# 1.13 Reaction yields  (Page 2/9)

 Page 2 / 9
$\text{mol HCl produced}=\text{3 mol}\phantom{\rule{0.2em}{0ex}}{\text{H}}_{2}\phantom{\rule{0.2em}{0ex}}×\phantom{\rule{0.2em}{0ex}}\frac{\text{2 mol HCl}}{\text{1 mol}\phantom{\rule{0.2em}{0ex}}{\text{H}}_{2}}\phantom{\rule{0.2em}{0ex}}=\text{6 mol HCl}$

Complete reaction of the provided chlorine would produce

$\text{mol HCl produced}=\text{2 mol}\phantom{\rule{0.2em}{0ex}}{\text{Cl}}_{2}\phantom{\rule{0.2em}{0ex}}×\phantom{\rule{0.2em}{0ex}}\frac{\text{2 mol HCl}}{\text{1 mol}\phantom{\rule{0.2em}{0ex}}{\text{Cl}}_{2}}\phantom{\rule{0.2em}{0ex}}=\text{4 mol HCl}$

The chlorine will be completely consumed once 4 moles of HCl have been produced. Since enough hydrogen was provided to yield 6 moles of HCl, there will be unreacted hydrogen remaining once this reaction is complete. Chlorine, therefore, is the limiting reactant and hydrogen is the excess reactant ( [link] ).

## Identifying the limiting reactant

Silicon nitride is a very hard, high-temperature-resistant ceramic used as a component of turbine blades in jet engines. It is prepared according to the following equation:

$\text{3Si}\left(s\right)+2{\text{N}}_{2}\left(g\right)\phantom{\rule{0.2em}{0ex}}⟶\phantom{\rule{0.2em}{0ex}}{\text{Si}}_{3}{\text{N}}_{4}\left(s\right)$

Which is the limiting reactant when 2.00 g of Si and 1.50 g of N 2 react?

## Solution

Compute the provided molar amounts of reactants, and then compare these amounts to the balanced equation to identify the limiting reactant.

$\text{mol Si}=2.00\phantom{\rule{0.2em}{0ex}}\overline{)\text{g Si}}\phantom{\rule{0.2em}{0ex}}×\phantom{\rule{0.2em}{0ex}}\frac{\text{1 mol Si}}{28.09\phantom{\rule{0.2em}{0ex}}\overline{)\text{g Si}}}\phantom{\rule{0.2em}{0ex}}=\text{0.0712 mol Si}$
$\text{mol}\phantom{\rule{0.2em}{0ex}}{\text{N}}_{2}=1.50\phantom{\rule{0.2em}{0ex}}\overline{)\text{g}\phantom{\rule{0.2em}{0ex}}{\text{N}}_{2}}\phantom{\rule{0.2em}{0ex}}×\phantom{\rule{0.2em}{0ex}}\frac{\text{1 mol}\phantom{\rule{0.2em}{0ex}}{\text{N}}_{2}}{28.02\phantom{\rule{0.2em}{0ex}}\overline{)\text{g}\phantom{\rule{0.2em}{0ex}}{\text{N}}_{2}}}\phantom{\rule{0.2em}{0ex}}=\text{0.0535 mol}\phantom{\rule{0.2em}{0ex}}{\text{N}}_{2}$

The provided Si:N 2 molar ratio is:

$\frac{\text{0.0712 mol Si}}{\text{0.0535 mol}\phantom{\rule{0.2em}{0ex}}{\text{N}}_{2}}\phantom{\rule{0.2em}{0ex}}=\phantom{\rule{0.2em}{0ex}}\frac{\text{1.33 mol Si}}{\text{1 mol}\phantom{\rule{0.2em}{0ex}}{\text{N}}_{2}}$

The stoichiometric Si:N 2 ratio is:

$\frac{\text{3 mol Si}}{\text{2 mol}\phantom{\rule{0.2em}{0ex}}{\text{N}}_{2}}\phantom{\rule{0.2em}{0ex}}=\phantom{\rule{0.2em}{0ex}}\frac{\text{1.5 mol Si}}{\text{1 mol}\phantom{\rule{0.2em}{0ex}}{\text{N}}_{2}}$

Comparing these ratios shows that Si is provided in a less-than-stoichiometric amount, and so is the limiting reactant.

