Formulae , Equations and Amount of Substance

Question 1

Whats Avagadro’s number ?

Answer 1

6.02 x 10^23

Question 2

How do you calculate the number of particles in a substance ?

Answer 2

Av x number of moles

Question 3

why do we need hess cycles ?

3

Answer 3

• its hard to measure the enthalpy change of a solid directly
• all solid reactant may not decompose
• difficult to decide when reaction is complete , reactions may be incomplete.

Question 4

what is meant by periodicity ?1

Answer 4

• repeating trends in each period