202-203 represent exothermic and endothermic reactions on a simple 4.14 energy level diagram 202-203 understand that the breaking of bonds is endothermic and 4.15 that the making of bonds is exothermic 203 use average bond energies to calculate the enthalpy change 4.16 during a simple chemical reaction. Equilibria 125 understand that some reactions are reversible and are 4.22 ⇌ indicated by the symbol in equations 125 describe reversible reactions such as the dehydration of 4.23 hydrated copper(II) sulfate and the effect of heat on ammonium chloride 4.24 125-126 understand the concept of dynamic equilibrium 127-129 predict the effects of changing the pressure and temperature 4.25 on the equilibrium position in reversible reactions. 133-134 understand that nitrogen from air, and hydrogen from natural 5.22 gas or the cracking of hydrocarbons, are used in the manufacture of ammonia 133-134 describe the manufacture of ammonia by the process, including the essential conditions: 5.23 i a temperature of about 450°C ii a pressure of 200 atmospheres iii an iron catalyst 133-134 understand how the cooling of the reaction mixture liquefies 5.24 the ammonia produced and allows the unused hydrogen and nitrogen to be recirculated 133-134 describe the use of ammonia in the manufacture of nitric acid 5.25 and fertilisers 135-136 recall the raw materials used in the manufacture of sulfuric 5.26 acid 135-136 describe the manufacture of sulfuric acid by the contact process, including the essential conditions: 5.27 i a temperature of about 450°C ii a pressure of about 2 atmospheres
4.14 represent exothermic and endothermic reactions on a simple energy level diagram 202-203 4.15 understand that the breaking of bonds is endothermic and that the making of bonds is exothermic 202-203 4.16 use average bond energies to calculate the enthalpy change during a simple chemical reaction. 203 Equilibria 4.22 understand that some reactions are reversible and are indicated by the symbol ⇌ in equations 125 4.23 describe reversible reactions such as the dehydration of hydrated copper(II) sulfate and the effect of heat on ammonium chloride 125 4.24 understand the concept of dynamic equilibrium 125-126 4.25 predict the effects of changing the pressure and temperature on the equilibrium position in reversible reactions. 127-129 5.22 understand that nitrogen from air, and hydrogen from natural gas or the cracking of hydrocarbons, are used in the manufacture of ammonia 133-134 5.23 describe the manufacture of ammonia by the process, including the essential conditions: i a temperature of about 450°C ii a pressure of 200 atmospheres iii an iron catalyst 133-134 5.24 understand how the cooling of the reaction mixture liquefies the ammonia produced and allows the unused hydrogen and nitrogen to be recirculated 133-134 5.25 describe the use of ammonia in the manufacture of nitric acid and fertilisers 133-134 5.26 recall the raw materials used in the manufacture of sulfuric acid 135-136 5.27 describe the manufacture of sulfuric acid by the contact process, including the essential conditions: i a temperature of about 450°C ii a pressure of about 2 atmospheres 135-136
chemistry_igcse_checklist.docx