[填空题]
When a sample of solid calcium carbonate is placed in hm i5hjqdkhj 7i 2+:7wvydroyxyt vv87d5a4 t2,8rhq r6imochloric acid, the following reaction takes plado8vhty4 t6r xivqyr7, 8m25ace.
$CaCO_3$(s)+2HCl(aq)→$CaCl_2$(aq)+$H_2O$(l)+$CO_2$
The temperature and mass of the solution are both monitored, as shown.
1.The standard enthalpies of formation of hydrochloric acid and the products of its reaction with calcium carbonate are shown.
.1.Define the term standard enthalpy of formation.
.2.Calculate the standard enthalpy of formation of calcium carbonate, in kJmol$^{-1}$.
2.A reaction profile shows how the enthalpies of the molecules in a reactant change as the reaction progresses.
Part of the reaction profile for the reaction of calcium carbonate and hydrochloric acid is shown.
Complete the reaction profile by showing how the enthalpy changes between the reactants and products and labelling the value of Δ$H_r^Θ$.
3.The sample of calcium carbonate is added to 100 cm$^3$ of dilute hydrochloric acid. During the reaction, the mass of the conical flask and its contents decreases by 6.28g due to the loss of carbon dioxide gas. The molar mass of carbon dioxide is 44.0g mol$^{-1}$.
.1.Calculate, to 1 decimal place, the maximum possible change in the temperature of the solution, using sections 1 and 2 of the data booklet. You should assume that the solution has the same density and specific heat capacity as water and does not change in mass during the reaction.ΔT=(+) ( $^{\circ}C$ ).
.2.The measured change in temperature is much less than the maximum possible value. State why the experimental and theoretical results are different, assuming that the value of Δ$H_r^Θ$, is accurate.
.3.Suggest why the measured mass loss during the reaction is likely to be less than the mass of carbon dioxide produced.
