• Question: What are the physical and chemical properties of water?

    Asked by to Ben, Emily, Hattie, Jemma, Veronica on 16 Jun 2014. This question was also asked by .
    • Photo: Emily Hayward

      Emily Hayward answered on 16 Jun 2014:

      Hi Lilymiss,

      What a great question….and a challenge to answer. There is so much I could tell you about the chemical and physical properties of water – how much detail would you like?!

      Water is the chemical substance with chemical formula H2O. This means it has two hydrogen atoms covalently bonded to a single oxygen atom.

      It occurs naturally and can be found in the form of solid, liquid or gas. It can be foind in many different forms….water vapour and clouds in the sky, liquid in the sea, rivers and lakes, and in our taps, and as a solid in ice in the north and south pole, glaciers and snow.

      The major chemical and physical properties of water are:
      – it is a liquid at standard temperature and pressure
      – it has no taste or smell
      – it appears colourless although in large quantities it is very slightly blue
      – water is called a ‘polar molecule’ which means it has a slight charge as the oxygen atoms are slightly negative and the hydrogen ones slightly positive
      – water bonds very strongly to itself and other molecules…this gives it s high ‘surface tension’ which is why if you put a drop on a table it sticks up rather than spreading our completely flatly. This is important for plants in the way the water gets from the ground to the top/leaves
      – water can be used as a ‘solvent’ as lots of things dissolve in it e.g. salts, sugars, acids, alkalis, and some gases – especially oxygen and carbon dioxide (carbonation)
      – Pure water has a low electrical conductivity, but this increases with the dissolution of a small amount of ionic material such as sodium chloride.
      -the boiling point is typically 100 deg C and freezing point 0 – however these can change if the pressure is changed and is why water boils at a lower temperature at the top of a mountain….at the top of mount everest it boils at 68 C!
      – water has a ‘high heat capacity’ meaning it can hold a lot of energy, this is why we use it in radiators as it holds heat well allowing it t be transferred around houses, schools, offices and many other places too.
      – liquid water typically has a density (mass per volume) of 1,000 kg/m3
      – electrolysis can be used to split water into hydrogen and oxygen

      I hope this helps, and let me know if you want more detail or anything explained more.

    • Photo: Ben Butler

      Ben Butler answered on 16 Jun 2014:

      The physical and chemical properties of water are pretty special, and is probably the main reason why life on earth exists!

      -Water freezes at 0 degrees celsius, and boils at 100 degrees.

      -Solid water (ice) is less dense than liquid water, which means that it floats… imagine what would happen if ice sank to the bottom!

      -Freshwater is most dense at 4 degrees celsius, which is very important for animals that live in lakes and the sea

      -Water is a solvent, which means it can dissolve other chemicals. This is vital for life because many biological substances need to be dissolved in order for living things to use them.

    • Photo: Jemma Rowlandson

      Jemma Rowlandson answered on 16 Jun 2014:

      Well to be honest Ben and Emily pretty much nailed it with all the properties.

      I would just add that physical properties all describe what state (how the atoms in your material are organised i.e. solid/liquid/gas) your material is in.

      This includes things like water is a liquid at room temperature, freezes at 0 degrees celsius, and boils at 100 degrees celsius. How well water conducts electricity and also it’s density (as Ben described) are both physical properties. All these physical properties can be measured, unlike chemical properties.

      A chemical property is different and describes how water behaves when a chemical change happens (normally this is to do with forming bonds to other molecules).

      In the case of water chemical properties include dissolving other chemicals (where it acts as a solvent), that it bonds strongly to itself and also it’s charge (negative electrons prefer to stay on the oxygen atom rather than the hydrogen atoms and so they all gather there, meaning the oxygen is negative).

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