Chapter 2 - Energy Calculations Flashcards Preview

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Flashcards in Chapter 2 - Energy Calculations Deck (17):
1

What is thermochemistry?

Study of how energy changes in a chemical reaction

2

What is enthalpy?

The total energy stored in a substance. We measure a change in enthalpy from reactants to products. It is measured at SLC with 1 molarity.

3

Exothermic delta H value

Release heat = negative

4

Endothermic delta H value

Absorb heat = positive

5

describe the Kinetic Molecular theory of gases (KMT)

-particles always in motion
-collisions are elastic
-all gases have the same average kinetic energy

6

What is pressure?

Pressure is force per unit of area. It describes the collision of gas molecules with the container.

7

conversion for pressure

760mmHg = 1 atm = 101.3 kPa

8

conversion for volume

1m^3 = 1,000 L
1cm^3 = 1 L
1mm^3 = 1 mL

9

What is the ideal gas equation?

PV = nRT

P= kPa
V= L
T= K

10

What value is R

8.314

11

How to find an equation from the ideal gas equation

1.Make everything that is constant the letter k

2. Get all the k letters on one side and everything else on the other

3. Once we have just k on one side we can use the rule as e.g: P1V1=k, therefore P1V1=P2V2

12

What is an energy profile diagram?

A diagram which shows the change in energy throughout the progress of a reaction

13

energy profile diagram EXOTHERMIC

high to low

14

energy profile diagram ENDOTHERMIC

low to high

15

describe how methane is considered both a non-renewable and renewable resource.

Depends on the source methane. When derived from fossil fuels and pockets in the earths crust it is considered non-renewable as these sources were made millions of years ago. However, when derived from biological matter and the anaerobic rotting of animals and plants it is renewable as it can be produced faster than it is used.

16

errors that can occur when measuring the heat of combustion of a substance

incomplete combustion - not all energy used
heat lost- into surroundings, container
impurities- in substance lead to false data

17

When having to rearrange equations to find an overall enthalpy what is the golden rule

We only reverse an equation if the species in question is on the wrong side of the arrow when compared to the desired equation.