First convert 1 lb of water to lb-moles which is 0.055 lb-moles (you'll need this later). This problem can be broken into 3 steps:
(1) You need to detemine how much heat is needed to raise room temperature water (68oF) to 212oF. This can be used using the heat capacity of water which at room temperature is 1 Btu/lboF. So the amount of heat needed for this is:
Q1 = m*Cp*ΔT
= (1 lb)*(1 Btu/lboF)*(212 - 68oF)
= 144 Btu
(2) Next you need to account for the phase change. The water changes to steam at 212oF. You use the heat of vaporization which you can look up in any Chemistry or Chemical Engineering Handbook. The Hvap that I found is 17493.5 Btu/lb-mole.
Q2 = n(lb-moles)*Hvap
= (0.055 lb-moles)*(17493.5 Btu/lb-mole)
= 972.64 Btu
(3) Next you need to find out how much heat is needed to raise the temperature of the steam from 212 to 213oF. You can look up the heat capacity of steam at 212oF to be 0.485 Btu/lboF.
Q3 = m*Cp*ΔT
= (1 lb)*(0.485 Btu/lboF)*(213-212oF)
= 0.485 Btu
To find the total heat needed add Q1+Q2+Q3 (144+972.64+0.485) =
1117.12 Btu
25
144
160 btu's. It takes 1 btu (British Thermal Unit) to change the temperature of 1lb of water 1°. This is referred to as sensible heat. This 1 to 1 ratio does not hold true when changing the state of that water to ice or to steam. Changing the state 1lb of water at 212° to 1lb of steam at 212° you must add 970 btu's and to change 1lb of water at 32° into 1lb of ice at 32° you must add 144 btu's. This is referred to as latent heat.
If you're in Celsius, 13459.5 Btu's. If you're in Fahrenheit, 12632.5 Btu's.
There are no units for the temperature. The temperature change could be 230 Celsius degrees or 170 Fahrenheit degrees (94 Celsius degrees). In fact they could be in less commonly used units: eg Reaumur.
It takes 180 BTUs to raise 1 pound of water from 32 degrees Fahrenheit to 212 degrees Fahrenheit to convert it completely into steam. This change in temperature includes heating the water from its freezing point to boiling point, then undergoing phase change from liquid to gas.
To change 5 pounds of ice at 20°F to steam at 220°F, you will need to go through multiple phases: raise ice temperature to 32°F, melt ice to water at 32°F, raise water temperature to 212°F, and then convert water to steam at 212°F to steam at 220°F. The total heat required, in BTUs, is around 503 BTUs per pound of ice, which translates to about 2515 BTUs for 5 pounds of ice.
It takes approximately 970 BTUs to convert one pound of water at 212°F (100°C) to steam at the same temperature.
It takes approximately 144 BTUs to change one pound of ice at 20°F to water at 212°F, and an additional 970 BTUs to change the water to steam at 220°F, for a total of 1114 BTUs.
One pound of steam at 212 degrees Fahrenheit contains 1150 BTUs of energy.
One BTU is the energy required to raise one pound of water by one degrees. Therefore, your answer would be one half.
To change 10 pounds of ice at 20 degrees Fahrenheit to steam at 220 degrees Fahrenheit, you need to supply enough energy to first melt the ice, then heat the water to the boiling point, and finally convert it to steam. This process requires approximately 180 BTUs per pound of ice to melt it, 180 BTUs per pound of water to heat it to the boiling point, and then 970 BTUs per pound of water to convert it to steam. So, for 10 pounds of ice, the total BTUs required would be around 18,300 BTUs.
To raise 1 pound of ice from 32°F to water at 32°F it requires 144 BTUs. Since you have 50 pounds of ice, you would need 50 * 144 BTUs to raise the ice to water at 32°F. To further raise the water from 32°F to 160°F, you would need an additional amount of BTUs based on the specific heat capacity of water.
1)This is a 5 part question. The first is realizing that 20F to 32F uses .5BTU per pound per degree. That means it takes 32-20=12*.5=6BTUs to get the ice to 32F. 2)Then you need to know the Latent Heat of Fusion for Ice which is 144BTUs (given). Lets assumes the ice changes from ice to water instantaneously at 32F. 3)Next we calculate the BTUs from 32F to 212F. Which is 1BTU per pound per degree F. 212-32=180 so it take 180BTUS. 4)Next we have to use the Latent Heat of Vaporization of water which will say instantaneously converts water to vapor. This takes 970BTUS (given). 5)Then we calculate the BTUS from 212F to 220F. Which is .5BTUs per pound per degree F which is 220-212=8*.5=4BTUs...... Finally add up all the BTUs and you get 6+144+180+970+4=1304BTUs.
Well, you seem like a very smart kid. Let me ask you something: if you had one pound of naiveness in one hand and one pound of idiocy in the other, which one weighs more? Let me tell you a secret: Its the same!
From high school science class; it takes 144 BTUs to melt a pound of ice. That takes it to 32 degrees F. To then raise the temp to 72 deg., would take about 40 more BTUs.
To raise the temperature of 1 pound of water by 1 degree Fahrenheit, it requires 1 BTU (British Thermal Unit). Therefore, to heat water by 10 degrees, it would require 10 BTUs per pound of water. This value may vary slightly depending on the specific heat capacity of the water.