Unit 1 Flashcards
What is random motion?
When particles move and they collide with each other and bounce off in all directions
What is diffusion
In 2 substances, when mixed, particles bounce off in all directions when they collide. The mixing process is called diffusion.
What is a molecule?
The particles consist of 2 atoms joined together. A group of atoms held together by covalent bonds.
What is an ion?
Particles that consist of atoms or groups of atoms that carry a charge.
What are solid properties?
Definite shape and volume Normally hard and rigid Large force required to change shape High density Incompressible
What is the model of solids?
Closely packed Occupy minimum regular pattern Vibrate in fixed position Not free to move
What are the liquid properties?
Definite model but no shape
High density
Not compressible
What’s the model of liquid?
Occur in clusters with molecules further apart compared to solids
free to move about within a confined vessel
What are the gas properties?
No fixed volume and no fixed shape
Low density
Compressible
What’s the model of gas?
Very far apart
Travel at high speed
Independent and Random motions
Negligible forces of attraction between them
Why does the lower mass of particles , the faster the gas diffuses?
Because the lighter the molecules, the faster it will travel
Why the higher the temperature, the faster a gas will diffuse?
Because particles gain energy as they are heated
What is a mixture?
Substance that contains more than one substance. They are just mixed together and not chemically bonded. E.g sand and water
What is a solution?
It is when a solute and a solvent mix. The solute dissolves in the solvent making a solution. E.g sugar (solute) dissolves in water (solvent) making a solution of sugar and water
How can you help a solvent dissolve?
Stir it
Rise the temperature
What does saturated mean ?
Cannot dissolve anymore. If you put an excess amount of sugar in a small amount of water it will not dissolve as there is no place for it. It becomes saturated
What is a solvent?
A substance that allows solute to dissolve in e.g water , ethanol
What is a pure substance?
A substance that has no particles of any other substance mixed with it
What is an impurity?
An unwanted substance , mixed with a wanted substance
How can you check if a substance is pure?
Check it’s melting and boiling points
Attributes of a pure substance?
Has a definite, sharp , melting point
Attributes of an impure substance?
The melting point falls and its boiling point rises. So he more impurity present, the wider and bigger the change in melting and boiling point
What is centrifuging?
The method is used to separate small amount of solid and liquid. Inside the centrifuge (it’s a machine), test tubes are spun very fast so the solid gets flung to the bottom.
What is crystallisation?
This method is similar to evaporation but here the solid forms crystals then the crystals are left to dry
What is simple distillation?
The impure liquid is heated
It boils and steam rises into the condenser
The impurities are left behind
The condenser is cold so the steam condenses to the pure liquid and it drops out
What is fractional distillation?
The mixture is heated
The wanted substance boils and evaporates(some of the unwanted liquid will evaporate too) and rises up the column
This substance will condense on the beads in the column causing them to heat
When the beads reach a certain temperature when the wanted liquid won’t condense anymore(that’s the boiling point) it will rise while the unwanted liquid will condense and drop . the wanted liquid will make its way through the condenser where it will condense and drop down into the beaker
What is a chromatogram?
The filter paper showing the separate substances
What is chromatography?
The method is used to separate a mixture of substances e.g to find how many coloured substances there are in black ink.
What are the uses of chromatography?
Separate mixtures of substances
Purify a substance by separating the impurities from it
Or to identify a substance
Brownian motion
The random movement of small visible particles in suspension caused by the un-equal random bombardment of molecules of gas or liquid on the visible particles.
