Today we are looking at pH.
We measure liquids using a pH scale, to find out about the way the liquid will behave when it comes into contact with other things.
Scientists discovered that liquids can behave as an acid, a base, or remain neutral and not react.
We are going to test a number of different liquids to find out if they are acids, bases or neutral.
To do this, we use indicator paper. You can make your own simple indicator paper by following these easy steps:
1. Grate a red cabbage into a bowl.
2. Pour boiling water over the red cabbage.
3. Leave the cabbage in the water for at least an hour.
4. Strain out the cabbage and keep the liquid.
5. Dip white paper towel into your purple liquid until it is completely wet, and then leave it to dry.
6. Cut your dry, purple paper towel into strips to use.
When you dip your strip into a liquid, it will turn pink if the liquid is an acid. It will turn blue if the liquid is a base. It will stay purple if the liquid is neutral.
Before you dip, try to predict whether the liquid is an acid, base or neutral from what you know about the liquid.
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For those of you interested in finding out more, you can read on. This is high school chemistry.
Atom - you can think of an atom as like a small Lego block, but so small you can't see it. Everything you see is made of atoms, just like you build things out of Lego blocks. Atoms come in different types, and you will know some of their names, for example: oxygen, carbon, gold, silver, helium, lead, copper.
All the different types of atoms that we know of are listed in a table called the Periodic Table. You don't need to know this, but if you are interested, this is what it looks like.
Molecule - a molecule is two or more atoms stuck together. When you build something complicated out of Lego, sometimes you put several small pieces together first before adding it to another section to make your construction. Molecules are like this. Atoms join together to make molecules, and molecules join together to make the things we see. Molecules are still to small for us to see without a special microscope.
Scientists noticed that when you put molecules in water, sometimes they break down and release a Hydrogen atom. Sometimes they break down and release a Hydroxide molecule. Sometimes they don't break down at all.
A liquid is usually water with molecules floating around in it. If the liquid has free Hydrogen atoms floating around, we call it an acid. If the liquid has free Hydroxide molecules floating around in it, we call it a base.
These molecules attach to our indicator paper and change the shape of the indicator molecules, which in turn changes their colour.
On the pH scale, a number between 0 and 14 is given to a liquid. Numbers between 0 and 7 are acids, and numbers between 7 and 14 are bases. 7 is neutral.
The scale below gives you examples of some common liquids you might know and what their measurement is on a pH scale. You will see some of the liquids we tested today on the scale below.
Thursday, 14 November 2013
Today we dropped two tennis balls together to see whether they would hit the ground at the same time or at different times. We made our predictions and considered how certain we were about that prediction.
After we completed the experiment, we found that they landed at the same time.
Mrs Emeleus then dropped a hammer and a feather. We found that they landed at different times.
We then watched the hammer and feather experiment on the moon. Our predictions were varied, but we found that they landed at the same time.
Majed correctly guessed that the difference between the experiment conducted on the moon and the one in our classroom was because of the air.
This is called air resistance.
We conducted further experiments ourselves with two objects, one heavy and one light, to prove that it was not the weight of the object which mattered, but the shape. Shapes like feathers have more air resistance and slow them down when they fall.
If you would like to try another experiment at home, try a piece of paper and something else light but with not much air resistance, like a pencil. You can post a comment below about what you found.
Thank you Mrs Emeleus for teaching us something new that we didn't know and its very unlucky that you will be only teaching us for a few weeks but on the good side we are going to be in High School :)
ReplyDeleteI dont know what to say for the comments. I have run out of words but thank you anyway :D
ReplyDeleteJoe, you can tell me what science experiments you have done at home, if you want to post on the science page. Did you try dropping different things? Do you have any other science experiments you like to do? Do you have any questions about science that we can discuss?
Deletemy sister does science and she tells about ph.now i now about ph is.
ReplyDeleteI hope you enjoyed the experiment. I think experiments are fun.
ReplyDeleteI was especially pleased you noticed that we don't drink bases, and that cleaning products are usually bases. Noticing patterns and thinking about what you see, whether in a science experiment or everyday life, makes life so much more interesting. The world is full of wonders.