To convert water at 35 C to 100 C and then it to steam, two types of energies wi

Question

To convert water at 35 C to 100 C and then it to steam, two types of energies will be required.

First is specific heat, which is energy required by one gram of water per degree rise in temperature. It is given as 1.0 cal/(g. C) for water.

By using the above data, calculate the energy required (E1) to heat 105 g of water from 35 C to 100 C.

Total rise in temperature of water is 65 C (Final temperature of 100 C minus the starting temperature of 35 C)

Therefore, E1 = 1.0 cal/(g. C) 105 g 65 C = 6825 cal

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Second type of energy needed is heat of vaporization which is the energy required to convert water at 100 C to steam. The given value of heat of vaporization is 540 cal/g.

Therefore, to calculate the energy required (E2) to convert the 105 g water to steam, multiply the heat of vaporization and quantity of water given

E2 = 540 cal/g 105 g = 57600 cal

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Total energy (E) required to convert 105 g water at 35 C to steam will be a sum of energies required to raise the temperature to 100 C (E1) and then to vaporize all of it (E2).

E = E1 + E2

E = 6825 cal + 57600 cal

= 63525 cal

Or 63.5 103 cal

Note: before solving this type of problems make sure that you look at the units of quantities given. They can be in terms of per g or kg or mole. Convert the quantity of substance given in the same units and then proceed as per directions above.

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Explanation / Answer

1. Question Be sure to answer all parts. How much energy (in calories) is needed to heat 105 g of water at 35.0-C to 100.0 C and vaporize the water to steam at 100.0C? Enter your answer in scientifie notation. The following values for water may be needed: 1.00 cal/(g..C) Specific heat Heat of fusion Heat of vaporization 540. calg 79.7 cal/g × 10L-cal Energy required =

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