DP Chemistry Questionbank

• Syllabus

Topic 5: Energetics/thermochemistry

Sub sections and their related questions

5.1 Measuring energy changes

• 15M.1.hl.TZ1.14: The same amount of heat energy is added to 1.00 g of each substance. Which statement is...
• 15M.1.hl.TZ1.16: Which equation represents the standard enthalpy of formation of liquid methanol? A.    ...
• 15M.1.hl.TZ2.16: Which equation represents the standard enthalpy change of formation, \(\Delta H_f^\Theta \), of...
• 15M.2.hl.TZ2.3a: Calculate the standard enthalpy change, \(\Delta {H^\Theta }\), in...
• 15M.1.sl.TZ1.14: Which processes are exothermic? I.    ...
• 15M.1.sl.TZ2.14: Which combination is correct for the standard enthalpy change of neutralization?
• 15M.2.sl.TZ1.5b.iv: Explain why the reaction is exothermic in terms of the bonds involved.
• 14M.1.sl.TZ1.14: Which statement is correct for the reaction with this enthalpy level diagram? A.     Heat...
• 14M.1.sl.TZ1.15: The specific heat capacities of two substances are given in the table below. Which statement...
• 14M.1.sl.TZ2.14: The table shows information about temperature increases when an acid and an alkali are...
• 14M.1.sl.TZ2.15: What is the value of \(\Delta H\) for the exothermic reaction represented by the diagram...
• 14M.1.sl.TZ2.16: What is the temperature rise when 2100 J of energy is supplied to 100 g of water? (Specific heat...
• 14M.2.sl.TZ2.6g.iv: The standard enthalpy change of combustion of A is...
• 14M.3.sl.TZ1.5a: When 1.13 g of a granola bar was combusted in a bomb calorimeter, the temperature of...
• 14N.2.hl.TZ0.2b: (i)     Define the term standard enthalpy change of formation.         (ii)     Determine...
• 14N.2.hl.TZ0.11e: Hydrochloric acid neutralizes sodium hydroxide, forming sodium chloride and...
• 14N.1.sl.TZ0.14: The enthalpy change for the reaction between zinc metal and copper(II) sulfate solution is...
• 14N.2.sl.TZ0.7e: (i)     Define the term standard enthalpy change of reaction, \(\Delta {H^\Theta...
• 13N.1.hl.TZ0.15: Which processes are exothermic?   I.    ...
• 13N.1.hl.TZ0.17: Which ionic compound has the most endothermic lattice enthalpy? A.     Sodium chloride B.   ...
• 13N.1.sl.TZ0.15: Which processes are exothermic? I.    ...
• 13N.2.sl.TZ0.4g.i: Methanol can also be burnt as a fuel. Describe an experiment that would allow the molar enthalpy...
• 13N.2.sl.TZ0.4g.ii: Explain how the results of this experiment could be used to calculate the molar enthalpy change...
• 13M.1.hl.TZ1.15: Which process is endothermic? A.    ...
• 13M.2.sl.TZ1.7a.i: Calculate the enthalpy change of combustion of methanol.
• 13M.2.sl.TZ1.7a.ii: Using the theoretical value in Table 12 of the Data Booklet, discuss the experimental results,...
• 13M.1.hl.TZ2.16: Which reaction has an enthalpy change equal to the standard enthalpy change of combustion? A.  ...
• 13M.2.hl.TZ2.5a.iii: Define the term standard enthalpy change of formation, \(\Delta H_{\text{f}}^\Theta \).
• 13M.2.hl.TZ2.5a.iv: Calculate the standard enthalpy change for the reaction, \(\Delta {H^\Theta }\), in...
• 13M.1.sl.TZ2.15: Which statements are correct for an exothermic reaction? I.     The products are more stable...
• 13M.1.sl.TZ2.16: The specific heat capacity of aluminium is...
• 13M.2.sl.TZ2.6c.iii: State whether the reaction given in stage 1 is exothermic or endothermic.
• 12N.1.sl.TZ0.14: Which combination is correct for the exothermic reaction that occurs between zinc and copper...
• 12N.1.sl.TZ0.15: A 5.00 g sample of a substance was heated from 25.0 °C to 35.0 °C using...
• 12N.2.sl.TZ0.1a: (i)     State the number of significant figures for the masses of...
• 10N.2.hl.TZ0.7c: (i)     The enthalpy change of formation, \(\Delta H_{\text{f}}^\Theta \), of liquid hydrazine is...
• 10N.1.sl.TZ0.14: Which statement is correct given the enthalpy level diagram below? A.     The reaction is...
• 10N.1.sl.TZ0.15: Identical pieces of magnesium are added to two beakers, A and B, containing hydrochloric acid....
• 09N.2.hl.TZ0.7b.i: The standard enthalpy change of three combustion reactions is given below in...
• 09N.2.hl.TZ0.7b.v: Suggest with a reason, why the values obtained in parts (b) (i) and (b) (iv) are different.
• 09N.1.sl.TZ0.15: Which is true for a chemical reaction in which the products have a higher enthalpy than the...
• 09N.1.sl.TZ0.16: In a reaction that occurs in 50 g of aqueous solution, the temperature of the reaction mixture...
• 10M.2.sl.TZ1.6a: (i)     Use the data to calculate the heat evolved when the ethanol was combusted. (ii)   ...
• 10M.1.sl.TZ2.16: Which is correct about energy changes during bond breaking and bond formation?
• 10M.1.sl.TZ2.17: Which processes are exothermic? I.     Ice melting II.     Neutralization III.   ...
• 09M.1.hl.TZ1.14: 1.0 g of sodium hydroxide, NaOH, was added to 99.0 g of water. The temperature of the solution...
• 09M.2.hl.TZ1.6b.ii: Deduce which two of the enthalpy changes a to e have negative signs.
• 09M.1.sl.TZ1.15: When some solid barium hydroxide and solid ammonium thiosulfate were reacted together, the...
• 09M.1.sl.TZ1.17: Some water is heated using the heat produced by the combustion of magnesium metal. Which values...
• 09M.1.sl.TZ2.14: What is the energy, in kJ, released when 1.00 mol of carbon monoxide is burned according to the...
• 09M.1.sl.TZ2.15: The specific heat of iron is \({\text{0.450 J}}\,{{\text{g}}^{ - 1}}{{\text{K}}^{ - 1}}\). What...
• 09M.1.sl.TZ2.16: Which of the following reactions are exothermic? I.    ...
• 09M.2.sl.TZ2.6a.iii: The standard enthalpy change for the complete combustion of octane,...
• 11M.1.sl.TZ1.14: When \({\text{100 c}}{{\text{m}}^{\text{3}}}\) of...
• 11M.2.sl.TZ1.1b.ii: Calculate the heat absorbed, in kJ, by the water.
• 11M.2.sl.TZ1.1b.iii: Determine the enthalpy change, in \({\text{kJ}}\,{\text{mo}}{{\text{l}}^{ - 1}}\), for the...
• 11M.2.sl.TZ1.1c.ii: Part (b)
• 11M.2.sl.TZ1.4a.ii: Calculate the amount, in mol, of ethanol and octane in 1.00 kg of the fuel mixture.
• 11M.2.sl.TZ1.4a.iii: Calculate the total amount of energy, in kJ, released when 1.00 kg of the fuel mixture is...
• 11M.2.hl.TZ2.6b.i: Outline why the value for the standard enthalpy change of formation of hydrogen is zero.
• 11M.2.hl.TZ2.6b.ii: Calculate the standard enthalpy change for the hydrogenation of propene.
• 11M.1.sl.TZ2.15: Which processes have a negative enthalpy change? I.    ...
• 11M.1.sl.TZ2.17: At 25 °C, \({\text{200 c}}{{\text{m}}^{\text{3}}}\) of...
• 11M.2.sl.TZ2.1a.ii: Determine what the temperature rise would have been, in °C, if no heat had been lost to the...
• 11M.2.sl.TZ2.1a.iii: Calculate the heat change, in kJ, when 3.99 g of anhydrous copper(II) sulfate is dissolved in the...
• 11M.2.sl.TZ2.1a.iv: Determine the value of \(\Delta {H_1}{\text{ in kJ}}\,{\text{mo}}{{\text{l}}^{ - 1}}\).
• 11M.2.sl.TZ2.1b.ii: Determine the value of \(\Delta {H_2}\) in \({\text{kJ}}\,{\text{mo}}{{\text{l}}^{ - 1}}\).
• 11M.2.sl.TZ2.6a.iv: The value of \({K_{\text{c}}}\) at 500 K is 160 and the value of \({K_{\text{c}}}\) at 700 K is...
• 12M.1.sl.TZ2.15: A simple calorimeter was set up to determine the enthalpy change occurring when one mole of...
• 12M.2.sl.TZ2.6d: (i)     Sketch and label an enthalpy level diagram for this reaction. (ii)     Deduce whether...
• 11N.2.hl.TZ0.5b.i: Suggest why the \(\Delta H_{\text{f}}^\Theta \) values for...
• 11N.2.hl.TZ0.5b.ii: Determine the standard enthalpy change at 298 K for the reaction.
• 11N.1.sl.TZ0.15: Which process is endothermic? A.    ...
• 11N.2.sl.TZ0.6d.i: Define the term endothermic reaction.
• 16M.3.sl.TZ0.10b: Calculate the energy, in kJ, produced from 15.0g of glucose if its enthalpy of combustion is...
• 16M.1.sl.TZ0.13: When 25.0cm3 0.100moldm−3 NaOH(aq) is mixed with 25.0cm3 0.100moldm−3 HCl(aq) at the same...
• 16M.2.sl.TZ0.2a: (i) 200.0 g of air was heated by the energy from the complete combustion of 1.00 mol phosphine....
• 16M.2.hl.TZ0.1d: Impurities cause phosphine to ignite spontaneously in air to form an oxide of phosphorus and...
• 16N.1.sl.TZ0.1: Which change of state is exothermic?  A. CO2(s) → CO2(g)B. H2O(l) → H2O(g) C. NH3(g) → NH3(l) D....
• 16N.1.sl.TZ0.15: 5.35g of solid ammonium chloride, NH4Cl(s), was added to water to form 25.0g of solution. The...
• 17M.1.sl.TZ1.13: Which expression gives the mass, in g, of ethanol required to produce 683.5 kJ of heat...
• 17M.2.sl.TZ1.4e: Hydrazine has been used as a rocket fuel. The propulsion reaction occurs in several stages but...
• 17M.2.sl.TZ1.4f: Determine the enthalpy change of reaction, ΔH, in kJ, when 1.00 mol of gaseous hydrazine...
• 17M.3.sl.TZ1.5a: Explain how the concentration may be calculated in this way.
• 17M.3.sl.TZ1.5b: Heat losses would make this method less accurate than the pH probe method. Outline why the...
• 17M.3.sl.TZ1.5c: Suggest how heat loss could be reduced.
• 17M.3.sl.TZ1.5d: State one other assumption that is usually made in the calculation of the heat produced.
• 17M.3.sl.TZ1.5f: Outline why the thermochemical method would not be appropriate for 0.001...
• 17M.3.sl.TZ1.15c: Explain, in terms of the molecular structure, the critical difference in properties that makes...
• 17M.2.sl.TZ2.8a.ii: The energy released by the reaction of one mole of hydrogen peroxide with hydroquinone is used to...
• 17M.2.hl.TZ2.8b.v: State a technique other than a pH titration that can be used to detect the equivalence point.
• 17N.1.sl.TZ0.13: Which statement is correct for this reaction? Fe2O3 (s) + 3CO (g) → 2Fe (s) + 3CO2 (g)       ΔH...
• 17N.1.hl.TZ0.17: The combustion of glucose is exothermic and occurs according to the following equation: C6H12O6...
• 17N.1.hl.TZ0.19: The enthalpy change for the dissolution of NH4NO3 is +26 kJ mol–1 at 25 °C. Which statement...
• 17N.2.sl.TZ0.1d.i: Determine the heat change, q, in kJ, for the neutralization reaction between ethanoic acid and...
• 17N.2.sl.TZ0.1d.ii: Calculate the enthalpy change, ΔH, in kJ mol–1, for the reaction between ethanoic acid and sodium...
• 17N.2.sl.TZ0.2b: Explain why the melting points of the group 1 metals (Li → Cs) decrease down the group.
• 17N.2.hl.TZ0.3b: Explain why the melting points of the group 1 metals (Li → Cs) decrease down the group whereas...
• 18M.1.sl.TZ1.13: The enthalpy of combustion of ethanol is determined by heating a known mass of tap water in a...
• 18M.1.sl.TZ2.15: Two 100 cm3 aqueous solutions, one containing 0.010 mol NaOH and the other 0.010 mol HCl, are at...

5.2 Hess’s Law

• 15M.2.hl.TZ2.3a: Calculate the standard enthalpy change, \(\Delta {H^\Theta }\), in...
• 15M.1.sl.TZ2.15: When four moles of aluminium and four moles of iron combine with oxygen to form their oxides, the...
• 14M.2.hl.TZ1.1a: (i)     Calculate the amount, in mol, of anhydrous magnesium sulfate.     (ii)     Calculate...
• 14M.2.hl.TZ1.1b: (i)     Determine the enthalpy change, \(\Delta H\), in...
• 14M.2.hl.TZ1.1c: Another group of students experimentally determined an enthalpy of hydration of...
• 14M.1.sl.TZ1.15: The enthalpy changes of three reactions are given below.     ...
• 14M.2.sl.TZ1.1b: (i)     Calculate the amount, in mol, of anhydrous magnesium sulfate.     (ii) Calculate the...
• 14M.2.sl.TZ1.1c: (i)     Determine the enthalpy change, \(\Delta H\), in...
• 14M.2.sl.TZ1.1d: Another group of students experimentally determined an enthalpy of hydration of...
• 14N.2.hl.TZ0.2b: (i)     Define the term standard enthalpy change of formation.         (ii)     Determine...
• 14N.2.hl.TZ0.2c: Comment on which of the values obtained in (a) and (b)(ii) is more accurate, giving a reason.
• 14N.2.hl.TZ0.11e: Hydrochloric acid neutralizes sodium hydroxide, forming sodium chloride and...
• 14N.1.sl.TZ0.15: Consider the following equations.     ...
• 14N.2.sl.TZ0.7e: (i)     Define the term standard enthalpy change of reaction, \(\Delta {H^\Theta...
• 13N.1.hl.TZ0.16: Consider the following two equations.     ...
• 13N.1.sl.TZ0.16: Consider the following two...
• 13M.2.hl.TZ1.8b.i: Calculate the standard enthalpy change of this reaction, using the values of enthalpy of...
• 13M.2.sl.TZ1.7b: Methanol can be produced according to the following...
• 13M.1.hl.TZ2.15: Enthalpy changes of reaction are provided for the following...
• 13M.2.sl.TZ2.2a: The standard enthalpy change of three combustion reactions are given...
• 12N.1.sl.TZ0.16: Using the equations...
• 10N.1.hl.TZ0.15: Consider the equations...
• 10N.1.hl.TZ0.16: Given the enthalpy change for the reaction...
• 09N.2.hl.TZ0.7b.i: The standard enthalpy change of three combustion reactions is given below in...
• 09N.2.sl.TZ0.3: The standard enthalpy change of three combustion reactions is given below in...
• 10M.1.sl.TZ2.15: The standard enthalpy changes for the combustion of carbon and carbon monoxide are shown...
• 09M.2.sl.TZ1.2b: Marit arranged the values she found in Table 12 into an energy cycle. Calculate the value for...
• 11M.1.hl.TZ1.17: Consider the two reactions involving iron and...
• 11M.1.sl.TZ1.16: Consider the following...
• 11M.1.sl.TZ2.16: Consider the following...
• 11M.2.sl.TZ2.1b.iii: Using the values obtained for \(\Delta {H_1}\) in (a) (iv) and \(\Delta {H_2}\) in (b) (ii),...
• 12M.1.sl.TZ2.15: A simple calorimeter was set up to determine the enthalpy change occurring when one mole of...
• 12M.1.sl.TZ2.16: Consider the...
• 12M.2.sl.TZ2.6d: (i)     Sketch and label an enthalpy level diagram for this reaction. (ii)     Deduce whether...
• 12M.2.sl.TZ2.6e: When 5.35 g ammonium chloride, \({\text{N}}{{\text{H}}_{\text{4}}}{\text{Cl(s)}}\), is added to...
• 11N.1.sl.TZ0.16: Consider the following enthalpy of combustion...
• 16M.1.sl.TZ0.14: What is the enthalpy of formation of ethyne, in kJmol−1,...
• 16M.1.hl.TZ0.16: The equation for the formation of ethyne is:   2C(s)...
• 16M.2.hl.TZ0.2a: (i) Deduce the equilibrium constant expression, Kc, for this reaction. (ii) At exactly 600°C the...
• 16N.1.sl.TZ0.13: Hydrazine reacts with oxygen. N2H4(l) + O2(g) → N2(g) + 2H2O(l)      ΔHθ = -623 kJ What is the...
• 17M.1.sl.TZ1.14: Which expression gives the enthalpy change, ΔH, for the thermal decomposition of calcium...
• 17M.2.sl.TZ1.4g: The standard enthalpy of formation of N2H4(l) is +50.6 kJ\(\,\)mol−1. Calculate the enthalpy of...
• 17M.1.sl.TZ2.14: Why is the value of the enthalpy change of this reaction calculated from bond enthalpy data less...
• 17M.2.sl.TZ2.8a.i: Calculate the enthalpy change, in kJ, for the spray reaction, using the data...
• 17M.2.hl.TZ2.6b: The overall equation for monochlorination of methane is: CH4(g) + Cl2(g) → CH3Cl(g) +...
• 17N.1.sl.TZ0.14: The enthalpy changes for two reactions are given. Br2 (l) + F2 (g) → 2BrF (g)         ΔH = x...
• 17N.2.hl.TZ0.5a: Calculate the standard enthalpy change for this reaction using the following data.
• 18M.2.hl.TZ1.3c.ii: Determine the standard enthalpy change, ΔHΘ, for the following similar reaction, using ΔHf values...
• 18M.1.sl.TZ1.14: What is the enthalpy of combustion of butane in kJ mol−1? 2C4H10(g) + 13O2(g) → 8CO2(g) +...
• 18M.2.sl.TZ1.3b.ii: Determine the standard enthalpy change, ΔHΘ, for the following similar reaction, using ΔHf values...
• 18M.1.sl.TZ2.14: What is the enthalpy change of combustion of urea, (NH2)2CO, in kJ mol−1? 2(NH2)2CO(s) + 3O2(g)...
• 18M.2.sl.TZ2.4b.i: Outline why no value is listed for H2(g).
• 18M.2.sl.TZ2.4b.ii: Determine the value of ΔHΘ, in kJ, for the reaction using the values in the table.
• 18M.2.hl.TZ2.5b.i: Outline why no value is listed for H2(g).
• 18M.2.hl.TZ2.5b.ii: Determine the value of ΔHΘ, in kJ, for the reaction using the values in the table.

5.3 Bond enthalpies

• 15M.2.hl.TZ1.5b.i: Define the term average bond enthalpy.
• 15M.1.sl.TZ1.16: Which equation corresponds to the bond enthalpy of the H–I bond? A.    ...
• 15M.1.sl.TZ2.16: Which enthalpy changes can be calculated using only bond enthalpy data? I.    ...
• 15M.2.sl.TZ1.5b.i: Define the term average bond enthalpy.
• 15M.2.sl.TZ2.1b.ii: Calculate the enthalpy change, in \({\text{kJ}}\,{\text{mo}}{{\text{l}}^{ - 1}}\), for the...
• 15M.2.sl.TZ2.7g.i: Define the term average bond enthalpy.
• 14M.3.hl.TZ1.16d: Explain, with the aid of Lewis (electron-dot) structures, the difference between oxygen and ozone...
• 14N.2.hl.TZ0.2c: Comment on which of the values obtained in (a) and (b)(ii) is more accurate, giving a reason.
• 13N.1.hl.TZ0.15: Which processes are exothermic?   I.    ...
• 13N.2.hl.TZ0.5c: Calculate the enthalpy change, in \({\text{kJ}}\,{\text{mo}}{{\text{l}}^{ - 1}}\), when one mole...
• 13N.1.sl.TZ0.15: Which processes are exothermic? I.    ...
