2.4_Bonding_AS91164

[[image:printButton.gif align="left" link="@http://www.nzqa.govt.nz/nqfdocs/ncea-resource/achievements/2015/as91164.pdf"]]
= 2.4 AS 91164 Demonstrate understanding of bonding, structure, properties & energy changes (5 credits) =

__ LEWIS DIAGRAMS __

 * [[image:level2lewis1.jpg width="252" height="185" link="@http://wps.prenhall.com/wps/media/objects/4678/4790506/ch07_05.htm"]] || [[image:chemicalminds/Level2lewis2.jpg width="279" height="143" link="@http://chemsite.lsrhs.net/bonding/flashLewis.html"]] || [[image:level2lewis3.jpg width="331" height="192" link="@https://www.wisc-online.com/learn/natural-science/chemistry/gch6404/lewis-dot-structures-of-covalent-compounds"]] ||

NCEA PAST EXAM QUESTION: Draw the Lewis structure (electron dot diagram) for each molecule


The table below provides an overview of the molecules and year that they appeared in the NCEA Exams
====Download and print the Lewis.doc below which contains the molecules (as shown above) with space to draw the Lewis diagrams. Check your answers. ====  ====Then, download, print and attempt the "Crystal Ball Activity" with other molecules that have not - as yet been asked in the NCEA Level 2 exam ====

__SHAPES OF MOLECULES __

 * [[image:phetmoleculebasics.jpg width="264" height="236" link="@https://phet.colorado.edu/en/simulation/molecule-shapes-basics"]] || [[image:molecule3d.jpg width="275" height="238" link="@file:molecule3d.swf"]] || [[image:chemicalminds/pbsshapes.jpg width="314" height="193" link="@http://www.pbslearningmedia.org/asset/lsps07_int_molecularshp/"]] ||

iii) state the bond angles


Download a Powerpoint "Summary of Level 2 Shapes of molecules"
====Draw a 3D diagram of the arrangement of the atoms for every molecule provided in the table above, then name the shape of each molecule with the correct bond angles. ====

You may find it useful to download and print the table where there is space provided to draw the 3D shapes


__DESCRIBING AND EXPLAINING SHAPES __
==NCEA EXAM QUESTION: Describing and Explaining shapes and bond angles. In your answer, you must make reference to the arrangement of electrons. ==  <span style="color: #f95725; font-family: Arial,Helvetica,sans-serif;">

<span style="font-family: Arial,Helvetica,sans-serif;"> • reference to the arrangement of electrons around the B and O atoms
<span style="color: #f95725; font-family: Arial,Helvetica,sans-serif;"> ==== Boron and phosphorus both bond with three fluorine atoms to form BF3 and PF3. However, the molecules have different shapes and bond angles. The following table shows the Lewis structures for the molecules BF3 and PF3. ====

• justification of your chosen bond angles for each molecule.
====<span style="color: #f95725; font-family: Arial,Helvetica,sans-serif;"> The following table shows the Lewis structures and bond angles for the molecules SO 2 <span style="font-family: Arial,Helvetica,sans-serif;">and H2CO. ====

<span style="font-family: Arial,Helvetica,sans-serif;">Discuss why these molecules have different bond angles. Your answer must include:
<span style="font-family: Arial,Helvetica,sans-serif;"> The Lewis structures of the molecules NCl 3 and SO 3 are given below.
 * ====<span style="font-family: Arial,Helvetica,sans-serif;">factors which determine the shape of each molecule ====
 * ====<span style="font-family: Arial,Helvetica,sans-serif;">the approximate bond angle for each molecule. ====
 * [[image:angles2009.jpg width="157" height="108" align="center"]] || [[image:angles20092.jpg width="155" height="137" align="center"]] ||

<span style="font-family: Arial,Helvetica,sans-serif;">• justify your answers.
<span style="font-family: Arial,Helvetica,sans-serif; line-height: 0px; overflow: hidden;">

<span style="font-family: Arial,Helvetica,sans-serif;">• justify your answer.
<span style="font-family: Arial,Helvetica,sans-serif;">
 * [[image:angles2008.jpg align="center"]] || [[image:angles20082.jpg]] ||

<span style="color: #f95725; font-family: Arial,Helvetica,sans-serif;">NCEA EXAM QUESTION: Tick the correct box to state whether the molecules contain a polar bond or non polar bond
<span style="color: #f95725; font-family: Arial,Helvetica,sans-serif;"> <span style="font-family: Arial,Helvetica,sans-serif;">

