GE-CHEM 1103 Module 4.1

Question 1

the ability to do
work or transfer heat

Answer 1

Energy

Question 2

the study of energy and its
transformations

Answer 2

Thermodynamics

Question 3

the study
of chemical reactions and the energy
changes that involve heat

Answer 3

Thermochemistry

Question 4

most important form
of potential energy in
molecules

Answer 4

electrostatic
potential energy (Eel = kQ1Q2/d)

Question 5

the unit of
energy commonly used

Answer 5

Joule ( 1J = 1 kg m^2/s^2)

Question 6

it is
seen between
oppositely charged ions

Answer 6

Electrostatic attraction

Question 7

what happens to energy when chemical bonds are formed?

Answer 7

Energy is released

Question 8

what happens to energy when chemical bonds are broken?

Answer 8

Energy is
consumed

Question 9

State the First Law of Thermodynamics

Answer 9

Energy can be converted from one form to
another, but it is neither created nor destroyed.

Question 10

The portion of the
universe that we single
out to study is called

Answer 10

system

Question 11

are
everything else that is not being studied

Answer 11

surroundings

Question 12

a region of the
universe being studied that
can exchange heat AND
mass with its surroundings.

Answer 12

Open System

Question 13

a region of
the universe being studied
that can ONLY exchange
heat with its surroundings

Answer 13

Closed System

Question 14

a region of
the universe that can NOT
exchange heat or mass with
its surroundings

Answer 14

Isolated System:

Question 15

the sum of all
kinetic and potential energies of all components
of the system

Answer 15

Internal energy; E
But we dont know E only how it changes so ΔE.

Question 16

final energy of the system minus the initial
energy of the system

Answer 16

change in internal energy, ΔE
ΔE = Efinal − Einitial

Question 17

the system absorbed energy from the
surroundings

Answer 17

ΔE > 0, Efinal > Einitial

Question 18

the system released energy to the
surroundings

Answer 18

ΔE < 0, Efinal < Einitial

Question 19

What is the value of ΔE if Efinal equals Einitial

Answer 19

ΔE = 0

Question 20

Thermodynamic Quantities
Have Three Parts

Answer 20

1) A number
2) A unit
3) A sign

Question 21

results when the system
gains energy from the surroundings.

Answer 21

positive ΔE

Question 22

results when the system
loses energy to the surroundings.

Answer 22

negative ΔE

Question 23

When energy is
exchanged between
the system and the
surroundings, it is
exchanged as either
heat (q) or work (w).

Answer 23

ΔE = q + w

Question 24

Sign conventions for q

Answer 24

+q = system gains heat
-q = system loses heat

Question 25

Sign conventions for w

Answer 25

+w = work done on system -w = work done by system

Question 26

Sign conventions for ΔE

Answer 26

+ΔE = net gain of energy by system -ΔE = net loss of energy by system

Question 27

When heat is absorbed by the system from the surroundings

Answer 27

endothermic

Question 28

When heat is released by the system into the surroundings

Answer 28

exothermic

Question 29

internal energy of a system

Answer 29

Is a state function (ΔE depends only on Einitial and Efinal)

Question 30

q(heat) and w(work)

Answer 30

Is not a state function

Question 31

the mechanical work associated with a change in volume of gas

Answer 31

the only work done by chemical or physical change

Question 32

measure the work done by the gas if the reaction is done in a vessel that has been fitted with a piston. work is NEGATIVE because it is work done BY the system

Answer 32

w = −PΔV

Question 33

the internal energy plus the product of pressure and volume

Answer 33

Enthalpy

Question 34

When the system changes at constant pressure, the change in enthalpy, ΔH, is

Answer 34

ΔH = ΔE + PΔV to Since ΔE = q + w and w = −PΔV, we can substitute these into the enthalpy expression: ΔH = ΔE + PΔV ΔH = (q + w) − w ΔH = q

Question 35

at constant pressure, the change in enthalpy is

Answer 35

the heat gained or lost

Question 36

ΔH is positive

Answer 36

process is endothermic

Question 37

ΔH is negative

Answer 37

process is exothermic

Question 38

is the enthalpy of the products minus the enthalpy of the reactants

Answer 38

The change in enthalpy, ΔH

Question 39

ΔHrxn

Answer 39

enthalpy of reaction, or the heat of reaction

Question 40

The Truth about Enthalpy of reaction

Answer 40

1. Enthalpy of reaction is an extensive property. 2. The enthalpy change for a reaction is equal in magnitude, but opposite in sign, to ΔH for the reverse reaction. 3. The enthalpy change for a reaction depends on the states of the reactants and the products.

Question 41

is defined as the enthalpy change for the reaction in which a compound is made from its constituent elements in their elemental forms

Answer 41

enthalpy of formation, ΔHf

Question 42

are measured under standard conditions (25 °C and 1.00 atm pressure).

Answer 42

Standard enthalpies of formation, ΔHf °

Question 43

enthalpy of formation for an element in its elemental state

Answer 43

0 because it takes no energy to form a naturally-occurring compound.

Question 44

Calculation of ΔH (see the answer right way)

Answer 44

Do some exercises on it

Question 45

Calculation of ΔH using Hess law

Answer 45

ΔH = ΣnΔHf,products – ΣmΔHf °,reactants

Question 46

The enthalpy associated with breaking one mole of a particular bond in a gaseous substance

Answer 46

Bond Enthalpy

Question 47

always positive because energy is required to break chemical bonds

Answer 47

bond enthalpy

Question 48

always released when a bond forms between gaseous fragments

Answer 48

Energy

Question 49

greater the bond enthalpy

Answer 49

stronger the bond.

Question 50

ALL bonds made

Answer 50

ADD bond energy

Question 51

ALL bonds broken

Answer 51

SUBTRACT bond energy

Question 52

Σ (bond enthalpies – Σ (bond enthalpies of bonds broken) of bonds formed)

Answer 52

ΔHrxn

Question 53

If a reaction is carried out in a series of steps, ΔH for the overall reaction equals the sum of the enthalpy changes for the individual steps.

Answer 53

Hess’s law

Question 54

measure ΔH through measurement of heat flow

Answer 54

calorimetry

Question 55

instrument used to measure heat flow

Answer 55

calorimeter

Question 56

The amount of energy required to raise the temperature of a substance by 1 K (1 °C)

Answer 56

heat capacity

Question 57

the amount of the substance heated is one gram

Answer 57

specific heat

Question 58

If the amount is one mole

Answer 58

molar heat capacity

Question 59

The specific heat for water

Answer 59

4.184 J/g∙K (can be used for dilute solutions)

Question 60

calculate ΔH for the reaction

Answer 60

qsoln = Cs × msoln × ΔT = –qrxn

Question 61

1. Reactions can be carried out in a sealed “bomb” 2. Because the volume in the bomb calorimeter is constant, what is measured is really the change in internal energy, ΔE, not ΔH.

Answer 61

Bomb Calorimetry

Question 62

The heat absorbed (or released) by the water is a very good approximation of the enthalpy change for the reaction.

Answer 62

qrxn = – Ccal × ΔT

Question 63

The energy released when one gram of food is combusted

Answer 63

fuel value

Question 64

Most of the energy in foods comes from carbohydrates, fats, and proteins

Answer 64

Carbohydrates (17 kJ/g) Fats (38 kJ/g) Proteins (17 kJ/g)

Question 65

The vast majority of the energy consumed in this country

Answer 65

fossil fuels

Question 66

8.6% of the U.S. energy needs

Answer 66

Nuclear fission

Question 67

produce 9.9% of the U.S. energy needs

Answer 67

Renewable energy sources