# 0.1 Analyzing chemical equations

 Page 1 / 3

Application of mole concept requires a balanced chemical equation. The different constituents of the reaction – reactants and products – bear a simple whole number proportion same as the proportion of the coefficients associated with constituents. According to mole concept, the molar mass of constituents participates in this proportion. For a generic consideration as given :

$xA+yB\to {A}_{x}{B}_{y}$

Here, 1 mole of compound ( ${A}_{x}{B}_{y}$ ) involves x mole of A and y mole of B. Using symbols :

$\text{x moles of A}\equiv \text{y moles of B}\equiv \text{1 mole of}{A}_{x}{B}_{y}$

The point to emphasize here is that this is a relation, which is connected by "equivalence sign (≡)" - not by "equal to (=)" sign. We know that 2 moles of hydrogen reacts with 1 mole of oxygen to form 2 moles of water. Clearly, we can not equate like 2=1=2. We need to apply unitary method to interpret this relation of equivalence. We say that since x moles of A react with y moles of B. Hence, 1 mole of A reacts with y/x moles of "B". Similarly, 1 mole of B reacts with x/y moles of "A". Once we know the correspondence for 1 mole, we can find correspondence for any other value of participating moles of either A or B.

## Mass of participating entities in a reaction

Mole concept is used to calculate mass of individual constituent of a chemical reaction. The proportion of molar mass is converted to determine proportion of mass in which entities are involved in a reaction. The symbolic mass relation for the chemical reaction as given above is :

$x{M}_{A}\phantom{\rule{2pt}{0ex}}\text{gm of A}\equiv y{M}_{B}\phantom{\rule{2pt}{0ex}}\text{gm of B}\equiv {M}_{{A}_{x}{B}_{y}}\phantom{\rule{2pt}{0ex}}\text{gm of}{A}_{x}{B}_{y}$

We apply unitary method on the mass relation related with equivalent sign (≡) to determine mass of different entities of the reaction.

Problem : Calculate mass of lime (CaO) that can be prepared by heating 500 kg of 90 % pure limestone ( $CaC{O}_{3}$ .

Solution : Purity of CaCO3 is 90 %. Hence,

$\text{Mass of}\phantom{\rule{1em}{0ex}}CaC{O}_{3}=0.9X500=450\phantom{\rule{1em}{0ex}}kg$

The chemical reaction involved here is :

$CaC{O}_{3}\to CaO+C{O}_{2}$

Applying mole concept :

$⇒\text{1 mole of}\phantom{\rule{1em}{0ex}}CaC{O}_{3}\equiv \text{1 mole of CaO}$

$⇒\text{(40 + 12 + 3X 16) gm of}\phantom{\rule{1em}{0ex}}CaC{O}_{3}\equiv \text{(40 + 16) gm of CaO}$

$⇒\text{100 gm of}\phantom{\rule{1em}{0ex}}CaC{O}_{3}\equiv \text{56 gm of CaO}$

$⇒\text{100 kg of}\phantom{\rule{1em}{0ex}}CaC{O}_{3}\equiv \text{56 kg of CaO}$

Applying unitary method :

$⇒\text{mass of CaO produced}=\frac{56X450}{100}=252\phantom{\rule{1em}{0ex}}kg$

Problem : Igniting $Mn{O}_{2}$ converts it quantitatively to $M{n}_{3}{O}_{4}$ . A sample of pyrolusite contains 80% $Mn{O}_{2}$ , 15 % $Si{O}_{2}$ and 5 % water. The sample is ignited in air to constant weight. What is the percentage of manganese in the ignited sample ? ( ${A}_{Mn}=55$ )

Solution : The sample contains three components. Since this question involves percentage, we shall consider a sample of 100 gm. Water component weighing 5 gm evaporates on ignition. $Si{O}_{2}$ weighing 15 gm does not change. On the other hand, 80 gm of $Mn{O}_{2}$ converts as :

$3Mn{O}_{2}\to M{n}_{3}{O}_{4}+{O}_{2}$

Applying mole concept,

$\text{3 moles of}Mn{O}_{2}\equiv \text{1 mole of}M{n}_{3}{O}_{4}$

$3X\left(55+2X16\right)\text{gm of}Mn{O}_{2}\equiv 1X\left(3X55+4X16\right)\text{gm of}M{n}_{3}{O}_{4}$

$261\text{gm of}Mn{O}_{2}\equiv 229\text{gm of}M{n}_{3}{O}_{4}$

Since sample is ignited in air to constant weight, it means that all of $\mathrm{Mn}{O}_{2}$ in the sample is converted. Using unitary method, we determine mass of converted mass of $M{n}_{3}{O}_{4}$ for 80 gm of $\mathrm{Mn}{O}_{2}$ :

$\text{Mass of}M{n}_{3}{O}_{4}\text{on conversion}=\frac{229}{261}X80=70.2\phantom{\rule{1em}{0ex}}gm$

We are required to find the percentage of Mn in the ignited sample. Thus, we need to determine the mass of the ignited sample. The ignited sample contains 70.2 gm of $M{n}_{3}{O}_{4}$ and 15 gm of $Si{O}_{2}$ . Total mass of ignited sample is 70.2+15 = 85.4 gm. On the other hand, amount of Mn in $M{n}_{3}{O}_{4}$ is calculated from its molecular constitution :

$229\text{gm of}M{n}_{3}{O}_{4}\equiv 3X55\text{gm of Mn}\equiv 165\text{gm of Mn}$

$\text{Amount of Mn in 70.2 gm of}M{n}_{3}{O}_{4}=\frac{165}{229}X70.2=0.72X70.2=50.54\phantom{\rule{1em}{0ex}}gm$

Clearly, 85.4 gm of ignited sample contains 50.54 gm of Mn. Hence,

$\text{Percentage amount of manganese in the ignited sample}=\frac{50.54}{85.4}X100=59.2%$

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
anyone know any internet site where one can find nanotechnology papers?
research.net
kanaga
sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
what does nano mean?
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
absolutely yes
Daniel
how to know photocatalytic properties of tio2 nanoparticles...what to do now
it is a goid question and i want to know the answer as well
Maciej
Abigail
for teaching engĺish at school how nano technology help us
Anassong
Do somebody tell me a best nano engineering book for beginners?
there is no specific books for beginners but there is book called principle of nanotechnology
NANO
what is fullerene does it is used to make bukky balls
are you nano engineer ?
s.
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
Tarell
what is the actual application of fullerenes nowadays?
Damian
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
Tarell
what is the Synthesis, properties,and applications of carbon nano chemistry
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
NANO
so some one know about replacing silicon atom with phosphorous in semiconductors device?
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
for screen printed electrodes ?
SUYASH
What is lattice structure?
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
what's the easiest and fastest way to the synthesize AgNP?
China
Cied
Got questions? Join the online conversation and get instant answers!