Flashcards in Moles Calculations Deck (11):

1

## What is the mass number?

### Total number of protons and neutrons in an atom

2

## What are isotopes?

### Atoms of the same element that have the same number of protons but different numbers of neutrons

3

## What is the relative atomic mass?

### The average mass of isotopes of an element compared to the mass of a Carbon-12 atom

4

## How to work out RAM

###
²⁴Mg = 77.6%

²⁵Mg = 10.1%

²⁶Mg = 11.3%

(24 x 78.6) + (25 x 10.1) + (26 x 11.3) / 100

5

## How do you calculate relative formula mass?

###
NH₃ = N + (Hx3) = 14 + 3 = 17

6

## How to calculate percentage abundance

### total mass of element in compound / RFM of compound x 100

7

## How to calculate mole calculations using relative atomic mass and relative formula mass

### mass = number of moles x RFM

8

## If the molecular formula is H₂O₂, what is the empirical formula?

### HO

9

## How to work out the empirical formula from the mass of each element in a compound

###
• Determine the mass or percentage of elements.

• Divide the given mass or percentage by their RAM.

• Calculate the ratio of the atoms by dividing by smallest value.

Ca Br

20 80

20/40 80/80

0.5 1

0.5/0.5 1/0.5

1 : 2

CaBr₂

10

## How to work out volume with moles

###
• volume = moles x 24(dm³)

• volume = moles x 24000(cm³)

11