Metals from rocks Flashcards
What are pigments?
Pigments are coloured substances used in paint.
What is another name from paints?
Paints are a type of mixture called a colloid.
What do paints contain?
They contain several components, including the pigment, a solvent and a binding medium.
How are thermochromic and phosphoresecent pigments useful?
Thermochromic and phosphorescent pigments are very useful, and extend the normal properties of paints.
What is a thermochromic pigment?
Thermochromic pigments are sensitive to temperature. They change colour when they are heated up or cooled down. This property is useful for indicating if the drink in a cup is hot, or if the water in a kettle is hot.
What is a phospheroscent pigment?
Phosphorescent pigments glow in the dark. They are able to absorb light energy and store it. This stored energy is released as light energy over a period of time. Phosphorescent pigments are useful for watch faces that glow in the dark.
What are dyes?
Dyes are substances that can be used to colour fabrics.
Who discovered the first synthetic dye?
The first synthetic dye, mauvine, was discovered by William Perkin accidentally in 1856, when he was just 18.
What does paints contain?
A pigment - gives the paint its colour.
A binding medium – a liquid polymer that hardens to form a continuous layer when the paint dries.
A solvent - dissolves the binding medium and makes the paint more fluid.
What is dissolved in oil paints?
Oil paints have a hydrocarbon oil as the binding medium. This is dissolved in a solvent. The pigment is dispersed within this solution.
What are the substances like in a colloid?
In a colloid, particles of one substance are mixed and dispersed with particles of another substance - but they are not dissolved in it.
What happens to the components in a colloid?
The components of a colloid are dispersed throughout the mixture. They do not separate out because their particles are small enough not to settle at the bottom.
What happens when oil paints dry?
When oil paints dry, the oil oxidises to form a hard film. This happens as the solvent evaporates and the oil reacts with oxygen in the air.
What are ores?
Ores are naturally occurring rocks that contain metal or metal compounds in sufficient amounts to make it worthwhile extracting them. For example, iron ore is used to make iron and steel.
What is a metal ore?
A metal ore is a rock containing a metal, or a metal compound, in a high enough concentration to make it economic to extract the metal.
