The Haber process The Haber process is about the production of ammonia (NH3) – the reversible reaction is: N2 + 3H2 <- -> 2NH3 + (heat) Volume will be higher on the left as there is two sets of molecules (volume includes space between them) – also the reaction...
Covalent substances: Giant Covalent These are similar to giant ionic structures – but no charged ions All the atoms are bonded to each other by strong covalent bonds This means they have very high melting and boiling points They don’t conduct electricity – except for...
RATES OF REACTION Things that effect rates of reaction Concentration (pressure/ strength of the liquid) Temperature Presence of a catalyst Surface area of solids
Ways to measure the rate of reaction How quickly the reactants are used up How quickly the product is formed Rate of reaction = How quickly the reactants are used up /How quickly the product is formed ...
Experiments Reaction of hydrochloric acid and marble chips (see pg. 109) – You can use the gas syringe method to measure the rate of the reaction. Repeat the experiment with the same mass of chips but different sizes of them to change the surface area. – The smaller...
COLLISION THEORY Collision theory says that the rate of reaction depends on the amount of collisions and how hard the particles collide. The harder the collisions and the more of them the faster the rate of reaction. Temperature – More energy of the particles...
Covalent Bonding – sharing electrons Non-metals prefer to share electrons through covalent bonds They only share atoms on their outer shells – and this makes them feel like they have full outer shells like a noble gas Each atom involved will make up enough covalent...
Covalent Substances: Simple Molecular Simple molecular structures Substances with covalent bonds can form simple molecules The atoms form very strong bonds covalently – these form strong molecules The forces of attraction between these molecules are very weak For...
Chemistry – Ionic and covalent bonding, polymers and materials Atoms and Compounds Atomic number and mass number describe an atom: Compounds are when two are more atoms chemically join together – e.g. carbon dioxide – they are hard to separate Isotopes:...
Acids and Alkalis pH scale 0- 14 : Acids – 0-6 Neutral – 7 Alkalis – 8-14 Universal indicator Red to yellow is acid green is neutral blue to purple is alkali Acids and alkalis neutralise each other Acid (pH less than 7) in water...
Oxides, Hydroxides, ammonia Metal oxides and hydroxides are bases Some dissolve is water and therefore are alkalis But they still can react with acids even if they don’t dissolve in water Acid + metal oxide = salt + water Acid + metal hydroxide = salt + water Ammonia...
Making salts Most chlorides, sulphates and nitrates (salts) are soluble in water – notable exceptions are lead chloride, lead sulphate and silver chloride Most oxides and hydroxides are insoluble The method to make a soluble salt depends are whether the base is...
Relative Formula mass Atomic Mass = A Ar = the relative atomic mass (usually the same as the atomic mass number) When an element has more than one isotope then the relative atomic mass number is the weighted average Weighted mass means that it is measured by how much...
Calculating the percentage mass of an element in a compound The percentage is the: Ar x number of atoms for that element in the formula / the Mr x 100 E.g. MgCl2 (Mg Ar = 24 Cl Ar = 35.5) Mr = 24 +(35.5 x 2) = 95 The percentage that is chlorine is: 5 x 2 / 95...
Calculating masses in reactions – 3 important steps Write out a balanced equation Work out the Mr Divide to get one and multiply to get all g. What mass of magnesium oxide is produce when 60g of magnesium is burnt in air Step 1: Write a balanced equation = 2Mg + O2 =...
Chemical Analysis using paper chromatography Artificial colouring may be separated by chromatography Food colouring may contain one dye or a mixture of dyes You place the food colouring (a few drops) in small cup with a few drops of solvent (water, ethanol etc.) Put...