How do I calculate the energy needed to convert ice at -20C to steam at 110C?

In summary, to calculate the energy needed to change 9 g of ice at -20 degrees Celsius to steam at 110 degrees Celsius, we must consider the processes of heating the ice to 0 degrees Celsius, melting it to form liquid, heating the water to 100 degrees Celsius, boiling it to form steam, and finally heating the steam to 110 degrees Celsius. Using the equations Q=hv, Q=mHf, and Q=mc(delta)t, we can calculate the total energy needed to be 27795 J. However, it is important to note that this calculation may be incorrect and further steps should be taken to confirm the answer.
  • #1

Homework Statement


Calculate the energy need to change 9 g of ice at -20 degrees Celsius to steam at 110 degrees Celsius. (C for ice=2.06 J/g, C for water=4.18 J/g, C for steam=2.02 J/g, Hf of ice=334 J/g, Hv of water=2260 J/g)


Homework Equations


Q=hv / Q=mHf / Q=mc(delta)t


The Attempt at a Solution


Q=(9 X 2.06 X 20) + (9 X 334) + (9 X 2.06 X 110) + (9 X 2260) + (9 X 2.06 X 110) = 27795 J

Okay so I did this problem in class with a group, but looking back on it, I think it is wrong. But I'm not sure! I'm just very very very confused on what to do. Step by step instructions would help! And the answer has to be in joules not calories. Thanks! :)
 
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  • #2
Hi SimplySydney, welcome to PF. What are the processes that the material (originally a solid at -20C) has to go through to reach the vapor form at 110C? It looks like the first two terms represent the energy needed to heat ice to 0C and the energy needed to melt it to form liquid at 0C. What do the other terms represent?
 

1. What is the difference between specific heat and latent heat?

Specific heat is the amount of heat required to raise the temperature of a substance by 1 degree Celsius, while latent heat is the amount of heat required to change the state of a substance without changing its temperature.

2. How are specific and latent heat related?

Specific heat and latent heat are related because they both measure the amount of heat required to change the energy of a substance. However, specific heat is related to temperature change while latent heat is related to state change.

3. What are some examples of substances with high specific heat?

Substances with high specific heat include water, which has a specific heat of 4.186 joules per gram per degree Celsius. Other examples include metals like copper and aluminum, which have specific heats of 0.385 and 0.900 joules per gram per degree Celsius, respectively.

4. How is specific heat measured?

Specific heat is typically measured using a calorimeter, which is a device that measures the heat absorbed or released by a substance during a chemical or physical change. The amount of heat is then divided by the mass and temperature change of the substance to determine its specific heat.

5. What is the significance of specific and latent heat in everyday life?

Specific and latent heat play important roles in everyday life. For example, the high specific heat of water allows it to act as a buffer against temperature changes in the environment, making it an important component of our climate. Latent heat is also important in processes such as cooking and refrigeration, where changes in state are utilized to cook food or cool down a space.

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