### Video Transcript

Every molecule of iodine, I2, has
an iodine–iodine bond, I–I. The energy required to break one of
these bonds is 2.51 times 10 to the minus 19 joules. How much energy is required to
break one mole of these I–I bonds?

We want to know the energy needed
to break one mole of I–I bonds. We’re given the energy needed to
break a single I–I bond which is 2.51 times 10 to the minus 19 joules. We should be able to find the
energy needed to break one mole of I–I bonds by multiplying the energy needed to
break a single I–I bond by one mole. One mole is equivalent to 6.022
times 10 to the 23.

So the energy to break one mole of
I–I bonds is equal to 2.51 times 10 to the minus 19 joules times 6.022 times 10 to
the 23. This is equal to 1.51102 times 10
to the five joules. Since the energy to break one I–I
bond was given to three significant figures, our answer should be given to three
significant figures as well. This means that the energy required
to break one mole of I–I bonds is 1.51 times 10 to the five joules.