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
Boling Point of Water
Freezing Point of Water
A Nice Day
Human Body Temperature
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!