I need help ASAP! Calculate the pH of the resulting solution for the neutralization of 100 mL of 0.050 M NH3 with 0.1 M HCL. (Kb for NH3 is 1.8 x 10^-5).

a) after adding 40.00 mL of HCl
b) after adding 70.00 mL of HCl
c) after adding 100.00 mL of HCL

All work is needed for full credit

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.