Puzzle 3 - Avogadro

Puzzle: a) Sunil, a dedicated Chemistry student, recently got a job at Avogadro’s Avocados and decides to

investigate a mysterious odor emanating from the back room of the store. Using his terrific

chemistry skills, he finds that the odor comes from a hydrocarbon containing 85.6% mass by

carbon.

Later that week, Sunil was devastated to be absent for a combustion lab in his Chemistry class.

Fortunately, upon reading the lab, he finds that the same gas he discovered in the store was

combusted in the lab! He again utilizes his magnificent chemistry skills to deduce the balanced

equation for the complete combustion of this gas. What is the coefficient of oxygen in this

equation?

b) In preparation for Halloween, Tina wants to paint her nails orange and black. But first, she must

remove the shimmering gold nail polish that she wore to Homecoming using a specific chemical.

What is the coefficient when the number of atoms in 4.82 g of this chemical is written in scientific

notation?

c) Charlotte has a sweet tooth. Every Halloween, her mother makes amazing candy apples that she

loves. However, her dentist Dr. Maldonado has warned her that if she doesn’t brush her teeth, the

acid in these candy apples will destroy the enamel of her teeth and lead to cavities. If the total

amount of malic acid (chemical formula = H2C4 H4O5) in the apples she eats amounts to 3.748 L,

how many moles of the hydroxyapatite in the enamel of her teeth will react? (Assume 1 mL of acid

= 1 g of acid.) (Hint: Unbalanced equation: Ca10(PO4)6(OH)2 + H+ ↔ Ca2+ + HPO4

2- + H2O)

Solution: Solve each of the three problems using stoichiometry. The three answers are 3 5 7, telling us to go to room 357.