1. Calculate the amount of heat required for 25.0 grams of water to
change from 10 degrees Celsius to 30 degrees Celsius. *
2 points
2090
2 points
2.50.0 grams of water at 100 degrees Celsius evaporated to water vapor
at 100 degrees Celsius. Calculate the amount of heat required for this
conversion.
113000
3. A student measured 15.0 grams of ice in a beaker. The beaker was then 2 points
placed on a hot plate where it was heated uniformly for a certain amount
of time. During the melting process of the ice, the student noted that the
temperature was at 0 degree Celsius. When all the ice converted to water,
the final temperature was also at 0 degree Celsius. How much heat was
used to melt the ice? *
Your answer
4. If 5.0 grams of water was cooled from 50 degrees Celsius to 40
degrees Celsius, then calculate the amount of heat released by the water.
2 points
209
5. A certain amount of water used exactly 84.0 Joules of heat energy to
change from 25.0 degrees Celsius to 35 degrees Celsius. How many
grams of water was used?
2 points
No

2. This question can be solved using the latent heat of vaporization of water. The latent heat of vaporization of a substance is the amount of heat required to convert a unit gram of a liquid into vapor without a change in temperature. The latent heat of vaporization of water per gram is:

2257 J/g

For 50grams of water, amount of heat that will be required will be: 50 × 2260

= 113,000J

3. For 15g of water, the amount of heat will be 15 × 2260 (latent heat of vaporization)

= 33,900J

4. Q = m × c × ∆T

Q = 5 × 4.184 × (40 - 50)

Q = 20.92 × (-10)

Q = -209.2 J

5. Q = m × c × ∆T

84 = m × 4.184 × (35 - 25)

84 = m × 4.184 × 10

84 = 41.84m

m = 84/41.84

m = 2.0076

m = 2g