Reactivity 1.2 Energy Cycle in Reactions

How does application of the law of conservation of energy help us to predict energy changes during reactions?

R1.2 Energy Cycles in Reactions.pptx

SKILLS focus

Experimental Techniques: Understand how to accurately measure the following to an appropriate level of precision: Mass, Volume, Time, Temperature
Applying techniques: Show awareness of the purpose and practice of calorimetry
Controlling Variables: calibrate measuring apparatus (calorimeter)
Controlling Variables: maintain constant environmental conditions of systems
Controlling Variables: insulate against heat loss or gain.
Technology: Applying technology to collect data by using temperature sensor
Applying general mathematics: Use basic arithmetic and algebraic calculations to solve problems.

R1.2 Energy Cycles in reactions (AHL).pptx

Applying general mathematics: Carry out calculations involving decimals, fractions, percentages, ratios, reciprocals and exponents.
Processing uncertainties: Express quantities and uncertainties to an appropriate number of significant figures or decimal places.
Graphing: Sketch graphs, with labelled but unscaled axes, to qualitatively describe trends.
Graphing: Construct and interpret tables, charts and graphs for raw and processed data including bar charts, histograms, scatter graphs and line and curve graphs.
Graphing: Extrapolate and interpolate graphs.

R1.2.1—Bond-breaking absorbs and bond-forming releases energy.
- Calculate the enthalpy change of a reaction from given average bond enthalpy data.
R1.2.2—Hess’s law states that the enthalpy change for a reaction is independent of the pathway between the initial and final states.
- Apply Hess’s law to calculate enthalpy changes in multistep reactions.
(AHL) R1.2.3—Standard enthalpy changes of combustion, ΔHc⦵, and formation, ΔHf⦵, data are used in thermodynamic calculations.
- Deduce equations and solutions to problems involving these terms.
(AHL) R1.2.4—An application of Hess’s law uses enthalpy of formation data or enthalpy of combustion data to calculate the enthalpy change of a reaction.
- Calculate enthalpy changes of a reaction
(AHL) R1.2.5—A Born–Haber cycle is an application of Hess’s law, used to show energy changes in the formation of an ionic compound.
- Interpret and determine values from a Born–Haber cycle for compounds composed of univalent and divalent ions.

Structure 2.2—How would you expect bond enthalpy data to relate to bond length and polarity?
Reactivity 3.4—How does the strength of a carbon–halogen bond affect the rate of a nucleophilic substitution reaction?
Structure 2.2—Would you expect allotropes of an element, such as diamond and graphite, to have different ΔHf⦵ values?
Structure 2.1—What are the factors that influence the strength of lattice enthalpy in an ionic compound?