7.1. Chemical equilibria: reversible reactions, dynamic equilibrium
A subsection of Chemistry, 9701, through 7. Equilibria
Listing 10 of 211 questions
Hydrogen is the most abundant element in the Universe, although on Earth only very small quantities of molecular hydrogen have been found to occur naturally. Hydrogen is manufactured on a large scale for use in the chemical industry and is also regarded as a possible fuel to replace fossil fuels in internal combustion engines. State one large scale use of hydrogen in the chemical industry. One common way of producing hydrogen on a large scale for use in the chemical industry is by the steam ‘reforming’ of methane (natural gas), in which steam and methane are passed over a catalyst at 1000–1400 K to produce carbon monoxide and hydrogen. CH4+ H2OCO+ 3H2∆H = +206 kJ mol–1 Use the information above to state and explain the effect on the equilibrium position of the following changes. increasing the pressure applied to the equilibrium decreasing the temperature of the equilibrium What will be the effect on the rate of the reaction of increasing the pressure at which it is carried out? Explain your answer. Further hydrogen can be obtained by the ‘water-gas shift’ reaction in which the carbon monoxide produced is reacted with steam. CO+ H2OCO2+ H2Kc = 6.40 × 10–1 at 1100 K A mixture containing 0.40 mol of CO, 0.40 mol of H2O, 0.20 mol of CO2 and 0.20 mol of H2 was placed in a 1 dm3 fl ask and allowed to come to equilibrium at 1100 K Give an expression for Kc for this reaction. Calculate the amount, in moles, of each substance present in the equilibrium mixture at 1100 K. CO+ H2OCO2+ H2initial moles 0.40 0.40 0.20 0.20
9701_w12_qp_23
THEORY
2012
Paper 2, Variant 3
View
Questions Discovered
211