The chemical formula for an emerald is Be3Al2(SiO3)6. An emerald can be described as a pure substance because it is a compound.
a pure substance because it is an element.
an impure substance because it is chemically combined.
an impure substance because it is a mixture.

the ratio of the conjugate base to the acid required to attain the desired ph.

he uptake of drugs from the intestine is often strongly influenced by diffusion. for example, consider a water-insoluble steroid for treating inflammation that is solubilized in aggregates of detergent molecules, called micelles. these micelles, aggregates of 80 soap molecules, have a molecular weight of 24,000, a diameter of 2.6 nm, and a charge of -27. the positively charge ions (counterions) in this system are na".