17th century Roman doctors believed that urine whitened teeth and also kept them firmly in place. As gross as that sounds, it most have worked because it was used as an active ingredient in toothpaste and mouthwash well into the 18th century. Would you believe it’s still used today? Thankfully, not in its original form! The formula for ammonia is NH3. a) How many mols are in 0.75 g of ammonia?

b) How many molecules of ammonia is this?