Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

CHEM 119 > Unit 7: Thermochemistry > Flashcards

Unit 7: Thermochemistry Flashcards

You may prefer our related Brainscape-certified flashcards:
Periodic Table flashcards Chemistry 101 flashcards AP® Chemistry flashcards Organic Chemistry 101 flashcards
1
Q

define energy

A

the capacity to do work or transfer heat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what is the equation for change in energy (delta energy)

A

delta E = Efinal - Einitial = q +w

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what is 1 calorie in joules

A

4.184 J

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

define system and surroundings

A
  • system: object(s) being studied
  • surroundings: everything outside of the system
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

describe what it means when the change in energy is <0

A
  • initial energy is higher than final energy
  • energy of reactants higher than energy of products
  • energy is lost to surroundings
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

describe what it means when the change in energy is >0

A
  • final energy is higher than initial energy
  • energy of products is higher than energy of reactants
  • energy gained from surroundings
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

define state functions

A
  • depend on initial and final states of a system
  • uppercase variables: V, E, P, T
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

define path functions

A
  • depend on the path a system takes to get from the initial to the final state
  • lowercase variables: q, w, t, d
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

which type of function is easier to measure

A

state functions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

define internal energy

A

energy contained within a system

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

define kinetic energy

A

energy associated with motion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what are the three types of kinetic energy

A
  • translation
  • vibration
  • rotation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

define potential energy

A

energy associated with position

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what are the two types of potential energy

A
  • chemical bonds
  • intermolecular forces
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what is the order of phase states from lowest energy to highest energy

A
  • lowest energy: solid
  • middle energy: liquid
  • highest energy: gas
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

is energy absorbed or released when water evaporates

A
  • liquid to gas: lower energy to higher energy
  • energy of products (gas) greater than energy of reactants (liquid)
  • energy is absorbed
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

define specific heat (C)

A

amount of heat required to raise the temperature of ONE GRAM of a substance one degree celsius

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

define molar heat capacity (Cm)

A

amount of heat required to raise the temperature of ONE MOLE of a substance one degree celsius

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

does water have an unusually high or low specific heat

A

high - 4.814 J/gC

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

define the variables in q=mCAT

A
  • q = heat (J)
  • m = mass (g)
  • C = specific heat (J/gC)
  • AT = temperature change, final-initial (C)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

how is the heat of the system related to the heat of the surroundings

A
  • q(system) = -q(surroundings)
  • heat from system is equal and opposite of heat from surroundings
  • system with either gain or lose heat while the surroundings do the other until the temperatures of both are equal
22
Q

define calorimetry

A

the measurement of heat changes

23
Q

describe the equation used in calorimetry

A
  • q(reaction) = -q(calorimeter)
  • q(reaction) = -q(water)
  • q(reaction) = -mCAT(water)
24
Q

what are two types of calorimeteres

A
  • coffee cup calorimeter
  • bomb calorimeter
25
Q

why is the molar energy of a reaction typically reported rather than just the energy of the reaction

A
  • molar energy takes into account the amount of substance that was reacted
  • used to compare with other experiments
26
Q

how do you find the molar energy of a reaction

A

q(reaction) of Xg / Xg = q(reaction) of 1 mole / molar mass

27
Q

define enthalpy (H)

A
  • heat flow under constant pressure (same as q but with constant pressure)
  • state function
28
Q

equation for change in H

A

delta H = Hproducts - Hreactants

29
Q

define endothermic and it’s relation to H

A
  • energy is absorbed by the reaction
  • reaction gets warmer, surroundings get cooler
  • change in H > 0
  • products have higher energy than reactants
30
Q

define exothermic and it’s relation to H

A
  • energy is released by the reaction
  • reaction gets cooler, surroundings get warmer
  • change in H < 0
  • products have lower energy than reactants
31
Q

what is the simple equation for endothermic reactions

A

energy + reactants = products

32
Q

what is the simple equation for exothermic reactions

A

reactants = products + energy

33
Q

is enthalpy intensive or extensive

A
  • extensive
  • scalable: double products = double H
34
Q

which takes more energy: phase changes or warming a substance in one phase

A

phase changes

35
Q

which phase change rakes the most energy

A
  • vaporization
  • liquid to gas
36
Q

how do you determine the energy used to heat a substance in a singular phase

A

q=mCAT

37
Q

how do you determine the energy used during a phase change

A

delta H(fus/vap) + moles of substance

38
Q

what are the three techniques for heats of reaction calculations

A
  • bond enthalpy
  • hess’s law
  • heats of formation
39
Q

which takes energy and which releases energy: making bonds and breaking bonds

A
  • takes energy to break a bond
  • energy released when bond is made
40
Q

define bond enthalpy

A

how much energy is required to break a bond

41
Q

are bonds being broken endothermic or exothermic

A
  • endothermic
  • energy taken in
42
Q

are bonds being made endothermic or exothermic

A
  • exothermic
  • energy released
43
Q

how can the heat of a reaction be approximated using bond enthalpies

A

heat of reaction = sum of reactant bond enthalpies - sum of product bond enthalpies

44
Q

is the reaction endothermic or exothermic if the heat of reaction is negative when using bond enthalpies technique

A
  • exothermic
  • means more energy is on the products side
45
Q

is the reaction endothermic or exothermic if the heat of reaction is positive when using bond enthalpies technique

A
  • endothermic
  • means more energy is on the reactants side
46
Q

describe hess’s law

A
  • if a reaction is carried out by a series of steps, enthalpy (H) for the overall reaction with be equal to the sum of the enthalpy changes for the individual steps
  • taking parts of a chemical reaction, rearranging them to mirror the overall reaction, and adding the enthalpies
47
Q

what happens to the enthalpy of a reaction when you switch the reactants and the products sides

A

flip the sign of the enthalpy (H)

48
Q

define enthalpy of formation (Hf)

A

enthalpy change for the reaction in which one mole of a compound is made from its constituent elements in their elemental forms

49
Q

define standard enthalpy of formation (Hf)

A

enthalpy of formation (Hf) measured under standard conditions (25 C, 1 atm, 1M)

50
Q

what is the enthalpy of formation value (Hf) for elements in their elemental state

A

0

51
Q

describe the equation used to determine the enthalpy of a reaction using enthalpy of formation

A

enthalpy of reaction (H) = sum of enthalpy of formations for products - sum of enthalpy of formations for reactants

CHEM 119 (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions