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- 1. Multiple Choice
How do you calculate Enthalpy of a reaction?
ΔH = ΔHproducts - ΔHreactants
ΔT = q / mC
ΔG = ΔH -TΔS
E = mc2
- 2. Multiple Choice
What is standard enthalpy of formation, ΔHfo?
Heat change when 1 mole of gaseous ions is hydrated in water at 25oC and 1 atm
Heat change when 1 mole of compound is formed from its elements in their standard states at 25oC and 1 atm
Heat change when 1 mole of gaseous atom is formed from its elements at 25oC and 1 atm
Heat change when 1 mole of electrons is removed from 1 mole of gaseous atoms at ground state at 25oC and 1 atm
- 3. Multiple Choice
Define standard enthalpy of combustion.
Heat released when one mole of substance is burnt completely in excess oxygen.
Heat absorbed when one mole of substance is burnt completely in excess oxygen under standard state.
Heat released when one mole of substance is burnt completely in excess oxygen under standard state.
Heat change when one mole of substance is burnt partially in excess oxygen under standard state.
- 4. Multiple Choice
Which of the following has a ΔHfo value of 0?
Br2(g)
N(g)
CO(g)
Ne(g)
- 5. Multiple Choice
Which of the equation below refers to the standard enthalpy of formation, ΔHfo?
Na(g) ---> Na+(g) + e- ΔH = -364 kJmol-1
C2H5OH(l) + 3O2(g) ---> 2CO2(g) + 3H2O (l) ΔH = - 1286 kJmol-1
2C(s) + 2H2(g) ---> C2H4 (g) ΔH = - 52.3 kJmol-1
Na+(g) ---> Na+(aq) ΔH = - 364 kJmol-1
- 6. Multiple Choice
When 1.0 mole of ZnO(s) decomposes,
ZnO(s) ---> Zn(s) + 1/2 O2(g) , enthalpy change is +348 kJ/mol.
What does this tell you about the formation of ZnO (s)?
the formation of ZnO (s) is endothermic
the formation of ZnO (s) is exothermic
the formation of ZnO (s) does not require energy
the formation of ZnO (s) absorbs heat.
- 7. Multiple ChoiceWhich statement is true regarding endothermic reactions?a) Temperature change is positive and enthalpy change is positiveb) Temperature change is positive and enthalpy change is negativec) Temperature change is negative and enthalpy change is positived) Temperature change is negative and enthalpy change is negative
- 8. Multiple ChoiceEndothermic reactions feelwarmcold
- 9. Multiple ChoiceDefine 'Enthalpy'a) Energy stored in the movement of molecules in a substanceb) The opposite of temperaturec) The temperature of a moleculed) Energy stored in the chemical bonds in a substance
- 10. Multiple ChoiceHeat is measured injoulesgramsdegrees celcius
- 11. Multiple ChoiceDescribe the energy change that takes place when bonds are broken.a) Energy is given outb) Energy is taken inc) Energy is taken in and then given outd) Energy is given out and then taken in
- 12. Multiple ChoiceWhich is an example of an endothermic physical reaction?a) Ice meltingb) Combustionc) Steam condensingd) Photosynthesis
- 13. Multiple Choice
Which statement is FALSE for an exothermic reaction?Reactants higher in energy and less stableProduct lower in energy and more stableProducts have stronger bonds than reactantsReactants have stronger bonds than products - 14. Multiple ChoiceDiagram below showsStandard lattice enthalpyStandard enthalpy of precipitationStandard enthalpy of formationStandard enthalpy of hydration
- 15. Multiple ChoiceΔH value in an endothermic reaction is a positive number.TrueFalse
- 16. Multiple ChoiceThe enthalpy change for the reaction
C(s, graphite) + 1⁄2O2(g) --> CO(g) cannot be measured directly since some carbon dioxide is always formed in the reaction.
It can be calculated using Hess’s Law and the enthalpy changes of combustion of graphite and of carbon monoxide.
C(s, graphite) + O2(g) --> CO2 ΔH=-394 kJmol–1
CO(g) + 1⁄2O2(g) --> CO2 ΔH=-283 kJmol–1
The enthalpy change for the reaction of graphite with oxygen to give carbon monoxide is-677 kJmol–1+111 kJmol–1-111 kJmol–1+677 kJmol–1 - 17. Multiple Choice
The standard enthalpy changes of combustion of carbon, hydrogen and methane are shown in the table.
Which one of the following expressions gives the correct value for the standard enthalpy change of formation of methane in kJ mol–1?
C(s) + 2H2(g) → CH4(g)
394 + (2 × 286) – 891
–394 – (2 × 286) + 891
394 + 286 – 891
–394 – 286 + 891
- 18. Multiple ChoiceGiven the following data: ΔH○f[FeO(s)] = –270kJmol–1
ΔH○f [Fe2O3(s)] = –820 kJ mol–1
Select the expression which gives the enthalpy change, in kJ mol–1, for the reaction:
2FeO(s) + 1⁄2O2(g) → Fe2O3(s)(–820 × 1⁄2) + 270 = –140(+820 × 1⁄2) – 270 = +140–820 + (270 × 2) = –280+820 – (270 × 2) = +280 - 19. Multiple ChoiceThe standard enthalpy changes of formation of iron(II) oxide, FeO(s), and aluminium oxide, Al2O3(s), are –266 kJ mol–1 and –1676 kJ mol–1 respectively.
What is the enthalpy change under standard conditions for the following reaction?
3FeO(s) + 2Al (s) -> 3Fe(s) + Al2O3(s)+878kJ–878kJ–1942kJ–2474kJ - 20. Multiple ChoiceC2H4(g) + H2(g) -> C2H6(g) ∆H°=-137 kJ mol-1
Which statement about this information is correct?The total energy of the bonds broken in the reactants is greater
than the total energy of the bonds
formed in the productThe bonds broken and the bonds made are of the same strengthThe total energy of the bonds broken in the reactants is less than the total energy of the bonds formed in the productNo conclusion can be made about the sums of the bond enthalpies in the product compared with the reactants - 21. Multiple Choice-296.1226-11255.95
- 22. Multiple Choice22625523311.3
- 23. Multiple Choice-233-11.3-805-226
- 24. Multiple Choice256202233804
- 25. Multiple Choice-804.6-202.3-296.1-233.0
- 26. Multiple ChoiceCalculate the change in enthalpy, ΔH, for the reaction:
NH4Cl(s) ---> NH3 (g) + HCl(g)176.9 kJ84.4 kJ-2.29 kJ34.4 kJ - 27. Multiple Choice
Calculate the change in enthalpy, ΔH, for the reaction:
H2O (g) + SnO (s) ---> H2 (g) + SnO2 (s)
ΔHf SnO (s) = -285 KJ/mol
-53.88 kJ
84.4 kJ
-83.2 kJ
34.4 kJ
- 28. Multiple ChoiceCalculate the change in enthalpy, ΔH, for the reaction:
2 H2S(g) + 3 O2(g) ---> 2 H2O(l) + 2 SO2(g)-1123.6 kJ-994.5 kJ1004.2 kJ992.2 kJ - Answer choicesTagsAnswer choicesTags