Unit 305 Session 8 Properties of water

​Properties of water 

​In its purest form, it's odourless, nearly colourless and tasteless.
It's in your body, the food you eat and the beverages you drink.


You use it to clean yourself, your clothes, your dishes, your car and everything else around you. You can travel on it or jump in it to cool off on hot summer days.

Many of the products that you use every day contain it or were manufactured using it. All forms of life need it, and if they don't get enough of it, they die. 

Fill in the Blank

Do you know the chemical make up of water?

​At its most basic, water is a molecule with one oxygen atom and two hydrogen atoms 

Open Ended

What properties of water can you name?

​Water is the only substance that occurs naturally as a solid (ice), a liquid and a gas (water vapour). 

​Water is everywhere on Earth, and it's super important! Let's dive into where we find it:

Oceans:
Oceans cover about 71% of Earth's surface and hold 96.5% of all water.

That's a lot of salty water!

Freshwater:
Only 2.5% of Earth's water is freshwater, which we need for drinking, farming, and more.

• Most of this freshwater (68.7%) is frozen in icecaps and glaciers.

• Around 30.1% of freshwater is hidden underground in aquifers.

• Just 0.3% of freshwater is found in rivers, lakes, and swamps.

Atmosphere:

Water also exists as vapor in the atmosphere, forming clouds and eventually falling as rain or snow.

Open Ended

How much water do you think we make in Wales each day???

​The answer is 0

the water we have now is the same as has always existed on earth.

​So how do we continue to have fresh water?

​The water cycle

​The water cycle is the continuous movement of water in and around the Earth.

As previously mentioned, water never really goes away -- it just changes form. 

Open Ended

Research and give a brief description of what the water cycle is:

​Physical properties of water

Multiple Choice

At what temperature does water reach its maximum density?

• 0°C

• 4°C

• 10°C

• 100°C

​So water is at its most dense when at 4°c.

This means the molecules are at their most tightly packed state.

​If we change the temperature of water then we can change it state:

​So water on earth can exist in 3 states:




Solid: Ice




Liquid: Water






Gas: Water vapor or steam

​Water is found in its liquid state normally at temperatures of between:

0°c and 99°c.

​Normally at -0°c Water freezes and turns to ice

​If we heat water to over 100°c then water will turn to steam:

Open Ended

What do you think these different states mean for plumbing systems?

​Freezing:

When installing plumbing systems we must always be mindful not put pipework at risk of freezing.





But why?

​So when we cool water below 4°c and it turns to ice at 0°c it expands by 10%

This is what causes pipes to burst.

​Water is unique that when water is heated it also expands.

For temperatures up to 100ºC, this expansion is usually up to 4%.

Open Ended

Research what is meant by the term sensible heat.

​Sensible heat 

When heat is applied to water the temperature will rise, but it remains water.

It can then be cooled (a change in temperature without a change in state). 

Open Ended

Research what is meant by the term latent heat.

​Latent heat 

If you keep heating water, it will change from water to steam; this is a change in state. 

So the heat required to raise the water temperature to 100°C is sensible heat.

The heat required to keep it boiling is latent heat. 

​

When water exceeds 100ºC it can turn to steam and expand to almost 1,600 times its original volume.



So we need to allow for expansion in all hot water and central heating system.

Open Ended

What is the term for the process where water seeps into the ground?

​

If the expansion of water is not controlled then this can cause serious issues in plumbing systems.

​This cylinder has split due to over expansion, but it could be much worse.

Multiple Choice

What percentage of Earth's surface is covered by water?

• 50%

• 60%

• 71%

• 80%

Multiple Choice

Which of the following holds the largest amount of Earth's freshwater?

• Rivers

• Lakes

• Groundwater

• Icecaps and glaciers

Multiple Choice

What percentage of Earth's water is freshwater?

• 1.5%

• 2.5%

• 3.5%

• 4.5%

Multiple Choice

Which process in the water cycle involves water changing from a liquid to a gas?

• A) Condensation

• B) Precipitation

• C) Evaporation

• D) Infiltration

Multiple Choice

What is the term for water that flows over the ground surface and collects in rivers, lakes, and oceans?

• A) Infiltration

• B) Transpiration

• C) Runoff

• D) Sublimation

Match

Match the following parts of the water cycle with their descriptions.

• A) Evaporation

• B) Condensation

• C) Precipitation

• D) Transpiration

Water changes from liquid to vapor.

Water vapor cools and changes back into liquid droplets.

Water returns to the Earth's surface as rain, snow, sleet, or hail.

Water is released from plants into the atmosphere.

• Water changes from liquid to vapor.

• Water vapor cools and changes back into liquid droplets.

• Water returns to the Earth's surface as rain, snow, sleet, or hail.

• Water is released from plants into the atmosphere.

Multiple Choice

Which process describes the movement of water from plants to the atmosphere?

• A) Evaporation

• B) Transpiration

• C) Condensation

• D) Precipitation

Multiple Choice

Which part of the water cycle is responsible for forming clouds?

• Evaporation

• Condensation

• Precipitation

• Transpiration

Hotspot

Identify the locations of groundwater flow.

Multiple Choice

What is the process called when water changes from a liquid to a solid?

• Melting

• Freezing

• Evaporation

• Condensation

Multiple Choice

What state is water in when it is in the form of steam?

• Solid

• Liquid

• Gas

• Plasma

Multiple Choice

What is the process called when water changes from a gas to a liquid?

• Melting

• Freezing

• Evaporation

• Condensation

Hotspot

Where does evaporation occur?

Multiple Choice

Which process involves water changing from a solid to a liquid?

• Melting

• Freezing

• Evaporation

• Condensation

Multiple Choice

Which state of water has molecules that are closest together?

• Solid

• Liquid

• Gas

• Plasma

Multiple Choice

At what temperature does water reach its maximum density?

• 0°C

• 4°C

• 10°C

• 100°C

Multiple Choice

Why does ice float on water?

• Ice is more dense than water

• Ice is less dense than water

• Ice has the same density as water

• Ice is heavier than water

Multiple Choice

What happens to the density of water as it is heated from 0°C to 4°C?

• It increases

• It decreases

• It stays the same

• It fluctuates

Hotspot

Where does condensation occur?