exam 4

Question 1

surroundings

Answer 1

Everything outside the system

Question 1

system

Answer 1

the part of the universe you’re studying

Question 2

heat (q)

Answer 2

flow of energy caused by a temp difference

Question 3

energy

Answer 3

capacity to do work or transfer heat

Question 4

work (w)

Answer 4

Energy used to move an object or expand/contract gas

Question 5

exothermic

Answer 5

releases heat into surroundings (warm to touch)

Question 6

endothermic

Answer 6

absorbs heat from surroundings (cold to touch)

Question 7

when is q+

Answer 7

when heat is being absorbed (endothermic)

Question 8

when is q-

Answer 8

heat being released (exothermic)

Question 9

when is w+

Answer 9

work is done on the system by surroundings

Question 10

when is w-

Answer 10

work done on the surroundings by the system

Question 11

change in energy (ΔU) formula

Answer 11

ΔU=q+w

Question 12

first law of thermodynamics and formula

Answer 12

energy can’t be created or destroyed
ΔE=q+w

Question 13

internal energy (U)

Answer 13

total energy in a system (kinetic+potential)

Question 14

what unit is used to measure q and w

Answer 14

joules (J)

Question 15

enthalpy (ΔH) definition and formula

Answer 15

change in heat at a constant pressure
ΔH=q

Question 16

when is enthalpy (ΔH) -

Answer 16

when heat is being released (exothermic)

Question 17

when is enthalpy (ΔH) +

Answer 17

when heat is being absorbed
(endothermic)

Question 18

Thermochemical Equation

Answer 18

A balanced chemical equation that includes energy change (ΔH)
ex: CH4+2O2→CO2+2H2O ΔH=−890kJ

Question 19

Thermal Equilibrium

Answer 19

heat is transferred between system and surroundings until they reach the same temp

Question 20

Calorimetry

Answer 20

Measurement of heat flow using a calorimeter. (coffee cup)

Question 21

is heat capacity extensive or intensive

Answer 21

extensive, depends on mass and type of material

Question 22

formula to find work

Answer 22

w= -(ΔP)xV

Question 23

specific heat capacity (Cs) definition and formula

Answer 23

Amount of heat to raise 1g of a substance by 1°C.
q=m x Cs x ΔT

Question 24

specific heat capacity unit

Answer 24

J/g°C

Question 25

Hess's Law

Answer 25

the enthalpy change of a reaction is independent of the pathway and depends only on the initial and final states. total enthalpy change for a reaction is the sum of the enthalpy changes of individual steps. (used in thermochemical reactions)

Question 26

Standard Enthalpy of Formation (ΔHf°)

Answer 26

Heat change for forming 1 mole of a compound from its elements in their standard states.

Question 27

standard state

Answer 27

Most stable form of a substance at 1 atm and 25°C

Question 28

Standard Enthalpy of Reaction (ΔHrxn°)

Answer 28

Enthalpy change when a reaction occurs with all substances in their standard states ΔHrxn∘=∑ΔHf∘(products)−∑ΔH f∘(reactants)

Question 29

water specific heat

Answer 29

4.184

Question 30

heat capacity (not specific) formula

Answer 30

q=CxΔT

Question 31

kinetic molecular theory for gases (4)

Answer 31

1. gas is made of small particles seperated by large distances 2. gas molecules are constantly in motion, moving in straight paths 3. gas molecules don't attract or repel eachother, their motion is random 4. avg kinetic E of a gas molecule is proportional to temp

Question 32

properties of gases (3)

Answer 32

1. assume size shape and volume of container 2. compressible 3. smaller density than solids and liquids

Question 33

what is pressure, formula

Answer 33

Caused by gas particles colliding with container walls. P=force/area

Question 34

how is pressure measured

Answer 34

mercury barometer

Question 35

pressure unit conversions

Answer 35

1mm Hg=1 torr 760mm Hg=1 atm 760 torr= 1 atm

Question 36

Boyles law and formula

Answer 36

V and P are inversely proportional P1V1=P2V2

Question 37

Charles law and formula

Answer 37

V and T are proportional (V1/T1)=(V2/T2)

Question 38

Gay Lussac's Law and formula

Answer 38

P and T are proportional (P1/T1)=(P2/T2)

Question 39

Avagadro's law and formula

Answer 39

V and n are proportional (V1/n1)=(V2/n2)

Question 40

combined gas law

Answer 40

(P1V1)/T1=(P2V2)/T2

Question 41

ideal gas law

Answer 41

PV=nRT

Question 42

Dalton's law of partial pressure

Answer 42

Ptotal=P1+P2+P3

Question 43

partial pressure formula

Answer 43

partial pressure= mol frac x total P

Question 44

P of CO2

Answer 44

P atm-P H2O