Tag Archives: chemistry

#TryThisTuesday: Oil and Water

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For this experiment all you will need is a clear bottle or jar with a lid, water, cooking oil and some washing up liquid.

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Fill the water bottle half full with water.

Pour about 100ml of oil in to the bottle and observe what happens.

The oil should float on the water. Try and mix them together or challenge other people to mix them! It is impossible, the oil and water always separate out again.

Add a squeeze of washing up liquid to the bottle and shake. The oil and water now mix together.

The Science

Oil is less dense than water so floats on top. Oil and water don’t mix together as the water molecules are more attracted to each other than the oil molecules. Oil molecules are hydrophobic or ‘water-fearing’.

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Washing up liquid molecules are attracted to both water and oil. When you add a squirt in, one end of the washing up liquid molecule attaches to a water molecule and the other end attaches to an oil molecule. This creates a mix of water with oil droplets spread throughout it. This is because one end of the washing up liquid molecule is hydrophobic (water fearing) and one is hydrophilic (water loving).

The washing up liquid acts as a stabiliser and creates an emulsion. This is a mixture of two liquids that wouldn’t normally mix.

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Real Life Applications

We use washing up liquid when we are washing up as it attaches to the oil on the dirty dishes and lifts it off into the water.

Animals that live in the ocean also stay warm by producing an oily substance on their fur or feathers which keeps the cold water away from their skin.

#TryThisTuesday Mini Fire Extinguisher

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You will need: large tall glass, bicarbonate of soda (baking soda), vinegar, a candle and some matches

image11. Add 4 teaspoons of bicarbonate of soda to the glass

2. Pour in roughly 150ml of vinegar, the mixture will fizz.

3. Light the candle.

4. Once the mixture has stopped fizzing, pick up the glass. Without pouring out the vinegar, gently tip the glass from a few centimeters above the candle. Imagine that there is an invisible liquid inside above the mixture. The candle will go out!

The Science

You have produced a gas, carbon dioxide, by mixing the bicarbonate of soda with vinegar (also known as acetic acid). Bicarbonate of soda contains carbon dioxide, but it is attached to other molecules. When you mix it with vinegar the bicarbonate breaks down and releases carbon dioxide as a gas.

The following reaction takes place:

bicarbonate of soda + vinegar → sodium acetate + water + carbon dioxide

NaHCO3 + HC2H3O2 → NaC2H3O2 + H2O + CO2

Carbon dioxide is heavier than air so stays in the glass until you tip it over the candle. When you pour carbon dioxide on a candle it stops the flow of oxygen which is needed for a flame to burn, and the candle is extinguished.

Real fire extinguishers also use carbon dioxide to put out fires, it is compressed (squashed) into cylinders and sprayed at fires.

Our top STEM jokes!

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It’s nearly Christmas and that means it’s time for awful Christmas cracker jokes. Hopefully our favourite STEM jokes will be a bit more funny! Scientific explanations are underneath each one.

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Neutrons make up the middle (nucleus) of atoms and don’t have any electric charge, unlike protons (positively charged) and electrons (negatively charged).

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Light is made up of small particles, these are called photons. Therefore, a photon is travelling light.

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The chemical symbol for oxygen is O and potassium is K.

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H2O is water, but H202 is hydrogen peroxide. Hydrogen peroxide would cause chemical burns and choking if it was drunk.

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Atoms are very small and make up everything, including us.

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Schrodinger’s Cat is a thought experiment in physics, where a cat is kept in a box with a radioactive source and poison. Until the box is opened, the cat can be assumed to be both dead and alive.

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Helium is a noble gas, this means it is doesn’t react with other elements so is inert.

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Extrapolation is when you estimate what the result may be beyond what you measured. The joke is that some people can’t extrapolate from data so can’t work out the end of the joke

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Binary is a way of using two different symbols, 0 and 1, to represent any number, this is often used to create code for computers. 10 in binary is the same as writing 2. Therefore, there are two types of people, those who understand binary and those who don’t.

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If an atom loses an electron (a negatively charged particle) it will become positively charged.

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If time travel is ever invented, it doesn’t matter when as you can just travel back in time with the time machine.

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Anti gravity is a place or object that is free from the force of gravity, so would float around.                       joke13

This is a play on words, as the atmosphere in a restaurant is how you feel when you are there, but in science terms the atmosphere is a mixture of gases that surrounds the Earth. The moon has a much thinner atmosphere than the Earth and was originally thought not to have one.

 

Why Perfumes are not the Perfect Christmas Present…

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Many animals rely heavily on their sense of smell for finding food, getting a whiff of the competition and even sniffing potential mates. You might not often see humans checking the scent of their partners, but scientists have found it does play a subtle role in helping us chose mates – as do perfumes.

