What would cause the percent yield of a reaction to be less than 100%?

the product participates in a side reaction.

a balanced chemical equation is used.

all of the limiting reagent gets used up.

pure reactants are used.

first one is correct

All of the limiting reagent gets used up causes the percent yield of a reaction to be less than 100%

Explanation:

It is rare for a chemical reaction to occur with the right proportion of reactants that reacts together to form resultant products.During this process, one of the reactants gets used up faster resulting in the lower percent yield. Such product that gets used up faster is called limiting reagent. This limiting reagent is responsible for lowering the percentage yield in the chemical reaction.

The limiting reactant can be found easily by calculating the yield of each reactant assuming they are consumed completely. The reactant which has least yield is the limiting reactant of the reaction.

given:

mass of na = 115 g

excess cl2

to determine:

mass of nacl produced

explanation:

given reaction is-

2na(s) + cl2(g) → 2nacl(s)

since cl2 is in excess, na will be the limiting reagent

as per the reaction stoichiometry na: nacl = 1: 1

i.e. moles of na reacted = moles of nacl formed

now, # moles of na = mass of na/atomic mass

                                  = 115 g/23 g.mol-1 = 5 moles

therefore, moles of nacl = 5

molar mass of nacl = 58 g/mol

mass of nacl = 5 moles * 58 g.mol-1 = 290 g

ans: amount of nacl produced = 290 g