<span style="color: #f95725; font-family: Arial,Helvetica,sans-serif;">NCEA EXAM QUESTION: State the polarity of the following molecules
<span style="color: #f95725; font-family: Arial,Helvetica,sans-serif; line-height: 0px; overflow: hidden;">

<span style="color: #f95725; font-family: Arial,Helvetica,sans-serif;">NCEA EXAM QUESTION For each molecule listed in the table above, explain the reason for your choice
<span style="color: #f95725; font-family: Arial,Helvetica,sans-serif;">

Justify your answer and draw diagrams of the possible molecules with dipoles labelled. You do not need to identify what elements M and X are.
<span style="font-family: Arial,Helvetica,sans-serif;">

<span style="color: #f95725; font-family: Arial,Helvetica,sans-serif;">NCEA EXAMINATION QUESTION: This question is based on a experiment that you should have carried out in class
<span style="color: #f95725; font-family: Arial,Helvetica,sans-serif;"> ====<span style="color: #f95725; font-family: Arial,Helvetica,sans-serif;">. <span style="font-family: Arial,Helvetica,sans-serif;">..you missed your practical lessons? This virtual experiment may help, click on the image below ====

====Two burettes are set up. One burette contains water (a polar liquid) and the other contains cyclohexane (a non-polar liquid). The liquid is allowed to run from each burette in a steady stream. A charged plastic ruler is then placed near the stream of each liquid.Describe and Explain what will be seen when the charged ruler is placed near the stream of each liquid.==== <span style="color: #221e1f; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> <span style="color: #221e1f; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> There are a "HEAP" of questions here, based on experiments in which you must interpret and explain polarity - good luck!

__<span style="color: #f95725; font-family: Arial,Helvetica,sans-serif;">SUMMARY OF BONDING __

 * [[image:summary1.jpg width="215" height="185" link="@http://www.visionlearning.com/en/library/Chemistry/1/Chemical-Bonding/55"]] || [[image:summary2.jpg width="273" height="176" link="@http://media.wwnorton.com/college/chemistry/chemtours/chapter_08/bonding/Interface.swf"]] || [[image:chemicalminds/summary3.jpg width="328" height="141" link="@http://www.creative-chemistry.org.uk/molecules/structures.htm"]] ||

<span style="color: #f95725; font-family: Arial,Helvetica,sans-serif;">iii) the bonding (attractive forces between particles)
<span style="color: #f95725; font-family: Arial,Helvetica,sans-serif;">

__ JUSTIFY PROPERTIES OF SUBSTANCES __

 * [[image:properties1.jpg width="220" height="181" link="@http://www.education.uoit.ca/lordec/ID_LORDEC/ionic_compounds/law_ionic_compounds.swf"]] || [[image:properties2.jpg width="229" height="172" link="@http://www.bbc.co.uk/education/guides/z94xsbk/revision/3"]] || [[image:properties3.jpg width="199" height="175" link="@http://www.avogadro.co.uk/structure/chemstruc/network/g-molecular.htm"]] || [[image:chemicalminds/properties4.jpg width="199" height="99" link="@http://www.ausetute.com.au/metallic.html"]] ||

<span style="color: #f95725; font-family: Arial,Helvetica,sans-serif;">NCEA EXAM QUESTIONS: Justify each of the properties of the following substances
<span style="color: #f95725; font-family: Arial,Helvetica,sans-serif; line-height: 0px; overflow: hidden;">

Silicon dioxide has a melting point of 1770°C.Explain why silicon dioxide has a high melting point by referring to the particles and the forces between the particles in the solid.
//see below a copy of a related question that was in the //

====The diagrams below show structural representations of the two solids ice, H 2 O, and sodium chloride, NaCl. <span style="font-family: Arial,Helvetica,sans-serif;">Ice melts at 0°C and sodium chloride melts at 801°C. ====

<span style="font-family: Arial,Helvetica,sans-serif;">On each diagram above, circle ONE of the forces of attraction which must be overcome for the substance to melt. Give a reason for your choice.
<span style="font-family: Arial,Helvetica,sans-serif;"> ====<span style="font-family: Arial,Helvetica,sans-serif;">Discuss the reasons why the following two carbon-containing compounds (methane and calcium carbide) have different melting points. The melting points are given in the table below. ====

