Viết phương trình hoá học cho mỗi chuyển đổi sau: a) S SO2 SO3 H2SO4 Na2SO4 BaSO4 b) SO2 Na2SO3 SO2 SO3 H2SO4 BaSO4 c) NaOH NaCl NaOH Na2SO4 NaNO3. d) FeO FeCl2 Fe(NO3)2 Fe(OH)2 FeO

it means there are 3 atoms of oxygen

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.