EasyChemistryHigh School (11–12)Chemical Bonding › Shapes of Molecules and HybridisationNumericalBoard Exam
The bond enthalpy of hydrogen is 435.8 kJ mol⁻¹…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
The bond enthalpy of hydrogen is . How much energy is needed to break every molecule in of hydrogen gas into atoms? The molar mass of is .
Need a reminder? The key ideaShow
A covalent bond forms when two half-filled orbitals overlap. Head-on overlap along the line of the nuclei gives a sigma bond. Sideways overlap of parallel p orbitals gives a pi bond, which is weaker. A single bond is one sigma bond, a double bond one sigma and one pi, and a triple bond one sigma and two pi. The bond enthalpy is the energy needed to break one mole of bonds into atoms.
The worked solution
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Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. Moles. of .
Step 2. Energy. .
Answer: must be supplied.
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