Hand Guide for Chemistry to Increase Your School Grade!

We constantly study to get satisfactory grades. In spite of this fact, there are some subjects that we collectively are not fond of… Chemistry is one of those subjects that most people can't reach the best grades. So let’s dig into this a bit… Here is the guide for chemistry!

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There are 2 types of matter: pure substance and mixture.

1. Pure substances are divided into 2 categories: Elements and Compounds

   1. Elements are substances made up of the same atoms and cannot be divided into simpler

   2. Compounds are substances made up of 2 or more elements chemically combined together.

2. Mixture is a physical combination of 2 or more pure substances.

   1. Homogeneous mixtures

   2. Heterogeneous mixtures

These substances can be in 3 different states: solid, liquid, and gas.

Physical changes:

• Solid to Liquid is called melting

• Liquid to Gas is called evaporation or boiling

• Solid to Gas is called sublimation

• Gas to Liquid is called condensation

• Liquid to Solid is called freezing

• Gas to Solid is called deposition

The movement of gases and liquids is explained in “Kinetic Theory of matter”. Diffusion is evidence for this theory. The molecules with a smaller molecular mass diffuse faster.

Solution is a mixture formed when a solute is dissolved in a solvent.

A saturated solution is a solution with the maximum concentration of solute dissolved in a solvent.

As temperature and pressure increase, solids become more soluble.

As temperature increases, gases become less soluble but as pressure increases, gases become more soluble.

Brownian Motion is the random motions of grains and the collision of air molecules.

To obtain a soluble solid, use simple distillation

To obtain nitrogen from air or water from ethanol or any two miscible liquids use fractional distillation

To obtain dyes, amino acids, or paints, use chromatography

Rf value is the distance moved by solvent divided by the distance moved by solute

Mass number is the total number of protons and neutrons in a nucleus of an atom.

Proton number is the number of protons in the nucleus.

Chemical properties are determined by electrons in the outer shell

Isotopes are atoms of the same element with the same number of protons but a different number of neutrons.

Relative atomic mass (Ar) is the average weight of an atom of an element compared to Carbon-12

Additionally, Alkali Metals are stored in oil containers because they vigorously react with water.

The lattice structure is the arrangement of atoms in space for ionic molecules. The arrangement is regular and repeating.

Macro molecules are giant covalent structures with lattice structures.

1. Diamond has no weak intermolecular forces. It is used for cutting tools and jewelry. Each carbon atom bonds to 4 carbon atoms.

2. Graphite has free, mobile electrons between layers. Each carbon atom bonds to 3 other carbon atoms.

3. Silicon 4 oxide is known as sand or quartz. Each oxygen atom bonds with 2 silicon atoms and each silicon atom bonds with 4 oxygen atoms. It has very strong covalent bonds but no intermolecular forces. It is very hard and has a high melting/boiling point. It is insoluble and cannot conduct electricity. (SO2)

The metallic structure is the attraction between freely moving, mobile, delocalized electrons and positive metal ions.

1. Metals have high melting/boiling points because

   1. A lot of energy is required to break the strong metallic bonds.

2. Metals conduct electricity because

   1. The free electrons in metallic structures can move through and electrons entering from one end can cause a delocalized electron to displace itself.

3. Metals are malleable/ductile because

   1. Layers of positive ions can slide over each other without breaking so they are flexible.

Covalent structures are formed when pairs of shared electrons from non-metals make a full shell of electrons.

Reactivity series is the order of metals to react and can be remembered with this list,

Please Stop Calling Me A Careless Zebra Instead Try Learning How Copper Saves Gold

which is the list for

Potassium, Sodium, Calcium, Magnesium, Aluminium, Carbon, Zinc, Iron, Tin, Lead, Hydrogen, Copper, Silver, and Gold

Extraction of aluminum can be made by passing an electrical current through the solution of bauxite ore which is dissolved in molten cryolite. Cryolite reduces the melting point of aluminum to save energy. Bauxite is purified in this reaction.

• In cathode, this reaction occurs:

Al+ +e- → Al which shows that reduction is present.

• In anode, this reaction occurs

2O→O2 + 4E- which shows that oxidation is present

Aluminum is used in aircraft bodies because it has a low density and is a strong matter.

To obtain energy, complete combustion, incomplete combustion, or fuel cell can be used.

1. Complete combustion equation, CxHy + O2→ H2O + CO2

2. Incomplete combustion occurs when insufficient oxygen is used to burn something, the equation is CxHy + O2→ H2O + CO

3. Hydrogen fuel cell equation, 2H2 + O2→2H2O.

   1. It is a good way because it is quiet, clean, and produces more energy.

   2. It may be bad because high pressure is needed, requires expensive raw materials, and is affected by low temperatures.

Effects of using a catalyst in a reaction are,

1. Lowers the activation energy

2. Increases the rate of reaction

3. More collision will have enough energy to react

Equilibrium requires constant concentration and the same reaction rates on both sides.

