Flashcards in C1c Deck (23):
What is a solution?
-mixture of solute and solvent that does not separate
What is a solvent?
-liquid a solute is dissolved into
What is a solute?
-a substance being dissolved
What does insoluble mean?
-will not dissolve
What does soluble mean?
What does solubility mean?
-measure of how much will dissolve
Why is nail vanish insoluble in water?
-the attraction between nail polish molecules to each other is stronger than its attraction to water molecules
-the attraction between water molecules to each other is stronger than its attraction to nail polish molecules
-more attracted to themselves than each other, and don't form a solution
Why is nail vanish soluble in acetone?
-the attractions between acetone molecules(nail polish remover) and nail polish molecules is stronger than the attractions holding the substances together
What do paints contain?
-pigment to give colour
-binding medium: carries pigment bits and holds them together, when it goes solid it stick the pigment to the painted on surface
-solvent: thins the paint and makes it easier to spread
What are colloids?
-tiny particles of one substance dispersed into another substance
-mixed but not dissolved
Why do colloids not separate?
-the particles are too small
-they don't settle out at the bottom
How do water-based (emulsion) paints dry?
-solvent used is water
-binding medium usually an acrylic or vinyl acetate polymer
-solvent evaporates, leaving the binder and pigment
-a thin layer dries quite quickly
- ideal for inside walls
How do oil-based paints dry?
-solvent:organic compound that dissolves oil
-binding medium is oil
2-the oil is oxidised by the air before it turns solid
-ideal for outside doors and metalwork
What are the advantages and disadvantages of oil paints?
-advantages:glossy, waterproof, hard-wearing
-disadvantages: solvents used often produce harmful fumes
What are the advantages of water-based paints?
-fast-drying, no harmful fumes
What are thermochromic pigments?
-pigments that change colour or become transparent when heated or cooled
-different pigments change colour at different temperatures
-a mixture of pigments can be used to make a colour-coded temperature scale, which are used to make basic thermometers that stick to your head and take temperature
What are some uses for thermochromic pigments?
-electric kettles that change colour as water boils
-baby products, e.g. bath toys and baby spoons, often have them added as a safety feature
-drink mugs to tell if drink it too hot
What happens if you mix thermochromic pigments with paint?
-mix with acrylic paint to give a wide range of colour changes
-e.g. blue thermochromic pigment loses colour at 27C, , with a yellow acrylic paint would give a paint that's green below 27C and yellow above 27C
-the blue pigment has become transparent
How do phosphorescent pigments work?
-absorb natural or artificial light and store energy in their molecules.
-energy is released as light over a period of time
What did people use to paint glow-in-the-dark watches and what was wrong with it?
-they would glow for years without being needed 'charging' by putting them in light
-they were not safe and could give quite a dose of atomic radiation
What are some uses of thermochromic pigments mixed with paint?
-these are also used in novelty mugs, designed to change colour when a hot drink is poured inside or become transparent and reveal a picture
What does solubility depend on?
-the solvent used