Use dimensional analysis to set up this propblem

Question

How long would it take the population of Earth to consume a mole of Skittles if each person consumed 1 bag/day?

Average bag Skittles contains 56 pieces.

Population of Earth is 8 billion

1 mole = 6.022 x 10^23

Answer 1

Hi Marilyn,

Let's first find how many pieces the entire population eats per day:

(56 pieces / person) * (8 x 10⁹ person / day) = 448 x 10⁹ pieces / day

Now, we can just do the whole problem in one line:

(1 day / 448 x 10⁹ pieces) * (N_A pieces / mol) = 1.34 x 10¹² days / mol

so it takes about 1.34 x 10¹² days to consume 1 mol of skittles. This is approximately 3.6 billion years. For context the Earth is approximately 4.5 billion years old.