Additionally, transition elements have 3 properties,

1. Forms colored compounds

2. Has variable oxidation states

3. Used as catalysts

Acids are proton/H+ ion donors that turn red in the methyl orange indicator.

Bases/Alkalis are proton/H+ ion receivers that turn yellow in the methyl orange indicator.

Acids will produce

1. Hydrogen and a salt when combined with a metal

2. Water and a salt when combined with a base

3. Carbon dioxide, water, and a salt when combined with a metal carbonate

Strong acids are differently defined, they are known to dissociate fully when combined with water.

Metals will produce basic oxides or hydroxides while nonmetals produce acidic oxides. And transition elements produce (Al2O3, ZnO) amphoteric oxides/hydroxides. If the amount of nonmetals that reacted with oxygen is equal, the compound (eg. CO, NO, N2O) is usually neutral oxide.

Sodium hydroxide (NaOH) is used in detergents or washing products.

To produce insoluble salts, use these steps

1. Add them and stir to mix

2. Filtrate to obtain the residue

3. Wash the residue with water

4. Let the residue evaporate or dry between two filter papers.

Some elements give different colors when combined with ammonia or Sodium hydroxide

1. Aluminum gives a white color

2. Calcium gives a pale white color

3. Chromium gives a green color

4. Copper gives a light blue color

5. Iron 2 gives a green color while Iron 3 gives a red-brown color

6. Zinc gives a white color

Ammonium won’t react with ammonia solution, it reacts with Sodium hydroxide.

The flame test can be used to identify some cations

1. Lithium gives red flames

2. Sodium gives yellow flames

3. Potassium gives lilac flames

4. Magnesium is colorless

5. Copper gives green flames

6. Calcium gives orange flames

First two elements of halogens (Fluorine and Chlorine) are gas in nature, the middle element (Bromine) is liquid and the last two elements (Iodine and Astatine) are solid/dust.

Group 1 metals have a shiny surface and vigorously react with water but are found in nature with oxidized surfaces.

Group 7 non-metals are poisonous and found as diatomic molecules in nature. Except for Astatine

Melting/Boiling points increase as you go down the group. They have different colors.

1. Fluorine is green and chlorine is pale green

2. Bromine is red-brown like a brick but forms a brown gas

3. Iodine is black and makes a purple gas when sublimates

4. Astatine has a dark black color.

Water is first filtered against large insoluble impurities then chlorinated and treated for soluble impurities and bacteria.

Hydrogen is obtained from fossil fuels

Nitrogen is obtained from air

Sulphur is obtained from petroleum

Oxygen is obtained from electrolysis of water or air

Zinc is obtained from pyrite

Aluminium is obtained from bauxite

Iron is obtained from hematite.

Fresh air has 78% of nitrogen, 21% of oxygen and 1% of argon/noble gases

Oxygen and water causes rusting. This can be prevented by greasing with oil or painting with plastic. Only steel and iron can rust, so other metals are having corrosion.

Fertilisers must have nitrogen, phosphate and potassium. Alkalis are good fertilisers but if acid rains make the water too acidic, it can be poisonous. Ammonia can be used to make fertilisers.

The Haber Process occurs to get ammonia. First hydrogen and nitrogen are pumped. Gases are compressed then. The equation is N2+3H2→2NH3. Unreacted gases are passed through cooling tanks. It starts again

1. Iron catalyst beds are used

2. 450 degrees temperature is used

3. 200 atm pressure is used

4. N2+3H2→2NH3

The Contact Process is used to produce sulphuric acid. Firstly, sulphur is oxidised with oxygen. S+O2→SO2. Then 2 moles of this are oxidised with oxygen again. 2SO2+O2→2SO3. Then sulphuric acid is added to produce oleum. SO3+H2SO4→H2SO7. Lastly water is added. H2SO7+H2O→2H2SO4

1. Vanadium (V) Oxide catalyst is used

2. 450 degrees temperature is used

3. 2 atm pressure is used

4. 2SO2+O2→2SO3

Thermal decomposition is breaking down substances into its components by the act of heat.

1. Limestone is heated to obtain quicklime ( and carbon dioxide. CaCO3→CaO+CO2

2. Quicklime is not extinguished so we put water on it. CaO+H2O→Ca(OH)2. So its slaked lime

3. We put slurry slaked lime and carbon dioxide together to obtain limestone, so slaked lime is carbonated. Ca(OH)2+CO2→CaCO3.