Which of the followinbja8t/m/i6 bo uf(hy.;rg4zm g statements is false?

  Choose the correct equation for the diagram belo9 - kt1t n18-hkhkz5wwb.z gcow:

  Which of the following is correct in an endothermic reactiob(t10/ vgzdekfn ic63n?

  Which shows the oxygen-to-oxygen bonds in order of increasing average o5iv*f7 *bfjp/zkr 4n bond enthalpy? r5kjz 7/ofi pnvf4b* *

  Which expression gives the enthalpy chazyc26;vk8ci d nge, ΔH, for the production of hydrated copper (II) sulfate fro8c; kyzd2vci 6m its anhydrous salt:

  Which statement about Born-Haber cycles is not owblh;rd, z33a zw k--correct?

  What is the enthalpy 6zo6fe.arx ofu0w:g g f528isΔH$_1$ in kJmol$^{-1}$?

  Which enthalpy change cannot be calculated directly from averae8l 0,evyk /gjwcqopv1h 7 w:5ge bond enthalpy datawpylw17,qhvg:o8kc /vj5 e e0?

  Which statements about average bond enthalpi,wjc53z n hi 8uce/-)h uyga:kt-z7pv9*oe k tes are correct?
I.Average bond enthalpies are endothermic
II.Average bond enthalpies depend on the strength of the covalent bonds
III.Average bond enthalpies are unique to the covalent bonds in a specific compound

  The following diagram shows tcjgq6.d8icls xs -26b-sugf 9t+ls 9t he enthalpy of the reactants and products of a reaction involving gaseo9+q6lsifs-.gtdgx6cbs9 - 2utsl8cj us covalent compounds. Which statement is correct?

  Given the enthalpy changes for the e69p tc /baqdo :o0-*ui8kazavp qh.2reactions below.
$\frac{1}{2}$$N_2$(g)+$O_2$(g)→$NO_2$(g); ΔH=+33.9kJ
$NO$(g)+$\frac{1}{2}$$O_2$(g)→$NO_2$(g); ΔH=-56.5kJ
What will be the enthalpy change for:
$\frac{1}{2}$$N_2$(g)+$\frac{1}{2}$$O_2$(g)→$NO$(g)?

  Hydrocarbons are common-krnexbs (p p27kyge 05j)g,lo( n/puly used as fuels.
1.1Define average bond enthalpy.
1.2Write a balanced chemical equation for the complete combustion of propene ($CH_3CHCH_2)$

2.Using section 11 (Section 12- 2025 Syllabus) of the data booklet, calculate the enthalpy of combustion for propene.
ΣΔH$_{BE}^θ$(bonds broken)=  kJ mol$^{-1}$ ;ΣΔH$_{BE}^θ$(bonds formed)=  kJ mol$^{-1}$;ΔH=-  kJ mol$^{-1}$
Important note: The section numbers mentioned in the video solution are specific to the 2024 syllabus.
You can refer to the question stem to find the section numbers for the 2025 syllabus.

  Given the following infok vxy0+wla8.)1nm b4 la7co lbrmation:
C(s)+$O_2$(g)→$CO_2$(g); ΔH= -393.5kJ mol$^{-1}$
CO(g)+$\frac{1}{2}$$O_2$(g)→$CO_2$(g);ΔH= -283.0kJ mol$^{-1}$
The standard enthalpy of formation of carbon monoxide (CO) is:

  Which expression represl*tfk d1e6-y aj7sdsnh6 , 9wpx.n c9eents the enthalpy change for $CO$(g)+$H_2O$→$CO_2$(g)+$H_2$(g)?

  Which statement about ozw* 8k 27uttnt)p,ip ypone is correct?

  Ethene reacts with hydrogen bgl17bei9.sk0,ppz r)hzlm a /romide at 298 K and 100 k Pa pressure to produce bromoethane. All three compounds are gases under thesep s/ ).l1 p,0hbgr7azelik9m z conditions.The enthalpy change of this reaction, ΔH$_r$, an be estimated from the enthalpies of formation (Method 1) or average bond enthalpies (Method 2) of the reactants and products. The enthalpy cycles used in these calculations are shown.

