C2 (OCR Gateway Science 2005 Specification)

This Series of Cards will cover the C2 Section of the OCR Gateway Science Books.



Ingredients of Paints:

A colloid contains A Pigment, A solvent and A Binding Medium

In this the solid particles are mixed and dispersed with particles of liquid but are not dissolved in the liquid.

The particles in a colloid will not separate because the particles are scattered throughout the mixture and are so small that they won't sink to the bottom

Emulsion paints are water-based. They contain a Pigment and a binding agent dispersed through the water.

A colloid is a mixture of two substances that do not normally mix. e.g. Milk, Butter, Mayonnaise and Smoke.

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Dyes and Special Pigments


Some dyes are natural. Most of them are obtained from Plants therefore limiting the spectrum available.

Other dyes are synthetic. This generally means that they are made in factories. The number of colours available for synthetic dyes are vast.

Pigments with special properties:

Thermochromic Pigments: These pigments change colour depending on the temperature of the substance it is in contact with. They can be used on kettles to show how hot the water is.

Phosphorescent Pigments: These pigments can glow in the dark. They absorb and store energy and release it as light over a period of time. They can be used in watch faces. They are safer than Radioactive substances.

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Construction Materials

Construction Materials:

Construction materials are used to build houses and buildings. Some of the material's source comes from the Earths crust.

We can also use the rocks and carve them into blocks so they form the structure of the building itself.

Examples are:

Granite, Limestone and Marble.

Granite is an Igneous this means that the product is very hard and can withstand weathering and tear.

Limestone and marble are made up of Calcium Carbonate. Limestone is Sedimentary and Marble is Metamorphic Rock.

The Hardness of a rock depends on how it was formed.

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Sedimentary , Metamorphic and Igneous Rocks

Sedimentary Rocks --  These rocks were formed by small pieces of Earth fall and settle in a lake and then layer after layer they put immense pressure on the pieces,these make these sedimentary.

Metamorphic Rocks -- Same process but Earth movements put immense heat and pressure resulting. The minerals in the rocks change chemically.

Igneous Rocks -- These rocks are formed by magma cooling.

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