<span style="font-family: Arial,Helvetica,sans-serif;">• the strength of these attractive forces.
====<span style="font-family: Arial,Helvetica,sans-serif;">There is no Crystal Ball activity here as once you've completed the student activity above and marked them you'll be sweet with Explaining properties of solids. ====

<span style="color: #f95725; font-family: Arial,Helvetica,sans-serif;">NCEA EXAM QUESTIONS: Compare and contrast the properties of the following substances
<span style="color: #f95725; font-family: Arial,Helvetica,sans-serif;">

Using your knowledge of structure and bonding, explain why, although both graphite and copper are good conductors of electricity, copper is suitable for electrical wires, but graphite is not.
<span style="font-family: Arial,Helvetica,sans-serif;">

=__Energy changes section of the exam paper__= ==<span style="color: #f95725; font-family: Arial,Helvetica,sans-serif;">NCEA EXAM QUESTIONS: Classify the following reactions as endothermic or exothermic == <span style="color: #000000; font-family: Arial,Helvetica,sans-serif;">

<span style="color: #f95725; font-family: Arial,Helvetica,sans-serif;">[[image:printButton.gif link="@file:explainingendoexo.pdf"]]

 * [[image:exograph.jpg width="318" height="327" link="@file:exothermicgraph.swf"]] || [[image:explainendoexo.jpg width="397" height="254" link="@http://www.emsb.qc.ca/laurenhill/science/exo.html"]] ||

<span style="color: #f95725; font-family: Arial,Helvetica,sans-serif;"> NCEA EXAM QUESTIONS: Answer the following questions to Explain Endothermic and Exothermic reactions
<span style="color: #f95725; font-family: Arial,Helvetica,sans-serif;">

** b) ** The freezing of water to form ice can be represented by the following equation. H 2 O( l ) → H 2 O(//s//)
<span style="color: #f95725; font-family: Arial,Helvetica,sans-serif;">

Choose the term **(endothermic or exothermic)** that best describes this process.
Choose the phrase that best describes what you would observe happening to the beaker during this process (gets colder, stays the same, gets warmer) Explain your choice. **(b)** Glucose is an important source of energy in our diet. The equation below shows the combustion of glucose to form carbon dioxide and water.C6H12O6(s) + 6O2(g) → 6CO2(g) + 6H2O(ℓ) Δr H° = –2 820 kJ mol–1

** (i) ** Choose the term **(endothermic or** **exothermic)** that best describes this process. Give a reason for your choice.
====** (ii) ** Females who are moderately active need 9 800 kJ of energy per day. Calculate the number of moles of glucose that would provide this daily energy<span style="color: #f95725; font-family: Arial,Helvetica,sans-serif;"> r equirement.==== ====** (c) ** Many portable BBQ and camping gas canisters contain butane, C4H10. Butane is a gas at room temperature, and has a boiling point of – 0.5°C. The gas canisters contain both gas and liquid butane. As the gaseous butane is used, some of the liquid evaporates. ====

Choose the term **(endothermic or** **exothermic)** that best describes this process.
====<span style="font-family: Arial,Helvetica,sans-serif;">Give a reason for your choice, and use your knowledge of structure and bonding, and energy changes, to explain the changes occurring as the liquid evaporates. ==== <span style="color: #f95725; font-family: Arial,Helvetica,sans-serif;">

a) Some Bunsen burners use methane gas, CH 4, as a fuel. The reaction for the combustion of methane in a Bunsen burner is shown in **Equation One** below.
Equation One: CH4+ 2O2→ CO2+ 2H2O ΔrH = –889 kJ mol–1

b) The equation for water boiling at 100°C is shown below in ** Equation Two **.
Equation Two: H2O(ℓ) → H2O(g) ΔrH = 40.7 kJ mol–1

b) The reaction between hydrogen gas and oxygen gas to form water in the gaseous state can be represented by:[[image:H2.jpg]]
====When this reaction occurs, bonds are broken and bonds are formed, state which bonds are broken and which bonds are formed. The bond breaking and bond forming processes above can be described as EITHER exothermic OR endothermic. State which process is exothermic and which process is endothermic and Explain your answer==== (a) For the reaction 4NH3(g) + 5O2(g) --> 4NO(g) + 6H2O(g), the enthalpy of reaction is ΔrH = –950 kJ mol–1. The reverse reaction is 4NO(g) + 6H2O(g) --> 4NH3(g) + 5O2(g) Two energy diagrams are shown below. One is for the forward reaction and one is for the same reaction in the reverse direction.

