AP Chemistry Thermodynamic Conceptuals
B)The system does work on the surroundings
For a particular process q=-17 kJ and w=21 kJ. Which of the following statements is false? A) Heat flows from the system to the surroundings B) The system does work on the surroundings C)delta E = +4 kJ D)The process is exothermic E)None of the above is false
C) delta E = 35 kJ
For a particular process q=20 kJ and w=15 kJ. Which of the following statements is true? A)Heat flows from the system to the surroundings B)The system does work on the surroundings C)delta E = 35 kJ D)All of the above are true E)None of the above are true
State function
A function that depends only on the initial and final states of a system, not on the path in between; a property of a system that does not depend on the pathway
False
A property that is independent of the pathway is called an intensive property, true or false?
Isothermal
An __________ process is a change of a system, in which the temperature remains constant: ΔT = 0; adiabatic
Isochoric
An ___________ process, also called a constant-volume process, an isovolumetric process, or an isometric process, is a thermodynamic process during which the volume of the closed system undergoing such a process remains constant.
A) I and II, (the reaction is exothermic when delta H is negative (the products have a higher energy than the reactants))
C2H5OH(l) + 3O2(g) = 2CO2(g) + 3H2O(l), delta H = -1.37 x10^3 kJ For the combustion of ethyl alcohol as described in the above equation, which of the following is true? I. The reaction is exothermic II. The enthalpy change would be different if gaseous water were produced III. The reaction is not an oxidation - reduction one IV. The products of the reaction occupy a larger volume than the reactants A)I and II B) I, II, and III C)I, III, and IV D)III and IV E)only I
B) It is equal to zero
Consider a gas in a 1.0 L bulb at STP that is connected via a valve to another bulb that is initially evacuated. Answer the following concerning what occurs when the valve between the two bulbs is opened. What is true about the value of delta E? A)It is greater than zero B)It is equal to zero C)It is less than zero D)More information is needed E)None of these
B) It is equal to zero
Consider a gas in a 1.0 L bulb at STP that is connected via a valve to another bulb that is initially evacuated. Answer the following concerning what occurs when the valve between the two bulbs is opened. What is true about the value of delta H? A)It is greater than zero B)It is equal to zero C)It is less than zero D)More information is needed E)None of these
B) It is equal to zero
Consider a gas in a 1.0 L bulb at STP that is connected via a valve to another bulb that is initially evacuated. Answer the following concerning what occurs when the valve between the two bulbs is opened. What is true about the value of q? A)It is greater than zero B)It is equal to zero C)It is less than zero D)More information is needed E)None of these
B) It is equal to zero
Consider a gas in a 1.0 L bulb at STP that is connected via a valve to another bulb that is initially evacuated. Answer the following concerning what occurs when the valve between the two bulbs is opened. What is true about the value of w? A)It is greater than zero B)It is equal to zero C)It is less than zero D)More information is needed E)None of these
D)delta H1 + 2 delta H2 - delta H3 A=2B(cancelled) 2B = 2C + 2D(cancelled) 2D = E
Consider the following numbered processes: A = 2B delta H1 B = C+D delta H2 E = 2D delta H3 Delta H for the process A = 2C + E is: A)delta H1 + delta H2 + delta H3 B)delta H1 + delta H2 C)delta H1 + delta H2 - delta H3 D)delta H1 + 2 delta H2 - delta H3 E)delta H1 + 2 delta H2 + delta H3
Exothermic reactions have a negative delta H and endothermic reactions have a positive delta H.
How can you tell whether a reaction is exothermic or endothermic?
Isobaric
In thermodynamics, an ________ process, i.e., one that is carried out at constant pressure
Greenhouse Effect
Natural situation in which heat is retained in Earth's atmosphere by carbon dioxide, methane, water vapor, and other gases
Work becomes positive
What happens to work if the system compresses?
Work becomes negative
What happens to work if the system expands?
delta E = q + w
What is the equation for the change in internal energy?
The coffee cup calorimeter
What kind of material (when mentioned) means it is isobaric?
The bomb calorimeter
What kind of material (when mentioned) means it is isochoric?
Heat is negative with exothermic reactions and positive with endothermic reactions, and work is vice versa (usually) unless work is done on the system (positive) or work is done BY the system (negative)
When is heat negative or positive? How is work related?
C) H20 (l) (all elements by themselves, either as a gas like N2 and H2, or as an element like Al and Li, have a standard enthalpy of zero)
Which of the following does not have a standard enthalpy of zero at 25 degrees Celsius at 1 atm? A)F2 (g) B)Al(s) C)H2O(l) D)H2(g) E)They all have a standard enthalpy equal to zero
D) methane
Which of the following is both a greenhouse gas and a fuel? A) carbon dioxide B)coal C)Freon D)methane E)nitrogen
C) II and IV
Which of the following properties is (are) intensive properties? I. mass II. temperature III.volume IV. concentration V. energy A)I, III, and V B)II only C)II and IV D)III and IV E)I and V
C) q is negative, w is positive (because volume would be negative since gases have more volume than liquids)
Which of the following statements correctly describes the signs of q and w for the following exothermic process at P=1 atm and T=370 K H2O(g) = H2O(l) A)q and w are negative B)q is positive, w is negative C)q is negative, w is positive D)q and w are both positive E)q and w are both zero
True
a state function does not depend on the system's path or future.
Adiabatic
change without heat transfer between the system and its surroundings
Examples of state functions
elevation, pressure, volume, temperature, internal energy, enthalpy, entropy, gibb's free energy, number of molecules in object
