Example: Calculate the pH of a buffer solution that initially consists of 0.0400 moles of ammonia and 0.0250 moles of ammonium ion, after 20.0 mL of 0.75 M NaOH has been added to the buffer. Ka for ammonium ion is 5.6 x 10 -10.
There are two types of bacteria. Aerobic bacteria live with oxygen, love the company of food particles in the mouth and feed on sugar. Anaerobic bacteria exist without oxygen and feed off dead skin cells and other bacteria.
Tiny particles of food can get lodged here. Bacteria that live in the mouth eat this food establishing a complex gloopy colony called Dental Plaque. Dental Plaque, which is a bit like cottage cheese in consistency, gets so stuck onto teeth after 24 hours that it cannot be removed with a tooth brush or floss.