The digestive system is the system that helps us break down the food we eat to its basic nutrients so that our body can use those nutrients to get energy. The digestive system is composed of the long continuous alimentary tract or...

The pH scale is used to determine whether a substance is acidic or basic, and to calculate how strong a chemical it is. A pH value is a number that ranges from 1 to 14 for most common chemicals, with seven being the middle or neutral...

A strong acid is one that is fully ionised in solution.
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The chemical process by which a base neutralises an acid, producing a salt and water.
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A Twig Science
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A type of unsaturated fatty acid, essential for human health.
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A Twig Science
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A substance that provides a visual indication of the pH of a test material.
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A Twig Science
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A compound which dissolves in water to form a solution with a pH of less than 7.
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A Twig Science
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A substance that reacts with an acid to form a salt and water.
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A Twig Science
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The pH scale measures the acidity or alkalinity of a solution.
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A Twig Science
Glossary Film.
Key scientific terms defined in just 60 seconds using stunning images and concise textual definitions. Twig Science...

Explore the pH scale, and discover whether a solution is acidic, alkaline or neutral.
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Chemistry - Reactions - L
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Alkalis and acids can be neutralised to great and varied effect. For example, it is neutralisation reactions that help us breathe underwater or cure indigestion. Chemistry - Reactions - Learning Points. A neutral solution is pH 7 Sodium...

Discover the chemical processes occurring deep within the Earth that create beautiful crystal structures in caves. Chemistry - Reactions - Learning Points. Caves are a result of rainwater slowly carving away rock. Carbonic acid forms in...

Easily eroded by water, limestone's composition means it makes up spectacular sights all over the world. Learn about some of the surface and underground features of this rock type. Earth Science - Geology - Learning Points. Limestone is...

Your teeth are exceptionally strong, but without the proper care they can be easily damaged. Learn how a few simple steps can help avoid tooth decay. Biology - Healthy Living - Learning Points. A build-up of plaque on your teeth can lead...

The properties of strong acids and alkalis can be extremely harmful. Where do we find them, and how can we tell how acidic or alkaline a substance is? Chemistry - Reactions - Learning Points. Bases neutralise acids, and if a base...

We compare the reactivity of Group 1 and Group 2 metals. We add sodium and then potassium to water. We observe the reactions. Next we add magnesium and then calcium to hydrochloric acid and observe the reactions. The results let us put...

We use vinegar to remove the shells from eggs without breaking them. Two eggs are placed in a beaker of vinegar, but one is half coated with clear nail polish. The exposed shells dissolve over time and the eggs swell as more water moves...

We use the enzyme pepsin and hydrochloric acid to simulate the conditions within the stomach in two boiling tubes. Cooked egg whites are ground and added to two boiling tubes of hydrochloric acid, but one is mixed with a crushed antacid...

We use lemons and strips of zinc and copper to make a battery. First, strips of copper and zinc are added to one lemon and they are connected across a voltmeter. This is repeated, this time with more lemons and metal plates, until a...

We use a drinking straw, some water and universal indicator to show that breathing out creates acid. Universal indicator is added to the water to show its pH value. When we blow into the water the indicator changes colour showing that...

We use coloured agar cubes to see how different shapes change the rate of diffusion. The cubes are made using sodium hydroxide and phenolphthalein indicator to give them a pink colour. When these are added to hydrochloric acid, the...

We inflate a rubber glove using the gas produced during a neutralisation reaction. Bicarbonate of soda is added to vinegar in a beaker covered by a rubber glove and it expands. The gas is used to extinguish a flame, showing that it is...

In between two extremes, neither one thing nor another. A Twig Science Glossary Film. Key scientific terms defined in just 60 seconds using stunning images and concise textual definitions. Twig Science Glossary Films reinforce abstract...

In chemistry, an ionic compound containing positive metal ions and negative non-metal ions. A Twig Science Glossary Film. Key scientific terms defined in just 60 seconds using stunning images and concise textual definitions. Twig Science...