iv) Determine the value for the enthalpy of reaction (ΔrH ) for the reaction shown in Diagram Two. Explain how you determined this value.
<span style="color: #000000; font-family: Arial,Helvetica,sans-serif;">



<span style="color: #f95725; font-family: Arial,Helvetica,sans-serif;">NCEA EXAM QUESTIONS: Carry out the following energy change calculations
<span style="color: #f95725; font-family: Arial,Helvetica,sans-serif;">

// M // ( CH3OH) = 32.0 g mol–1 // M // ( C2H5OH) = 46.0 g mol–1
<span style="color: #f95725; font-family: Arial,Helvetica,sans-serif;">

Your answer should include calculations of the heat energy produced for the given mass of iron formed. M(Fe) = 55.9 g mol–1.
<span style="color: #f95725; font-family: Arial,Helvetica,sans-serif;">

2) Magnesium burns in oxygen to produce magnesium oxide. The equation for the chemical reaction is be represented by:
2Mg(//s//)+ O2(//g//) --> 2MgO(//s//) <span style="font-family: 'Arial','sans-serif';">∆ r//H// = –1200 kJ mol–1

ii) Calculate the mass of magnesium that must react to release 98.2kJ of energy.
<span style="color: #f95725; font-family: Arial,Helvetica,sans-serif;">

(1) The overall reaction occurring in many disposable hand warmers can be represented by:
4Fe(s) + 3O2(g) → 2Fe2O3(s) ΔrH = –1652 kJ mol–1

(2) Hydrogen and methane can be used as fuels.
2H2(g) + O2(g) → 2H2O(ℓ) Δr H = –570 kJ mol–1CH4(g) + 2O2(g) → CO2(g) + 2H2O(ℓ) Δr H = –890 kJ mol–1

When a 12.2 g sample of ammonia is burned, 275 kJ of energy is released. Calculate the energy released for the reaction below, when four moles of ammonia are burned.
4NH3(g) + 3O2(g) → 2N2(g) + 6H2O(ℓ)

The equation for the reaction between calcium oxide, CaO, and water can be represented as Calculate the mass of calcium oxide required to release 287 kJ of energy.
CaO(s) + H2O(ℓ) → Ca(OH)2(aq) ΔH = –82.0 kJ mol–1

When an 18.4 g sample of ethanol is burned, 546 kJ of energy is released. Determine the enthalpy change, Δ r // H //, for the reaction when one mole of ethanol is burned.
C2H5OH(l) + 3O2(g) → 2CO2(g) + 3H2O(l) ====(1) 29.6 g of sodium hydroxide was dissolved in water and excess hydrochloric acid was added. Using the temperature increase and the heat capacity of water, it was calculated that 43.5 kJ of heat was released.====

(i) Determine the enthalpy change, Δ r//H//, for the following reaction:
NaOH(//aq//) + HCl(//aq//) → NaCl(//aq//) + H 2 O(//l//)

(ii) What mass of sodium hydroxide is required to produce 150 kJ of energy?
====<span style="font-family: Arial,Helvetica,sans-serif;">(2) The principle of a fireworks-type explosion can be demonstrated by igniting a sucrose jellybaby with sodium chlorate, NaClO <span style="font-family: Arial,Helvetica,sans-serif; vertical-align: sub;">3 <span style="font-family: Arial,Helvetica,sans-serif;">. The equation for the explosion reaction is: ==== 2NaClO3(s) + C12H22O11(s) → 2NaCl(s) + 9C(s) + 3CO2(g) + 11H2O(g) <span style="font-family: Arial,Helvetica,sans-serif;">Δr H° = –2192 kJ mol <span style="font-family: Arial,Helvetica,sans-serif; vertical-align: super;">–1

<span style="font-family: Arial,Helvetica,sans-serif;">Calculate...
====<span style="font-family: Arial,Helvetica,sans-serif;">(i) the quantity of heat released when one jelly-baby containing 4.56 g of sucrose (C <span style="font-family: Arial,Helvetica,sans-serif; vertical-align: sub;">12 <span style="font-family: Arial,Helvetica,sans-serif;">H <span style="font-family: Arial,Helvetica,sans-serif; vertical-align: sub;">22 <span style="font-family: Arial,Helvetica,sans-serif;">O <span style="font-family: Arial,Helvetica,sans-serif; vertical-align: sub;">11 <span style="font-family: Arial,Helvetica,sans-serif;">) is exploded. ====

