EXTRA Flashcards
Why do many ionic compounds dissolve easily in water?
Because water is a POLAR SOLVENT
Why do most covalent compounds not dissolve in water?
Because they are RELATIVELY NON-POLAR (e.g. Nail vanish)
What is the name of the polar protein that makes up our nails?
Keratin
When is centrifugation used as a separation technique?
Separating solid particles from liquid
E.g. Separation of blood components in hospitals (the blood cells are collected at the lower half of the tube)
E.g. Separation to obtain cream from milk in dairies
When is chromatography used as a separation technique?
Separating/identifying similar substances
E.g. Separating different pigments in ink
When is distillation used as a separation technique?
Separating a solvent from a solution
E.g. Making pure drinking water from sea water
E.g. production of alcoholic spirits in industry
When is fractional distillation used as a separation technique?
Separating liquids which mix completely
E.g. Separating different fractions in crude oil
When is evaporation/crystallisation used as a separation technique?
Separating a soluble solute from a solution
E.g. Separating salt from seawater
When is filtration used as a separation technique?
Separating an insoluble solid from a fluid
E.g. Making clear water from muddy water
Define:
Suspension
Particles held in a fluid (liquid or gas)
Define:
Filter
The material that causes the separation
Define:
Filtrate
The fluid that has passed through the filter
Define:
Residue
The material left on the filter
Why is centrifugation used for separation instead of filtration?
Sometimes the solid particles are so small that they can pass through the tiny holes of the filter paper.
centrifugation forces the denser particles to the end of a centrifuge tube leaving the liquid as a layer on top which can be poorer off.
What is the salt in seawater?
Sodium chloride
Define:
immiscible liquids
Liquids which settle and remain as two distinct layers when mixed.
E.g. Water and oil
Define:
Miscible liquids
When two liquids are mixed, they mix so well that they are indistinguishable from each other
E.g. When Alcohol and water are mixed
They can be separated using fractional distillation because of their different boiling points
How can the gases in air be separated?
Fractional distillation can be used to separate the gases in air.
The gas enters through a filter and then goes through a compressor, a separator, and a heat exchanger.
The water and carbon dioxide are removed early in the process because they would freeze in the heat exchanger.
Complete:
The more soluble the pigment, the ________ it will be on the chromatography paper.
The more soluble the pigment, the HIGHER it will be on the chromatography paper
Why do solids melt when they are heated up?
The forces of attraction between the particles are no longer strong enough to hold them together as a solid.
What is a DIATOMIC GAS?
In a diatomic gas, each molecule consists of two atoms. (E.g. Oxygen, chlorine, hydrogen)
What are the 3 ways which particles can move in?
Translation - straight lines of movement, unless the particles collide or are acted upon by gravity.
Rotation - the turning of a particle around a fixed point (e.g. The planets)
Vibration - the rapid movement of particles from side to side, about a fixed point. (When the particles are too close together to freely move)
How many times will a gas particle as room temp. Usually collide with the particles around it?
Around 1 million times per second
Why is no energy lost when particles collide?
The collisions are ELASTIC.
