Electricity in Your Home: Activity 1 :Key

One molecule of methane plus two molecules of oxygen will
burn to produce two molecules of water, one molecule of carbon dioxide, and heat.



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Molecular equation

Word Equation

Mass equation


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  1. Using the graph provided, determine the mass (in kilograms) of natural gas that is burned in order to generate

    1. 20kWh of electrical energy.
      Answer: approximately 6kg.

    2. 40kWh of electrical energy.
      Answer: approximately 12kg.

    3. 100kWh of electrical energy.
      Answer: approximately 28kg.

  2. A single 1500 W electrical baseboard heater will use about 216kWh in one month of operation, having a 20% duty cycle (meaning that it is "on" 20% of the time). How much natural gas is burned to generate this amount of electrical energy?
    Answer: approximately 60kg.

  3. Acquire an electrical utility bill*. Examine the bill and determine the amount of electrical energy used. What mass of natural gas was burned to generate this amount of electrical energy?
    Answer: various quantities will be used depending upon the billing season. Typically 2000kWh of electricity will require 560 kg of natural gas.

*Note: Not everyone is willing to share their electricity consumption information with others. It may be prudent to have a couple of "anonymous" billing samples available for student use.

* Footnote: Fossil fuels are a complex blend of hundreds of kinds of hydrocarbon molecules. The molecule in this example is one of the most abundant in the fuel being described, and as such, represents a good approximation of the entire combustion process

This activity assumes that all the electricity used is from a single type of fuel. This is generally not the case. The actual amount of each type of fuel varies from region to region as will be shown later.

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