6.1-6.3 Quiz

Question 1

If the surroundings is pushing on the system and compressing a piston, the work is …..

Answer 1

Positive

Question 2

What does an endothermic reaction profile look like?

Answer 2

The products are higher in energy than the reactants

Question 3

How is the energy between the system and the surrounding connected according to the first law of thermodynamics?

Answer 3

The first law of thermodynamics states that energy cannot be created or lost, only transferred. So energy of the system= - energy of the surroundings.

The negative side will go on whatever is LOSING energy

Question 4

How do you find the activation energy for a reverse reaction?

Answer 4

You do Top of the graph- products

Question 5

Dissociation; would this be an endothermic or exothermic process?

Answer 5

Breaking up larger compounds into smaller ones

This would be endothermic because the system NEEDS energy to break up the compounds so it is absorbing energy

Question 6

What phase changes are related to exothermic reactions?

Answer 6

Changes that involve combining materials.
Freezing
Condensation
Deposition

Question 7

When the energy of a system decreases what type of reaction is it?

Answer 7

Exothermic

Question 8

If an equation is talking about a change in temperature, what are they referencing?

Answer 8

THE SURROUNDINGS

Question 9

When products are higher than reactants what does that mean about the stability of the products?

Answer 9

The products are less stable

Question 10

E (subscript a) or activation energy

Answer 10

The energy necessary to start a reaction. They are used to break bonds or IMFs in the reactants.

Question 11

Electron Affinity; would this be an endothermic or exothermic process?

Answer 11

The amount of energy released when an electron is added(electron on left side of equation) ; Exothermic because energy is being released

Question 12

If the system is pushing on the surroundings and expanding a piston, the work is …..

Answer 12

Negative

Question 13

Work

Answer 13

Energy needed to move something against a force. Think about expanding gases pushing on a piston

Question 14

Universe

Answer 14

System and surroundings together

Question 15

How do you label the coordinates for an energy profile?

Answer 15

The x axis is reaction coordinate and the y axis is potential energy

Question 16

Surroundings

Answer 16

everything else around the system

Question 17

How do you answer the questions that ask for justification and ask you to choose the BEST answer?

Answer 17

Look for causation and not js correlation
Also on this quiz look for answers that talk specifically about breaking or forming bonds.

Question 18

Vaporization vs boiling

Answer 18

Liquid to vapor
vs
Liquid to gas

Question 19

Catalysts

Answer 19

Increase reaction rate and are not consumed in the reaction. They also provide lower activation energies.

Question 20

Words related to exothermic reactions

Answer 20

Exiting
Losing
Releasing
Negative

Question 21

Sublimation

Answer 21

Solid to gas

Question 22

Ionization energy; would this be an endothermic or exothermic process?

Answer 22

Energy required to remove an electron(electron on right side of equation)
This would be endothermic because the system NEEDS energy so it will be absorbing energy

Question 23

If you are told to draw a reaction pathway and are given the reactants and the activation energy(ex: reactants- 40 kJ and Ea- 50 kJ), then how do you graph this?

Answer 23

The reactants will be at 40 and the Ea will be at 90 kJ, because you do 40 plus the Ea.

Question 24

Condensation

Answer 24

Gas to liquid

Question 25

Describe how heat flows with systems and surroundings for an endothermic reaction.

Answer 25

The system gains(or absorbs) energy from the surroundings.

Question 26

System

Answer 26

The part of the world that you are studying. Typically a chemical reaction

Question 27

When the energy of a system increases what type of reaction is it?

Answer 27

Endothermic

Question 28

What does an exothermic reaction profile look like?

Answer 28

The products are lower in energy than the reactants

Question 29

A solution of ammonium nitrate was created by dissolving 5.02 grams of ammonium nitrate in 100.0 mL of water at 22.3°C. After forming the solution the temperature was 17.3°C. Did heat enter the system or leave the system? What is the sign for q? Was the dissolution process endothermic or exothermic?

Answer 29

Entered the system Positive Endothermic This is because the system is ammonium nitrate and the surroundings are everything else. The water's temperature decreases because the system absorbs its heat which is why this process is endothermic.

Question 30

How do phase changes affect kinetic energy?

Answer 30

They don't. Going from solid to liquid to gas, the temperature remains constant and the average kinetic energy stays the same

Question 31

Heat(q) - Units

Answer 31

Amount of thermal energy transferred from something that is hotter to something that is colder. Units are J or kJ.

Question 32

Words related to endothermic reactions

Answer 32

Positive Increase Absorb

Question 33

Deposition

Answer 33

Gas to solid

Question 34

Describe how heat flows with systems and surroundings for an exothermic reaction.

Answer 34

The system loses(or releases) energy and it is gained by the surroundings.

Question 35

What phase changes are related to endothermic reactions?

Answer 35

Changes that involve breaking/ separation Melting Boiling Vaporization Sublimation

Question 36

What does a catalyst due to the enthalpy?

Answer 36

NOTHING, it is not affected by it.

Question 37

Work equation

Answer 37

- P delta (V) P= pressure in atm Delta V is the change in volume

Question 38

The lower the activation energy, the ____________ the rate of reaction

Answer 38

Faster

Question 39

What part of a reaction energy profile is new bonds being formed?

Answer 39

When the energy is released, when the graph is dropping

Question 40

How does temperature affect average kinetic energy and speed?

Answer 40

Particles in a warmer body will typically have a higher average kinetic energy and speed. However, if you are comparing two elements, the smaller element will have a greater speed regardless.

Question 41

Thermal equilibrium

Answer 41

When the average kinetic energy and temperature of both bodies are the same

Question 42

Heat transfer/ Heat exchange/ Transfer of energy as heat

Answer 42

When hotter particles and colder particles collide, energy is transferred between them. The hotter particles lose some energy and the colder particles gain some energy.

Question 43

How is heat always transferred?

Answer 43

From the HOTTER substance to the COLDER substance

Question 44

In terms of what occurs at the particulate level, explain how the temperature of water increases after an alloy sample is added.

Answer 44

The atoms in the alloy transfer kinetic energy to the molecules in the water

Question 45

What occurs at the particulate level when the water and the alloy reach thermal equilibrium?

Answer 45

At equilibrium the average kinetic energy of the atoms in the alloy is equal to the average kinetic energy of the water molecules

Question 46

What is happening on a heating curve when the temperature is constant, and what is happening when the temperature is increasing?

Answer 46

Constant- IMFs are being overcome and average kinetic energy and temperature are constant Increasing- Average kinetic energy and temperature are increasing

Question 47

What is the heat calculation with phase changes?

Answer 47

Mass times enthalpy change

Question 48

Which enthalpy change are you looking for with phase changes when they reference freezing and melting?

Answer 48

Fusion

Question 49

What temperature does water melt at and what temperature does water boil at?

Answer 49

Melt- 0 degrees celsius Boil- 100 degrees celsius

Question 50

How do you answer phase change questions like this: How much energy does it take to heat 50.0 g of water at 25.0°C to steam at 107.0°C?

Answer 50

You have to use multiple steps and add them all together. Ex: 1) Heat water, 2) Water to gas(because the question says steam), 3) Heating gas(because it says 107) Water to gas is the only one where you do mass times enthalpy change and you would do mass times delta H of vaporization

Question 51

Which enthalpy change are you looking for with phase changes when they reference boiling and steam, condensing and vaporizing?

Answer 51

Vaporization

Question 52

What happens to the temperature of something as it undergoes a phase change?

Answer 52

It remains constant