• 13N.2.sl.TZ0.4c: Calculate the enthalpy change, in \({\text{kJ}}\,{\text{mo}}{{\text{l}}^{ - 1}}\), when one mole...
• 13N.2.sl.TZ0.4g.iii: Predict, with an explanation, how the result obtained would compare with the value in Table 12 of...
• 13M.1.sl.TZ1.15: Which statement is correct for the enthalpy level diagram shown? A.     The reaction is...
• 13M.1.sl.TZ1.16: Which combination is correct about the energy changes during bond breaking and bond formation?
• 13M.1.sl.TZ2.17: The reaction between methane and oxygen is...
• 13M.2.sl.TZ2.6c.ii: Determine the enthalpy change, \(\Delta H\), in \({\text{kJ}}\,{\text{mo}}{{\text{l}}^{ - 1}}\),...
• 12N.2.sl.TZ0.2a: Define the term average bond enthalpy.
• 12N.2.sl.TZ0.2b: (i)     Determine \(\Delta H\), the enthalpy change of the reaction, in...
• 10N.3.hl.TZ0.E4: (a)     (i)     Explain the dependence of the dissociation of diatomic oxygen, O2, and ozone, O3,...
• 10N.1.sl.TZ0.16: Which equation best represents the bond enthalpy of HCl? A.    ...
• 10N.2.sl.TZ0.4d: Hydrazine is a valuable rocket fuel. The equation for the reaction between hydrazine and oxygen...
• 10N.3.sl.TZ0.B1a: Glucose, \({{\text{C}}_{\text{6}}}{{\text{H}}_{{\text{12}}}}{{\text{O}}_{\text{6}}}\), is a...
• 09N.2.hl.TZ0.7b.iv: Using bond enthalpy values, calculate \(\Delta {H^\Theta }\) for the following...
• 09N.2.hl.TZ0.7b.v: Suggest with a reason, why the values obtained in parts (b) (i) and (b) (iv) are different.
• 09N.1.sl.TZ0.17: Use the average bond enthalpies below to calculate the enthalpy change, in kJ, for the following...
• 10M.2.hl.TZ2.4e: Comment on the environmental safety of the products of the reaction of...
• 09M.2.hl.TZ1.3b: Determine the value for the enthalpy of hydrogenation of ethene using the values for the...
• 09M.2.hl.TZ1.3c: Suggest one reason why John’s answer is slightly less accurate than Marit’s answer and calculate...
• 09M.1.sl.TZ1.16: Which process represents the C–Cl bond enthalpy in tetrachloromethane? A.    ...
• 09M.2.sl.TZ1.2a: Calculate the value for the enthalpy of hydrogenation of ethene obtained using the average bond...
• 09M.2.sl.TZ1.2c: Suggest one reason why John’s answer is slightly less accurate than Marit’s answer.
• 09M.2.sl.TZ1.2d.i: Use the average bond enthalpies to deduce a value for the enthalpy of hydrogenation of cyclohexene.
• 09M.2.sl.TZ1.2d.ii: The percentage difference between these two methods (average bond enthalpies and enthalpies of...
• 09M.2.hl.TZ2.4a: The standard enthalpy change of formation for \({\text{C}}{{\text{H}}_{\text{3}}}{\text{OH(g)}}\)...
• 09M.2.sl.TZ2.4c: Sketch an enthalpy level diagram to describe the effect of a catalyst on an exothermic reaction.
• 09M.2.sl.TZ2.6a.i: Define the term average bond enthalpy.
• 09M.2.sl.TZ2.6a.ii: Use the information from Table 10 of the Data Booklet to determine the standard enthalpy change...
• 11M.1.sl.TZ1.15: Which statement about bonding is correct? A.     Bond breaking is endothermic and requires...
• 11M.2.sl.TZ1.1a: Using the information from Table 10 of the Data Booklet, determine the theoretical enthalpy of...
• 11M.2.sl.TZ1.1c.i: Part (a)
• 11M.1.hl.TZ2.17: Which equation represents the bond enthalpy for the H–Br bond in hydrogen bromide? A.    ...
• 11M.2.sl.TZ2.6b.ii: Enthalpy changes can be determined using average bond enthalpies. Define the term average bond...
