When blood in your body becomes oxygenated where does it go to and what is it used for/to do.

When you breathe in oxygen goes in and through the alveoli which has blood capillaries on it.These capillaries are single celled thick so the oxygenated blood diffuses in and the deoxygenated blood which has CO2 in it diffuses out when we exhale.The oxygenated blood goes into the heart via the pulmonary vein and then from the aorta to rest of the body.

1) according to the law of conservation of mass ,in all chemical reactions total mass is unchanged