chapter 4

Question 1

heat describes?

Answer 1

• a type of energy transfer
  
  • work instead refers to ways that energy, potential and kinetic, is transferred from one object to another so heat is basically analogous to work, but it involves the transfer of energy through temperature

Question 2

what is temperature?

Answer 2

• a property of the average kinetic energy of the particles that compose a substance

Question 3

KE = 1/2mv²_rms

and v_rms = square root of 3RT/M_m

when we combine them we get the equation:

Answer 3

• KE = 3/2T (Rm/M_m)
  
  • kinetic energy of a particle in an ideal gas
    
    • v_mrs, or root mean of velocity
    • T is temperature in K
    • R is the ideal gas constant
    • M_m is the molar mass
      
      • temperature is directly proportional to kinetic energy

Question 4

a thermodynamic system is at?

Answer 4

• thermodynamic equilibrium internally
  
  • means that no macroscopic transfers of energy or matter are taking place within a system

Question 5

what are open systems?

Answer 5

• have boundaries but can exchange both matter and energy with the surroundings

Question 6

what are closed systems?

Answer 6

• can exchange energy with their surroundings but not matter

Question 7

what are isolated systems?

Answer 7

• can exchange neither energy nor matter with their surroundings

Question 8

a system at equilibrium can be described interms of a set of?

Answer 8

• state functions
  
  • they describe the state of the system without any reference to how the system got that way

Question 9

What is the zeroth law of thermodynamics?

Answer 9

• The zeroth law of thermodynamics states that if two thermodynamic systems are each in thermal equilibrium with a third system, then they are in thermal equilibrium with each other.

Question 10

what is the first law of thermodynamics?

Answer 10

• The first law of thermodynamics, also known as Law of Conservation of Energy, states that energy can neither be created nor destroyed; energy can only be transferred or changed from one form to another.
  
  • the total energy change of a system (deltaU) is equal to the transfer of energy into tne sustem (Q) minus the work performed by the system on its surroundings (W)
  • deltaU = Q - W
    
    • energy being added to the system (positive)
    • energy being taken away from the system (negative)
      
      • so work being done by the system on its environment is deltaU = Q + (-W)
      • so work performed on the system by the environment is deltaU = Q + W

Question 11

table summarizing 1st law of thermodynamics:

Answer 11

deltaU | Q | work by system

+ | system gaining energy | heat flow into system | work by system

• | system losing energy | heat flow out of system | work on system

Question 12

what is the second law of thermodynamics?

Answer 12

• if 2 objects are in thermal contact but not in thermal equilibrium, heat energy will spontaneously flow from the object with the higher temperature to the object with the lower temperature
• the entropy of an isolated system will increase over time

Question 13

what is the third law of thermodynamics?

Answer 13

• At the lowest possible temperature, at absolute 0 or 0 K, a pure crystal has zero entropy

Question 14

a calorie corresponds to?

Answer 14

• the amount of energy needed to heat up 1g of water by 1°C and is about 4.184 J
  
  • kilocalories in food (Calories, C) kcal

Question 15

what is conduction?

Answer 15

• refers to how heat is directly transferred between 2 substances placed in direct contact with each other, mediated through the transfer of kinetic energy from the particles of one substance to those of the other
  
  • good conductors transmit heat very well while good insulators are poor conductors of heat

Question 16

what is convection?

Answer 16

• refers to heat transfer that occurs due to the circulation of fluids (iquid or gases)
  
  • used to maintain the thermal gradient

Question 17

what is radiation?

Answer 17

• not requiring direct contact between 2 substances for heat transfer
  
  • electromagnetic waves are generated by all objects with a temperature greater than absolute zero, and these electromagnetic waves carry a certain amount of energy

Question 18

what is thermal expansion?

Answer 18

• heating a substance will generally cause it to expand

Question 19

for solids, and for fluids held in a container such that they can only expand in one direction, we can measure expansion in terms of linear expansion and are defined using this equation:

Answer 19

• delta: = alpha_{L or V} L deltaT
  
  • L and V represent the length and volume
  • the constans alpha_{L or V} are coefficients of thermal expansion that are specific to each substance
  • deltaT measures the change in temperature
    
    • Delta L and delta V are proportional to deltaT but are also proportional to L and V

Question 20

If we hold T constant, we get?

Answer 20

PV = k, where k equals some constant (Boyle’s law)

Question 21

what is an isothermic system?

Answer 21

• one in which the temperature is held constant, and isotherms are hyperbolic lines that can be included in a pressure-volume graoh that correspond to specific temperatures

Question 22

what is an adiabatic system?

Answer 22

• one in which no heat or matter is transferred between a system and its surroundings
  
  • correspond to constant entropy values rather than constant temperature values seen in isothermic systems

Question 23

what is an isobaric system?

what is an isochoric system?

Answer 23

• if the pressure is held constant in a system
• if the volume is held constant in a system

Question 24

summary of all 4 effects on a pressure-volume curve:

Answer 24