RPAL Excess Reagents

Question 1

What is an excess reagent?

Accepted Answer

A reactant present in greater amount than needed to react with the limiting reagent

Answer

The reactant that is fully consumed in the reaction

Answer

Any product formed in a reaction

Answer

A catalyst added to speed up the reaction

Question 2

How is the amount of excess reagent remaining calculated?

Accepted Answer

Subtract the moles consumed (based on limiting reagent) from the initial moles

Answer

Divide the initial moles by the molar mass

Answer

Add the moles of product formed to the initial moles

Answer

Multiply the limiting reagent moles by Avogadro's number

Question 3

In 2H₂ + O₂ → 2H₂O, if 6 mol H₂ and 2 mol O₂ react, which is the excess reagent and how much remains?

Accepted Answer

H₂; 2 mol remain

Answer

O₂; 2 mol remain

Answer

H₂; 1 mol remains

Answer

O₂; 1 mol remains

Question 4

If you increase the amount of excess reagent in a reaction, what happens to the amount of product formed?

Accepted Answer

Nothing — product amount depends only on the limiting reagent

Answer

Product increases proportionally

Answer

Product decreases because the excess interferes

Answer

Product doubles for every mole of excess added

Question 5

Which of the following best describes 'leftover' in the RPAL context?

Accepted Answer

The unreacted excess reagent remaining after the reaction stops

Answer

The amount of limiting reagent consumed

Answer

The theoretical yield of the product

Answer

The activation energy of the reaction

Question 6

For the reaction C + O₂ → CO₂, if 3 mol C and 5 mol O₂ are combined, what is the excess reagent?

Accepted Answer

O₂

Answer

C

Answer

CO₂

Answer

There is no excess reagent