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AQA A Level Chemistry > Amount of Substance > Flashcards

Flashcards in Amount of Substance Deck (19)
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1
Q

What is a total ionic equation?

A

A chemical equation that shows all the ions in a reaction

2
Q

What are spectator ions?

A

Ions that don’t get involved in the reaction. They don’t change charge

3
Q

Give the ionic equation for NaOH + HCl –> NaCl + H2O

A

OH- + H+ –> H2O

4
Q

State what is meant by the term ‘relative atomic mass’

A

The average mass of an atom of an element compared to 1/12th the mass of a 12C atom

5
Q

State what is meant by the term ‘relative molecular mass’

A

The average mass of an molecule compared to 1/12th the mass of a 12C atom

6
Q

What is Avogadro’s number and what is meant by this term?

A

6.023x (10 to the power 23)

It is the number of atoms found to be in 12g o 12C

7
Q

How can you work out mass using Mr and moles?

A

Mass = Mr x moles

8
Q

How do you work out the number of molecules in a certain amount of a substance?

A

Find the moles and then times that by Avogadro’s number

9
Q

What is empirical formula?

A

The simplest ratio of atoms of each element in a compound

10
Q

What is the ideal gas equation?

A

pV=nRT

11
Q

What do the letters represent in the ideal gas equation, and what are the units for each?

A
pV=nRT
p=pressure in Pascals
V=volume in metres cubed
n=moles
R=gas constant (8.31 Jk-1mol-1)
T=temperature in Kelvin
12
Q

O*C is how many Kelvin?

A

273K

13
Q

What do you have to do to convert from cm3 to dm3?

A

divide by 1000

14
Q

What do you have to do to convert from cm3 to m3?

A

divide by 1,000,000

15
Q

Give three reasons why 100% yield may not be obtained

A
  • the reaction is reversible
  • some of the product is lost when it is separated from the reaction mixture
  • some of the reactants may react in other reactions
16
Q

How do you calculate % yield?

A

Actual/possible x100

17
Q

State what is meant by atom economy

A

The measure of what proportion of the products of a reaction are desired and how much is waste

18
Q

What can a company do to maximise profits when a reaction has a low atom economy, without changing the reaction conditions or production costs?

A

Sell unwanted products

19
Q

How can you calculate moles from concentration and volume?

A

m = c x v