Moles notes

Question 1

How to find the value of moles

Answer 1

Mass/Mr

Question 2

How to convert the volume to dm^3

Answer 2

vol in cm^3/1000

Question 3

How to find the volume (dm^3)

Answer 3

volume (dm^3) = 24 x no of moles

Question 4

How to find the conc of a solution

Answer 4

C = m/v

c = concentration of the solution (g/dm^3)
m = mass of solute (g)
v = volume of solution (dm^3)

Question 5

Which piece of apparatus should be used to measure 25.0cm^3 of KOH?

Answer 5

Pipette

Question 6

Balance this formula -

Cl2 + Al –> AlCl3

Answer 6

3Cl2 + 2Al –> 2AlCl3

Question 7

What is a limiting reagent?

Answer 7

the reactant that gets fully used first in a chemical reaction and therefore limits how much product can be formed.

Question 8

What is the charge of an element from group 4

Answer 8

4+ or 4-

Question 9

What is the charge of an element in group 6

Answer 9

-2

Question 10

How to find the empirical mass?

Answer 10

Get the mass of each element, convert it into moles, find the simplest ratio, use the mole ratio to write the empirical formula

Question 11

Definition of a mole

Answer 11

the unit of measurement of a chemical substance.

a mole is actually 6.022140857×1023mol−1but 1 mole is easier to remember.

Question 12

How to find the empirical formula?

Answer 12

• If it’s a dot and cross diagram, count up how many atoms there are of each element. That is your empirical formula.