Temperature and Heat - what am i doing wrong?

In summary, to convert 9 kg of ice at 0◦C to steam at 100◦C, three processes involving heat must occur: melting the ice, heating the water, and vaporizing the water. The energy required to melt the ice is 9 * 79500 = 715500 cal. The energy required to heat the water is 9 * 1000 * 100 = 9000000 cal. The energy required to vaporize the water is 9 * 5.4 * 10^5 = 4860000 cal. Therefore, the total heat needed is 715500 + 9000000 + 4860000 = 14565000 cal = 145.65
  • #1
grandprix
28
0

Homework Statement



lf = 79500 cal/kg ,
lv = 5.4 × 105 cal/kg ,
c = 1000 cal/kg ◦ C.

9 kg of ice at 0◦C is converted to steam at
100◦C.
How much heat is needed? Answer in units
of kcal.


Homework Equations



q=mct

The Attempt at a Solution



100*9kg + 79.5 + 540 = 1519.5

I am getting this wrong I don't know why
 
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  • #2
Can you explain what each term in your attempted solution means? They don't seem to make sense. They don't match the numbers given in the problem? It would be helpful if you explained what you were doing.

Also, what three processes (involving heat) have to occur in order to get from ice at 0C to steam at 100C?
 
  • #3
If lf is 79500 cal/kg, and you have 9 kg of ice, then how much energy is required to melt the ice?

Hint: the answer it not 79.5.

Also, what is the value of c for water?
 
  • #4
I got the answer! Thanks for your help.
 

FAQ: Temperature and Heat - what am i doing wrong?

What is the difference between temperature and heat?

Temperature is a measure of the average kinetic energy of particles in a substance, while heat is the total energy transferred between two objects due to a temperature difference.

Why does my thermometer show different readings in different locations?

Temperature can vary in different locations due to factors such as altitude, proximity to heat sources, and local weather conditions. This can affect the accuracy of a thermometer's readings.

How do I convert between Celsius, Fahrenheit, and Kelvin?

To convert from Celsius to Fahrenheit, use the formula F = (C x 1.8) + 32. To convert from Fahrenheit to Celsius, use the formula C = (F - 32) ÷ 1.8. To convert from Celsius to Kelvin, simply add 273.15 to the Celsius value.

Why does the temperature of a substance change during a phase change?

During a phase change, the temperature of a substance remains constant as the energy is used to break or form intermolecular bonds, rather than increasing the kinetic energy of the particles.

How does heat transfer occur?

Heat can be transferred through three methods: conduction, convection, and radiation. Conduction is the transfer of heat through direct contact, convection is the transfer of heat through the movement of fluids, and radiation is the transfer of heat through electromagnetic waves.

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