. Write reactions for which the enthalpy change will be a. Hf for solid aluminum oxide. b. The standard enthalpy of combustion of liquid ethanol, C2H5OH(l). c. The standard enthalpy of neutralization of sodium hydroxide solution by hydrochloric acid. d. Hf for gaseous vinyl chloride, C2H3Cl(g). e. The enthalpy of combustion of liquid benzene, C6H6(l). f. The enthalpy of solution of solid ammonium bromide.

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answer: semi-infinite solid initially at a uniform temperature of 400 ◦c is cooled at its surface by convection. the cooling fluid at a constant temperature of 200 ◦c has a convective coefficient (ha) of 250 w/m2.k. the physical properties of the solid: k = 20 w/m.k and α = 4 * 10-5  m2/s. using δx = 0.04 m and δt = 10 s. write the finite difference equations describing the transient heat transfer of the first five δx and the temperature profile after 30 s.