Quantities in Chemical Reactions

Question 1

avogadro’s constant

Answer 1

6.02 x 10^23

Question 2

molar mass

Answer 2

the mass of an atom/compound per 1 mole of the atom/compound

unit: g/mol and can be found on periodic table

Question 3

mass percentage composition (%m)

Answer 3

the breakdown (by percentage) that each elemnt takes up in the compound by mass (or molar mass)

Question 4

empirical formula (EF)

Answer 4

the fully reduced formula of any compound

Question 5

molecular formula (MF)

Answer 5

the actual formula of a molecule when ratios are applied by multiplying subscripts of the EF by some coefficient

how to find: M of MF / M of EF

Question 6

formula of hydrate compounds

Answer 6

• hydrate = ionic compound with water
• anhydrate = ionic compound without water

how to find: n of h20 / n of anhydrate

Question 7

limiting reactant (LR)

Answer 7

the reactant that gets used up first

Question 8

excess reactant (ER)

Answer 8

the reactant(s) that will have left over amounts of the reaction is complete

Question 9

percentage yield

Answer 9

the comparison of my actual yield (experimentally collected) to the theoretical yield (calculated using stoic)

% yield = actual/ theoretical x 100%

Question 10

reason for % yield

not 100%

Answer 10

• human errors: calculations, measurement, transfer loss
• rate of rxn: wait time
• competing rxn: could use up reactant(s) or product
• contamination: not careful about cross-contamination