Isabelli (10) asked a follow up question on- Why are things absorbed and how does temperature affect water?

Isabelli, a couple of interrelated interesting questions. I asked my team to prepare the scene …be back later.

adsorption-absorption

First a little experiment. Put a small amount of water into a saucepan and place it on a heat source (parental permission required) carefully observe what happens (observation is an incredibly important science skill). Make notes of what you see. when the water is obviously boiling switch off the heat source and leave the water to cool down. Avoid moving it. Now repeat the experiment, again making notes on your observations. Are there any differences?

Look at the water molecules in the diagrams above. Water is a dipolar liquid. That means that there is an uneven charge distribution in each molecule. It has a negative ‘end’ and a positive ‘end’. This gives it the capability of making the Oxygen molecules (which are not normally dipolar) dipolar and subsequently creates an attractive force between the water and Oxygen molecule (bit like two magnets). The Oxygen molecules like this arrangement and are held within the water structure.

But …. if you heat up the water the water molecules begin to move about faster so the tentative attraction between the water molecule and the oxygen molecule breaks and it escapes from the water. Can this explain what you observed when you heated the water?

Thanks for your comment. Please feel free to ask further questions and make further comments.

‘If you had a hot and cold sponge, which would absorb the most water’ asks Isabelli

sponge-hotcold

I liked the question but also recognise the difficulties in testing it. Firstly all sponges are different so to make the testing experiment fair you would have to use the same sponge. You would need to dry it in between the tests. I think a microwave could help with that.

You then have to think about the water. If you put the hot sponge into a bucket of cold water it would very quickly cool down so the temperature of the water should be about the same as temperature of the sponge BUT water expands on heating so maybe the sponge will not be able to absorb as much water because of the expansion. Finding out how much water is absorbed can be done by squeezing the water out into a measuring cylinder BUT how can you be sure that all the water has been squeezed out.

So we have an idea (a hypothesis) but we need to think more about how we can test that idea. Have you got any further ideas Isabelli? If so you could leave a comment.

 

Alka asked – Where do puddles go to?

Many thanks for the great question Alka. I put it to my friends and as usual they came up with some interesting thoughts.

puddles2
Many thanks team. What we need to do is set up some experiments that might help us find a possible answer. If we had a bowl of water how would we protect it from insects, and other animals drinking from it?  How would we prevent leaks into the ground? How would you stop the Sun grabbing it?

This could lead to lots of different experiments.

Try making some small puddles in a some bowls. Keep one bowl in a cupboard and one on a window ledge for a couple of days. Put one bowl outside and another outside with a cover over it to stop animals getting to it.  Maybe leave them both in a shady spot so they cannot see the Sun. Create a puddle on some solid ground and another on some ground with some plastic between the puddle and the ground.  These are some possible investigations that you could carry out to find an answer to your question.

Fair testing is an important part of  investigations, it is difficult but amazingly rewarding. How do you make all those tests fair? does leaving them all for the same length of time make it fair? What about the amount of water? Would that influence the fairness of the test?

It maybe that for all real puddles a bit of everything happens.

Let us know your thoughts/answers by using the ‘Leave a Reply‘ section below. Unsure about something..then ‘Ask a Question‘.

Here is a little video of somebody else with the same problem. It uses a word that you might not understand ‘evaporation’. If you want help Ask a Question.

 

Bridget (10) asks – “How is water made?”

A difficult question Bridget. I asked my friends about this and they suggested an interesting way to solve it.

electrolysis

 

I think their approach gives a possible route to answering your question – or better still a route for you to answer your own question. The name for breaking up something using electricity is ‘electrolysis’.

Look at the two test tubes. One has twice as much gas in it than the other. I wonder what that means? If we tested the gases in the tubes we would find that the gas in the test tube with twice as much gas – is lighter than air! Fill a balloon with it and it would fly away. Drop a burning match in it and you might get a ‘pop’. Drop a burning match in the other tube and you might see a ‘flare’. BEFORE YOU DO THIS TALK TO AN ADULT ABOUT IT, PLAYING WITH MATCHES IS DANGEROUS. 

Do you know what the gases are? Mix them and you get that magic substance called water.

I hope that answers your question. If not ask another question.