### Video Transcript

The molar bond energy of F two is
159 kilojoules per mole. Calculate the energy of one F–F
bond.

The molar bond energy is the energy
needed to break a chemical bond per mole of bonds. This means that it must take 159
kilojoules of energy to break one mole of F–F bonds. But we’re working for the energy of
one F–F bond. We should be able to find the
energy of one F–F bond by dividing the energy of one mole of F–F bonds by one
mole.

The energy of one mole of F–F bonds
is 159 kilojoules. One mole is always equivalent to
6.022 times 10 to the 23 of something, in this case bonds. So we should divide by 6.022 times
10 to the 23. This gives us 2.6412 times 10 to
the minus 22 kilojoules. Since the molar bond energy was
given to three significant figures, our answer should be given to three significant
figures as well. So we get an answer of 2.64 times
10 to the minus 22 kilojoules.

Now our kilojoules are a perfectly
appropriate unit to express our answer in. This is a very small amount of
energy. So let’s convert our answer to
joules. Since there 1000 joules in a
kilojoule, we can convert to joules by multiplying by 1000, which gives us 2.64
times 10 to the minus 19 joules, which is the energy of one F–F bond.