Amount Of Substance (2) ✨

Question 1

Define relative atomic mass

Answer 1

The weighted average mass of an atom of an element taking into account of its naturally occurring isotopes, relative to 1/12 of the mass of an atom of C12.

Question 2

Define relative molecular mass

Answer 2

The mass of a molecule relative to 1/12 the mass of C12 (mr)
Can be found by adding the air of elements in molecule.

Question 3

How to convert degrees to kelvin

Answer 3

+273

Question 4

What is the gas constant?

Answer 4

8.31 jk^-1 mol^-1

Question 5

What is the empirical formula?

Answer 5

The simplest whole number ratio of its elements
Number of moles=mass/mr
Then find out simplest ratio

Question 6

What is the molecular formula?

Answer 6

The actual number of atoms of each element in a compound
Ratio of molecular formula to empirical= Mr/RAM of empirical formula

Question 7

What do ionic equations do?

Answer 7

Leave out the spectator ions (ions that don’t change)

Question 8

What is important about ionic equations

Answer 8

Charges need to be balanced aswell as moles

Question 9

What is atom economy?

Answer 9

How many atoms from the reactants are found in the useful products.
Improve it by finding a use for waste products or changing reaction to have fewer waste products.
Atom economy=Mr of desired products/total Mr of all products

Question 10

What is percentage yield?

Answer 10

Tells you about the efficiency of the reaction which can be affected by reversible reactions, by not continuing to completion or by side reactions and practical errors.
Percentage yield=number of moles obtained of desired products/theoretical max number of moles of desired product. X 100

Question 11

Give the equation of an ideal gas

Answer 11

pV=nRT

Question 12

Suggest to reasons why the sulphur dioxide by product of a process is removed from the exhaust gases

Answer 12

It’s toxic and can cause acid rain
So there’s a higher percentage yield

Question 13

How to you convert cm cubed to metres cubed?

Answer 13

X10 to the power of -6

Question 14

How would you use the mean titre to calculate the percentage by mass of sodium ethanoate in the original sample

Answer 14

1- find moles of sodium hydroxide
2- find moles of ethanoic acid
3- find moles in OG sample
4- find mass of ethanoic acid
5- find mass of sodium ethanoate
6-find percentage by mass