Thermodynamics: Introduction

Question 1

First Law of thermodynamics

Answer 1

The internal energy of an isolated system remains constant

Question 2

What is thermodynamics?

Answer 2

The branch of physical chemistry concerned with the study of the transformations of energy.

Question 3

Force is directly proportional to….

Answer 3

Directly proportional to acceleration

Question 4

Which standard unit depicts force?

Answer 4

Newtons depict this!

Question 5

What is force the product of?

Answer 5

Mass and acceleration

Question 6

What is the equation for force?

Answer 6

F = ma
N = kg ms^-2

Question 7

What is pressure, exactly?

Answer 7

This measure is the force per unit area, (F/A)

Question 8

What is the equation for pressure?

Answer 8

F/A = N/m^2 = N m^-2 = Pa

Question 9

What is the definition of energy?

Answer 9

The ability to do work

Question 10

What is energy the product of, conceptually?

Answer 10

The product of force and distance.

Question 11

What is the equation for kinetic energy?

Answer 11

Ek = (1/2)mv^2 = (p^2)/2m

Question 12

What is the definition of potential energy?

Answer 12

The energy stored due to the attractive forces between atomic nuclei and their electrons, or chemical bonds, in molecular interaction.

Question 13

What are the 4 variables of state? What do they describe?

Answer 13

These variables describe the physical state of any pure substance. They are: V, p, T, and n.

Question 14

When there is work, what has happened?

Answer 14

When a force, F, moves a body through a distance, D.

Question 15

What can generally be said about work?

Answer 15

This is done to achieve motion against an opposing force and corresponds to a form of energy transfer.

Question 16

How does motion differ between the two work equations?

Answer 16

In one equation, motion is against a constant opposing force (gravity). In the other equation, motion is against a changing opposing force (sloping of a hill).

Question 17

How can a conversion be made from Celsius (oC) to Kelvin (K)?

Answer 17

Celsius + 273.15 !

Question 18

In which way does temperature determine the direction energy will flow as heat when objects are in contact?

Answer 18

Energy flows from higher temperature to lower temperature.

Question 19

What is thermal equilibrium?

Answer 19

When the net flow of energy is zero because two bodies have the same temperature.

Question 20

What is the Zeroth Law of Thermodynamics?

Answer 20

If A is in thermal equilibrium with B, and B is in thermal equilibrium with C, then A and C must also be in thermal equilibrium.

Question 21

What is Avogadro’s number, with units?

Answer 21

6.022 x 10^23 mol^-1

Question 22

How can you tell if a property of a substance is intensive or extensive?

Answer 22

An intensive property of a substance retains the same value regardless of the amount of that substance (ie. pressure, temperature, molar volume, molarity)

An extensive property is a value which depends upon the amount of a substance present (ie mass and volume)

Question 23

What are the variables of state?

Answer 23

Four interdependent quantities which describe the physical state of a pure substance.

V = volume (dm^3)
p = pressure (kPa)
T = temperature (K)
n = # of moles

Question 24

What is a unique conclusion which can be drawn from the dependent nature of the variables of state?

Answer 24

Knowing the values of three of the variables of state allows the fourth variable’s value to be known without measurement, since they are all interdependent

Question 25

What is Boyle’s Law?

Answer 25

At a constant temperature, volume and pressure are inversely proportional. That is, an increase in pressure necessitates a decrease in volume, and vice versa.

Question 26

What is Charles’s Law?

Answer 26

At a constant pressure, the volume of a gas is directly proportional to the absolute temperature.

Question 27

What is Avogadro’s Principle?

Answer 27

Equal volumes of gases at constant temperature and pressure contain equal numbers of molecules.

Question 28

What does the Ideal Gas Equation tell us?

Answer 28

It links all of the properties needed to define the state of a gas; it describes the nature of an ideal gas given the four variables of state and the ideal gas constant, R.

Question 29

What is the Ideal Gas Equation and what are its components?

Answer 29

pv = nRT, where

p = pressure
v = volume
n = # of moles
R = ideal gas constant (8.314 J K^-1 mol^-1)

Question 30

What is Standard Ambient Temperature and Pressure (SATP)?

Answer 30

A standardized temperature and pressure was defined for use in the ideal gas equation; T = 298.15K and p = 1 bar

Question 31

What does Dalton’s Law state?

Answer 31

The pressure of a gas mixture is equal to the sum of the individual partial pressures

Question 32

How do partial moles relate to partial pressures?

Answer 32

The molar fraction of a given gas is equal to the partial pressure of the same substance in a mixture.

Question 33

How can Boyle’s Law be demonstrated in an equation?

Answer 33

p = constant x 1/V (where the constant is a proportionality constant)

Question 34

What is unique about the volume of gases at varying pressures at -273.15K?

Answer 34

At varying pressures, the volume of all gases is equal at the temperature -273.15K.

Question 35

What is the ideal gas constant?

Answer 35

8.314 J K^-1 mol^-1

Question 36

How does 1 bar convert to Pascals?

Answer 36

1 bar = 10^5 Pa

Question 37

What is molar volume?

Answer 37

The volume that one mole of a substance occupies, expressed as Vm, in units of m^3mol^-1.