Quantitative chemistry

Question 1

what is the % mass of an element in a compound

Answer 1

the % mass of an element in a compound = Ar / Mr x 100

Question 2

what’s the equation for the number of moles

Answer 2

No. of moles = mass in g / Mr

Question 3

what’s the equation for the volume of gas

Answer 3

volume of gas = mass of gas / Mr of gas x 24
or
volume of gas = mol of gas x 24

Question 4

what’s the equation for the concentration of a solution

Answer 4

concentration = mass of solute / volume of solute

Question 5

what is then other equation for the concentration of a solution

Answer 5

concentration = moles of solute / volume of solute

Question 6

what is the equation for the atom economy

Answer 6

atom economy = Mr of desired product / Mr of all reactants x 100

Question 7

what’s the equation for the percentage yield

Answer 7

percentage yield = mass of product actually made / maximum theoretical mass of product x 100

Question 8

why is the yield always less than 100%

Answer 8

1) not all reactants react to make a product
2) there might be side reactions
3) you lose some product when you separate it from the reaction mixture