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The change in internal energy (ΔU) for a system that releases 25 J of heat to its surroundings, and has 75 J of work done on it is ______.
+50 J
Calculate the change in internal energy (ΔU) for a system that absorbs 47 J of heat and does 103 J of work.
-56 J
Select the correct relationships between units of energy. Select all that apply, (The symbol "≡" is used in mathematics to mean "identically equal to.")
1 cal ≡ 4.184 J 1 Cal ≡ 1000 cal 1 Cal ≡ 4184 J
In which of the following systems would the energy change be associated with a negative sign?
A compressed spring (the system) is allowed to uncoil. A hot rock (the system) cools at sunset.
Select all the statements that correctly describe a state function.
A state function is a property that is independent of the path taken to achieve it. A state function depends on the initial state of the system.
"ΔU" indicates a ____ in the internal energy of a system.
Blank 1: change, transfer, or difference
The first law of thermodynamics states that the total amount of ___ in the universe remains constant.
Blank 1: energy, total energy, or total E
The total change in the internal energy of a system is the sum of the energy transferred as ____ and/or ____.
Blank 1: heat, heat exchanged, or heat exchange Blank 2: work or work done
The SI unit of energy is the ____, which is abbreviated by the symbol _____.
Blank 1: joule Blank 2: J
A change in internal energy of a compound is always a combination of changes in the ____ energy (associated with molecular motion) and the ____ energy (associated with attractive and repulsive forces due to chemical interactions).
Blank 1: kinetic Blank 2: potential
True or false: To understand the total change that occurs in a state function, we must have a record of the conditions ("states") at all times between the initial and final states.
F
True or false: A chemical reaction is observed to take place in a flask. When the reaction is complete, the flask feels colder than it was before the reaction took place. The reaction was exothermic.
False
Match each term with its associated definition.
Heat: The transfer of thermal energy Thermochemistry: The study of thermal energy changes in chemical reactions Energy: The capacity to do work
Which of the following statements about internal energy are correct?
Internal energy has two components: kinetic and potential energy. Changes in internal energy are usually measured instead of measuring internal energy directly.
An experiment is developed to determine the energy change during a precipitation reaction, represented by the following balanced equation: AgCH3COO (aq) + NaCl (aq) → NaCH3COO (aq) + AgCl (s) Which of the following are part of the system? Select all that apply.
NaCl AgCH3COO
Match each type of system with its associated properties. Instructions
Open system: May exchange both mass and energy with its surroundings Closed system: May exchange energy, but not mass, with its surroundings Isolated system: Exchanges neither mass nor energy with its surroundings
Match each example with the type of system it represents.
Open system: Pasta boiling in an uncovered pan Closed system: Stew cooking in a pressure cooker on a stove Isolated system: Hot soup in an air-tight insulated thermos
Which of the following are state functions? Select all that apply.
Pressure Temperature Mass
True or false: Both heat and work can be measured in joules.
T
Hot coffee is poured into a mug. It slowly cools, releasing heat to the environment. If we consider the coffee to be the system, which of the following are part of the surroundings? Select all that apply.
The air in the room The mug The table underneath the mug
Imagine that a car drives from the bottom to the top of a hill. If the initial and final values of each property below remain constant, which of the following represent state functions in this scenario? That is, which properties do not depend on the path taken to reach that specific value. Select all that apply.
The temperature of the car's engine increases. The car's elevation increases. The volume of gasoline in the car's tank decreases.
Select all the statements about the study of energy changes that are correct.
Thermochemistry is a branch of thermodynamics. One aspect of thermodynamics is the study of energy transfer in the form of heat.
Match each branch of study with the correct description. Instructions
Thermodynamics: The study of the interconversion of heat and other kinds of energy Thermochemistry: Focuses primarily on the exchange of heat in chemical systems
If there is a change in internal energy during a chemical reaction, ΔU, which of the following expressions could be used to calculate this? Select all that apply.
Uproducts - Ureactants Ufinal - Uinitial
If the system gains heat as it does work on its surroundings, the total change in internal energy of that system will ______.
be positive, negative, or zero
Match each unit symbol with its name. Instructions
c: kilocalorie C: calorie J: joule
The term _____ indicates that heat is absorbed by the system from the surroundings, while _____ indicates that heat is released by the system into the surroundings.
endothermic; exothermic
Based on the first law of thermodynamics, the energy gained by a system is _____ the energy lost by the surroundings.
equal to
Fill in the property for the following thermodynamic symbols: q is the symbol for ____, w is the symbol for ____, and U is the symbol for ____ ____.
heat, work, internal energy
If heat is transferred from a system to its surroundings and the surroundings do work on the system, the sign of q will be _____, and the sign of w will be _____.
negative; positive
The study of the heat associated with chemical reactions is called .
thermochemistry
Match each type of energy change with its associated symbol.
work: w heat: q internal energy: U
