An acid is: a proton acceptor
any substance that reacts to keep blue litmus blue
any compound containing hydrogen
a proton donor
a compound having hydrogen as a cation and oxygen as an anion.

An observation that requires measurement is called quantitative observable or qualitative

Ican determine the molar mass of an element by looking on the under the atomic mass for the element. for example the molar mass of phosphorus is 30.974 grams/mole. avogadro’s number tells me the amount of representative particles in 1 mole of any substance. this means 12.011 gram sample of carbon and a 32.0 gram sample of sulfur have the same number of atoms.

Suppose you wanted to make 100 grams of water. what is the molar mass of water (h2o)?