You are asked to prepare a ph=3.00 buffer solution starting from 1.25 l of a 1.00m solution of hydrofluoric acid (hf) and an excess of sodium fluoride (naf). part a what is the ph of the hydrofluoric acid solution prior to adding sodium fluoride? express your answer using three significant figures. ph p h = nothing request answer part b how many grams of sodium fluoride should be added to prepare the buffer solution? neglect the small volume change that occurs when the sodium fluoride is added. express your answer using two significant figures. m m = nothing g.

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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.