Here's a molar heat problem I just have one question on. How much heat will be transferred if 2 moles of hydrogen reacts with excess oxygen according to the reaction below?
2H2 + O2 yields 2H20 + 572 kJ
The answer according to my answer key is
2 mole H2 x 572 kJ/2moles H2.
I understand where the first 2 moles comes from, but what about the second one on the bottom of the equation? I heard there's a chart online that tells you where to find this value. Could you show me a link if there's a such chart? Thanks for your help!
http://en.wikipedia.org/wiki/Standard_enthalpy_change_of_formation_(data_table)
I answered the first post but I don't see it now.
To determine the heat transferred in a chemical reaction, you can use the concept of molar heat. The molar heat is the amount of heat released or absorbed when one mole of a substance reacts in a chemical reaction.
In the given reaction, 2 moles of hydrogen react with excess oxygen to form 2 moles of water and release 572 kJ of heat.
To calculate the heat transferred, you can use the concept of proportionality. You know that 2 moles of H2 release 572 kJ of heat. Thus, you can set up a proportion:
(2 moles H2 / 2 moles H2) = (572 kJ / X)
Where X represents the heat transferred in kilojoules.
By cross-multiplying and solving for X, you get:
X = (2 moles H2 * 572 kJ) / 2 moles H2
The moles of H2 cancel out, leaving you with:
X = 572 kJ
So, in this reaction, 572 kJ of heat will be transferred.
Regarding the second "2 moles H2" in the equation, it comes from the stoichiometry of the reaction. The balanced equation tells you that for every 2 moles of hydrogen (H2) that react, 2 moles of water (H2O) are produced. Therefore, you need to include the stoichiometric coefficient of hydrogen (2 moles H2) in the calculation.
As for the chart you mentioned, there isn't a specific chart that provides the values for heat transfers in chemical reactions. However, there are various tables and databases available that provide thermodynamic data, including enthalpies of formation or combustion, which can be used to calculate molar heats. One commonly used reference is the NIST Chemistry WebBook (https://webbook.nist.gov/chemistry/), which provides extensive thermodynamic data for chemical substances.