?
Which method gives the least accurate estimate of ΔH$_r$

  Using the table below, choose the correct expression that represents the ent;9.h ,;r gdznpujygz5 halpy change for the followinhd, g;9zg uypnj.; z5rg hydrogenation reaction:
$C_2H_4$(g)+$H_2$(g)→$C_2H_6$(g)

Substance is $C_2H_4$(g) ; ΔH (Enthalpy of Formation) kJ mol$^{-1}$ is x
Substance is $C_2H_6$(g) ; ΔH (Enthalpy of Formation) kJ mol$^{-1}$ is y

  1.Define standard enthalpy of form15*+p6r xpy rb yvxmh1ation.
2.Draw a Hess diagram for the following reaction:
2$CO$(g)+$O_2$→$CO_2$(g)
Make sure to label all enthalpies of formation.
3.Refer to section 12 (Section 13- 2025 Syllabus) of the data booklet to calculate the enthalpy of reaction, ∆H$^ᶱ_r$, for:
2$CO$(g)+$O_2$→$CO_2$(g)
∆H$^ᶱ_r$=-  kJ mol$^{-1}$
Important note: The section numbers mentioned in the video solution are specific to the 2024 syllabus.
You can refer to the question stem to find the section numbers for the 2025 syllabus.

  What is the enthalpy change for the combustion of mk 9:aa/tig +pwethane:
$CH_4$(g)+2$O_2$(g)→$CO_2$(g)+2$H_2O$(g) in kJmol$^{-1}$?

  Ethanol can be produced throuzuzoo6(1de(4 j8nhfdgh the fermentation of glucose:
$C_6H_12O_6$(aq)→2$C_2H_5OH$(l)+2$CO_2$
1.1.Predict whether the entropy change for this reaction is positive or negative. Explain your reasoning.
1.2.The absolute entropy for glucose is +209.2JK$^{-1}$mol$^{-1}$ . Using section 12 (Section 13- 2025 Syllabus) of the data booklet, calculate the entropy change for this reaction.
ΔS$_{reaction}$=+  K$^{-1}$mol$^{-1}$.
2.The enthalpy of formation of glucose is -1273.3kJmol$^{-1}$ .Using section 12 (Section 13- 2025 Syllabus) of the data booklet, calculate the enthalpy change for this reaction.
ΔH$_{reaction}$=-  kJ mol$^{-1}$
3.Using your answers to (a)(ii) and (b), calculate the Gibbs free energy change at 298K.
ΔG=-  kJ mol$^{-1}$
Important note: The section numbers mentioned in the video solution are specific to the 2024 syllabus.
You can refer to the question stem to find the section numbers in the 2025 syllabus.

  Refer to the Born-Haber cyq: o 7z3wv plf7v0fq,3 n9d jx6vwda8kcle for potassium chloride below:

What is the correct name for the enthalpy changes labeled x, y, and z?

State Hess’s law.
Suggest why it may be useful to use Hess’s law to determine the heat of formation.
Calculate a value for ΔH$_f^θ$ [$CH_3OH(l)$] using the enthalpies of combustion data from section 13 (Section 14- 2025 Syllabus) of the Data Booklet.
Important note: The section numbers mentioned in the video solution are specific to the 2024 syllabus.
You can refer to the question stem to find the section numbers for the 2025 syllabus.

  When a sample of solid g.lp)lf/gs- 7kbw0,x) pnr necalcium carbonate is placed in hydrochloric acid, the following r,xn nf.p 0p)gs- gwr7ek)l /bleaction takes place.
$CaCO_3$(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.

  Cracking is a process by which gaseous alkanes are converted to smallrcau4+l(br vf(x),s lo: w63a 0u semter-chain alkanes and alkenes. One possible ream(6arbe 0 u s,xl3u+ ):(rtoa vls4wcfction in the cracking of butane is shown.


What is the enthalpy change of the cracking reaction?

