Consider the steps you followed to calculate the mass % concentration of vinegar and rationalize how will the following affect the calculated mass % concentration:
measured out 11 ml vinegar sample each time instead of 10 ml;
before titration, rinsed the buret with di water only without using naoh solution;
some naoh solution remained on the wall of flask and never reached the reaction mixture.

there are two significant figures.

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.