chem 2

Heat is the________________________________

transfer of thermal energy between two bodies that are at different temperatures.

Heat will always flow from the _________substance towards the__ ______________ substance. 

hotter, cooler

Fast moving particles are associated with having more _______________, while _____moving particles are associated with having less energy. 

energy, slow

Temperature is the measurement of_____________________

thermal energy

When fast moving molecules hit the sides of a thermometer, they transfer energy to the ___________________

thermometer

As this energy is ______________to the liquid within the thermometer, the liquid will go up inside the thermometer.

transferred

does temperature equal thermal energy?

no

Temperature measures__________________________________

how fast particles are moving 

Energy measures ____________and is given in the units of _________

heat , Joules (J).

________________________ is the study of heat changes in chemical reactions.

Thermochemistry

_________________ describes the energy lost or gained within the system of the reaction.

Enthalpy

enthalpy (ΔH) you will do as follows

ΔH = Hproducts - Hreactants

As enthalpy is a measurement involving __________its units will be based in Joules (J). 

energy

Enthalpy units will be ______________

kJ/mol

 alternate equation for enthalpy:

\

ΔH=−Q/mol

Since enthalpy is a finite, measurable amount it can be either a ______________value or a ___________value

positive , **negative**

**________________________**processes are any processes that give off heat

**Exothermic** 

**__________________** processes are any processes where heat has to be absorbed 

Endothermic

supplied to the system from the surroundings

**Endothermic** 

that is to say, that they transfer thermal energy from the system into the surroundings.

**Exothermic** 

endo or exo

exo

endo or exo

endo

_______________ processes have less energy in the reactants than in the products

 endothermic

_______________ processes have less energy in the products than the reactants

 exothermic

the amount energy it takes to get beyond the activated complex and complete the reaction

activation energy

______________ reactions have a small reaction energy

exothermic

___________________________________reactions have a large activation energy

endothermic

endo or exo and why

exo, ΔH = Hproducts - Hreactants= ΔH = 50 - 150= -100kJ(negative)

endo or exo

endo, ΔH = Hproducts - Hreactants= ΔH = 150 - 50= +100kJ(postive)

1. Reactants =______________          Products = 100.0 kJ/mol

ΔH = Products – Reactants= _____________ __–__ __________ __=__ _____________


1. – ΔH values are _______________, and we know that this shape of graph is an ________________graph.

 450.0 kJ/mol, 100.0 kJ/molΔH , 100.0 kJ/mol, 450.0 kJ/mol, -350.0 kJ/mole, exothermic

1. Reactants = __________________        Products = __________________ΔH = Products – Reactants
2. __________________– __________________= __________________ kJ/mole
3. ______ΔH values are __________________, and we know that this shape of graph is an __________________ graph.

1. Reactants = __210.0 kJ/mol__        Products = __150.0 kJ/mol__ΔH = Products – Reactants
2. __150.0 kJ/mol__– __210.0 kJ/mol__= __-60.0__ kJ/mole
3. __-__ΔH values are __exothermic__, and we know that this shape of graph is an __exothermic__ graph.

1. Reactants = __________________        Products = __________________ΔH = Products – Reactants
2. __________________– __________________= __________________ kJ/mole
3. ______ΔH values are __________________, and we know that this shape of graph is an __________________ graph.

1. Reactants = __12.5 kJ/mol__        Products = __50.0 kJ/mol__ΔH = Products – Reactants
2. __50.0 kJ/mol__– __12.5 kJ/mol__= +__37.5__ kJ/mole
3. __+__ΔH values are __endothermic__, and we know that this shape of graph is an __endothermic__ graph.

1. Reactants = __________________        Products = __________________ΔH = Products – Reactants
2. __________________– __________________= __________________ kJ/mole
3. ______ΔH values are __________________, and we know that this shape of graph is an __________________ graph.

1. Reactants = __125.0 kJ/mol__        Products = __950.0 kJ/mol__ΔH = Products – Reactants
2. __950.0 kJ/mol__– __125.0 kJ/mol__= +__825.0__ kJ/mole
3. __+__ΔH values are __endothermic__, and we know that this shape of graph is an __endothermic__ graph.

1. Reactants = __________________        Products = __________________ΔH = Products – Reactants
2. __________________– __________________= __________________ kJ/mole
3. ______ΔH values are __________________, and we know that this shape of graph is an __________________ graph.

1. Reactants = __50.0 kJ/mol__        Products = __12.5 kJ/mol__ΔH = Products – Reactants
2. __12.5 kJ/mol__– __50.0 kJ/mol__= -__37.5__ kJ/mole
3. __-__ΔH values are __exothermic__, and we know that this shape of graph is an __exothermic__ graph.

Temperature measures heat

  

False

 

temperature measures the _______________

kinetic energy of molecules

heat measures __________

energy

Which part of a reaction has more energy for an exothermic reaction?

