Which gives of more energy, combing with H2. (hydrogen) o2 (oxygen) or F2(Fluorine)?

Question

also what does (triangle) H mean?


and Rocket Fuel is rated as energy per weight of fuel. Which would be better rocket fuel H2, gasoline, or glucose.

Answer 1

Combining hydrogen with oxygen will give more energy than fluorine. The reason is due to its electronegativity. Considering fluorine is more electronegative it will react faster than oxygen. Considering it reacts faster then it will give off less energy. Also the triangle is the greek symbol delta. It is basically the change or difference. In this case it is deltaH. Basically it is the change in enthalpy. Or you could think of deltaT which stands for the change in temperature.

Answer 2

Ritha,

Fluorine will produce more energy when burned with hydrogen, and the reason is that it is more electronegative than oxygen. That means the fluorine wants to take hydrogen's electrons more badly than oxygen does, so when the reaction happens there is a larger release of energy.

(triangle)H, which is read "delta H", is the change in enthalpy when a reaction occurs. The triangle means "change in", and the capital H is the symbol for enthalpy. For most purposes, enthalpy can be thought of as heat energy (although there is a more precise thermodynamic definition), hence the H symbol. So if a reaction is listed as having a (triangle)H of -100 kJ/mol, it means that when 1 mole of reactants is reacted, there will be 100 kJ of heat given off.

Per weight of fuel, hydrogen is probably the best fuel. But you would need to either look up or calculate the enthalpy change of each of those combustion reactions in order to know for sure. The reaction of H2 with O2 is very exothermic (gives off a LOT of energy), and is also very light. The other two would be good fuel sources as well, but aren't as light, and would require the breaking of more bonds per molecule in order to burn.

Answer 3

if you are looking a fixed amount of H2 and enough O2 and F2, then the latter gives more energy. the reason lies in electronegativity, as is given by previous answers.

there maybe other restrictions. eg we can assume we have same amount of O2 and F2 in moles, then the answer would be different.

Answer 4

mnrlboy gave a good answer.
I would only add that his suspicion that hydrogen is the best fuel is definitly correct due to the fact that due to it's low weight, its exhaust velocity would be higher thus providing the best 'specific impulse`.