Assignment 7

Question 1

phase change

Answer 1

breaking IMFS

Question 2

chemical reaction

Answer 2

breaking bonds

Question 3

making a bond (energy)

Answer 3

gives off

Question 4

breaking a bond (energy)

Answer 4

costs energy

Question 5

ΔH

Answer 5

enthalpy of reaction
change in heat of a system
found by heat of formation
ΔH = Ef - Ei
= Hproducts - Hreactants

Question 6

Ef

Answer 6

final energy (product’s energy)

Question 7

Ei

Answer 7

initial energy (reactant’s energy)

Question 8

exothermic

Answer 8

gives off energy, ΔH is negative, reaction gets hot

Question 9

endothermic

Answer 9

takes (absorbs) energy, ΔH is positive, reaction gets cold

Question 10

Q (J)

Answer 10

transferred heat
Q = mCpΔT
m - mass (g)
Cp - heat capacity (J/gK or J/gC)
ΔT - change in heat (Tf - Ti) (C or K)

Question 11

heat capacity (Cp)

Answer 11

the heat needed to change the temp of 1g by 1degC (1K)
unique to each substance and state
related to IMFs

Question 12

calorie

Answer 12

ener needed to increase temp of 1g by 1degC

Question 13

heat of fusion (hf)

Answer 13

IMF term, unique to each substance
Q = mhf
m - mass
hf - heat of fusion

Question 14

heat of vaporization (hv)

Answer 14

unique to each substance
Q = mhv
m - mass
hv - heat of fusion

Question 15

is there a temp change during a state change

Answer 15

no, because the energy is going into increasing the KE of the particles, so they can change state, not into heating up the substance

Question 16

Hess’s Law

Answer 16

the heat of reactions is the algebraic sum of the subreactions
Qrxn = Q1 + Q2 + Q3…
ΔHrxn = ΔH1 + ΔH2 + ΔH3…

Question 17

enthalpy

Answer 17

heat an object or substance contains

Question 18

heat or enthalpy of formation (ΔHf)

Answer 18

combination of 2 or more elements to form a non-elemental product
used in lieu of bond energy
heat gained from the formation of the elements

Question 19

if you have a question where a substance goes through a phase change, then

Answer 19

you solve for each step of the phase change with the Q equations and add up all the answers
Q = mCpsolidΔT
Q = mhf
Q = mCpliquidΔT
Q = mhv
PV = nRT

Question 20

finding enthalpy using heat of formation

Answer 20

given the molecular equations, do a system of equations until you reach the final equation

Question 21

gibbs free energy (ΔG)

Answer 21

ΔG = ΔH - (TΔS)

Question 22

entropy

Answer 22

how much the energy:temp ratio changes in a system

Question 23

free energy

Answer 23

measure of imbalance of energy

Question 24

ΔG = 0

Answer 24

equalibrium

forward and reverse equations are spontaneous

Question 25

ΔG is negative

Answer 25

extra energy

spontaneous with free energy

Question 26

ΔG is positive

Answer 26

need energy

non-spontaneous