Chemistry Vocab Flashcards
Define melting point:
Temperature at which a substance changes from a solid to a liquid when heater or from a liquid to a solid when cooled.
A physical property, all parts of a pure substance will melt at the same temperature because pure substances have the same composition throughout.
Define physical change:
A change in which no new substances are formed- like changes of state
Define a physical property:
How a material behaves and responds to forces and energy, e.g hardness
Define a pure substance:
1A single substance, with a fixed composition(the make up does not change), that does not have anything else mixed with it.
2.Is that same in all parts of a piece of the substance
3. Cannot be separated using physical methods (compounds)
Define residue:
Material remaining in the filter after mixture has passed through it
Define risk & risk assessment:
Risk: the chance of a hazard causing harm
Risk assessment: identification of the hazards of doing an experiment
Define saturated solution:
Contains the maximum amount of solute that can dissolve in that amount of solvent at that temperature
A sentence linking solute, solution, solvent
a solute dissolved in a solvent to make a solution
What is chromatography used for and why does it work?
Chromatography is used to find out which coloured compounds a mixture contains. It works because different compounds dissolve better in a solvent than others. When a solvent moves along a strip of paper it carries the substances at different speeds, so they are separated.
Stationary phase of paper chromatography:
The surface through which the solvent and dissolved substances move in (PAPER)
The mobile phase of paper chromatography:
The solvent that moved along the paper carrying the dissolved samples with it
Define chromatogram:
The piece of paper showing the results of carrying out chromatography on substances
Define Rf value:
The ratio of the distance traveller by the solute on a chromatography to the distance traveller by the solvent under the same conditions.
= distance travelled by substance/distance travelled by solvent
Define distillation:
The process of separating a liquid from a mixture by evaporating the liquid and then condensing it (so it can be collected)
Define fractional distillation:
A method of separating a mixture of liquids with different boiling points into individual components (fractions)
Define a mixture:
A mixture contains elements and or components that are not chemically joined together. You can use physical processes to separate them into different substances.
They do not have the same composition throughout e.g - air is a mixture of gases which is constantly changing as we breathe
Mixtures melt at a range of temperatures and not all parts melt at the same time
Define a still:
The apparatus used to carry out distillation or fractional distillation
Define an aquifer:
Underground layer of rock containing groundwater, which can be extracted using a wall or pump
Define chemical analysis:
Using chemical reactions or sensitive machines to identify and measure substances in a sample
In what order is water treated?(3)
1 filtration
Sedimentation
Chlorination
Define desalination
Produces fresh drinking water by separating the water from the salts in salty water
Define precipitate:
Insoluble substance formed when two soluble substances react together
Define chlorination: (water treatment)
The process of adding chlorine to a water to kill harmful microorganisms and bacteria
Define filtration(water treatment):
Smaller insoluble particles are removed using sand and gravel beds
