Number of Particles Calculations

Question 1

‘Particle’ can be a…?

Answer 1

Molecule, atom, electron, proton, neutron, etc.

Question 2

1 mole of an particle = ?

Answer 2

6.02 x 10^23

Question 3

Equation for no° of particles?

Answer 3

No° of it particles = no. of moles x number of particles in 1 formula unit (eg. atoms) x 6.02 x 10^23

Question 4

How to do no° of molecules in 1.00g of ammonia, NH3?

Answer 4

• No° of molecules in one NH3 is 1
• Mass/Mr -> 1/17= 0.0588mol
• 0.0588 x 1 x 6.02 = 0.353976
• x 10^23= 0.353976 x 10^23
• Stand. F -> 3.53976 x 10^22
• 3sf -> 3.54 x 10^22

Question 5

Reverse no° particles calculation:

What mass of CO2 is 3.01 x 10^23 molecules?

Answer 5

•Divide by Avogadro’s constant:
3.01 x 10^23
_________ —> 0.5 moles
6.02 x 10^23

•Moles = mass/Mr… So:
Mass = Moles x Mr
•Mr of CO2 is 44
•0.5 x 44 = 22g