• 11M.2.sl.TZ2.6b.iii: Determine a value for the hydrogenation of propene using information from Table 10 of the Data...
• 11M.2.sl.TZ2.6b.iv: Explain why the enthalpy of hydrogenation of propene is an exothermic process.
• 12M.3.hl.TZ1.E1a: Oxygen absorbs much of the ultraviolet (UV) radiation from the sun, but ozone is important...
• 12M.3.sl.TZ1.B1a: (i)     Calculate the heat required, in kJ, to raise the temperature of the water, using data in...
• 12M.3.hl.TZ2.E3a: Explain, in terms of their bonding, how the presence of oxygen and ozone in the ozone layer helps...
• 11N.1.sl.TZ0.14: A student measured the temperature of a reaction mixture over time using a temperature probe. By...
• 11N.2.sl.TZ0.4a: Define the term average bond enthalpy.
• 11N.2.sl.TZ0.4c: Determine the standard enthalpy change, in \({\text{kJ}}\,{\text{mo}}{{\text{l}}^{ - 1}}\), for...
• 16M.1.sl.TZ0.15: Which equation represents the average bond enthalpy...
• 16M.2.sl.TZ0.3b: (i) Sketch the potential energy profile for the synthesis of phosgene, using the axes given,...
• 16M.2.hl.TZ0.3b: The enthalpy change for the reaction between nitrogen monoxide and hydrogen is −664 kJ and its...
• 16N.1.sl.TZ0.10: The C=N bond has a bond length of 130 pm and an average bond enthalpy of 615kJmol-1. Which values...
• 16N.1.sl.TZ0.14: In which reaction do the reactants have a lower potential energy than the products?  A. CH4(g) +...
• 16N.2.sl.TZ0.1a: Ethane-1,2-diol can be formed according to the following reaction. 2CO (g) +...
• 16N.2.hl.TZ0.1b: (i) Calculate ΔHθ, in kJ, for this similar reaction below using \(\Delta H_{\rm{f}}^\theta \)...
• 16N.3.sl.TZ0.6c: (i) Suggest why incomplete combustion of plastic, such as polyvinyl chloride, is common in...
• 17M.1.sl.TZ1.15: In which order does the oxygen–oxygen bond enthalpy increase? A.     H2O2 < O2 < O3 B.  ...
• 17M.1.sl.TZ2.13: What can be deduced from this reaction profile? A.     The reactants are less stable than the...
• 17M.1.sl.TZ2.15: What can be deduced from the facts that ozone absorbs UV radiation in the region of 340 nm...
• 17M.2.sl.TZ2.5b: Nitrogen dioxide and carbon monoxide react according to the following equation: NO2(g) + CO(g)...
• 17N.1.sl.TZ0.15: What is the enthalpy change, in kJ, of the following reaction? 3H2 (g) + N2 (g)...
• 17N.2.hl.TZ0.1e: Suggest why the enthalpy change of neutralization of CH3COOH is less negative than that of HCl.
• 18M.2.hl.TZ1.3c.i: Under certain conditions, ethyne can be converted to benzene. Determine the standard enthalpy...
• 18M.2.hl.TZ1.3c.iii: Explain, giving two reasons, the difference in the values for (c)(i) and (ii). If you did not...
• 18M.1.sl.TZ1.15: Which statement is correct? A.     In an exothermic reaction, the products have more energy than...
• 18M.2.sl.TZ1.3b.i: Under certain conditions, ethyne can be converted to benzene. Determine the standard enthalpy...
• 18M.2.sl.TZ1.3b.iii: Explain, giving two reasons, the difference in the values for (b)(i) and (ii). If you did not...
• 18M.1.sl.TZ2.13: Which describes the reaction shown in the potential energy profile? A.     The reaction is...
• 18M.2.sl.TZ2.4a: Hydrogen gas can be formed industrially by the reaction of natural gas with steam.              ...
• 18M.2.sl.TZ2.4b.iii: Outline why the value of enthalpy of reaction calculated from bond enthalpies is less accurate.
• 18M.2.hl.TZ2.5a: Hydrogen gas can be formed industrially by the reaction of natural gas with steam.              ...