Energetics | Multiple Choice Question Walkthrough | A level Chemistry

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Energetics
Multiple Choice Question Walkthrough
00:05 Introduction
00:17 Enthalpy of formation
02:23 Calculating Enthalpy Change
07:17 Hess' Law
09:49 Bond Dissociation Enthalpy
12:40 Using Enthalpy of Formation
17:17 Temperature Change Calculation
18:27 Using Enthalpy of Combustion
21:31 Calorimetry
23:29 Percentage Uncertainty

[@hxrmxn2034]

in question 3 why have you used 2Fe and 3/2 02 as the elements and not Fe and 02 ? You picked equation 2 not 1? Someone pls help I have a test tomorrow :(

[@maarr77]

I’m a bit confused, question 5 the answer is negative but for question 7 its positive but they are both formation (shouldn’t formation always be negative)

[@chemistrytutor]

Lattice enthalpy of formation should always be negative, and dissociation positive. However, standard enthalpy of formation can be negative or positive. We encounter more exothermic ones in nature as they are more likely to occur spontaneously, but there are still some positive ones

[@maarr77]

@@chemistrytutor Thank you!! I just have 2 more questions if that’s ok, what is lattice enthalpy of formation? And in these multiple choice questions, would my answer always give me the right sign, like - or + or would i have to change it according to the question?

[@ifty873]

videos for organic topics pls

[@chemistrytutor]

It's on my list 😃