All animals are made up of a collection of genes that are inherited from parents, these code for all sorts of things like eye colour and taste buds. All mammals, including us, have a section of genes called the major histocompatibility complex (MHC) which affects how well your immune system fights diseases. It is also linked to your natural scent.

There have been experiments on mice, mandrills, meerkats and many other animals showing that females tend to mate with males that have a different MHC to their own. This ensures that their offspring have a more varied set of genes and so will likely have a better immune system and survive for longer – which is what every parent wants for their child.

When tested in humans, the usual method is to get a group of men to wear a t-shirt for several days to get it nice and sweaty and smelly. Women will then smell each of the t-shirts and rate the odours in order of which they find the most pleasant. These experiments have consistently found that women tend to prefer the scent of men with MHC genes different to their own.

So what happens when you wear perfume and cover up that lovely natural odour of yours? Two researchers, Wedekind and Milinski wanted to find out. They asked over 100 people to rate a selection of perfumes based on whether they would like to smell like that. They found a correlation between the type of MHC and the scents selected, suggesting that we choose perfumes for ourselves that will enhance our natural odour. However, when asked to rate perfumes based on whether they would like their partner to smell like that, they found no significant link.

It appears that we are great a picking out odours for ourselves, but not so much at selecting the perfect perfume for others. Maybe a gift card would be better this year…

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#TryThisTuesday: Making Snow

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We’re feeling very festive this Tuesday so we thought it was the perfect time to make snow with science. All you need for this one is some shaving foam and bicarbonate of soda.

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Simply mix the bicarbonate of soda and shaving foam together in a bowl until you get a powdery consistency.

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Pick it up and have a play – you might notice that your fake snow actually feels cold too. This is due to the reaction between the bicarbonate of soda and the shaving foam. The reaction is endothermic meaning that it requires heat to occur, it takes this from the environment and so decreases the temperature around it.

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The Science of Shaving Foam

Do you think shaving foam is a liquid or a solid? It’s actually a colloid. A colloid is a substance which has droplets of one state surrounded by another state. There are lots of different types of colloids with different combinations of states making up the droplets and the surrounding. In the case of shaving foam, the droplets are gas and the surrounding is liquid making it a foam colloid.

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#TryThisTuesday: Pop or not?

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Today we will be experimenting to see what happens when you put a lighter or a flame underneath a balloon filled with two different states of matter: air and water.

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You will need two balloons, some water and a lighter

  1. Blow up one of the balloons with air and tie it up.
  2. Fill the other balloon with a little bit of water, blow it up the rest of the way and tie it up.
  3. Hold the lighter under the balloon with the air in it and see what happens. Be careful as it should pop!

    Balloon with air in
  4. Light the lighter under the balloon with some water in it, be careful to hold the lighter under the part of the balloon where the water is. The balloon won’t pop!

    Balloon with water in

The Science

This happens because water can absorb heat a lot easier than air and is a better conductor of heat. Water keeps the heat away from the balloon. This is called its ‘heat capacity’ and is why water is often used to cool things down in places such as power plants. The air is not very good at absorbing the heat, so the balloon heats up and pops!

 

Stu Brew – Our very own student run brewery

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Stu Brew is Europe’s first student-run microbrewery based at Newcastle University.  We are managed by students for students through Newcastle University Students’ Union. There are over 120 students involved in Stu Brew. The brewery is capable of producing around 800 pints in one day and the beer is sold at a variety of pubs and bottle shops throughout the North East.

The Brewery

Our brewery is where all the magic happens. The brewery is made up of a number of stages. The brewery can be seen in the picture below which shows all the different vessels.

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  1. Hot Liquor tank: This is where all the water that is needed for the brewing process is heated up to around 77°C . Our brewery uses around 500 litres of water per brew!
  2. Mash Tun: This is where the hot water is mixed with grain to extract all the sugars that are used to make the beer. Different types of grain are used to create different styles of beer. We have made over 15 different styles of beer with many more to come.
  3. Whirlpool: The grain is separated from the sugar rich water which is known as wort in this stage
  4. Kettle: The wort is boiled for an hour killing off any bacteria that may infect the beer. Hops are added at various points in the boil to add different flavours to the beer. For example adding hops at the start of the boil gives the beer its bitterness whereas hops added towards the end of the boil yield more aromatic flavours.
  5. Heat Exchanger: This is used to cool the boiling wort down to 20°C.
  6. Fermentation: The yeast is added to the beer which reacts with the sugars within the wort and converts them into alcohol. After about 72 hours this reaction is complete and the beer is then put into casks and is ready to be sold and drunk!

