How much heat in KJ is needed to change 3.0 kg of ice at -10C into (superheated) steam at +150C ?
Do I need to find specific heat?
(3.0kg)(2100)(150-10)= 882kj right?
http://www.jiskha.com/display.cgi?id=1289868027
To find the amount of heat required to change 3.0 kg of ice at -10°C to superheated steam at +150°C, you need to account for the different phases of the substance and their respective heat transfer processes.
The process can be divided into three stages:
1. Heating the ice (solid) from -10°C to 0°C.
2. Melting the ice at 0°C.
3. Heating the resulting water (liquid) from 0°C to +150°C and then into steam (gas).
Now, let's calculate the heat required for each stage:
1. Heating the ice from -10°C to 0°C:
To heat the ice, you need to use the specific heat capacity of ice:
Q1 = (mass of ice) × (specific heat capacity of ice) × (change in temperature)
= (3.0 kg) × (2,093 J/kg°C) × (0 - (-10)°C)
= (3.0 kg) × (2,093 J/kg°C) × (10°C)
= 62,790 J
Note: Here, we used the specific heat capacity of ice, which is 2,093 J/kg°C.
2. Melting the ice at 0°C:
To melt the ice at 0°C, you need to use the latent heat of fusion of ice:
Q2 = (mass of ice) × (latent heat of fusion of ice)
= (3.0 kg) × (333.55 kJ/kg)
= 1,000.65 kJ
Note: The latent heat of fusion of ice is 333.55 kJ/kg.
3. Heating the water from 0°C to +150°C and then into steam:
To heat the water, you need to use the specific heat capacity of water:
Q3 = (mass of water) × (specific heat capacity of water) × (change in temperature)
= (mass of water) × (4,186 J/kg°C) × (+150 - 0)°C
= (3.0 kg) × (4,186 J/kg°C) × (150°C)
= 188,370 J
To convert J to kJ, divide the values by 1,000:
Q1 = 62,790 J ÷ 1,000 = 62.79 kJ
Q3 = 188,370 J ÷ 1,000 = 188.37 kJ
Now, let's find the total heat required:
Total Heat = Q1 + Q2 + Q3
= 62.79 kJ + 1,000.65 kJ + 188.37 kJ
= 1,251.81 kJ
So, the amount of heat needed to change 3.0 kg of ice at -10°C into superheated steam at +150°C is approximately 1,251.81 kJ.
Note: Your calculation, (3.0 kg) × (2,100 J/kg°C) × (150 - (-10)°C) = 882 kJ, is not correct because it doesn't account for the different phases and their associated heat transfer processes.