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Flashcards in Semester Two Exam Deck (384)
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1

evaporation

The transfer of water from the Earth to the atmosphere. The water utilises energy from the sun to convert it from a liquid state to a gaseous state. This transfer occurs when some molecules in a water body attain sufficient kinetic energy to eject themselves from the water surface.

2

transpiration

The evaporation of water from plants through stomata. Water moves from the soil into the roots and through the leaves and then out of the plant.

3

sublimation

The evaporation of water from snow and ice. Water transfers from a solid to a gas.

4

condensation

The transition process where water vapour loses kinetic energy and turns from a gaseous state into a liquid state once again.

5

precipitation

Water vapour is released by condensation to form precipitation as rain and falls back towards Earth.

6

deposition

Water Vapour is converted directly to a solid and falls to Earth as snow or hail.

7

percolation

Rainfall seeps into the ground by a process called percolation (infiltration). Some of this ends up in ground water.

8

surface flow/ground water flow

Water runs off into oceans, lakes and large rivers. Ground water flow moves slow compared to surface.

9

evapotranspiration

all 3 processes, evaporation, transpiration and sublimation can be referred to as this.

10

the ocean

The ocean plays a key role in the water cycle. 97% of the water on Earth is in the ocean. 86% of evaporation comes from the ocean. 78% of precipitation occurs over the ocean.

11

how increase in temperature/climate change can effect conditions

As temperature increases evaporation rates increase as the air gets warmer and can hold more water vapour. This can lead to intense storms which increases the risk of flooding. When flooding occurs, it increases the chances of surface flow and decreases percolation so the soil is not dampened, this combined with increased temperatures increase the risk of drought.

12

weather

Short term conditions, present in the moment. (cool and wet on a particular day)

13

climate

Weather conditions present in an area over a long term. (typically Hot and Dry at this time of year).

14

3 states of water

Ice: solid. Water freezes at 0°C.
Water: Liquid.
Water Vapour: Gas.

15

how does amount of water vapour present affect climate

The amount of water vapor present in the atmosphere varies in different areas. Areas in which the atmosphere can hold more water are prone to humidity, while areas that hold little moisture have very dry air.

16

water and temperature in surrounding environment

- As water evaporates heat from the earth’s surface is carried away with the water vapour. This means areas with higher evaporation rates will be cooler. Likewise, as rain falls heat will be transferred back from the atmosphere to the ground.
- Water responds to temperature change much more slowly than land. It takes longer to heat water and cool it down. As a result, areas near the ocean experience milder changes in climate. Ice requires even more energy for evaporation making these areas cooler.

17

structure of water characteristics

polarity
surface tension- meniscus
specific heat capacity
density
buoyancy
solubility

18

the charges of each side of water atom

- Water is composed of one oxygen atom and two hydrogen atoms. Each hydrogen atom is covalently bonded to the oxygen by a pair of shared electrons. Oxygen has two unshared pairs of electrons of the hydrogen atoms, giving the oxygen atom a partially negative charge.

19

polarity

- As the hydrogen atoms share electrons with the oxygen atom this gives them a partially positive charge. An electrostatic charge between the partial positive end and the partial negative end results in the formation of hydrogen bonds between the two molecules. The hydrogen bonds give water many unique properties.

20

definition of surface tension

- The tendency of a liquid to resist rupture when placed under tension or stress. Water at the surface (at water, air interface) will form hydrogen bonds to their neighbours, however as they are exposed to air on one side they have fewer neighbouring water molecules to bond with, therefore will create stronger bonds with the neighbours they do have.

21

surface tension of water measurement

- Surface tension is measured in dynes/cm, water has a high surface tension of 72.8dynes/cm.

22

cohesive forces

- Cohesive forces are responsible for the property of surface tension. Cohesive forces are attractive forces between like molecules. This is due to the polarity of water, it is attracted to itself forming hydrogen bonds.

23

meniscus

Adhesive forces are attractive forces between unlike molecules. A meniscus is created due the adhesive forces between water and the walls of the glass tube, which are stronger than the cohesive forces between water molecules. This leads to an upward turning meniscus.

24

relationship of heat and temperature

Heat is the amount of thermal energy present, temperature is how fast the molecules are moving in the substance. When a substance is heated the molecules move faster, as the molecules are moving faster they also move further apart and the temperature increases.

25

what is specific heat capacity

- Specific heat is the amount of heat per unit mass required to raise the temperature by 1°C.

26

waters specific heat capacity

- Water has a high specific heat capacity due to hydrogen bonds. In order to increase the temperature of water the molecules have to vibrate, due to the large presence of many hydrogen bonds in water, a larger amount of energy is required to make the molecules break by vibrating them.
- It takes 4180 joules of energy to raise the temperature of 1kg of water by 1°C. Therefore, the specific heat capacity of water is 4180/kg/°C.

27

why is specific heat capacity vital to life on the planet

› Water can absorb a lot of energy without changing much in temperature. The large amounts of water on the earth absorbs plenty of heat from the sun, but the temperature of that water remains relatively stable, allowing it to stay as a liquid.
› If water had a low specific heat capacity, our oceans and seas would boil and dry up and life on earth would not be possible.
> Because water absorbs and releases heat at a much slower rate than land, air temperatures in areas near large bodies of water tend to have smaller fluctuations.
› Daily temperature fluctuations are more moderate than they would be if we were devoid of water.
> Many individual organisms rely on the specific heat capacity of water, as their bodies are made up of large amounts of water, which help them resist changes in their body temperature.
Overall water has a moderate effect on climate in terms of annual temperature ranges.

28

how to calculate specific heat capacity

E = mcΔT
- E is the change in thermal energy (J)
- M is the mass of the body (kg)
- C is the specific heat capacity of a substance. It depends on the nature of the material of the substance (J/kg/°C)
- ΔT is the change in temperature (final temp – initial temp) (°C)

29

what is density

- Mass is the amount of matter in an object, weight is a measure of the pulling force of gravity on mass. Volume is the space something takes up. Density is the word used to describe the comparison between an objects mass and its volume.

30

calculating density

D = m/V
M is mass (g)
V is volume (cm3)
D is density (g/cm3)