Tetrafluoroethene is made from chlorodifluoromethane in this reversible reaction:
2CHClF2(g)⇌C2F4(g)+2HCl(g)ΔH=+128 kJ mol−1 2\text{CHClF}_2\text{(g)} \rightleftharpoons \text{C}_2\text{F}_4\text{(g)} + 2\text{HCl(g)} \quad \Delta H = +128\text{ kJ mol}^{-1} 2CHClF2(g)⇌C2F4(g)+2HCl(g)ΔH=+128 kJ mol−1A 3.50 mol3.50\text{ mol}3.50 mol sample of CHClF2\text{CHClF}_2CHClF2 is placed in a container of volume 18.5 dm318.5\text{ dm}^318.5 dm3 and heated. When equilibrium is reached, the mixture contains 0.380 mol0.380\text{ mol}0.380 mol of CHClF2\text{CHClF}_2CHClF2.
Calculate the amount, in moles, of C2F4\text{C}_2\text{F}_4C2F4 and of HCl\text{HCl}HCl in the equilibrium mixture.
Give an expression for KcK_cKc for this equilibrium.
Calculate a value for KcK_cKc. Give its units.
State and explain the effect of using a higher temperature on the equilibrium yield of tetrafluoroethene.
Chemists provided evidence that was used to support a ban on the use of chlorodifluoromethane as a refrigerant. Many refrigerators now use butane as a refrigerant. State the environmental problem that chlorodifluoromethane can cause, and give one reason why butane does not cause this problem.
