[填空题]
The enthalpy of neutralizlflmbud3f 1f7i3* v6esubb w1/:c 6gmation for the reaction between sulfurice89;+ovw.ora 8jy xd v1 jsle: acid and potassium hydroxide can be determiso .oe ;j:91w vld8yervj 8a+xned experimentally.
$H_2SO_4$(aq)+2KOH(aq)→$K_2SO_4$(aq)+2$H_2O$(l)
A student recorded the temperature of 20.0cm$^3$ of 0.500 mold m$^{-3}$
sulfuric acid every minute. At four minutes,25.0cm$^3$KOH(aq) is added to the solution, stirred immediately, and temperature recorded for another four minutes. The results are represented in the graph below.
1.Calculate the lowest concentration of aqueous KOH that must be used to ensure it is in excess.
C$_{KOH}$= mold m$^{-3}$
2.Use the graph above to estimate a value for the maximum temperature change,ΔT.
ΔT= $^{\circ}$
3.State one assumption you made in part (b).
4.Identify the anomalous result and suggest a possible type and source of error.
5.In another experiment with the same reactants, the student measured the initial and final temperatures and presented their results below:
Initial Temperature ($^{\circ}$C $\pm$$^{\circ}$C) 24.8 25.1 24.9
Final Temperature($^{\circ}$C $\pm$$^{\circ}$C) 26.4 26.6 26.4
1.Calculate the average change in temperature (ΔT)giving its percentage uncertainty.
Average= $^{\circ}$C; Absolute uncertainty=$\pm$ $^{\circ}$C; Percentage uncertainty= %
2.Use sections 1 and 2 of the data booklet to calculate the energy released and its uncertainty. You may assume that the only source of uncertainty is from the temperature change.
Energy released (q)= J;Uncertainty=$\pm$ J
