Dougherty Valley HS AP Chemistry
Heating Curve Practice Problems
Name:
Date:
Period:
[1] A heating curve for ice at -35ºC being converted to steam at 128ºC:
[2] Label the following on the graph above:
Write the formula used:
Warming
Q=
Melting see graph above
Q= see graph above
Vaporizing
Q=
[3] What are the following values for water (include units):
Hfus=
Hvap=
[4] How many calories are needed to convert 312.0g of ice at -35.0°C to liquid water at 25.0°C: (HINT: Use the graph
above to determine the formula(s) needed). 38220 cal
[5] How many joules are required to melt 275.0kg of ice (ASSUME: the ice starts at 0.0°C): 9.185E7J
6. What mass of water (in kg) at 100.0°C could be completely vaporized with 2.70E3 cal of energy:
5.00E-3kg
7. How many joules (J) of energy are released when 6.80x103g of steam at 100.0°C are completely frozen to ice at 0.0°C:
2.05E7J
8. Convert the Hf value for water (80 cal/g) to units of J/mol: (HINT: You will need to use the molar mass of water) 6025
J/mol
[9] How much energy (in J) is required to completely melt 205.0 mol of ice at 0.0°C: 1.235E6J
Compound
H2O
K
Hg
Ag
s (sol.)
𝑱
( )
𝒈∙𝑲
M.P.
(C)
Hfus
𝑱
( )
s (liq.)
𝑱
( )
𝒈∙𝑲
B.P.
(C)
Hvap
𝑱
( )
s (gas)
𝑱
( )
2.09
0.560
--0.217
0
62
-39
961
334
61.4
11
105
4.184
1.070
0.138
0318
100
760
357
2212
2260
2025
294
2355
1.97*
0.671
0.104
---
𝒈
𝒈
*at 100C. The specific heat (s) of steam increases slightly with increasing temperature. For example, the Cp of steam at 200 C is 2.00.
[10] How much heat is needed to raise the temperature of a 25.0 g sample of H2O from −25C to 125C?
[11] How much heat is needed to raise the temperature of 85 g of potassium from 25C to 2,500C?
𝒈∙𝑲