How many moles of c2h2 are needed to react completely with 84.0 mol o2?

33.6 moles

Explanation:

According to the law of conservation of mass, mass can neither be created nor be destroyed. Thus the mass of products has to be equal to the mass of reactants. The number of atoms of each element has to be same on reactant and product side. Thus chemical equations are balanced.

Combustion of ethylene is represented by following balanced equation:

According to stoichiometry:

5 moles of react completely with = 2 moles of  

Thus 84.0 moles of react completely with = moles of  

Thus 33.6 moles of are needed to react completely with 84.0 mol

in 1783 cavendish was working with his hydrogen gas and found that when he burned it and condensed the vapor it was water. this was very significant since it disproved the greek theory of elements completely since water was not a simple substance but the product of two gases. it was lavoisier who hearing of the experiment gave cavendish's gas the name hydrogen ("water-producer") and added that hydrogen burned by combining with oxygen and that water was a hydrogen-oxygen combination.

explanation: