Chapter 3

Question 1

What is a mol ?

Answer 1

The amount of a substance containing 6.02x10^23 entities

(the number of entities in 12 grams of carbon-12)

Question 2

What is the empirical formula ?

Answer 2

The simplest whole number ratio of atoms of each element in a compound

Question 3

What is a Molecular formula ?

Answer 3

The number of atoms of each element in a compound

Question 4

What is a Relative molecular mass ?

Answer 4

Add up all the relative atomic masses in the molecular formula

Question 5

What is the Relative formula mass ?

Answer 5

Add up all the relative atomic masses in the empirical formula

Question 6

Finding empirical formula from mass ?

Answer 6

1.Use mole formula and calculate moles
2. Divide by smallest mol to find empirical ratio

Question 7

How to find the molecular formula from mass/percentage ?

Answer 7

Take percentage as mass
Calculate moles
Find the empirical formula by finding the smallest WHOLE NUMBER ratio of moles
You would be given the relative molecular mass
Divide that by relative mass of the empirical formula
Find multiplier
Multiply empirical formula by that

Question 8

What is the ideal gas equation ?

Answer 8

pV=nRT

P = pressure
V = volume
N = moles of gas
R = ideal gas constant
T = temp (kelvin)

Question 9

What is percentage yield ?

Answer 9

( Actual yield / theoretical yield ) x 100

Question 10

What is the atom economy ?

Answer 10

( Mr of desired / Mr of all ) x 100

Question 11

What is the limiting reactant ?

Answer 11

The reactant with three least number of moles