5.1 Calculating enthalpy changes (SL)

This video covers how to calculate enthalpy changes in
neutralization and combustion reactions.

Link to practice worksheet:

[zeynep-rjtn]

hello in the questions in description, mass of water is not given so we use volume of both reactants as mass (in cm³) I didn't understand the reason. I thought we must find mass by mol value is if something like ratio? if it is resulting value is not an exact value i am literally confused

[joshina]

How is the reaction exothermic at 3:55 if the system is gaining

[Titorites]

When calculating q for the enthalpy of neutralization, is m the mass of NaCl solution or that of H2O?

[rohiljuneja]

I have a CT coming up so before doing thermochemistry should I first do stoichiometry

[god]

do u add the mass of the two reactants together since the mole rations are 1:1 and therefore the mass of the products will be the same? im a bit confused since u added the mass of the reactants but used the specific heat capacity of water and the only way it made sense to me was what i wrote at the start of the comment

[LFCdiehard]

Hi sir,

Thank you! I was wondering, I noticed a question where there was a line drawn from the max temperature towards the y-axis (extrapolation/interpolation or something) - do we need to know about that for the current syllabus + what does it do?

Thank you, Mr Jones

[nejsnek]

If at 2.45 there was a limiting reactant, do we use the moles of that limiting reactant when calculating delta H?

[estifanossolomon]

6:11 should we not convert the mass in kg?

[noah]

very epic video indeed, just as good as Gangnam style :)

[malharkookada]

why do we assume that all the heat generated from the neutalization reaction is transferred to water and not also the NaCl? Does it have something to with the states, I'm not sure?

[gardenmenuuu]

Sir please reply plzzz
When we say the enthalpy change of a reaction, are we saying the heat change for that particular reaction no matter the moles or we mean 1 mole?I mean when we just say the enthaloy of reaction not form combustion like that?

[sencotm]

Hello is the hemoglobin levels included in this or in a different cell

[ivo]

How do we know if the reaction is exothermic or not if the question does not include the + and - signs?

[abhimanyugupta]

in the question at 5:02 why do u multiply with the mass of water and not methanol?

[susheelkona]

Why do you divide by mols of water for the neutralisation but divide by mols of methanol for the combustion to find the delta H? Thanks

[mayaiam]

Isn't number of moles (n) = mass/molar mass? The first example used n=CV, and would both give different values for n. Why?

[rafe]

How did you get a specific heat of 4.18?

[davidsafi]

Is there any reason that fo the second worked example you rounded from 192280 Jmol to 190kJ mol?
Would it not be rounded to 192kJ mol?

Also, I simply do (initial - final) for ΔT because it gives you the sign in the front of the calculation instantly and just wanted to make sure it works (gave the same final answer in both examples disregarding the rounding situation in Example B)

[mindbreaker]

5:57 how did you get 32.05 as the molar mass of methanol, how do you calculate it?

[eqelvvf]

When do you know to convert to K for temperature or to use degrees celsius