Year 5/6 ScienceDissolving

Fill in the spaces using the words below

An atom is the very smallest _______ building block.Some of the parts that make up an atom carry a special property called a ______. There are two types of this property which are called ________ or ________.

NEGATIVE, CHARGE, POSITIVE, CHEMICAL,

Balancing chargesIf like charges repel and opposites attract, which of these molecules will stay together?

If you have 5 + charges and 4 - charges, fill in the picture below so they fit without ‘breaking up’

Atoms being snootyWhen things get hotter do the atoms movea: Faster or b: SlowerAtoms or molecules which have unbalanced charges will try and mix witha:Other unbalanced chargesb:Balanced charges Atoms or molecules which have all their charges balanced will try and mix witha:Other balanced chargesb:Unbalanced chargesc:Neither really

Dissolving ExperimentIn this experiment we tested a number of substances to see if they mixed or dissolvedOur materials wereVegetable Oil, Water, Washing Up Liquid, Vinegar, Sand, Brown Sugar, Flour, SaltOur apparatus includedBoiling Tubes, boiling tube rack, pipettes, spatula’s

Results Table (Dissolved or Not?) Water Oil Vinegar Wash L

Water

Oil

Vinegar

Wash L

Sand

Flour

Sugar

Salt

What have we found?Salt and sugar dissolve in water, vinegar and washing up liquid.

This is because all of these things have unbalanced charges which means they can interact with each other

Oil doesn’t mix with water or vinegar, but is ‘broken up’ into tiny droplets by the washing up liquid

Washing up liquid has a charge at one end and a long tail with balanced charges at the other. This means it can mix with the oil and the water at the same time

Good Words for the DayHydrophobic

A water ‘repelling’ substance (which would have balanced charges)

Hydrophilic

A water mixing substance (which would have some unbalanced charges)

Emulsion

A fine dispersion of minute droplets of one liquid in another

Separating Solutions and Mixtures

In this experiment we tested the same mixtures and solutions from our previous experiment to see if if we could separate them out againOur materials wereVegetable Oil, Water, Washing Up Liquid, Vinegar, Sand, Brown Sugar, Flour, SaltOur apparatus includedBoiling Tubes, boiling tube rack, pipettes, spatula’s, filter paper, funnels, watch glasses

Separating ExperimentThere are a total of 22 different solutions or mixtures. These will be split among the class.Each group will be given a number of filter papers which need to be labelled with their names, the date and the mixture they are trying to separateThe filter papers need to be folded and put into funnels and then the solutions pass through into boiling tubes.

Separating Demonstration

There are a total of 22 different solutions or mixtures. These will be gently heated by the teacher.What will happen? Will the heat help separate the mixtures?

Filter Results Table (Separated or Not?)

Water Oil Vinegar Wash L

Water

Oil

Vinegar

Wash L

Sand

Flour

Sugar

Salt

Heating Results Table (Separated or Not?) Water Oil Vinegar Wash L

Water

Oil

Vinegar

Wash L

Sand

Flour

Sugar

Salt

What did we find?Filter paper separates substances based on their size (in much the same way as a sieve does)

This means that things that have not dissolved (the sand or the flour for example) will stopped by the paper

Those that have been dissolved have been broken up by the water so they are so small that they pass straight through the paper

So what else can we use to separate things

Have you ever played a game called 20 questions? The idea is that you have to try and guess an object by asking just 20 questions (when you only get a yes or no answer)

Separating substances is a bit like this game only you have to know the right questions to ask (and of course how to get the answers)

Are you bigger than this?Do you have lots of charges?Can you stick to this particular substance?Do you dissolve in this substance?Are you magnetic?What temperature do you boil or freeze?

What temperature does this evaporate?

This demonstration shows how you can simply separate two substances based on when they evaporate

Take 4 of the mixtures that we have seen before

Water and SaltWater and Brown SugarWater and SandWater and Flour

And we heat these over a bunsen flame.What do you think will happen?

Separating by size...(the very small)

Here we are going to see how we can separate out even very small things using just a piece of paper.

We are used to seeing a drop of water spreading out on a piece of paper as it soaks in

We are going to separate out the components of black ink using a process called chromatography.

How do you think that this works?

Draw a picture of what you find