What Drives Chemical Reactions D.2 Energy Cycles in Reactions (id: fd47ac3c0)

本题目来源于试卷: What Drives Chemical Reactions D.2 Energy Cycles in Reactions，类别为 IB化学

[单选题]
Ethene reacts with hydrogen bromide at 298 K and 100 k Pa presseu ;gwc .9bt1 olkv/q,c/wgu5ure to p xt4qbm7 ;j7qr-rp8ch roduce bromoethane. All three compounds are gases under these conqxrcbr ;87pq- h 7tmj4ditions.The enthalpy change of this reaction, ΔH$_r$, an be estimated from the enthalpies of formation (Method 1) or average bond enthalpies (Method 2) of the reactants and products. The enthalpy cycles used in these calculations are shown.

?
Which method gives the least accurate estimate of ΔH$_r$

A. Method 1, because the reaction is not taking place under standard conditions
B. Method 1, because the elements are not all gases in their standard states
C. Method 2, because bond enthalpies may differ from the average values
D. Method 2, because boiling and sublimation processes are not accounted for


参考答案:  C


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