Alternatively, compute the amount of product expected for complete reaction of each of the provided reactants. The 0.0712 moles of silicon would yield

$\text{mol}\phantom{\rule{0.2em}{0ex}}{\text{Si}}_{3}\phantom{\rule{0.1em}{0ex}}{\text{N}}_{4}\phantom{\rule{0.2em}{0ex}}\text{produced}=\text{0.0712 mol Si}\phantom{\rule{0.2em}{0ex}}×\phantom{\rule{0.2em}{0ex}}\frac{1\phantom{\rule{0.2em}{0ex}}\text{mol}\phantom{\rule{0.2em}{0ex}}{\text{Si}}_{3}\phantom{\rule{0.1em}{0ex}}{\text{N}}_{4}}{\text{3 mol Si}}\phantom{\rule{0.2em}{0ex}}=\text{0.0237 mol}\phantom{\rule{0.2em}{0ex}}{\text{Si}}_{3}\phantom{\rule{0.1em}{0ex}}{\text{N}}_{4}$

while the 0.0535 moles of nitrogen would produce

$\text{mol}\phantom{\rule{0.2em}{0ex}}{\text{Si}}_{3}\phantom{\rule{0.1em}{0ex}}{\text{N}}_{4}\phantom{\rule{0.2em}{0ex}}\text{produced}=\text{0.0535 mol}\phantom{\rule{0.2em}{0ex}}{\text{N}}_{2}\phantom{\rule{0.2em}{0ex}}×\phantom{\rule{0.2em}{0ex}}\frac{\text{1 mol}\phantom{\rule{0.2em}{0ex}}{\text{Si}}_{3}\phantom{\rule{0.1em}{0ex}}{\text{N}}_{4}}{\text{2 mol}\phantom{\rule{0.2em}{0ex}}{\text{N}}_{2}}\phantom{\rule{0.2em}{0ex}}=\text{0.0268 mol}\phantom{\rule{0.2em}{0ex}}{\text{Si}}_{3}\phantom{\rule{0.1em}{0ex}}{\text{N}}_{4}$

Since silicon yields the lesser amount of product, it is the limiting reactant.

## Check your learning

Which is the limiting reactant when 5.00 g of H 2 and 10.0 g of O 2 react and form water?

O 2

## Percent yield

The amount of product that may be produced by a reaction under specified conditions, as calculated per the stoichiometry of an appropriate balanced chemical equation, is called the theoretical yield    of the reaction. In practice, the amount of product obtained is called the actual yield    , and it is often less than the theoretical yield for a number of reasons. Some reactions are inherently inefficient, being accompanied by side reactions that generate other products. Others are, by nature, incomplete (consider the partial reactions of weak acids and bases discussed earlier in this chapter). Some products are difficult to collect without some loss, and so less than perfect recovery will reduce the actual yield. The extent to which a reaction’s theoretical yield is achieved is commonly expressed as its percent yield    :

$\text{percent yield}=\phantom{\rule{0.2em}{0ex}}\frac{\text{actual yield}}{\text{theoretical yield}}\phantom{\rule{0.2em}{0ex}}×\phantom{\rule{0.2em}{0ex}}100%$

Actual and theoretical yields may be expressed as masses or molar amounts (or any other appropriate property; e.g., volume, if the product is a gas). As long as both yields are expressed using the same units, these units will cancel when percent yield is calculated.

#### Questions & Answers

where we get a research paper on Nano chemistry....?
what are the products of Nano chemistry?
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
hey
Giriraj
Preparation and Applications of Nanomaterial for Drug Delivery
revolt
da
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
I only see partial conversation and what's the question here!
what about nanotechnology for water purification
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
what is the stm
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
why we need to study biomolecules, molecular biology in nanotechnology?
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
why?
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
how do you find theWhat are the wavelengths and energies per photon of two lines
The eyes of some reptiles are sensitive to 850 nm light. If the minimum energy to trigger the receptor at this wavelength is 3.15 x 10-14 J, what is the minimum number of 850 nm photons that must hit the receptor in order for it to be triggered?
A teaspoon of the carbohydrate sucrose contains 16 calories, what is the mass of one teaspoo of sucrose if the average number of calories for carbohydrate is 4.1 calories/g?
4. On the basis of dipole moments and/or hydrogen bonding, explain in a qualitative way the differences in the boiling points of acetone (56.2 °C) and 1-propanol (97.4 °C), which have similar molar masses
Calculate the bond order for an ion with this configuration: (?2s)2(??2s)2(?2px)2(?2py,?2pz)4(??2py,??2pz)3
Which of the following will increase the percent of HF that is converted to the fluoride ion in water? (a) addition of NaOH (b) addition of HCl (c) addition of NaF