  Consider the formatio8md 50;q2enknl.gt m vn of water:
$H_2$(g)+$\frac{1}{2}O_2$(g)→$H_2O$(l)
1.Using section 11 (Section 12- 2025 Syllabus) of the data booklet, calculate the enthalpy change for this reaction.
ΔH =-  kJ mol$^{-1}$
2.1.Compare the theoretical value of enthalpy of formation of water found in section 12 (Section 13- 2025 Syllabus) of the data booklet to your answer in part (a). Suggest two reasons why they differ.
2.2.State the enthalpy change required to make your answer in part (a) more accurate.
Important note: The section numbers mentioned in the video solution are specific to the 2024 syllabus.
You can refer to the question stem to find the section numbers for the 2025 syllabus.

  In the presence of a catalyst, aqwr9xnb*b +zo z*rs,ots+5c f6ueous hydrogen peroxide decomposes into water and oxyo zxbn5ob* +,* 9wrcstfs +6rzgen. 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=-  (kJ mol$^{-1}$)
.2.Suggest one reason why the enthalpy change calculated in (i) differs from the enthalpy change for the decomposition of aqueous hydrogen peroxide.

  1.Define standard enthalpy of comui)*gu-+vsjc bustion.
2.Outline how Hess’s law differs or concurs with the law of conservation of energy.
3.Using the equation provided below, draw a Hess’s law diagram using enthalpy of combustion equations, and calculate the enthalpy change for the hydrogenation of ethene using section 13 (Section 14- 2025 Syllabus) of the data booklet.
$C_2H_4$(g)+$H_2$→$C_2H_6$
ΔH$_r$=-  kJ mol$^{-1}$
Important note: The section numbers mentioned in the video solution are specific to the 2024 syllabus.
You can refer to the question stem to find the section numbers for the 2025 syllabus.

  Consider the followin,jta v y,s:5co h.l9wd 9i(tvwg reaction:

$C_2H_4$(g)+$H_2$(g)→$C_2H_6$(g)

ΔH −136kJ mol$^{-1}$
ΔS −121JK$^{-1}$mol$^{-1}$
ΔG at 298K −99.9kJ mol$^{-1}$

1.1Explain why the enthalpy of formation of $H_2$ is 0kJmol$^{-1}$.
1.2Explain why the entropy change for this reaction is negative.
2.Explain how a reaction can be spontaneous with a negative entropy change.
3.Calculate the temperature at which this reaction is no longer spontaneous.
T=  K

  The enthalpies of combustion of hydrogen and carbon are5gkcr . andd44ck *rsu3j( i(u given in the data booklet. The enthalpy of(d cn(c4j sk43iu5 .ragkur *d formation of ethene,$C_2H_4$,from its elements is ΔH$_f^θ$=+52.0kJ mol$^{-1}$.
1.Write the thermochemical equation for the formation of ethene.
2.Calculate the enthalpy of formation of ethene, using enthalpies of combustion from section 13 (Section 14- 2025 Syllabus) of the Data Booklet. Then compare to the given value above, and comment on the difference, if any.
ΔH$_r$=+  kJ mol$^{-1}$.
Important note: The section numbers mentioned in the video solution are specific to the 2024 syllabus.
You can refer to the question stem to find the section numbers for the 2025 syllabus.

  Carbon monoxide is pejrqh5: q nnj.n)sl(,roduced when there is insufficient oxygen in combustion reactions. It reacts with o(n : ,jq.ejlrqn)h5n sxygen to produce carbon dioxide according to the following equation: $CO$(g)+$\frac{1}{2}$$O_2$(g)→$CO_2$(g).

1.Define enthalpy change of combustion.

2.Using sections 11 and 13 (Sections 12 and 14- 2025 Syllabus) of the data booklet, calculate the average bond enthalpy for C≡O.

ΔH $_{BE}^{θ}$ (C≡O)=  kJ mol $^{-1}$

Important note: The section numbers mentioned in the video solution are specific to the 2024 syllabus.
You can refer to the question stem to find the section numbers for the 2025 syllabus.

  Sulfur dioxide ($SO_2$) reacts with oxygen and sulfuric acid($H_2SO_4$) to produce oleum($H_2S_2O_7$) in two reaction steps. The enthalpy cycle for this process is shown.

