on doughnuts and calories.Experimentally we had to find the number of calories.(delta H)

My mass of water was 100g
delta t of water= 25-23=2

my mass of dougnut before was:6.24
and my after mass was 1.84
therefore delta m= -4.4

I started by finding the Q of water(Q=mc delta t )
which gave me 838 joules
which is 0.838 Kj

now i need to find delta h

the only formula i can think of to solve the question is
 Qwater/delta M = delta H/molar mass
I know Qwater and delta m.But i have no molar mass.so i cant find delta H.

 I need to find my Delta h and i cant think of how since i have 2 variables.Is there another way of finding delta h.Please help me out cuz like im stuck on this thing for an hour trying how to find delta h but i just cant find a way

thanx so much
pat

Title: Re:How to find delta H when molar mass is unknown
Post by: sdekivit on December 04, 2005, 04:03:45 AM

you can also express H in J/g doughnut