The Mole

Question 1

What is an “Amount”

Answer 1

A quantity of a substance in moles

Question 2

What is a mole?

Answer 2

The number of atoms in 12g of C12 = 6.02x10 ^23

Question 3

What is the avagadro constant?

Answer 3

6.02x10 ^23

Question 4

What is “Molar mass”

Answer 4

The mass per mole of a substance (gmol^-1)

Question 5

What is empirical formula and how do you calculate it?

Answer 5

The simplest whole number ratio of atoms in a compound.

1. Write the masses / percentages of each element
2. Write the molar masses of each
3. Write the number of moles of each you have
4. Divide all of the numbers of moles by the smallest one
5. Round to nearest whole numbers

Question 6

What is the calculation linking moles, molar mass and mass

Answer 6

Moles = Mass / Molar mass

Question 7

What is the molecular formula and how do you calculate it using the empirical formula?

Answer 7

Formula that shows the number and type of atoms of each element present in a molecule.
Divide the known Mr of the formula by the Mr of the empirical formula.

Question 8

What do:
a) Anhydrous
b) Hydrated
c) Water of crystallisation 
Mean?

Answer 8

a) A crystalline compound containing no water molecules
b) A crystalline compound containing water molecules
c) Water molecules bonded into a crystalline structure

Question 9

How do you calculate percentage error of a calculation?

Answer 9

Percentage error = Total uncertainty / Value measured X 100

Question 10

What is total uncertainty?

Answer 10

The ability of a piece of equipment to only measure to certain amount of D.P., thus we cannot be sure past that decimal place.

Question 11

What does EMMA stand for when it comes to reacting masses?

Answer 11

Equation
Moles (total)
Moles (Used) Answer

Question 12

What is a solute?

Answer 12

Something to be dissolved

Question 13

What is a solvent?

Answer 13

Something that causes a solute to dissolve

Question 14

What is a solution?

Answer 14

A solute having dissolved in a solvent.

Question 15

What is a standard solution?

Answer 15

A solution containing a precisely known concentration of a substance.

Question 16

What equation links number of moles, Concentration and volume?

Answer 16

Moles = Concentration x Volume

Question 17

What is volume measured in?

Answer 17

dm^3

Question 18

What do you do in titration calculations when you have 3 concordant values?

Answer 18

Take an average of all 3

Question 19

What is the general volume of one mole of gas at room temperature and pressure (r.t.p.)?
As such, how do you calculate number of moles of gas given volume or vice versa?

Answer 19

24.

Number of moles = volume/24
Volume= Number of moles x 24

Question 20

What is the ideal gases equation and what does each part of it mean?

Answer 20

P x V = n x R x T
P= Pressure 
V= Volume
n= Number of moles
R= Ideal gas constant = 8.314
T= Temperature

Question 21

What units must the ideal gas equation be in?

Answer 21

PV =nRT
P = Pa
V = m^3
n = moles
R = Has no units, is a constant
T = Kelvin (Celcius + 273)

Question 22

How many Pascals = 1 atm

Answer 22

100,000

Question 23

1 dm^3 = How many m^3?

Answer 23

0.001