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Offline xxlauraleexx64

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homework help
« on: April 22, 2009, 09:03:38 PM »
Hello

If the heat to melt the ice is provided by isopropyl alcohol, 1. what is the density and molar heat of combustion of isopropyl alcohol? 2. What is the balanced reaction for combustion of isopropyl alcohol? 3. How many liters of isopropyl alcohol are needed to burn to melt 0.75 kg of block ice?

Any and all help is appreciated

Offline UG

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Re: homework help
« Reply #1 on: April 22, 2009, 09:12:43 PM »
How much heat needed to melt the ice sample? You have not given this information.

---------
EDIT: What is ΔfusHo(H2O)?


Offline UG

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Re: homework help
« Reply #2 on: April 22, 2009, 09:31:00 PM »
The formula for isopropyl alcohol is C3H7OH, in combustion reactions, oxygen is always one of the reactants. The products of complete combustion is H2O and CO2. See if you can work it out now :)
Question number 3 can only be solved if you give the ΔfusHo(H2O) and the enthalpy of combustion of isopropyl alcohol.


Offline xxlauraleexx64

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Re: homework help
« Reply #3 on: April 22, 2009, 09:44:06 PM »
the ice is at -25 F that is placed in a 950 ml insulated container and heated at a rate of 45 watt. The ice is heated to 390 K

Offline xxlauraleexx64

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Re: homework help
« Reply #4 on: April 22, 2009, 09:47:16 PM »
Thank you UG for the formula  ;D

Offline UG

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Re: homework help
« Reply #5 on: April 22, 2009, 10:35:19 PM »
the ice is at -25 F that is placed in a 950 ml insulated container and heated at a rate of 45 watt. The ice is heated to 390 K
And how much alcohol was used?

------
Can you convert -25 F into Kelvin for me?

Offline xxlauraleexx64

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Re: homework help
« Reply #6 on: April 23, 2009, 09:39:30 AM »
Good Morning UG

temp it 170.55 K

the amount used of isopryopyl alcohol is one of the questions needed in liters

Offline Borek

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Re: homework help
« Reply #7 on: April 23, 2009, 09:48:38 AM »
ChemBuddy chemical calculators - stoichiometry, pH, concentration, buffer preparation, titrations.info

Offline AWK

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Re: homework help
« Reply #8 on: April 23, 2009, 10:01:33 AM »
AWK

Offline xxlauraleexx64

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Re: homework help
« Reply #9 on: April 23, 2009, 08:39:33 PM »
I'm sorry, it was explained to me to add -32 and multiply by 1.8(5/8). The correct answer is 241.48 K.

This is the complete problem:

A 0.75 kg. block of ice at -25 F is placed in an 950 ml insulated container and heated at a rate of 45 watt (energy).  The ice is heated to 390 K.

a.Make a graph that shows in detail the heating of the ice with temperature.

b. Indicate on what phase of mater exist in each part of graph

c. Indicate regions of sensible and latent heat.

d. Show the amount of heat absorbed by the ice in each part of the graph and calculations.

e. What is the final pressure in the container?

f. If the heat to melt the ice provided by the combustion of isopropyl alcohol

What is the density and molar heat of combustion of isopropyl alcohol?
Write the balanced reaction for the combustion isopropyl alcohol
How many liters of isopropyl alcohol are needed to burn to melt the ice block

Offline xxlauraleexx64

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Re: homework help
« Reply #10 on: April 27, 2009, 12:20:06 PM »
any help?

Offline ARGOS++

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Re: homework help
« Reply #11 on: April 27, 2009, 01:26:45 PM »

Dear xxlauraleexx64;

First you have to convert 45 Watt into Joule per second (J/s), because all heat will remain/be given in Joule.

Then you may use the following links as guidance:
         http://www.chemicalforums.com/index.php?topic=32502.0
         http://www.chemicalforums.com/index.php?topic=30045.msg114165#msg114165 
         (There are other similar topics at the Forums.)

And for the missing properties of water you may see on:
         http://www.engineeringtoolbox.com/water-thermal-properties-d_162.html

Good Luck!
                    ARGOS++

Offline xxlauraleexx64

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Re: homework help
« Reply #12 on: April 27, 2009, 03:15:25 PM »
Thank you Argos

Offline ARGOS++

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Re: homework help
« Reply #13 on: April 27, 2009, 03:37:24 PM »

Dear xxlauraleexx64;

This may also be of some help:
            http://chapsipc.wetpaint.com/page/Calculating+Heating+Curve+of+Water?t=anon

Watch also the video therein called "wiki video" (the second video)!

Hope to have been of help to you.
Good Luck!
                    ARGOS++

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