Calculate the heat change at 100C in each of the following problems.Indicate whether heat was absorbed or released.

a. calories to condense 10.0 g of steam
b. kilocalories to condense 75g of steam
c. kilocalories to vaporize 44 g of water.

First you multiply 10.0 with 540cal/1 g of H2O.

To calculate the amount of heat added to (or removed from) a sample of water, the mass of the sample is mulitipled by the heat of vaporization, which is 2260. As before, no temperature change occurs during a change of state.

the answer for a will be 5400

a.

q = mass steam x delta Hvap.
b.
see a. Convert to kcal.
c.
mass H2O x deltaH vap. Convert to kcal.

To calculate the heat change in each of these problems, we need to use the specific heat and the heat of vaporization for water, as well as the mass of the substance involved.

a. To calculate the heat change to condense 10.0 g of steam, we need to use the heat of vaporization of water, which is 540 calories/gram. The formula to calculate the heat change is:

Heat change = mass * heat of vaporization

So, the heat change for condensing the steam is:

Heat change = 10.0 g * 540 cal/g = 5400 cal

Since the steam is being condensed, heat is released.

b. To calculate the heat change to condense 75 g of steam, we again use the heat of vaporization of water. In this case, we need to convert the units to kilocalories since the question asks for it. The heat of vaporization of water is 540 cal/g, which is equivalent to 0.54 kcal/g. The formula to calculate the heat change is:

Heat change = mass * heat of vaporization

So, the heat change for condensing the steam is:

Heat change = 75 g * 0.54 kcal/g = 40.5 kcal

Since the steam is being condensed, heat is released.

c. To calculate the heat change to vaporize 44 g of water, we need to use the heat of vaporization of water and the specific heat of water. The heat of vaporization of water is 540 cal/g and the specific heat of water is 1 cal/g°C. The formula to calculate the heat change is:

Heat change = mass * heat of vaporization

So, the heat change for vaporizing the water is:

Heat change = 44 g * 540 cal/g = 23,760 cal

Since water is being vaporized, heat is absorbed.

Therefore, the answers are:
a. Heat change = 5400 cal (heat released)
b. Heat change = 40.5 kcal (heat released)
c. Heat change = 23,760 cal (heat absorbed)

a. 12