[填空题]
In the presence of a catalys g+ 19d5,imd (o cyk*ne+flympt ;ex0 2gxs:,epuk -pnh)vc9k 6q ie)qc, aqueous hydrogen peroxide decomposes into water and opk6pv)e)g, eekqx2hc9s0:i uq- n ;cxxygen. The equation for this reaction and the enthalpy change
ΔH$_{dec}^{θ}$ is related to three other enthalpy changes,ΔH$_{A}^{θ}$,ΔH$_{B}^{θ}$ and ΔH$_{C}^{θ}$.
.1.State the name given to the enthalpy change labelled ΔH$_{A}^{θ}$.The name is (of aqueous hydrogen peroxide)
.2.Calculate ΔH$_{A}^{θ}$ in kJ mol$^{-1}$ using the information in the enthalpy cycle and section 12 (Section 13- 2025 Syllabus) of the data booklet.ΔH$_{A}^{θ}$= kJ mol$^{-1}$.
2.A solid catalyst was added to 100 cm$^{-1}$ of an aqueous hydrogen peroxide solution and the temperature was monitored using a thermometer. The resulting temperature-time graph is shown.
The maximum theoretical temperature change during the reaction, ΔT, is determined by the molar concentration of hydrogen peroxide,[$H_2O_2$]
.1.State why ΔT is determined by extrapolating the trend of the temperature profile between 65 and 120 s.
.2.Using the value of ΔH$_{dec}^{θ}$ the information in the temperature-time graph and sections 1 and 2 of the data booklet, calculate the initial concentration of the hydrogen peroxide solution in mold\m$^{-3}$.
Assume that the specific heat capacity of the solution is 4.18J g$^{-1}$K$^{-1}$. [$H_2O_2$] = mold\m$^{-3}$.
3.The decomposition of gaseous hydrogen peroxide into water vapour and oxygen is an important atmospheric reaction.
.1.Calculate the enthalpy change of this reaction, using the bond enthalpy values in section 11 (Section 12- 2025 Syllabus) of the data booklet.
Enthalpy change=- (kJmol$^{-1}$)
.2.Suggest one reason why the enthalpy change calculated in (i) differs from the enthalpy change for the decomposition of aqueous hydrogen peroxide.
参考答案: 空格1: Standard enthalpy|heat of formation
空格2: 109.7±3%
空格3: 0.25±5%
空格4: 105±3%
