Gr.11 T3 Chemistry (energy+chemical change, gases) Flashcards Preview

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Flashcards in Gr.11 T3 Chemistry (energy+chemical change, gases) Deck (35):
1

Activation energy

The minimum amount of energy required to make a reaction happen

2

Bond energy

The amount of energy needed to break the bonds in a molecule

3

Catalyst

A substance that increases the rate of the reaction by lowering the activation energy.

4

Enthalpy

The total energy of a system.

5

Chemical potential energy

Energy due to the relative positions of atoms

6

What happens to enthalpy when wood burns?

Enthalpy of the system decreases, so heat energy is given off (NB!)

7

Endothermic reaction

Products contain more chemical potential energy than reactants.

8

What is the symbol for enthalpy ?

H

9

Define combustion of fuels

An exothermic reaction if a substance reacts rapidly with oxygen

10

Fuel

A substance that releases energy when it burns

11

What is an ideal gas?

A hypothetical gas that obeys all the gas laws

12

What is the ideal gas model? (5)

Particles in continuous motion in all directions

Very small particles - don't contribute to volume

No forces between molecules/ between container and molecules except when colliding

Collisions are elastic (no energy lost to surroundings)

All molecules are identical

13

Define temperature of a gas

A measure of the average kinetic energy of all the molecules in that gas

14

Pressure of a gas

A result of the collisions of particles with the sides of the container

15

What happens at 0 Kelvin?

Particles don't move or exert pressure

16

State Boyle's Law

The volume of a given gas is inversely proportional to the pressure exerted on it, at a constant temperature

17

What formula represents Boyle's Law?

p1V1 =p2V2

18

Explain Boyle's Law using the Kinetic Molecular Theory

Volume decreased
Less space for molecules to move
Collide more with walls of container in same amount of time
Pressure increases

19

T versus t?

T: temperature in Kelvin
t: temperature in degrees Celcius

20

State Charles' Law

The volume of a given gas, at constant pressure, is directly proportional to its temperature (K)

21

State the Gay-Lussac relationship
(Won't be asked in tests)

The pressure of an enclosed mass of gas is directly proportional to the temperature (K) of the gas for constant volume

22

What formula represents Charles' Law?

V1 V2
-- = --
T1 T2

23

What formula represents the Gay-Lussac relationship?

p1 p2
-- = --
T1 T2

24

What is the air pressure at sea level?

101,3 kPa

25

Explain Charles' Law using the Kinetic Molecular Theory

Volume decreases
Less space for molecules to move
Collide more in same amount of time
Average kinetic energy increases
Energy increases, so temperature increases

26

Give the units of measurement for the following formula:

pV=nRT

p: Pa
V: m3
n: mol
R: 8,31 (unit unimportant)
T: K

27

What shows us the change in enthalpy?

the heat of a reaction (at constant pressure)

28

How does ice cool something down?

Ice melts
Heat energy absorbed from surroundings
Surrounding get colder

29

Why does panting cool a dog down?

Water evaporates from tongue
Heat taken from surroundings
Dog cools down

30

Give an application of exothermic and endothermic reactions.

Cold packs (endothermic)
Hot packs (exothermic)
Self-heating cups (exothermic)

31

The Kinetic Molecular Theory

Explains observed changes in terms of position and speed of particles

32

Fill the gap:

1 Pa = 1 ____

-2
N.m

33

Fill the gap:

1 bar = ____ kPa

100 kPa

34

Fill the gap:
-3
1 kPa = ____ N.m

1000

35

What can be used to measure pressure?

A pressure meter/ pressure guage