4. Which of these best describes what happens to the energy of the H₂O molecules as a sample of ice melts at 0°C? A) The kinetic energy increases and the potential energy decreases. B) The potential energy increases and the kinetic energy decreases. C) The potential energy remains the same and the kinetic energy increases. D) The kinetic energy remains the same and the potential energy increases. E) The potential energy and the kinetic energy both increase. ㅑ
Thermochemistry
Thermochemistry can be considered as a branch of thermodynamics that deals with the connections between warmth, work, and various types of energy, formed because of different synthetic and actual cycles. Thermochemistry describes the energy changes that occur as a result of reactions or chemical changes in a substance.
Exergonic Reaction
The term exergonic is derived from the Greek word in which ‘ergon’ means work and exergonic means ‘work outside’. Exergonic reactions releases work energy. Exergonic reactions are different from exothermic reactions, the one that releases only heat energy during the course of the reaction. So, exothermic reaction is one type of exergonic reaction. Exergonic reaction releases work energy in different forms like heat, light or sound. For example, a glow stick releases light making that an exergonic reaction and not an exothermic reaction since no heat is released. Even endothermic reactions at very high temperature are exergonic.
![4. Which of these best describes what happens to the energy of the
H₂O molecules as a sample of ice melts at 0°C?
A) The kinetic energy increases and the potential energy decreases.
B) The potential energy increases and the kinetic energy decreases.
C) The potential energy remains the same and the kinetic energy increases.
D) The kinetic energy remains the same and the potential energy increases.
E) The potential energy and the kinetic energy both increase.
Physical Data for Water
Tmp = 0 °C
Tbp = 100 °C
AHfus
334 J/g
AHvap
2260 J/g
Temperature (°C)
Cliquid 4.184 J/g°C
Csolid=2.09 J/g°C
Cgas = 2.03 J/g °C
5. Three ice cubes at 0°C with a total mass of 48.22 g are placed in a glass of tea. How much
heat will be absorbed from the tea in order to completely melt the ice?
200
Heat
6. Heat is applied to a sample of solid ice until the entire sample is converted to hot vapor.
The heating curve for the process is shown here (not to scale). If each of the heat values
given below corresponds to one line segment in the heating curve, which heat value
corresponds to the line segment labeled 4?
284
q=
kJ
A) 4232 J
B) 5481 J
C) 45,090 J
D) 56,484 J
E) 305,100 J](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Fa4a40cee-b6e7-4175-94ff-7eded3f3eb47%2Ff5280454-1ff4-47db-a876-fd51ed69a3c9%2F1u8asvi_processed.jpeg&w=3840&q=75)
![25°C
32°C
bum wohl 891 10 228
1. Two aqueous reactants are mixed in a flask with a balloon over the
top and the following change is observed. What are the signs on
q and w for the system? Enter >, <, or in each box below.
W
0
2. You drop a piece of potassium metal into water and the following exothermic reaction
occurs:
2 K(s) + 2 H₂O(l) → 2 KOH(aq) + H₂(g)
What are the signs on q and w for this reaction, at constant temperature and pressure?
A) q is positive and w is negative.
B) q is negative and w is positive.
C) q and w are both negative.
D) q and w are both positive.
E) There is not enough information given.
3. What is the change in internal energy when one mole of helium gas in a flexible-walled
container at STP is heated to 100°C? (CHe(g) = 5.30 J/g°C)
AU =](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Fa4a40cee-b6e7-4175-94ff-7eded3f3eb47%2Ff5280454-1ff4-47db-a876-fd51ed69a3c9%2Fj7nq3ex_processed.jpeg&w=3840&q=75)
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