The Limiting Reactant (Leaving Cert Chemistry): Flashcards
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Define: Limiting reactant
Define: Limiting reactant
Substance used up first; determines max product amount
Define: Excess reactant
Define: Excess reactant
Substance not completely used up; some left over after reaction
What does the limiting reactant determine?
What does the limiting reactant determine?
The maximum amount of product that can be formed
Formula to calculate moles from mass
Formula to calculate moles from mass
First step to identify limiting reactant
First step to identify limiting reactant
Write the balanced chemical equation
How to identify which reactant is limiting?
How to identify which reactant is limiting?
Convert to moles, compare mole ratios; reactant used up first is limiting
State of limiting reactant at end of reaction
State of limiting reactant at end of reaction
Completely consumed; none remains
What controls the amount of product formed?
What controls the amount of product formed?
The limiting reactant
What happens to excess reactants?
What happens to excess reactants?
They are left over; not completely used up
When must you identify limiting reactant?
When must you identify limiting reactant?
Before calculating product yields
4 Fe + 6 S → ? (1:1 ratio reaction)
4 Fe + 6 S → ? (1:1 ratio reaction)
4 FeS formed; 2 S left over; Fe is limiting
Max FeS from 10g Fe (0.18 mol) + 10g S (0.31 mol)?
Max FeS from 10g Fe (0.18 mol) + 10g S (0.31 mol)?
15.83 g (Fe limiting; 0.18 mol FeS formed)