The Earth is made up of a large number of antithetic substances: elements, compounds & mixtures
We skunk classify elements & compounds as pure substances. These are forever HOMOGENEOUS. Mixtures are not pure substances and can be each homogeneous or HETEROGENEOUS.
Pure substances provoke a quick-frozen composition
eg copper metal, sulfur, carbon dioxide (CO2), methane (CH4).
Mixtures have variable composition and can also be separated into its components relatively easily.
Eg. Alloys brass Cu: 65% Zn 35%
Elements are pure substances that cannot be broken down into any other substance. Compounds can be broken down, but this requires chemical means and is not as easy as separating mixtures.
The Spheres of the Earth
Atmosphere:
Hydrosphere:define each,
Lithosphere:and bring out an example of a mixture
Biosphere:found in each.
Separating Mixtures
Solids of different sizes - seiving
Solids & liquids evaporation, filtration, distillation, decanting
dissolve solids crystallisation by evaporating
Solvents - distillation
Two liquids immiscible liquids using a separating funnel
-fractional distillation due to different boiling points
H/W P.18 Qu.
11-18
Identifying Pure Substances
Colour some substances have a characteristic colour, eg CuSO4 = blue. We can use this knowledge in a qualitative way to image if a sample has impurities.
liquescent & Boiling Point The mp & bp of a substance is a good indicator of its purity. A pure substance volition have a sharp melting point and its mp & bp will not change after further attempts at purification.
Impurities can lower or raise bp, but scarce lower mp.
Density = mass/volume pure substances have characteristic densities eg glass.
Gravimetric Analysis
This is a method used to con the composition by mass of a substance.
Mining determine the % of a mineral in an ore deposit
Quality control of products
...If you postulate to get a full essay, order it on our website: Orderessay
If you want to get a full essay, wisit our page: write my essay .
No comments:
Post a Comment