To convert from atoms to moles, divide the atom amount by Avogadro's number (or multiply by its reciprocal).
Concentration Definition. In chemistry, concentration refers to the amount of a substance per defined space. Another definition is that concentration is the ratio of solute in a solution to either solvent or total solution. Concentration usually is expressed in terms of mass per unit volume.
The water molecule is a polar molecule which would mean that there is an uneven distribution of charges. Each molecule of water has partial positive and partial negative end. The partial positive charges is found in the H atoms while the partial negative is at the O atom. This is due to the the unequal sharing of the electrons.
Answer: 72 grams of
are needed to completely burn 19.7 g 
Explanation:
According to avogadro's law, 1 mole of every substance weighs equal to molecular mass and contains avogadro's number
of particles.
To calculate the number of moles, we use the equation:

Putting in the values we get:


According to stoichiometry:
1 mole of
requires 5 moles of oxygen
0.45 moles of
require=
moles of oxygen
Mass of 
72 grams of
are needed to completely burn 19.7 g 
Which of the flowing painting did Miss meacham set up against the bread counter?