Vitamin K antagonists (VKA) are a group of substances that reduce blood clotting by reducing the action of vitamin K. They are used as anticoagulant medications in the prevention of thrombosis, and in pest control, as rodenticides. 1  1 Mechanism of action.  2 Coumarins (4-hydroxycoumarins)
Calculate the average atomic mass of oxygen. Solution: ((15.994915*99.757) + (16.999132*0.038) + (17.999160*0.205))/100 = 15.999405 . Using our equation for determining average atomic mass, we see that the average atomic mass for oxygen is 15.999405 amu. If we check the periodic table, we will see that our average atomic mass is the same as the atomic mass indicated on the element oxygen. Ã
Barium chlorate has a formula weight of 304.23. Sure, there are 6 oxygens, but there is a lot of weight in the Barium atoms. A 100 gram sample of Barium Chlorate contains 31.55 grams of oxygen atoms. Potassium chlorate has a formula weight of 122.55, with 3 oxygens. This means that a 100 gram sample contains 39.17% oxygen. In fact, on a weight/weight basis, there is more oxygen in a gram of Potassium Chlorate than in a gram of Barium Chlorate.