Compare your answer from Exercise 66 to the ΔH value calculated from standard enthalpies of form

Compare your answer from Exercise 66 to the ΔH value...

Key Concepts

Error Analysis in Thermochemical Calculations

Error analysis in the context of thermochemical calculations involves assessing potential inaccuracies such as experimental measurement errors, heat loss to the environment, or differences in the treatment of idealized conditions versus real-world scenarios. Recognizing these sources of error is crucial for understanding and explaining any discrepancies between different methods of obtaining reaction enthalpy values.

Standard Enthalpy of Formation

Standard enthalpy of formation refers to the heat change when one mole of a substance is formed from its elements in their standard states. This concept is fundamental in thermochemistry as it provides tabulated reference values that serve as the basis for calculating the overall enthalpy change of chemical reactions.

Hess's Law

Hess's Law states that the total enthalpy change for a chemical reaction is independent of the pathway taken from reactants to products. This allows one to calculate the reaction enthalpy by summing the standard enthalpies of formation of products and subtracting those of reactants, even if the direct experimental measurement may not be feasible.

Comparison of Experimental and Theoretical Calculations

Often, the enthalpy change determined from experiments may differ from the value calculated using standard enthalpies of formation. Key points of consideration include the inherent uncertainties or approximations in both methods, which can lead to discrepancies. These differences underscore the importance of validating experimental methods and assumptions against theoretical calculations.

Transcript

00:01 So in this video, we're gonna go over question 80 from chapter eight, which says, compare your answer from exercise 72 to the delta h value, calculated from standard in puppies information and appendix four explain any discrepancies.

00:13 So in question 72 we're told acetic acid is responsible for the sour taste of vinegar.

00:18 It can be manufactured using the following reaction used tabulated values of bond energies from table 8.5 to estimate the age for this reaction.

00:27 Eso first we're gonna estimate all to age using boned energies and then we're going to calculate it using standard and abuse of formation.

00:35 Eso first, let's do our bond energies.

00:37 So, um, which bonds are being broken and which bonds are being formed? well, we need to break this carbon oxygen bond here, and we need to break this carbon oxygen triple bond here and then the bonds we need to form when we need to form this carbon oxygen double bon and this carbon oxygen single bond on dhe.

01:01 That's all of the bonds.

01:04 Um oh, and we also need to form one carbon carbon ee bond.

01:08 Here, we need to form one carbon carbon bond s o hear our bond energies.

01:13 So we're breaking this carbon oxygen bond in this carbon oxygen triple bond.

01:17 And then we're forming a carbon carbon bond.

01:20 A carbon oxygen doubled on in a carbon oxygen single bond.

01:23 I noticed that my bond energies for bonds, that i'm breaking our positive because you have to put energy in to break a bond.

01:30 But energy is released when i'm forming a bond.

01:33 So my bond energies a rh negative, then s o...

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