the thermochemical equation for th edissocation of hydrogen gas into atoms may be written :

h2-> 2H delta H 1824.2

what is the ration of the energy yield on combustion of hydrogen atoms to steam to yield ion combustion of an equal mass of hydrogen molecules to steam given

2H2(g) = O2 (g) -> 2h20 (g) delta H = -2023.7 kj

I know you want a ratio but I don't know what ratio you want? What is "to yield ion combustion of....."

excatly, im just as confused. I tried to email him, no reply.

The problem says what is the ratio of energy yield on combustion of hydrogen atoms to steam to the yield on combustion of an equal mass of hydrogen molecules to steam given.

what am i missing

I'm still confused but not as much. Compare the two parts of your post, take out the i typo on ion for on and add in a word or two you omitted and it makes a little more sense. Do you suppose the prof means this?

The dissociated of H2 into atoms is done by adding 1824.2 J. So if we start with H atoms and they combine to form H2 first before combusting we should get an additional 1824.2 OUT (as a - sign). So we would get 2*2023.7 (4g H2) for 2 mols H2 and we would get 4047.4 + 2*1824.2 (4 gH atoms) if we started with H atoms? So the ratio is
atoms/molecules = ? Looks like almost double. Let me know how it turns out.

Dr.Bob222 can you work this problem out fully. I don't understand at all.

To find the ratio of the energy yield on combustion of hydrogen atoms to steam, compared to the combustion of an equal mass of hydrogen molecules to steam, we need to calculate the energy yield for each scenario and compare them.

First, let's calculate the energy yield for the combustion of hydrogen atoms to steam. According to the given thermochemical equation, the enthalpy change for the dissociation of hydrogen molecules into atoms is ΔH = 1824.2 kJ/mol. Since we have 2 moles of hydrogen atoms in the equation, the energy yield can be calculated as follows:

Energy yield for the dissociation of hydrogen atoms:
= (1824.2 kJ/mol) * 2 mol
= 3648.4 kJ

Next, let's calculate the energy yield for the combustion of hydrogen molecules to steam. According to the given thermochemical equation, the enthalpy change for the combustion of 2 moles of hydrogen molecules to form 2 moles of water is ΔH = -2023.7 kJ. The energy yield in this case is:

Energy yield for the combustion of hydrogen molecules:
= (-2023.7 kJ/mol) * 2 mol
= -4047.4 kJ

However, we need to find the ratio of the energy yields. To compare them, we can divide the energy yield for the dissociation of hydrogen atoms by the energy yield for the combustion of hydrogen molecules:

Ratio of energy yields:
= Energy yield for dissociation of hydrogen atoms / Energy yield for combustion of hydrogen molecules
= 3648.4 kJ / -4047.4 kJ
≈ -0.901

The ratio of the energy yield on combustion of hydrogen atoms to steam to the energy yield for combustion of an equal mass of hydrogen molecules to steam is approximately -0.901.