Reactants

 

A thermometer works by directly measuring the amount of heat energy around it.

False

You light a campfire to cook s’mores. The system for this reaction is ___________, and the surroundings are ___________.

 

the logs burning on the fire; everything outside of the fire

 

Which part of a reaction has more energy for an endothermic reaction?

Products

Which of the statements below are true regarding systems and surroundings?

  

A system is where the reaction occurs, while the surroundings are where the reaction came from

 

  

Surroundings include the reaction itself

  

A system is where the reaction occurs, while the surroundings are everything outside of that reaction

 

  

A system is outside of the reaction itself

 

A system is where the reaction occurs, while the surroundings are everything outside of that reaction

An ice cube melts on your hand. This is an example of an ______________ reaction.

Endothermic

A campfire is an example of an _____________ reaction.

\
  

Exothermic

 

A sample of salt is placed within a Styrofoam cup filled with water. The salt dissolves rapidly. The water inside the cup gets colder, while the cup stays the same temperature. The salt is the _______, while the water is the ___________.

  

system, surroundings

 

Liquid water is placed into a freezer. Heat transfers from the __________ to the ________, resulting in an ___________ process.

  

water, freezer, exothermic

 

an exothermic reaction loses energy, so the products will have _______________ than the reactants.

less energy

a thermometer measures the amount of ______________ from molecules. This kinetic energy is transferred to the molecules inside of the thermometer.

kinetic energy

the system is where the ______________happens, the surroundings are ________________________

reaction, everything outside of that

an endothermic reaction __________energy, so it will have__ _________energy after it has reacted

gains, more

First, the ΔH values for the _______________must be found, and then the ΔH values for the _________must be found.

products , reactants

. First, the ΔH values for the products must be found, and then the ΔH values for the reactants must be found. After finding these values, solving _________minus __________________will give you the ΔH value.

products, reactants

Equation:  C6H12O6  +  6 O2   --> 6 CO2    +  6 H2O

(-4076.034) – (-2800) = **-1276 kJ/mol, Exothermic, and – ΔH**

 

**Exothermic ΔH values (-ΔH), are placed on the far ____________of an equation**.

right 

Endothermic ΔH values (+ΔH), are placed on the far ___________of an equation

left 

 Exo = ________

exit

Endo = ______________

enter

H2  +  Cl2  →  2 HCl  +  185 kJ/mol

Information =

Exothermic, and -ΔH

\

 H2  +  F2   →  2 HF  +  546 kJ/mol

Information =

Exothermic, and -ΔH

\

38\.0 kJ/mol +  Fe3O4  + CO  --> 3FeO  +  CO2

Information =

\

Endothermic and + ΔH

Equation: N2 +  3H2  -->  2NH3

Step 1:

Step 2:

Step 3:

Step 4:

Equation: N2 +  3H2 →  2NH3

Step 1: N2 = 0, H2 = 0, NH3 = -46.11 \* 2 = -92.22

Step 2: Products = -92.22, Reactants = 0+0 = 0

Step 3: Products - Reactants; -92.22 - 0 = -92.22 kJ/mole

Step 4: Exothermic,   -ΔH

\

Equation: LiOH + HCl  -->  H2O  +  LiCl

Step 1:

Step 2:

Step 3:

Step 4:

Equation: LiOH + HCl → H2O  + LiCl

Step 1: LiOH = -481.93, HCl = -167.159, H2O = -285.830, LiCl = -408.7

Step 2. Products = -285.830 + -408.7 = -694.53;  Reactants = -481.93 + -167.159 = -649.089

Step 3: Products - Reactants; (-694.53) - (-649.089) = -45.44 kJ/mole

Step 4: Exothermic, -ΔH

\

Energy from a reaction was determined to be 12552 J, when burning 16.3 grams of CH4. What is the total enthalpy of the reaction?

dive j by 1000 to kj, multiple by molar mass (12.011+ 4x1.008) divide by 16.3,   

\
\-12.4 kJ/mole

 

Energy from a reaction was determined to be 11563 J, when burning 15.0 grams of H­2. What is the total enthalpy of the reaction?

  

\-1.54 kJ/mole

 

amount of energy being present fortmula

Q = m･c･Δt

**Q meaning in Q = m･c･Δt**  and unit

the amount of heat leaving or entering a substance, and is measured in Joules.

**m meaning in Q = m･c･Δt**  and unit

mass of substance being heated. Mass is measured in grams. 

 **m in Q = m･c･Δt**  This mass is not what is being ________, but the mass of the substance that is being heated or cooled because of the reaction. This substance is located in the ____, and not in the system.

reacted, surroundings

**c meaning in Q = m･c･Δt**  and unit

**specific heat of substance being heated. Specific Heat is measured in J/g*°C**

Specific heat is defined as_________________________________________

the amount of heat that is required to raise the temperature of 1 gram of a substance by 1 degree Celsius (or 1 kelvin).

