HChem Test Chapter 17

Question 1

When solving an equilibrium equation (think lab) make sure to…

Answer 1

Make the side losing the heat negative (make sure answer makes sense

Question 2

What is the equation to find Qwater

Answer 2

Mass * 4.184 * delta T

Question 3

What is the equation to solve for an equilibrium with a metal

Answer 3

Mass(m)Cp(m)delta T(m)=Mass(w)4.184deltaT(w)

Question 4

Heat lost by metal=

Answer 4

Heat gained by water (make -)

Question 5

When solving an equation, make sure your units ______

Answer 5

Agree (kJ, mole, Kelvin for Gibbs)

Question 6

When doing heat of formation, make sure that the thing being combusted has a coefficient of ____
These are _________

Answer 6

1

Combustion

Question 7

What is the typical combustion equation

Answer 7

__+O2—>CO2+H2)

Question 8

What is Hess’s Law

Answer 8

Regardless of the multiple stages or steps of a reaction, the total enthalpy change for the reaction is the sum of all changes

Question 9

What is the summation equation

Answer 9

Sum of all products’ heat of formation-sum of all the reactants’ heat of formation
(Multiply by coefficients)

Question 10

If you are asked to calculate the heat of combustion for butane for a specific compound, make that compound’s coefficient ____

Answer 10

1

Don’t do this is asked to find the heat of reaction for the entire process

Question 11

If energy is being added on product side, the reaction is _____
If energy is being added on reactant side, the reaction is _____

Answer 11

Exothermic

Endothermic

Question 12

Positive delta S means _______

Answer 12

More disorder

Question 13

If something needs a continuous energy supply, it is most likely ____

Answer 13

Endothermic

Question 14

An ____ reaction produces energy as it proceeds

Answer 14

Exothermic

Question 15

What is the “direction” or trend most chemical reactions move toward in terms of energy and disorder

Answer 15

Lower energy, higher disorder

Question 16

Delta H stands for ___
Delta S stands for ___
Delta G stands for __

Answer 16

Enthalpy
Entropy
Gibbs

Question 17

What is the formula for Gibbs

Answer 17

Delta G=delta H-(T*deltaS)

T must be in kelvin

Question 18

-delta G is ____

Answer 18

Spontaneous

Question 19

If a reaction is spontaneous it does not need _____ help

Answer 19

Outside (catalyst)

Question 20

The heat content of the activated complex of any reaction is the ___ to the _____

Answer 20

Bottom, top

Question 21

The heat content of anything (reactants, products, AC) is ____

Answer 21

How talk it is (y axis)

Question 22

Name 4 things that will speed up or slow down a chemical reaction

Answer 22

Concentration, temperature, catalyst, surface area

Question 23

When drawing a graph, label the _____ and give it a ____

Answer 23

Axes, title

Question 24

• heat is equal to __________

Answer 24

Heat released (you can say either/or)

Question 25

When finding a limited reactant, what do you do

Answer 25

Go from grams of the reactant to grams of the product

Whichever is less is limiting reactant

Question 26

When doing dimensional analysis, remember that if the element is diatomic, factor that into ____

Answer 26

Molar mass

Question 27

qH2O=___

Answer 27

-qrxn

Question 28

What is the Hf value for elements

Answer 28

0 (they are naturally occurring and no heat is absorbed)

Question 29

Delta H =

Answer 29

qrxn/moles

Question 30

When doing enthalpy calorimetry and finding final temperature, what do you do

Answer 30

Set enthalpy =qrxn/moles, find moles, cross multiply to find qrxn, turn it negative and set equal to mass, Cp, and Tf-Ti

Question 31

1.00 ml of water=

Answer 31

1.00 g of water

Question 32

When doing specific heat equation, put temp in ___

Answer 32

C

Question 33

What is the second law of thermodynamics

Answer 33

Changes in the universe tend towards a state of greater disorder

Question 34

More moles to less moles is __ delta S

Answer 34

-

Question 35

The tendency for all reactions is to have __delta H and __ delta S

Answer 35

-,+

Question 36

The equation for the delta Hf of N2O is:

Answer 36

N2(g)+3/2O2(g)—>N2O3(g)

Question 37

Disorder is ___ delta S

Answer 37

+

Question 38

The equation for Hf is not _______, but you write the equation for one mole of the compound asked

Answer 38

Summation

Question 39

The equation for the delta Hf of any molecule always contains either __ or ___

Answer 39

02 or H2

Question 40

Delta H must be in ___

Answer 40

kJ/mol