 

#TryThisTuesday: Lava Lamp

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This week’s experiment will show you how to create the 1960’s invention – the lava lamp – at home!

You can create your lava lamp in a beaker, a glass or a plastic bottle, whatever you have lying around that you can see through.

  1. Start by filling your container 1/4 full with water and add some food colouring of your choice.20161108_160122
  2. Add oil until its nearly full to the top. Wait a minute or two and the oil should separate out and sit above the water.20161108_160212
  3. Drop in a Alka-Seltzer or any other effervescent (fizzy) tablet and watch the bubbles rise.

The Science

Oil floats on top of water because it is less dense and water molecules stick closely together due to their hydrogen bonds, making it difficult for the oil to mix in.

The tablet is more dense than the oil and the water so sinks directly to the bottom. There it reacts with the water to produce the gas, carbon dioxide (CO2). CO2 is less dense than both the water and oil so it rises to the top, carrying some water molecules with it, these are the bubbles that you can see. The bits dropping back down are the water molecules sinking again once the gas has escaped.

A real lava lamp uses wax that is heated by a bulb. The hot wax expands, becomes less dense than the water and so rises. When it cools, it shrinks, becomes denser and sinks.

Celebrating Marie Curie

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Marie Curie was born 149 years ago today. We think she is one of the most inspiring female scientists as one of the first women to make an outstanding contribution to science. Her work overturned established ideas in physics and chemistry and helped overcome societal barriers for women.

Marie Sklodowska was born in Poland in 1867. In 1891 she went on to study physics and maths at Sorbonne University in Paris. She met Pierre Curie, professor of the School of Physics, who she married in 1895, becoming Marie Curie.

The Curies worked together investigating radioactivity, the process where atoms decay by emitting radiation. With help from other physicists they discovered new elements, polonium (named after her home country, Poland) and radium in 1898. This work was extremely difficult as they were constantly exposed to radioactive elements, which made them feel ill, an effect known as radiation sickness. They received the Nobel Peace Prize in Physics for their work in 1903. Marie Curie was the first woman to win a Nobel Prize.

Unfortunately, Pierre died from being knocked down by a carriage in 1906. Marie Curie took over his professor post and became the first woman to teach at Sorbonne University. She received a second Nobel Peace Prize in 1911 for her work in chemistry where she determined a way to measure radioactivity.

Her research was crucial in development of X-rays. Marie developed small mobile X-rays that were used in World War One to diagnose injuries. She worked with her daughter at the front line to help diagnose injuries.

Marie Curie died due to exposure to radioactivity during her work in 1934. The Marie Curie Hospital was opened in 1930, specialising in radiological treatment of women suffering from cancer. The Marie Curie charity was established in 1948 which now offers care, support and guidance for people with a terminal illness.

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The Science of Fireworks

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We all know the history of Bonfire Night, but do you know the science?

The Explosion

All fireworks are essentially a combustion reaction, like fire, that produces light and heat.

Fireworks tend to have a long fuse that burns slowly so you have time to light the fuse and run away before the big bang! The fuse first reaches a compartment containing gunpowder, it ignites this causing the firework to launch into the night. There is a delayed fuse to ignite the next explosion, this heats the “stars”.

The stars in a firework are individual compartments containing a different composition of chemicals, depending on the desired colour and effect of the firework. The stars may even be arranged inside the shell of the firework so that they burst in a certain formation to form a shape.

The Colours

Firework displays always use a range of striking colours, the variety of colours comes from the use of different chemicals. Elements such as barium, copper and lithium burn with a coloured flame and are chosen for use in fireworks due to the bright colours they produce.

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The Sound

When the chemicals inside the firework’s shell are heated they convert from a solid to a gas. The gas takes up more space than there is available inside the shell so it bursts out creating a loud BANG.

Crackling noises come from fireworks which contain lead. When lead oxide is heated and vapourised, the vapour atoms produce crackling noises.

The whistling sound that you hear when the fireworks shoot up in the air, comes from the firework tube itself, not the chemicals. When the tube is partly empty, it will vibrate the air passing through it, causing a whistle.

How can you write your name with a sparkler?

I’m sure you’ve all held a lit sparkler at some point and twirled it around in the air to see a trail of light lingering in the air for a few seconds. The truth is the light isn’t really still there but your eyes play a trick on your brain to make you think that it is. Image resultOur eyes don’t react as quickly as you might think when our view changes, they usually keep the old view around for a fraction of a second. This is known as visual persistence and it’s what allows us to view a series of still images as movement. The effect is increased in the case of the sparklers due to the very bright light emitted form the sparks contrasting against the dark background. This makes the light appear to last longer.

 

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