1.1 Moles and Molar Mass

Can one count particles directly while performing laboratory work?

No

There must be a connection between the ______ of substances reacting and the ______ of particles undergoing chemical changes

Masses, actual number

Why must there be a connection between the masses of substances reacting and the actual number of particles undergoing chemical changes?

One cannot count particles directly while performing laboratory work

What is Avogadro’s number?

6.02×10^(23)

Avogadro’s number provides the connection between:

The number of moles in a pure sample of a substance and the number of constituent particles (or formula units) of that substance

Expressing the mass of an individual atom or molecule in ______ is useful

Atomic mass units (amu)

Why is it useful to express the mass of an individual atom or molecule in atomic mass units (amu)?

The average mass in amu of one particle (atom or molecule) or formula unit of a substance will always be numerically equal to the molar mass of that substance in grams

There is a quantitative connection between the ______ of a substance and the number of particles that the substance contains

Mass

There is a quantitative connection between the mass of a substance and the ______ that the substance contains

Number of particles