P5 Water and Changes of State (Concept Map)

Water and Changes of State

water exists in three states — solid, liquid and gas; it changes state when it gains or loses heat

processes of gaining / losing heat

Gains heatmelting (0°C) · boiling (100°C) · evaporation (any temp)

Loses heatfreezing (0°C) · condensation (any temperature)

Melting point 0°CPure ice melts at 0°C, and pure water freezes at 0°C too.

Boiling point 100°Cpure water boils at 100°C and bubbles throughout

Impurities shift itsalt or sugar lowers freezing and raises boiling

Impurities change itSalt or sugar raises boiling point and lowers freezing point

common graphs

Heating curvetemperature constant at melting point & boiling point

Cooling curvetemperature constant at freezing point

Temperature stays flattemperature stays the same during melting and boiling

Mass of the waterThe cold cup gains mass from droplets; the hot cup does not

rates & effects

Rate of evaporationWET — wind speed, exposed surface area, temperature

Evaporative coolingevaporation takes heat, so the surroundings cool

The WET factorswind speed, exposed area and temperature

Evaporative coolingevaporation takes heat, so the surroundings cool

Drops on a cold cupvapour loses heat to the cold cup and forms droplets

Temperature differencethe bigger the temperature difference, the faster it is

the water cycle

Evaporation → Condensation → Precipitation (rain) → Run-off → back to water bodies

The Sun starts itthe Sun heats water, so it evaporates

Clouds get heavywhen the droplets get heavy they fall as rain

Rain and run-offRain falls and run-off takes the water back to the Earth

caring for our water

ConservationReduce · Reuse · Recycle

Water pollutioncauses → effects → reduction / prevention methods

three states

Solid examplesIce, hail, icicles and snow are all solid water.

Liquid and gas examplesclouds, dew, mist, fog are liquid; steam is gas

boiling vs evaporation

Boiling vs evaporatingBoiling: whole liquid · evaporation: surface only