How Much Heat is Needed to Turn Ice at -10°C into Steam at 110°C?

[domyy]

Homework Statement

Calculate the amount of heat to be added to warm 150g of ice from -10C to produce steam at 110C.

Homework Equations

Ice = cice = 0.5cal/gC, L = 80 cal/g.
Water = Cw = 1.0 cal/gC;
Steam = csteam = 0.5 cal/gC; Lv = 540 cal/g

The Attempt at a Solution

I know the answer should be 109.5kcal.

I have found 12,000 cal. BUT I HAVE ABSOLUTELY NO IDEA HOW TO GET TO 109kcal. I JUST NEED SOME DIRECTION.

 

[Borek]

Show how you got 12 kcal.

 

[domyy]

Q = mLf = 150g x 80 Cal/g = 12,000

 

[domyy]

I know this problem is more complex than that.

Another equation that is possible to use is q=mcdeltat

I remember my professor drawing a graph, with equations for solid, liquid and gas...
I think I am supposed to have that in mind.

 

[domyy]

The graph shows increase, then constant, then increase and constant, then increase.

 

[Borek]

Q = mLf = 150g x 80 Cal/g = 12,000

That's just a melting part.

Another equation that is possible to use is q=mcdeltat

I remember my professor drawing a graph, with equations for solid, liquid and gas...
I think I am supposed to have that in mind.

The graph shows increase, then constant, then increase and constant, then increase.

And that's a good hint at equations that should be used. Have you copied that graph?

What must happen to the ice so that water becomes a steam?

 

[Pengwuino]

There are 5 processes at work here. First, you must heat the water from -10C to 0C. Then more energy must be provided to turn the 0C ice to 0C water. Then you must heat the water from 0C to 100C. Then you must turn the 100C water to 100C steam. Finally, you heat the steam to the final 110C. Phase changes require energy as well as temperature changes. The equations you have can be used to determine exactly how these processes occur.

 

[domyy]

One of the solutions would be q=mlf
=150g x 540=81,000?

 

[domyy]

I will also have q=150g x 80cal/g = 12,000

 

[domyy]

Am i doing it right? I will have to sum the values later?

 

[Borek]

You can sum them all as the last step.

 

[domyy]

Oh yes I already got the answer. Thanks a lot!

 

[domyy]

Can I ask you something? I read that as bubbles rise in deep column of water the diameter increases. Could explain this more clear to me?

 

[Borek]

Please don't hijack threads, if you have a new question - start a new thread.

PV=nRT, P=ρh