Question

How many Btu of heat are required to melt 33.0 lb of ice at 32°F and to raise the temperature
of the melted ice to 72°F?

Answer 1

q1 = heat to change phase ice from solid at 32 F to liquid at 32F.
q1 = mass ice x heat fusion

q2 = heat to raise T from 32 F to 72 F
q2 = mass H2O x specific heat x (Tfinal-Tinitial)

Then total btu = q1 + q2

Answer 2

So,is this the setup to find heat?
q1= 33.0 X 3.35X10^5
q2=2.26X10^6*1*(72-42)

Answer 3

on q2 I mean (72-32)

Answer 4

I don't think so. What's 3.35E5? Usually I don't work in BTU/lb but that isn't the number I see for heat fusion in the tables.

Then for q2 what is 2.26E6?

Answer 5

I got it all wrong, confusing the tables

But for Q1
Q1=0.51*33.0*80cal/kg (not sure how to
convert to BTU)

Answer 6

You can use Google to convert but you want q in btu so why not look up heat fusion in btu/lb for metling and specific heat in btu/lb*F for raising the T from 32 to 72.
I looked up the heat fusion and came away with 144 btu/lb but you should confirm that. I also looked up the specific heat H2O and it appears it is more less constant at about 1.0 btu/lb*F. Again, you should confirm that.

Answer 7

thanks
144 BTU/lb is the heat fusion of water and ice

and the specific heat for ice is 0.51BTU/lb

So would I need to set it up Q1 like this?
0.51*33.0*144

Answer 8

No. Look back at my original response.
q1 for changing phase of ice from solid at 32 F to liquid at 32 F is
q1 = mass ice x heat fusion.
q1 = 33 lb x 144 btu/lb = ? btu

You don't need specific heat ice, only the heat fusion at the melting point.

I looked up specific heat water and found about 1 btu/lb*F (but you should confirm that), then (from my first response)
q2 = mass water x specific heat H2O x (Tfinal-Tinitial)
q2 = 33 x 2.0 x (72-32) = ? btu. That's the amount of heat that must be added to liquid water at 32F to raise the temperature from 32F to 72F.
Then qtotal btu = q1 + q2

Answer 9

=6072btu
thank you for clearing this up, really appreciate all the help.

Answer 10

q2 = mass water x specific heat H2O x (Tfinal-Tinitial)
q2 = 33 x 2.0 x (72-32) = ? btu. That's the amount of heat that must be added to liquid water at 32F to raise the temperature from 32F to 72F.
Then qtotal btu = q1 + q2

<b> That should be a 1.0 and not a 2.0 above. I hope you confirmed that and used the right number. </b>

Answer 11

yes I noticed it, but its still the right setup. thanks