lesson 5 & 6

Question 1

what is energy?

Answer 1

the capacity to do work or to produce heat.

Question 2

law of conservation of energy.

Answer 2

energy can be converted from one form to another but it can’t be created or destroyed.

Question 3

what is potential energy?

Answer 3

energy because of the position or composition.

Question 4

kinetic energy

Answer 4

energy because of the motion of the object.

Question 5

heat?

Answer 5

transfer of energy due to temperature differences.

Question 6

work?

Answer 6

force acting over a distance.

Question 7

energy is a state function, what doe that mean?

Answer 7

only the present matters.

the past or future of system doesn’t matter.

Question 8

whats the difference between heat and temperature.

Answer 8

temperature is the random motion of particles. while heat is the difference in temperature.

Question 9

what is a system?

Answer 9

the part of the universe that we focus on

Question 10

what is surroundings?

Answer 10

everything in the universe.

Question 11

what are endothermic reaction?

Answer 11

a reaction that absorbs energy from surroundings,

energy from surroundings to system

Question 12

what is an exothermic reaction?

Answer 12

a reaction that releases energy into the surrounding.

energy from system to surroundings

Question 13

thermodynamics?

Answer 13

the study of energy and its conservation.

Question 14

what is the first law of thermodynamics.

Answer 14

law of conversion of energy.

Question 15

law of conversion of energy states …

Answer 15

the energy of the universe is constant.

Question 16

internal energy?

Answer 16

sum of potential energy of all the “particles” in a system.

Question 17

what affects internal energy

Answer 17

flow of work, heat, or both.

Question 18

change in energy equals?

Answer 18

change in E = q + w

Question 19

internal energy consists of

Answer 19

is a vector. so it consists of a number and sign.

Question 20

when is q positive and when is it negative.

Answer 20

positive: endothermic
negative: exothermic.

Question 21

when is work negative and when is it positive?

Answer 21

negative: when the system does the work
positive: when the surrounding does the work.

Question 22

how did we reach to the equation that W = P * (change in V)

Answer 22

W = F (change in distance)
F = P * A
if we substitute F with its equation we get W = P * A * (change in h)
(change in V) = final volume - initial volume = A * (change in h)
substituting with that we ger. W = P * (change in V)

Question 23

1 L·atm = ? J

Answer 23

101.3

Question 24

enthalpy

Answer 24

the combination of internal energy and work done by/on system
H = E + PV

Question 25

when is a reaction endothermic and when is it exothermic?

Answer 25

``` endothermic = change in enthalpy is positive exothermic = change in enthalpy is negative ```

Question 26

Calorimetry

Answer 26

Science of measuring heat

Question 27

Specific heat capacity:

Answer 27

The energy required to raise the temperature of one gram of a substance by one degree Celsius.

Question 28

Molar heat capacity:

Answer 28

The energy required to raise the temperature of one mole of a substance by one degree Celsius

Question 29

Types of Calorimeter

Answer 29

Constant P Calorimeter (Coffee Cup) | Constant V Calorimeter (Bomb Calorimeter)

Question 30

what is a coffee cup calorimeter made of?

Answer 30

Two Styrofoam Cups

Question 31

Constant-pressure calorimetry is used ......

Answer 31

pressure remains constant during the process. Constant-pressure calorimetry is used in determining the changes in enthalpy (heats of reactions) for reactions occurring in solution.

Question 32

Energy released (heat) = ?

Answer 32

Energy released (heat) = s × m × ΔT

Question 33

when is bomb calorimeter used

Answer 33

When the volume remains constant during a reaction, (in a | closed container), a bomb calorimeter is used.

Question 34

how do we measure the energy released by reaction in a bomb calorimeter?

Answer 34

The energy released by the reaction = change in T x heat capacity of Calorimeter

Question 35

Bomb Calorimeter made of

Answer 35

thermometer, steel bomb, reactants in the sample cup, water, insulation container.

Question 36

what is Hess’s Law?

Answer 36

In going from a particular set of reactants to a particular set of products, the change in enthalpy is the same whether the reaction takes place in one step or in a series of steps

Question 37

Characteristics of Enthalpy Changes

Answer 37

If a reaction is reversed, the sign of ΔH is also reversed. | The magnitude of ΔH is directly proportional to the quantities of reactants and products in a reaction.

Question 38

Standard Enthalpy of Formation

Answer 38

Change in enthalpy that accompanies the formation of one mole of a compound from its elements with all substances in their standard states

Question 39

Conventional Definitions of the Standard States For a Compound

Answer 39

For a gas, pressure is exactly 1 atm. For a solution, the concentration is exactly 1 M. Pure substance in the condensed state the standard state is the pure liquid or solid)

Question 40

Conventional Definitions of the Standard States For an Element

Answer 40

The form [N2 (g), K(s)] in which it exists at 1 atm and 25°C