15. a) combustion is always exothermic change, b) for the evaporation of water is necessary to brin

14. a) C + 1/2 O 2 CO = ΔfH double dagger (CO) - ΔfH (C) - 1/2 * ΔfH (O2) = - 110 kJ / mol - 0 - 0 = - 110 kJ / mol b) CO + 1/2 O2 CO2 = ΔfH double dagger (CO2) - ΔfH (CO) - 1/2 * ΔfH (O2) = - 393 kJ / mol - (-110 kJ / mol ) - 0 = - 283 kJ / mol c) CH4 + 2O2 CO2 + 2H2O. Double dagger = ΔfH (CO2) + 2 * ΔfH (H2O) - ΔfH (CH4) - 2 * ΔfH (O2)
15. a) combustion is always exothermic change, b) for the evaporation of water is necessary to bring the heat, this endothermic change, c) for photosynthesis requires sunlight, this endothermic process, d) condensation process is the opposite of evaporation ( which is endothermic) so it can be concluded that the condensation exothermic process (create a connection between the particles of water in the steam and it becomes a liquid state of matter). 16th 2AL + 3/2 O2 Al2O3 double dagger = 1670 kJ / mol 13.5 kJ g 2 * 27 g 1670kJ x = 417.5 kJ 17th NH3 1/2 3/2 N2 + H2 = double dagger ? (First necessary to calculate this value !!!) 3 mol x 1 kJ mol? (90 kJ) x = 270 kJ double dagger = 1/2 * ΔfH (N2) - 3/2 * ΔfH (H2) - ΔfH (NH 3) = 0 + 0 - (- 90 kcal / mol) = 90 kJ / mol CH4 + 2O2 18th CO2 + 2H2O = double dagger? 3.2 g 18 kJ 16 kJ gx x = 90 kJ, and the double dagger = 90 kJ / mol (the negative value of the standard enthalpy of reaction because the task writes to relieve the heat, that is that the reaction of combustion) 19. CO + 1/2 O2 CO2, double dagger =? 2.8 g of 28.3 kJ 28 kJ gx x = 283 kJ IS double dagger = 283 kJ / mol of double dagger on the basis of the expression can be calculated ΔfH (CO) that is required kimye by the task! = ΔfH double dagger (CO2) - ΔfH (CO) - 1/2 * ΔfH (O2) is ΔfH (CO) = ΔfH (CO2) - double dagger - 1/2 * ΔfH (O2 ) = - 393 kJ / mol - (-283 kJ / mol) - 0 = - 110 kJ / mol