Temperature and States of Matter

Measuring Temperature Using States Of Matter

Solids can turn into liquids, and liquids can turn into gasses and back again - depending on the temperature.

So, we can use the effect of heat on states of matter to measure the temperature of something.

COLD WARM HOT

Using Gasses To Measure The Temperature

For example, a balloon filled with air shrinks as it gets cold, and expands as it gets hot.

This is a very sensitive way of measuring temperature BUT it’s not very accurate because the size of a balloon also depends on other things like air pressure!

VERY COLD HOT

Using Liquids To Measure The Temperature

Liquids are less sensitive to temperature changes but are better than gasses they are hardly effected by air pressure!

Which is why we use coloured alcohol or mercury in most thermometers!

The Fahrenheit ScaleThe Fahrenheit scale was invented in the early 1700s by G. Daniel Fahrenheit.

The start of the scale is at 0F which is the temperature of a mixture of equal parts of water, ice, and salt.

And 212F is the top of the scale which is the boiling point of water.

So the Fahrenheit scale has 212 degrees in it

The Celsius ScaleThe Celsius scale was invented in 1742 by Anders Celsius

The start of the scale is at 0C which is the temperature of the freezing point of water.

And 100C is the top of the scale which is the boiling point of water.

So the Celsius scale has just 100 degrees in it!

Useful Temperatures To Know

Celsius is a scale that is easier to use and easier to measure

100C

37C

25C

0C

Boling Point of Water

Freezing Point of Water

A Nice Day

Human Body Temperature

212F

99F

77F

32F

Fahrenheit Celsius

Colour Changes Can Also Be Used For Measuring Temperature

Another way of measuring temperature is by using materials that change colour with temperature.

For very hot temperatures people like blacksmiths use the way metal changes colour to estimate the temperature; For more normal temperatures liquid crystal displays can be used

Fixed PointsWhat do you think happens to ice and water at 0C and 100C?

Did you know that at 0C water turns into ice and ice turns into water but the temperature of a water ice mixture stays at 0C until all the ice has become water or all the water has become ice

The same is true at 100C water turns to steam, but the water stays at 100C until all the water has turned to steam

Solid, Liquid And Gas?

Most types of matter have solid, liquid and gas forms, for example water has ice, water and steam forms.

BUT some types of matter don’t have certain states, for example dry ice (solid CO2 ) just goes from solid to gas on heating – the solid DOESN’T melt and become a liquid

Ice Floats On Water!If you put the solid form of a material into the liquid form of the same material it will usually sink to the bottom, but ice is strange as it actually floats on water!

This is because water is one of the few materials that expands when it freezes.

This property of water is very important environmentally because if this didn’t happen icebergs would sink to the bottom of the sea and cause the sea to freeze over!