Chapter 3 (Composition Of Substances And Solutions)

Question 1

How do you calculate the Formula mass?

Answer 1

Formula mass = (# of element (1) in compound x element (1) amu) + (# of element (2) in compound x element (2) amu) + …(etc.)

Question 2

What is Mole?

Answer 2

Word representing Avagadros number:
6.02 x 10^23 (used mostly for atoms, molecules, protons, etc.)
(Atoms are too small to use as a unit, convert to moles.)
Ratio: 1 mole of atoms/ 6.022 x 10^23 atoms

Question 3

What is Molar Mass?

Answer 3

The mass in grams of one mole of molecules (or formula units) of a compound.

Question 4

What is percent composition?

Answer 4

An element’s percentage of the total mass of a compound.

Mass % x = (mass of x in 1 mol Compound/
mass of 1 mole of Compound)x100

Question 5

What is a Chemical Solution?

Answer 5

A homogeneous mixture of two or more substances.

Question 6

What is a Solute?

Answer 6

The substance which does the dissolving (usually present in the majority).

Question 7

What is a Solvent?

Answer 7

The substance which is dissolved (usually present in the minority).

Question 8

What is Molarity (M)?

Answer 8

The concentration of a solution expressed as:
(M) = mole of solute/ L of solution.

Question 9

How do you calculate Mass Percentage?

Answer 9

% by mass = (mass of Solute/
mass of Solution)x100

Question 10

What is Parts per Million (ppm) formula?
Why is it used?

Answer 10

ppm = (mass of Solute/
mass of Solution) x 10^6 (1000000)

It is a measure of concentration, commonly used to measure contaminantes in water.