# Another HELP problem: Steam to Ice

1. Nov 16, 2007

### delecticious

Another URGENT HELP problem: Steam to Ice

1. The problem statement, all variables and given/known data

How many J of energy must be removed when 127.0 g of steam, at a temperature of 153.0°C, is cooled and frozen into 127.0 g of ice at 0°C? Take the specific heat of steam to be 2.1 kJ/(kg·K).

2. Relevant equations
Q1 = mc(delta T) <---- c= heat capacity of steam
Q2 = mLv
Q3 = mc(deltaT)<---- c=heat capacity of water
Q4 = mLf

3. The attempt at a solution

first I converted grams to kilograms and got .127kg for the mass then I follwed through with my equations
Q1 = (.127)(2100)(153-100)= 1.4135E4
Q2 = (.127)(2259.36)= 2.869E2
Q3 = (.127)(4186)(100-0)= 5.316E4
Q4 = 4.241E4

I added these up and got a total Q of 1.10E5, what am I doing wrong?

2. Nov 16, 2007

### mgb_phys

3. Nov 16, 2007

### delecticious

he had a different problem (that is to say a different problem regarding the same problem) than me, I just need to know if I'm doing it right and when went wrong.

4. Nov 16, 2007

### mgb_phys

You have the constants wrong.
specifically the heat of vapourisation - the water/steam change should be the largest energy.
Just put you hand over a kettle to find out!

Last edited: Nov 16, 2007
5. Nov 16, 2007

### Staff: Mentor

Please check units!

I strongly recommend writing units with values, so that one properly accounts for orders of magnitude.

6. Nov 16, 2007

### delecticious

I seriously don't know how I keep messing up my units, but thanks again.

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