Which row representsia5t nol-g- x. the enthalpy change for condensation and sublimation phase chan- gx 5.tnial-oges?

  Which of the following is true inq -o9wv*zkkr5 tl 6bu l3j(dm) exothermic reactions?

  Which of the following is corr1n5ionlb6k+c3r 7 kw 5ncp 2feect in an endothermic reaction?

  If a reaction is endothelj3z-l g;jx-y6i r7 ngrmic:

  Which statement is true for an endothermic reaction that results in an increase in entropy?

  The enthalpy diagramkts*v8 .3 nw/anhb(rr.9b dxt vdo-;b below shows that:

  A block of nickel of mass m=70g whose initial temperaturz6 kbyf)0 :xxae $T_1$=18.70$^{\circ}C$, absorbs 350J of heat. Given that the specific heat capacity of Ni is approximately 0.50Jg$^{-1}$K$^{-1}$ calculate the final temperature of the block $T_f$, in $^{\circ}C$.

  The following diagram shows the enthalpy of the reactants andnpb)4ibnc:noiyn2;qtr1x+ rt: my7 0 products of a reaction involving gaseous covalent compounds. Whi42)tbpi+yi ntr17bmr qoyc;xn :0 n:nch statement is correct?

  When a small amount of solid sodium hbuc i3 kvk yik(k+1,5o9jo8 ylydroxide is added to a sample of dilute hydrochloric acid, an exothermic reactk89 jkbio +ioy 3 ,l1ckky(5uvion takes place.
The following graph shows the temperature of the acid during the reaction. The cooling of the solution after the initial reaction follows an approximately linear trend, as indicated by the dotted line.

What value for the temperature change, ΔT, should be used to calculate the change in energy, q, during the reaction? q=mcΔT

  A given mass of magnesium was2 w16*kxki,oml(ln(j- dysmi nt* r i4 added to 500cm$^3$ of aqueous hydrochloric acid in a Styrofoam cup to form magnesium chloride. The temperature at the start was 18$^{\circ}C$ and after the magnesium had dissolved, the temperature rose to 20$^{\circ}C$
1.State a balanced chemical equation for this reaction. Mg+  HCl → MgCl$_2$ + $H_2$
2.Given that the change in enthalpy, ΔH is0.185kJ and the specific heat capacity of water is 4.18Jg$^{-1}$K$^{-1}$, calculate the mass of magnesium added to the hydrochloric acid. m=   g.
3.Determine the systematic errors caused by the use of styrofoam cups.

  Which of the four reactions below is an endothermiq l pnb 5y5,7zdl osg8nke*.2kc reaction?

  When a 2.80g of anhydrous* fvl )rabv ;gxb,ft; fe5)6tn copper sulfate sample, $CuSO_4$ was added to 20.0g of water in a calorimeter, a rise in temperature of 15.0$^{\circ}C$ was recorded.
Given that the specific heat capacity of water is 4.18J$g^{-1}K^{-1}$;
1.Define specific heat capacity.
2.Calculate the change in enthalpy in kJ. q=  kJ.
3.Calculate the number of moles of copper Sulfate. n($CuSO_4$)=  mol.
4.Calculate the molar enthalpy of reaction.ΔH= -  kJ\mol$^{-1}$

  The temperature of dilute mqxj u1q ar:9+-bj7j1g0a elvsulphuric acid rises when it reacts with zinc according to the following chemia 7j-xveujlqb:1m+1a0rg9jqcal equation:

1.State whether the reaction is  ----待选择----exothermicendothermic .
2.Explain what this implies in terms of the chemical potential energy contained in the reactants and the products.
3.Draw an energy level diagram for this reaction.

  Which reaction below isrzs* bk3x/znshgy,b/o 86 2of endothermic?

  When a sample of solid calcium carbonate is placed in hydrochloric a 3isu0w 0sx.w(rq(p pzcid, the following reactiowz pu0 q .p(03isw(xrsn 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.

  In the presence of a catalyst, aqumd 4utfwtc4wsv9b7z/.x- b- p eous hydrogen peroxide decomposes into water and oxygen. The equation for thiu9b cm.xtp44-z-7 w/ftsvdwb s 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.

  The following graph repr3im/jm91h;cx i;i:cz p ozrlx iu8i,9esents the change of concentration of a gaseous reactant and gaseoruczh izij 1;,xx;9i oc/3mlipi8 m9:us product during a reaction. At t=10mins, the temperature is increased and at t=15mins, the volume of the reaction vessel is increased.

  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.

  Colorimetry was used to determine the chaj -a0 j22(tq bk)ebtpknge in color for the below system at equilibrium as temperature incre 2)a-bjbpe jq( ttk2k0ases.
Which statement(s) is/are correct for the following reaction?


I.The forward reaction is exothermic
II.The backward reaction absorbs energy
III.$K_c$ decreases with increasing temperature

  The standard enthalpy of formation of gaseddaezq 6 15v2w9sia(p ous nitric oxide,ΔH$_f^θ$(NO(g)),is +kJmol$-1$.
1.Write a reaction equation, including state symbols, corresponding to the standard enthalpy of formation of gaseous nitric oxide.
$\frac{1}{2}$$N_2$(g)+$\frac{1}{2}$$O_2$(g)→   (g)
2.Calculate the bond enthalpy of nitric oxide, using the value of ΔH$_f^θ$ (NO(g)) above and section 11 (Section 12- 2025 Syllabus) of the data booklet.
3.In the Ostwald process, nitric oxide (NO) is reacted with oxygen and then water to produce aqueous nitric acid ($HNO_3$) 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$_1$=-576.4kJmol$^{-1}$
Calculate the enthalpy of formation of aqueous nitric acid, ΔH$_f^θ$(HNO$_3$ (aq)), using the values of ΔH$_f^θ$ (NO(g))= +90.3kJmol${-1}$,and
ΔH$_1$ and section 12 (Section 13- 2025 Syllabus) of the data booklet.
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.
$4NO(g)$+$5O_2(g)$→$4NO(g)$+$6H_2O(g)$
ΔH$_2$=-906.0kJmol$^-1$
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.
$4NO(g)$+$6NO(g)$→$5N_2(g)$+$6H_2O(g)$
1.Calculate the enthalpy change for the side reaction, ΔH$_{side}$=-  (kJmol$^{-1}$);using the values of ΔH$_f^θ$ (NO(g)) and ΔH$_2$.
2.Suggest how the value of ΔH$_2$ would differ if water were produced in the liquid phase.