estimate the enthalpy change for each of the following reaction:
a) H2C=O(g)+HCl(g .....> H3C-O-Cl(g)
b)H2O2(g)+2CO(g).....> H2(g)+2CO2(g)
c)3H2C=CH2(g).....> C6H12(g)
(the six carbon atoms form a six-membered ring with two H atoms on each C atom)
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To estimate the enthalpy change of a reaction, we can use Hess's Law and the enthalpy values of known reactions. Hess's Law states that the overall enthalpy change of a reaction is independent of the pathway taken.
In order to estimate the enthalpy change for each of the given reactions, we need to access enthalpy values for known reactions. These values can be found in tables or databases, such as the NIST Chemistry WebBook or other reliable sources.
a) H2C=O(g) + HCl(g) → H3C-O-Cl(g)
The enthalpy change for this reaction can be estimated by using known enthalpy changes for the formation of the reactants and products:
ΔH = (ΔHf[H3C-O-Cl(g)]) - (ΔHf[H2C=O(g)] + ΔHf[HCl(g)])
b) H2O2(g) + 2CO(g) → H2(g) + 2CO2(g)
To estimate the enthalpy change for this reaction, we need to find the enthalpy changes for the formation of H2, CO2, H2O2, and CO:
ΔH = (ΔHf[H2(g)] + 2 * ΔHf[CO2(g)]) - (ΔHf[H2O2(g)] + 2 * ΔHf[CO(g)])
c) 3H2C=CH2(g) → C6H12(g)
For this reaction, the enthalpy change can be estimated by finding the difference in enthalpy values for the formation of C6H12 and 3H2C=CH2:
ΔH = (ΔHf[C6H12(g)]) - (3 * ΔHf[H2C=CH2(g)])
Remember that the enthalpy values, ΔHf, represent the enthalpy change for the formation of one mole of the substance from its elements in their standard states at a given temperature (usually 25°C or 298 K).
To calculate the estimated enthalpy change, you can substitute the appropriate values from the tables or databases into the equations and perform the necessary calculations to find the answer.
All of these are gases; I would use bond energies.
dHrxn = (n*BE reactants) - (n*BE products)
You should have a table in your book with bond energies.