3.1.2 - Amount Of A Substance

Question 1

ATOM ECONOMY =

Answer 1

Mr of wanted product/total mr of reactants x 100

Question 2

What is the ideal gas equation?

Answer 2

pV = nRT

Question 3

P = ?

Answer 3

Pressure (Pa)

Question 4

V = ?

Answer 4

Volume (m^3)

Question 5

R = ?

Answer 5

8.31

Question 6

T = ?

Answer 6

Temperature (K)

Question 7

How do you get from °C to K?

Answer 7

+ 273

Question 8

How do you get from cm3 to m3

Answer 8

Divide by a million

Question 9

How do you get from KPa to Pa?

Answer 9

x 1000

Question 10

How do you get from cm3 to dm3 ?

Answer 10

Divide by 1000

Question 11

No. of particles = ?

Answer 11

Avagadros number x no. Of mol

Question 12

What’s the importance of percentage yield

Answer 12

To get as much product as possible because in chemical reactions not all of the reactants actually react

Question 13

How do you calculate density

Answer 13

Mass/volume

Question 14

What’s the importance of atom economy

Answer 14

To maximise the mass of reactants that end up in the desired product

Question 15

How to work out limiting reagent when there’s not a 1:1 ratio in equation

Answer 15

• calculate 1 mole of both.
  E.g if 1:2 ratio then divide the one with 2 moles by 2
• then compare which one is in excess

Question 16

If asked to work out limiting reagent then work out an equation eg pv=nRT which do you use limiting or excess?

Answer 16

You use 1 MOL of the limiting reagent

Question 17

How do you work out molecular formula from the empirical formula

Answer 17

1) Divide the relative molecular mass given in the question by the Mr of your empirical formula
2) whatever number that gives you, times it by the numbers in the empirical formula
eg if emp is CH2, and answer to step 2 is 4 then molecular formula would be C4H8