PROBLEM # 1
A student measures out 225 grams of water, which they heat from 50 degrees Fahrenheit to 110 degrees Fahrenheit.

A. How many Btu’s of heat energy were needed to change the water’s temperature to the new temperature?
B. How many kilocalories of energy were needed?
C. How many kilowatt-hours of energy were needed?

1 gram of water =  1 milliliter of water
1 pound of water = 454 milliliters
1 Btu = .252 kilocalorie
1 kilowatt-hour = 3413 Btu
Specific heat of water 1Btu / lb F  (It takes one Btu to raise the temperature of one pound of water, 1 degree F)
 

PROBLEM #2
A family is building a new home in Alaska which experiences severe winters.  Assume the following

• The house has 4000 square feet
• 100,000 BTU’s of heat per square foot are required to heat the house for the winter
• Natural gas sells for $5.00 per thousand cubic feet
• One cubic foot of natural gas supplies 1000 BTU’s of heat energy
• 1 kilowatt-hour of electricity supplies 10,000 BTU’s of heat energy
• Electricity costs $50 per 500 kWh

 Calculate the following, showing all the steps of your calculations, including units

A. The number of cubic feet of natural gas required to heat the house for the winter
B. The cost of heating the house using natural gas
C. The cost of heating the house using electricity