Every __________________has its own specific heat.

molecule

**Δt =** change in temperature of substance being heated. Because temperature is measured in delta T, both Kelvin and Celsius can be put in. Since temperature is a delta, that means that in order to find it, you must take the Tfinal – Tinitial.

change in temperature of substance being heated.

\
Kelvin or Celsius

\
Tfinal – Tinitial.

A hot 5.00 gram piece of aluminum is placed into 75.0 mL of water. The water increases in temperature from 23.0°C to 28.0°C. The specific heat capacity of aluminum is 0.90, and water is 4.184. How much energy was lost by the aluminum?

**G:**mAl = 5.00 g         Vwater = 75.0 mL          t1 = 23.0 ℃         t2 = 28.0 ℃  \n cAl = 0.90 J/g･℃         cwater = 4.184 J/g･℃ 

**U**:Q = ?

**E:** Q = m･c･Δt          Δt = tfinal - tinitial           Dwater: 1 g = 1 mL

**S**:use water values since this is what is heating up

**S:(**75 g)(4.184 J/g･℃)(5℃) = 1569 → (sig figs) → **1570 J**

_________________ is used to measure amounts of heat transferred to or from a substance

Calorimetry

A___________________________is a device used to measure the amount of heat involved in a chemical or physical process

calorimeter

For example, when an ______________________reaction occurs in solution in a calorimeter, the heat produced by the reaction is absorbed by the solution, which increases its temperature

exothermic

 When an ____________________reaction occurs, the heat required is absorbed from the thermal energy of the solution, which decreases its temperature.

endothermic

The temperature change, along with the specific heat and mass of the solution, can then be used to calculate the amount of __________________involved in either case.

**heat**

what is Q

the amount of heat being lost or gained

Calorimetry can find __ and _______ of a reaction. 

Q and ΔH

3 things needed when solving for the amount of energy released or gained by a reaction

mass of the substance gaining or releasing the energy

\
specific heat of that substance.

\
the change of temperature for that substance. 

ΔH is measured in ______________________

kJ/mole

while Q is measured in ___________

J

whebn solving for ΔH, 2 things to remember

convert Joules, into kilojoules (kJ)

convert grams into moles as well

*kinetic molecular theory* (KMT), a simple microscopic model that effectively explains ____________________

the behavior of gases

describe kmt in 5 rules

1. Gases are composed of molecules that are in continuous motion, traveling in straight lines and changing direction only when they collide with other molecules or with the walls of a container.
2. The molecules composing the gas are negligibly small compared to the distances between them.
3. The pressure exerted by a gas in a container results from collisions between the gas molecules and the container walls.
4. Gas molecules exert no attractive or repulsive forces on each other or the container walls; therefore, their collisions are *elastic* (do not involve a loss of energy).
5. The average kinetic energy of the gas molecules is directly proportional to the kelvin temperature of the gas.

meaning of

Gases are composed of molecules that are in continuous motion, traveling in straight lines and changing direction only when they collide with other molecules or with the walls of a container.

as particles are always moving and bounce off of each other and their container.

meaning of the molecules composing the gas are negligibly small compared to the distances between them.

compared to how far apart gas particles are, the individual molecules themselves are relatively small

meaning of The pressure exerted by a gas in a container results from collisions between the gas molecules and the container walls.

 gas pressure comes from gas particles hitting the walls of their container.

meaning of Gas molecules exert no attractive or repulsive forces on each other or the container walls; therefore, their collisions are *elastic* (do not involve a loss of energy).

they bounce off of each other perfectly, without sticking to or repelling one another, and no energy is lost when they do

meaning The average kinetic energy of the gas molecules is directly proportional to the kelvin temperature of the gas.

 gas particles gain more energy when they are heated, and lose energy when they are cooled. That energy is displayed through the speed of the gas particles, as they go faster and faster the hotter they get.

_______________is the result of gas molecules hitting the sides of their container

**Pressure** 

 As the energy of the molecules increases, the pressure exerted by those molecules will also increase as those molecules hit the walls of their “container,” both with more _________and more frequently.

force

**______________** can be thought of as the intensity of heat present in a substance, and it has a direct relationship with the kinetic energy of gas molecules (when the temperature of gas molecules increases, their kinetic energy does as well).

**Temperature** (T)

 one mole of any gas occupies a volume of 22.4 liters

The temperature of gases is always measured in degrees___________ (K), which can easily be converted from Celcius (C°) by adding ____________to any Celsius temperature.

Kelvin, 273

______________is caused by the force exerted by gas molecules colliding with the surfaces of objects

Gas pressure

**expansion -**

 gases have no definite shape or volume

**low density -**

 the particles of a substance in the gaseous state are about 1/1000th the density of the same substance in a solid or liquid state

**compressibility -**

 the volume of a given sample of a gas can be greatly decreased