This process is used to produce a dilute solution of oleum in 5000g sulfuric acid from 0.80 mol sulfur dioxide. During the reaction, the temperature of the sulfuric acid increased by 22.8$^{\circ}C$.
What are the enthalpy changes of the second step,ΔH$_2$, and the overall process, ΔH$_total$, assuming no heat is lost during the reaction?
·Specific heat capacity of $H_2SO_4$,c=1.60Jg $^{-1}$K$^{-1}$;
·q=mcΔT.

  Liquid dinitrogen tet ndzlrm; eps03o23(oc dd0:y5 fid zn4roxide ($N_2O_4$) is converted to gaseous nitrogen dioxide when heated, as shown in the diagram. No other molecules react or form during this reaction.


The standard enthalpy change of the reaction,ΔH$_r^θ$, is +85.8kJmol$^{-1}$.The standard enthalpy of formation of gaseous $NO_2$ , ΔH$_r^θ$($NO_2$), is +33.1kJmol$^{-1}$.
What is the standard enthalpy of formation of liquid $N_2O_4$,ΔH$_r^θ$($N_2O_4$)?

  Hydrazine ($N_2H_4$) is a commonly used rocket fuel.
The rocket is propelled by the decomposition of liquid hydrazine into nitrogen and hydrogen gases. The equation and enthalpy change of this decomposition reaction are shown.



1.Hydrazine may also decompose via the following reactions:
Reaction 2: 3$N_2H_4$→4$NH_3$+$N_2$
Reaction 3: $N_2H_4$+4$NH_3$→3$N_2$+8$H_2$
The enthalpy changes of reactions 2 and 3 are ΔH$_2$ and ΔH$_3$, respectively.
Explain why it is possible to calculate ΔH$_1$ from ΔH$_2$ and ΔH$_3$
2.Using section 12 of the data booklet, calculate an alternative value for ΔH$_1$ in kJ mol${-1}$.
ΔH$_1$=-  (kJ mol${-1}$)
3.Suggest two reasons why the value calculated in (b) differs from the measured value of ΔH$_1$.

  The standard enthalpy of formatph c8y;ercdx3 b *z:ft-m, 1-ad0 mfidion of gaseous nitric oxide,ΔH$_f^θ$(NO(g)),is +90.3kJmol$^{-1}$.
1.Write a reaction equation, including state symbols, corresponding to the standard enthalpy of formation of gaseous nitric oxide.
2.Calculate the bond enthalpy of nitric oxide, using the value of ΔH$_f^θ$(NO(g)) above and section 11 (Section 12- 2025 Syllabus) of the data booklet.
E(N≡O)=  (kJ mol$^{-1}$)
3.In the Ostwald process, nitric oxide (NO) is reacted with oxygen and then water to produce aqueous nitric acid($HCO_3$).The overall equation and enthalpy change of this reaction are given below.
4NO(g)+3$O_2$(g)+2$H_2O$(l)→4$HNO_3$(aq)
ΔH$_1$=-576.4kJ mol$^{-1}$
Calculate the enthalpy of formation of aqueous nitric acid, ΔH$_f^θ$($HNO_3$(aq)),using the values of ΔH$_f^θ$(NO(g))=+90.3kJ mol$^{-1}$,and ΔH$_1$ and section 12 (Section 13- 2025 Syllabus) of the data booklet.

ΔH$_f^θ$($HNO_3$(aq))=  (kJ mol$^{-1}$)
4.The nitric oxide used in the Ostwald process is formed by reacting gaseous ammonia ($NH_3$) with oxygen. The equation and enthalpy change of this reaction are given below.
4$NH_3$(g)+5$O_2$(g)→4$NO$(g)+6$H_2O$(g)
ΔH$_2$=-906.0kJ mol$^{-1}$
The yield of the Ostwald process may be lower than expected if some of the nitric oxide product reacts with the remaining ammonia. The equation for this side reaction is shown.
4$NH_3$(g)+6$NO$(g)→5$N_2$(g)+6$H_2O$(g)
4.1Calculate the enthalpy change for the side reaction, Δ$H_{side}$,using the values of ΔH$_f^θ$(NO(g)) and ΔH$_2$.
Δ$H_{side}$=-  (kJ mol$^{-1}$)
2.Suggest how the value of ΔH$_2$ would differ if water were produced in the liquid phase.
The value of ΔH$_2$ would be  ----待选择----largerless  negative