<span style="font-family: Arial,Helvetica,sans-serif;">(ii) The heat released by the explosion can be used to vaporise strontium chloride to give the fireworks colour.
====<span style="font-family: Arial,Helvetica,sans-serif;">(iii) The heat required to convert SrCl <span style="font-family: Arial,Helvetica,sans-serif; vertical-align: sub;">2 <span style="font-family: Arial,Helvetica,sans-serif;"> from the solid to the gas state is 343 kJ mol <span style="font-family: Arial,Helvetica,sans-serif; vertical-align: super;">–1 <span style="font-family: Arial,Helvetica,sans-serif;">. ==== ====<span style="font-family: Arial,Helvetica,sans-serif;">(iv) Use your answer to (i) above to calculate the mass of solid SrCl <span style="font-family: Arial,Helvetica,sans-serif; vertical-align: sub;">2 <span style="font-family: Arial,Helvetica,sans-serif;"> that can be vaporised by exploding one jelly baby containing 4.5 g of sucrose. ==== <span style="font-family: Arial,Helvetica,sans-serif;">

<span style="font-family: Arial,Helvetica,sans-serif;">Octane is a key component in petrol, and burns according to the following equation:
C8H18(l) + 12 1/2 O2(g) → 8 CO2 (g) + 9 H2O(l) ΔrH = -5500 kJ mol-1

<span style="font-family: Arial,Helvetica,sans-serif;">(i) 1.00 litre of octane contains 6.12 moles of the fuel. Calculate the energy released when 1 litre of the fuel is burnt.
====<span style="font-family: Arial,Helvetica,sans-serif;">Using hydrogen gas (H <span style="font-family: Arial,Helvetica,sans-serif; vertical-align: sub;">2 <span style="font-family: Arial,Helvetica,sans-serif;">) as a fuel for cars, rather than octane, is often viewed as better for the environment. ==== ====<span style="font-family: Arial,Helvetica,sans-serif;">(ii) Calculate the mass of H <span style="font-family: Arial,Helvetica,sans-serif; vertical-align: sub;">2 <span style="font-family: Arial,Helvetica,sans-serif;"> required to produce the same amount of energy as 1.00 litre of octane, as calculated in part (b) above. State your answer to 3 significant figures. H <span style="font-family: Arial,Helvetica,sans-serif; vertical-align: sub;">2 <span style="font-family: Arial,Helvetica,sans-serif;">(g) + 1/2 O <span style="font-family: Arial,Helvetica,sans-serif; vertical-align: sub;">2 <span style="font-family: Arial,Helvetica,sans-serif;">(g) → H <span style="font-family: Arial,Helvetica,sans-serif; vertical-align: sub;">2 <span style="font-family: Arial,Helvetica,sans-serif;">O(g) ΔrH= -286 kJmol <span style="font-family: Arial,Helvetica,sans-serif; vertical-align: super;">-1 ====

__<span style="color: #f95725; font-family: Arial,Helvetica,sans-serif;">BOND ENTHALPY __

 * [[image:chemicalminds/bondenthalpy.jpg width="324" height="172" link="@http://www.media.pearson.com.au/schools/cw/au_sch_lewis_cw1/int/bonds/0911.html"]] || [[image:bondenthalpy2.jpg width="366" height="239" link="@http://www.slideshare.net/mrtangextrahelp/tang-06-bond-energy-17729639"]] ||

<span style="color: #f95725; font-family: Arial,Helvetica,sans-serif;">NCEA EXAM QUESTIONS: Carry out the following Bond Energy Calculations
//<span style="font-family: Arial,Helvetica,sans-serif;">Use the Bond Enthalpy values provided in the table below to answer the questions (referenced from previous NCEA Exams) // <span style="display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> <span style="display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;">Hydrogen gas, H2(g), reacts with oxygen gas, O2(g), as shown by the following equation <span style="display: block; font-family: Arial,Helvetica,sans-serif; text-align: center;">H2(g) + ½ O2(g) → H2O(g) Δr Ho = –242 kJ mol–1 <span style="display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;">Given the average bond enthalpies in the table below, calculate the average bond enthalpy of the O – H bond in H2O.

