Chemistry

• Catalysis is the process in which the rate of a chemical reaction is changed by a substance called a catalyst.
• Catalysts speed up chemical reaction, they do this by lowering the activation energy needed. The more catalysts the greater the surface area for the reaction to take place.
• Catalysts that speed up the reaction are called positive catalysts.
• Catalysts that slow down the reaction are called negative catalysts or inhibitors.
• Catalysts are important in industry because they reduce costs.

• An Alkene is a hydrocarbon containing double bonds (shown as=)
• They contain unsaturated compounds.
• Alkanes the opposite of alkenes are Hydrocarbons in which there are only single bonds between carbon atoms
• Alkenes form polymers by opening up their double bonds to "Hold Hands" in a long chain.
• The first two alkenes are ethene and propene.
• Alkanes dont decoloursise in Bromine water however Alkenes do.

• The Haber process,is the nitrogen fixation reaction of nitrogen gas and hydrogen gas, over an iron catalyst, to produce ammonia,
• The reaction is reversible- it occurs in both directions, not all of the nitrogen and hydrogen will convert to ammonia.
• The reaction is an equilibrium(Condition in which the products of a chemical reaction are formed at the same rate) because once the reaction has started, the amounts of reactants and products do not change.
• Equation; N₂ (g) + 3H₂ (g) <----> 2NH₃ (g) [Ammonia]

• A covalent bond is a strong bond between two non-metal atoms .
• A covalent bond can be represented by a straight line or dot-and-cross diagram.
• Hydrogen and chlorine can each form one covalent bond.
• Each covalent bond provides one extra shared electron for each atom.
• Each atom invlobed has to make enough covalent bonds to fill up its outer shell.
• 2-D or 3-D molecular models are especially useful for showing the relationship between atoms in multiple covalent bonds.
• The electrons in a covalent bond come from the highest occupied energy level.
• The opposite of covalent bonding is ionic bonding- this typically is between a metal and a non-metal (from groups 1 + 2 and 6 + 7 on the periodic table

• An alloy is a compound of one or more metals or other elements
• Brass is the alloy of copper and zinc
• Bronze is the alloy of copper and tin
• Alloys generally have properties that are radically different from any of the base metals in them

• Copper is less reactive than carbon, so it can be extracted from its ores by heating it with carbon. For example, copper is formed if copper oxide is heated strongly with charcoal - which is mostly carbon:

  copper oxide + carbon → copper + carbon dioxide

  Copper is purified by electrolysis. Electricity is passed through solutions containing copper compounds, such as copper sulphate. The anode - positive electrode - is impure copper. Pure copper forms on the cathode - negative electrode.

• Cracking of hydrocarbons involves thermal decomposition.
• Cracking an alkane produces a small alkane plus an alkene
• Cracking takes place at about 600 degrees celcius
• Crude oil is a mixture of hydrocarbons
• Hydrocarbons are separated into useful products, such as fuels, using a process called fractional distillation.

Fractional distillation of crude oil.