The limiting reagent in a chemical reaction is the reactant that controls how much of the products are produced. Since some of the other reactants remain after the limiting reagent has been consumed fully, it is often discovered that they are in excess in the reactions. The theoretical yield is the most product that can theoretically be produced.
To determine the percentage yield of a reaction, the limiting reagent should be found. There are multiple equivalent ways to find the limiting reagent and determine the excess amounts of other reagents in the reaction given the equilibrium chemical equation that describes the reaction. We will go through the definition of a limiting agent, how to find out limiting reagents, and limiting reactant calculator in this post.
What is Limiting Reagents?
Limiting reagents are chemicals that are used up entirely during the course of a chemical reaction. They are additionally known as limiting reactants or limiting agents. A predetermined quantity of reactants are necessary for the reaction to be completed, based on the stoichiometry of chemical reactions. You should use a limiting reactant calculator to get accurate digits. Let’s take a look at the ammonia formation reaction described below:
3H2 + N2 → 2NH3
In the aforementioned reaction, 2 moles of ammonia are created when 3 moles of hydrogen gas react with 1 mole of nitrogen gas. But what if, during reaction, just 2 moles of hydrogen gas are present alongside 1 mole of nitrogen.
In that circumstance, the complete amount of nitrogen cannot be utilized (because the entirety of nitrogen requires 3 moles of hydrogen gas to react). As a result, the reaction is limited by hydrogen gas, which is why it is known as the limiting reagent in this reaction. Keep reading to know more about limiting reactant calculator.
Another example is how much bread and sausages are required to make a hot dog. A hot dog requires both bread and sausage. Hot dogs won’t be produced in sufficient numbers if there are not an equal quantity of the reactants (product). We can only make 5 hot dogs using 10 buns and 5 sausages, and we’ll still have 5 buns. While there are plenty of buns, the quantity of hot dogs that can be produced is limited by the availability of sausages.
Limiting Reagent Examples
Now let’s take a look at a few examples of limiting reagents.
Example
Consider the following chemical equation, which describes how benzene burns:
2C6H6(l) + 15 O2(g) —> 12CO2(g) + 6HO2(l)
It means that in order to react with 2 moles of benzene C6H6, 15 moles of molecular oxygen O2 are required.
Cross-multiplication is used to determine the quantity of oxygen needed for other amounts of benzene. For instance, 11.25 mol O2 is needed if 1.5 mol C6H6 is present:
1.5 mol C6H6 x 15molO2 / 2molC6H6
= 11.25 mol O2
When all of the benzene is used up, there will be an excess of (18 – 11.25) = 6.75 mol of un – reacted oxygen if there were 18 mol of oxygen present. Therefore, the limiting reagent is benzene. You can make all these calculations easily with help of a limiting reactant calculator.
How to Find a Limiting Reagent in a Reaction?
Let’s now discover how to identify the reaction limiting reagent.
There are two approaches to determining the limiting reagent. Finding and comparing the mole ratios of the reactants used in the process is one way. Another approach is to determine the grams of products produced from the quantities of reactants, where the limiting reagent is the one that produces the least quantity of product. Let’s check out both methods as we are discussing the limiting reactant calculator.
Method 1: Calculating the moles of each reactant to determine the limiting reagent.
Find the balanced chemical equation for the mentioned chemical process first. Then, create moles from all of the provided information (by using molar mass as a conversion factor). The mole ratio must then be determined using the available data.
Next, make a comparison between the calculated and actual ratios. Calculate the amount of product created using the amount of the limiting reactant. Finally, if required, determine how much extra non-limiting agent is still present. Continue reading to know more about the limiting reactant calculator.
Method 2: Calculating the amounts of products that each reactant would make and comparing them to find the limiting reagent.
The chemical equation must first be balanced for the specified chemical reaction. Then, transform the provided data into moles. For each individual reactant, use stoichiometry to calculate the mass of the product that is created. The limiting reagent would be the reactant that produces the least amount of product.
The excess reagent would be the reactant that produces the most product. Finally, subtract the mass of consumed excess reagent from the total mass provided for the excess reagent to determine how much surplus reactant is still present. Keep reading to get more info about the limiting reactant calculator.
How Limiting Reactant Calculator Works?
The calculator finds the limiting reactant and allows the reaction to end. Let’s look at how!
Input
- First, enter the chemical equation in the space provided or load previously saved example equations.
- Next, press the calculate button.
- A properly balanced equation with specific coefficients and moles will be displayed for you.
- You must now enter the mass of the reactants or the number of moles in the appropriate boxes.
Output
The following figures will be calculated using the free limiting reactant calculator:
- limiting the number of reactants used in a chemical reaction
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End Note
As we can see, the reactant that completely burns up and stops a reaction from proceeding is known as the limiting reagent or limiting reactant. Additionally, it establishes how much of the finished product will be produced.
Undoubtedly, you cannot determine the minimal yield of any chemical process without a limiting reactant. For this reason, the limiting reactant calculator with moles helps you to calculate this yield, which further helps in keeping the reaction’s smooth running.