S1.4 (The Mole)

Question 1

A mole

Answer 1

represents the mass of a substance that contains 6.022 × 10²³ atoms, molecules or ions

Question 2

Symbols of avogadros constant

Answer 2

N subscript A or L

Question 3

Formula for moles based an mass

Answer 3

n= g/Mr

Question 4

Formula for moles based on conc. and volume

Answer 4

n= cxV

Question 5

Empirical formula

Answer 5

simplest whole number ratio of atoms present in compound)

Question 6

Molecular formula

Answer 6

tells us the type of elements & number of atoms of each element

Question 7

Empirical formula of H2O2

Answer 7

HO

Question 8

Why empirical formula does not work on ionic compounds

Answer 8

• ionic compounds are already empirically written
• they are expressed nas the simplest unit of a repeating lattice

Question 9

Calculating empirical formula

Answer 9

1. determine molar ratio
2. divide by smallest ratio
3. round up

Question 10

How to convert from empirical formula to molecular formula if they molecular formula mass is given

Answer 10

1. determine empirical formula mass
2. divide molecular formula mass by empirical formula mass

this shows how many times the simplest ratio fits in the ultimate compound

3. multiply elemnts of empirical formula by ANS

Question 11

Determining amount of atoms in a substance

Answer 11

1. Find the moles of substance
2. determine moles of atoms within substance (using molecular ratio)
3. find particles using Avogadros Constant

Question 12

Mole calculation involving uncertainties

Answer 12

• take the percentages of the uncertainties from their original units
• add the uncertainties together
• multiply added uncertainties by final value
• makes uncertainty of final value! yay