Calculate the delta H and delta S for the reaction. From there, calculate the delta G at 25 degrees Celsius. Predict whether it the reaction is spontaneous or non-spontaneous under standard conditions.
CH3OH(l)+ O2(g)--> HCO2H(l)+ H2O(l)
*i could not find the find the delta H or delta S values anywhere for HCO2H and CH3OH. Is there another way to approach this problem?
Not in my text either.
delta H and S for formic acid.
http://en.wikipedia.org/wiki/Formic_acid_%28data_page%29
MeOH is here.
http://en.wikipedia.org/wiki/Methanol_%28data_page%29
-456
Yes, there is another way to approach this problem. You can use the standard enthalpies of formation (ΔHf) and standard entropies (ΔS) to calculate the ΔH and ΔS for the reaction. The standard enthalpy change (ΔH) can be calculated using the following equation: ΔH = ΣnΔHf(products) - ΣnΔHf(reactants), where n represents the stoichiometric coefficients.
First, let's determine the standard enthalpy change (ΔH) for the reaction:
CH3OH(l) + O2(g) → HCO2H(l) + H2O(l)
Given that the standard enthalpy of formation (ΔHf) for CH3OH(l) and O2(g) is available, you can look up their values in a reference table or database. The standard enthalpy of formation for HCO2H(l) and H2O(l) is not provided, but you can assume that their values are similar to their standard enthalpies of formation in the liquid phase.
Next, let's determine the standard entropy change (ΔS) for the reaction. The standard entropy change (ΔS) can be calculated using the following equation: ΔS = ΣnΔS(products) - ΣnΔS(reactants), where n represents the stoichiometric coefficients.
Just like with standard enthalpy, if the standard entropies (ΔS) for HCO2H and CH3OH are not given, you can make an assumption that their values are similar to the standard entropies of other substances in the liquid phase.
Once you have calculated ΔH and ΔS, you can use the equation ΔG = ΔH - TΔS to calculate the change in Gibbs free energy (ΔG) at 25 degrees Celsius (298 K). If the value of ΔG is negative, the reaction is spontaneous under standard conditions. If the value of ΔG is positive, the reaction is non-spontaneous under standard conditions.
Yes, there is another way to approach this problem when the delta H and delta S values are not given directly. You can use Hess's Law and standard enthalpy of formation values to determine the delta H value for the reaction.
Hess's Law states that if a reaction can be expressed as the sum of two or more other reactions, then the overall enthalpy change is the sum of the enthalpy changes of those reactions.
In this case, let's break down the given reaction into a series of simpler reactions for which the delta H values are available:
1. CH3OH(l) + 1.5O2(g) --> CO2(g) + 2H2O(l) (Complete combustion of methanol)
2. CO2(g) + H2O(l) --> HCO2H(l) (Formation of formic acid)
3. 2H2(g) + O2(g) --> 2H2O(l) (Formation of water)
Now, we can look up the standard enthalpy of formation values for methanol (CH3OH), carbon dioxide (CO2), formic acid (HCO2H), and water (H2O). These values represent the enthalpy change when one mole of the respective compound is formed from its elements in their standard states.
Using these values, we can calculate the delta H value for each individual reaction and then add them together to obtain the overall delta H value for the given reaction.
Next, we can use the equation delta G = delta H - T delta S to calculate the delta G value at 25 degrees Celsius. However, since we don't have the delta S values directly, we need to make some assumptions.
Typically, for condensed phase reactions like the one given (where all reactants and products are in liquid or solid states), the delta S value is assumed to be approximately zero. Therefore, we can neglect the delta S term in our calculation. This simplifies the equation to delta G = delta H.
Finally, if the calculated delta G value is negative (delta G < 0), the reaction is spontaneous under standard conditions. If the delta G value is positive (delta G > 0), the reaction is non-spontaneous under standard conditions.
Please note that this approach assumes ideal behavior and standard conditions.