[Denu]

We did a Chemistry lab where we had to determine the amount of NaOH required to neutralize H2SO4. We were told on the question paper that the reaction between the two reagents was exothermic. We were also told to take fixed volumes of H2SO4, and add varying volumes of NaOH (10, 20, 30, 40, 50 cm3) and measure the rise in temperature of the solution, and then use these values to plot the graph. We were told to take two additional readings of our own choice. We noticed that the rise in temperature was falling until we came about 30 or 40 cm3 of NaOH. The rise in temperature started to increase from the dropped values at this stage. Subsequent addition to higher volumes of NaOH also showed that the temperature rise was increasing. The statement above the graph stated that we would have to draw two lines of best fit; one for the decrease in the rise of temperature, and one for the increase in the rise in temperature, and then find the intersection between these two points.

We did the experiment, and solved the calculations portion of the practical pretty well. But I'm confused over why the temperature rise started to decrease, and then suddenly increase, and why the intersection between the two graphs showed us the amount of NaOH required to neutralize the acid. Btw, this isn't part of the question, so don't start telling me this is homework and doesn't belong here. This is my own question, and I can't seem to get an answer to it. Also, the volume of NaOH was plotted against the temperature rise on the graph.

Thanks.

[Borek]

Please show the plot, it is unclear to me what you did and what happened.