Chlorine reacts with methane to form chloromethane and hydrogen chloride, as shown in the equation below.
CH4(//g//) + Cl2(//g//) → CH3Cl(//g//) + HCl(//g//)

**a)** The equation for the combustion of propan-1-ol is:
CH 3 CH 2 CH 2 OH(//g//) + 4½O 2 (//g//) → 3CO 2 (//g//) + 4H 2 O(//g//) Δ r //H// = –2010 kJ mol –1

Complete combustion of methanol can be represented by the following equation: Use the bond enthalpies to calculate Δr//H// for this reaction.
2CH3OH(g) + 3O2(g) → 2CO2(g) + 4H2O(g)

Calculate the enthalpy change for the reaction below using the bond enthalpy data in the table.
CH3Cl(g) + NH3(g) → CH3NH2(g) + HCl(g) <span style="display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;">

Methylhydrazine, N2H3CH3, can be used as a fuel. The structural formula for methylhydrazine is
<span style="display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;">**i)** Define the term bond enthalpy.

<span style="font-family: Arial,Helvetica,sans-serif;">**ii)** Use the bond enthalpies given in the table below to calculate the energy released when one mole of methylhydrazine vapour is burned.
<span style="display: block; font-family: Arial,Helvetica,sans-serif; text-align: center;">N2H3CH3(g) + 2½O2(g) → CO2(g) + N2(g) + 3H2O(g) <span style="display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;">

Calculate the enthalpy of formation of water in the gas state, <span style="font-family: Arial,Helvetica,sans-serif;">Δ fH°(H2O, g)
<span style="display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;">

<span style="font-family: Arial,Helvetica,sans-serif;">Carbon monoxide is reacted with steam to produce hydrogen gas.
<span style="display: block; font-family: Arial,Helvetica,sans-serif; text-align: center;">CO(g) + H2O(g) --> H2(g) + CO2(g) ΔrH = – 41.2 kJ mol–1

<span style="font-family: Arial,Helvetica,sans-serif;">The bond enthalpies for the carbon to oxygen bonds in CO2 and CO are different.
====<span style="font-family: Arial,Helvetica,sans-serif;">**i)** Use the bond enthalpies and the enthalpy of the reaction to calculate the bond enthalpy of the carbon to oxygen bond in CO. Why are bond enthalpy values always positive? Explain the difference between the following bond enthalpies. ====

**iii)** Explain the difference between the C – O and C = O enthalpies
====<span style="font-family: Arial,Helvetica,sans-serif;">A fuel cell, such as that used on a space-craft, is similar to a battery. An example is the fuel cell that ‘burns’ hydrogen and oxygen to produce water and energy. ====

<span style="font-family: Arial,Helvetica,sans-serif;">The overall equation for the reaction is
<span style="display: block; font-family: Arial,Helvetica,sans-serif; text-align: center;">2H2(g) + O2(g) --> 2H2O(l ) ΔrH ° = – 572 kJ mol–1

<span style="font-family: Arial,Helvetica,sans-serif;">**a)** If the water produced is in the gas phase the equation for the reaction is
<span style="display: block; font-family: Arial,Helvetica,sans-serif; text-align: center;">2H2(g) + O2(g) --> 2H2O(g) ====<span style="font-family: Arial,Helvetica,sans-serif;">**b)** Use the bond enthalpies to calculate Δ<span style="font-family: Arial,Helvetica,sans-serif;">rH ° for this reaction. Write an equation for which the enthalpy change is equal to Δ <span style="font-family: Arial,Helvetica,sans-serif;">vapH ° (H2O). ====

<span style="font-family: Arial,Helvetica,sans-serif;">**d)** Using the information above, calculate the value of Δ <span style="font-family: Arial,Helvetica,sans-serif;">vapH ° (H2O).
<span style="color: #000000; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;">



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 * === sciPAD Exam ===

Reviseonline 2012 Exam
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Reviseonline 2013 Exam
|| <span style="display: block; height: 1px; left: -40px; margin-left: 56pt; overflow: hidden; position: absolute; text-indent: -56pt; top: 11237px; width: 1px;"> The following table describes the shapes around two of the atoms in the molecule above.
 * ===sciPAD ANSWERS=== ||  || ===2012 ANSWERS=== ||   || ===2013 ANSWERS=== ||

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