Recycling just two glass bottles saves enough energy to boil water for how many cups of tea

A)1 cup of tea
B)7 cups of tea
C)3 cups of tea
D)5 cups of tea



  1. 0 Votes

    I don’t know how much energy it takes to manufacture a glass bottle from virgin material, so I will try to extrapolate the value for you. Let’s say that recycling glass uses only half of the energy that manufacturing it from virgin material takes. Let us also assume that each glass bottle weighs 200g, so we are recycling 400g of glass in total. Glass has to be heated to 1400-1600 degrees Celsius or more before it melts. If we start the glass at 20 degrees Celsius, we would expect to heat the glass about 1500 more degrees to melt it. The specific heat of glass is about 0.20 calories/g K. Kelvin and Celsius are equivalent changes in temperature even though they have different starting points on the scale. Since we are concerned with temperature changes rather than absolute temperatures, the conversion is easy. To figure out how many calories it takes to melt those two bottles, we multiply the change in temperature (1500K) by the weight of the glass (400g) and multiply that by the specific heat (0.20 calories/g K). This gives us 120 kilo-calories (a kilo-calories is 1,000 calories). Since it takes double that energy to manufacture glass from virgin material, that is also the amount of energy that we save.

    To find out how much energy it takes to boil a cup of water, we follow a similar process. The specific heat of water is 1calorie/g K. The metric system is actually based on water, so this portion of the calculations are made easy. A metric cup of water is approximately 250ml. Since water weighs 1g/ml, that means we have 250g of water per cup. We will assume that the initial temperature is 20 degrees Celsius and boiling is 100 degrees Celsius under current atmospheric conditions (the boiling point of water decreases with increasing altitude). So, that means that we much change the water temperature by 80 degrees. Now we multiply the weight of a cup of water (250g) by 80K and then multiply it by the specific heat of 1. This gives us 20 kilo-calories.

    If we divide the amount of energy we save from recycling the two glass bottles (120 kilo-calories) by the amount of energy it takes to boil a cup of water (20 kilo-calories), we find that we can boil 6 cups of water from the energy saved through recycling the glass bottles. Of course, there may be some inefficiencies in the recycling process or the boiling process that change the actual value figures, and the glass bottles may weight more or less than 200g. So, the actual value of this answer may vary. You’ll need to do your own calculations to find out more. Also, you might want to double-check my calculations just in case I made an error somewhere.

    Re-using glass bottles takes a lot less energy than recycling them through melting. In Canada, all beer bottles are standardized so that they can be collected, washed, and refilled rather than recycled. The glass is washed with water hot enough to kill all germs, but not hot enough to melt the glass. As we have just discovered through our calculations, it takes a lot less energy to boil water than it takes to melt glass. Milk bottles are also a commonly re-used glass bottle. Some stores offer re-usable glass bottles that you can return to the store.

  2. 0 Votes

    If you recycle just two glass bottles, it will save enough energy to boil water for five cups of tea. You should know that recycling is done in order to protect the environment from harmful waste. It also saves on the cost of energy used to produce these bottles.

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