AQA GCSE CHEMISTRY PAPER 2 EXAM. QUESTIONS WITH 100% CORRECT ANSWERS.

What is the advantage of borosilicate glass over soda-lime glass? Borosilicate glass melts at a higher temperature Give two examples of clay ceramics Pottery and bricks How are clay ceramics made? By shaping wet clay and then heating in a furnace What do the properties of polymers depend upon What monomers the polymer is made from and the conditions under which they are made Name the two polymers made from ethene Low density poly(ethene) (LDPE) and high density poly(ethene) (HDPE) How is low density poly(ethene) produced? Under conditions that produce branches in the polymer so the polymers are arranged randomly How is high density poly(ethene) produced? Under conditions which produce less branching so that the polymer chains line up more closely What are thermo softening polymer? Polymers that melt when heated and so can be easily recycled What are thermosetting polymers? Polymers that do not melt when heated as there are crosslinks containing strong covalent bonds between the polymer chains (which are not there in thermosoftening polymers) What is a composite material? A material made up of two materials with different properties What is a composite material made up of? A material made from two components, a matrix or binder surrounding and binding fibres or fragments of the other material, which is called the reinforcement Give four examples of composite materials Reinforced steel (reinforcement:steel, matrix:concrete), Fibreglass (glass fibres, polymer resin), carbon fibre (carbon fibres, polymer resin), chipboard ( wood chips, resin glue) What is the Haber process used to manufacture? Ammonia What is ammonia used to make? Nitrogen-based fertilizers What are the raw materials for the Haber process Nitrogen from the air and hydrogen from natural gas What is the symbol equation for the Haber process? N2 (g) + 3H2 (g) D 2NH3 (g) Describe the Haber process (reversible reaction) Purified gases are passed over a catalyst at 450°C and 200 atmospheres. Some of the hydrogen and nitrogen react to form ammonia which on cooling liquifies and is removed. The remaining hydrogen and nitrogen are recycled. Which conditions would produce the highest yield of ammonia? Low temperature, high pressure Why does a low temperature produce a higher yield of ammonia? The forward reaction is exothermic so a lower temperature moves the equilibrium to the right to increase the temperature making more products Why does a high pressure increase the yield of ammonia? There are fewer molecules on the right hand side of the reaction so the equilibrium will shift to the right to reduce the pressure Why is a temperature of 450°C used in the Haber process? It is a compromised temperature to produce a reasonable yield of ammonia at a suitable rate Why is a pressure of 200 atmosphere used in the Haber process? To increase the yield of ammonia without incurring the very high energy and equipment costs for achieving very high pressures What effect does using a catalyst have on the yield of ammonia in the Haber process? None. It just reduces the time for the system to reach equilibrium. What types of compounds are used in artificial fertilizers? Compounds of nitrogen, phosphorus and potassium are used to make NPK fertilizers