# Limiting Reagent Question

• Cromptu
In summary, the conversation discussed the process of determining the limiting reagent in a chemical equation, using the example of Zn and HCl. The steps involved calculating the amount of ZnCl2 produced by each reactant and determining which one produces the least amount. The conversation also addressed the importance of having given amounts of reactants in order to find the limiting reagent.

#### Cromptu

I have some doubts in determining the limiting reagent in a question

Based on my understanding, I will explain how I found out the limiting reagent in this problem. Please tell me if my explanation is correct or not.

Equation : Zn + 2HCl - ZnCl2 + H2

To determine the limiting reagent, we need to see how much ZnCl2 will Zn and HCl produce separately.
So,
65.4g of Zn gives 136.4g of ZnCl2
Thus 1g of Zn will give 2.08g of ZnCl2

Now,
73g of HCl gives 136.4g ZnCl2
Thus 1g of HCl will give 1.86g of ZnCl2

Now the limiting reagent is the one which produces the least amount of ZnCl2

Thus in this equation, HCl is the limiting reagent.

please tell me if my explanation is correct or not.

It has been a long time since I've done a question like this, but are limiting reagent questions to be done in terms of mass or in terms of moles? If they are in terms of moles then you have a problem because you'll need to know how many moles of 2HCl you need.

First of all - limiting reagent exists only if amounts of reactants are given. So if the question is "if you react 1g of Zn with 1g of HCl, which one is a limiting reagent" - you can calculate an answer. But if the question is "which is the limiting reagent if you mix Zn with HCl" - it doesn't make sense.

In other words - limiting reagent is not a "property" of the reaction.

Last edited:
Borek beat me to it so I leave it in his good hands.

As often here we are given an answer and have to work out what is the question; we are not too bad at it. Thankyou so much :)
You guys rock! :D

## What is a limiting reagent?

A limiting reagent is the reactant in a chemical reaction that is completely consumed, limiting the amount of product that can be formed.

## How do you identify the limiting reagent in a chemical reaction?

To identify the limiting reagent, you must first determine the mole ratio of the reactants in the balanced chemical equation. Then, compare the amount of each reactant present to the amount needed to completely react with the other reactant. The reactant with the smaller amount is the limiting reagent.

## Why is it important to know the limiting reagent in a chemical reaction?

Knowing the limiting reagent allows us to accurately predict the amount of product that will be formed in a reaction. It also helps to determine the efficiency of a reaction and how much of each reactant is needed for a desired amount of product.

## What happens if the limiting reagent is not used up completely?

If the limiting reagent is not completely consumed, it will limit the amount of product that can be formed. This means there will be some excess of the other reactant(s) left over after the reaction is complete.

## Can there be more than one limiting reagent in a chemical reaction?

No, there can only be one limiting reagent in a chemical reaction. This is because the limiting reagent is the reactant that is completely consumed and determines the maximum amount of product that can be formed.