Know More About Limiting Reagent 

Whilst there is no sufficiency of a single element in a chemical reaction, the reaction ceases to exit unexpectedly. To discern the quantity of emergent produced, it has to be a firm reactant that will restrict the causal nexus, called the limiting reagent and which reactant is inadequate(the adequate reagent). 

A way of finding the limiting reagent is by calculating the quantity of product that can be established using every reactant; the only one that produces the comparatively slighter product is the limiting reagent.

Let us consider the following situation that illustrates the importance of limiting reagents along with limiting reagent examples. To collect an automobile, four tires and a couple of fog lights are essential. In this case, consider that the tires and fog lights are reactants simultaneously as the automobile is the product fashioned from the reaction of four tires and two fog lights. 

If you possess sixteen tires and ten fog lights, how many automobiles could be constructed? With sixteen tires, four automobiles can be constructed as there are four tires to a vehicle. 

With ten fog lights, five vehicles can be constructed (every automobile wishes two fog lights). Even though greater vehicles can be crafted from the fog lights to be had, the handiest four full vehicles are viable due to the restrained variety of tires to be had. In this scenario, the fog lights are in abundance. 

Due to the fact, the variety of vehicles shaped through sixteen tires is least as compared to the number of automobiles produced using ten fog lights, the tires that we possess are the limiting reagent. 

The limiting reagent is the reactant that is entirely fueled up in a reaction and hence determines when the reaction can cease to exist. The perfect amount of reactant needed to react with some other element can be estimated readily from the reaction. 

Suppose the reactants are not shuffled together with the perfect ratio(as represented by the balanced chemical equation). In that case, one of the reactants may be consumed even as every other reactant remains. The limiting reagent is the one that is fed on; it restricts the reaction from moving on because nothing is yet remaining to react with the inadequate reactant.

There are ways and means to decide the limiting reagent. One Technique is to locate and examine the mole ratio of the reactants consumed in the reaction (Technique one). An alternate method is to determine the quantity of merchandise comprised of the provided portions of reactants; the reactant that produces the least quantity of product is the limiting reagent (Technique two).

Technique One:

Find the restricting reagent via searching on the range of moles of each reactant.

  1. Decide the chemical equation for the chemical reaction.
  2. Change all the data provided into moles (most possibly, using molar mass as a Changing aspect).
  3. Determine the mole ratio from the given records. Evaluate the calculated ratio to the actual ratio.
  4. Use the necessary quantity of limiting reactant to determine the quantity of product produced.
  5. If necessary, determine how a great deal is left in extra of the non-limiting reagent.

Technique Two:

Find the limiting reagent by using calculation and evaluation of the amount of product every reactant will produce.

  1. Balance the chemical equation for the chemical response.
  2. Convert the given data into moles.
  3.  For every individual reactant, try to locate the weight of the product produced.
  4. The reactant that establishes a slighter quantity of product is the limiting reagent.
  5. The reactant that establishes a higher quantity of product is the excess reagent.
  6. To determine the quantity of ultimate excess reactant, reduce the mass of extra reagent engrossed from the entire mass of excess reagent provided.

Limiting Reagent Examples: Photosynthesis

Consider respiration, one of the most common chemical reactions on earth.

C6H12O6+6O2→6CO2+6H2O+energy(1)

What mass of CO2 forms in the reaction of 25 grams of C6H12O6 with 40 grams of O2?

Solution

When analysing this problem, notice that every one mole of C6H12O6 needs six moles of O2to gain six moles of CO2 and six moles of H2O.

First, establish the chemical equation for this chemical reaction.

Now, Change all the information provided into moles (by using molar mass as a determining factor).

25g×1mol180.06g=0.1388mol C6H12O6

40g×1mol32g=1.25mol O2 

And then take up to determine the mole ratio with the information that is provided. Now, start Comparing the determined ratio with that of the original ratio.

  1. If every 1.25 moles of O2 were to be fed up, there is an absolute necessity of 1.25×16  moles of C6H12O6. There are only 0.1388 moles of C6H12O6 present that could bring it up as the limiting reactant.

1.25mol O2×1mol C6H12O6 6 mol O2=0.208mol C6H12O6

  1. If every 0.1388 moles of C6H12O6 were used up, there would need to be 0.1388 x 6 or 0.8328 moles of O2. Because there is an excess of O2, the C6H12O6 amount is used to estimate the quantity of the products in the reaction.

0.1388mol C6H12O6×6mol O21mol C6H12O6=0.8328mol O2

If more than six moles of O2 are present per mole of C6H12O6, the O2is in abundance and C6H12O6 is the limiting reactant. Oxygen is the limiting reactant if less than six moles of O2 are present per mole of C6H12O6. The ratio is six-mole oxygen per one mole C6H12O6 or one-mole oxygen per 1/6 mole C6H12O6. This means 6 mol O2 / 1 mol C6H12O6.

Hence, the mole ratio is: (0.8328 mol O2)/(0.208 mol C6H12O6)

This produces a 4.004 ratio of O2 to C6H12O6.

Then, try to use the amount of limiting reactant and determine the amount of CO2 or H2O produced.

For CO2 produced: 

 0.1388moles glucose×61=0.8328moles CO2 .

Finally, if necessary, do determine how much is left in excess.

1.25 mol – 0.8328 mol = 0.4172 moles of O2 leftover.

Conclusion

We hope now you have a clear idea about Limiting Reagent along with its examples.