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The definition of a mole is Avogadro's number (6.02 x 1023) of particles (atoms, molecules, ions, electrons etc.). Moles are a very important part of chemistry especially in stoichiometry since it is part of many other calculation quantities and formulas including molar mass, solution calculations and gas volume calculations.
The mole is also used in chemical reactions and equations to calculate the amount of reactant needed to react completely with another reactant or to calculate the product produced from the amount of reactant provided and vice versa.
This is done by using the ratio of the coefficients in a balanced equation. This ratio of coefficients is also known as the mole ratio.
In the following experiment, a simple displacement reaction would occur from the reaction of an aqueous solution of copper (II) sulphate and zinc powder.
Zn (s) + CuSO4 (aq) � ZnSO4 (aq) + Cu (s)
This reaction would be set up to allow the zinc to be the limiting factor therefore react completely, in order for that to happen, copper (II) sulphate would be in excess.
As zinc is the limiting factor, it will be used to calculate the expected amount of copper produced from the 1 to 1 mole ratio of zinc and copper from the balanced equation above.
Aim: To find the mole ratio of a reactant to a product in a chemical reaction .
Reagents: - Copper (II) Sulphate Crystals
Then weigh out 7.0 g of copper (II) sulphate using the beaker
97.37g
104.37g
7.0g
98.66g
99.96g
1.30g
98.78g
1.41g
n =
=
= 0.0222 mol
n =
=
= 0.0199 mol
Zn : Cu
0.0199 mol
:
0.0222 mol
1
:
1
=
n(Cu) = 1 x 0.0199
= 0.0199 mol
m = nM
= 0.0199 x 63.55
= 1.26 g
x 100
= 89.4%
The mole ratio from calculation 3 is approximately 1 to 1, same as the expected mole ratio from the balanced equation. The expected mass of copper is 1.26 g but 1.41g of copper was weighed out therefore, the percentage yield of the above experiment is 89.4%. This is mostly caused by the impurity of the copper since there might be a small amount of leftover zinc sulphate in the beaker.
Evaluation: From the experiment above, some things could have been done better to achieve a higher percentage yield. The glass rod should've been dipped into water before stirring the copper (II) sulphate and zinc in order for no copper to attach to the glass rod after stirring. More importantly, I could have improved and made this experiment more accurate by rinsing the copper more thoroughly so no zinc sulphate would be left in the beaker.
Relating Moles to Coefficients of a Chemical Equation. (2017, Nov 17). Retrieved from https://studymoose.com/relating-moles-to-coefficients-of-a-chemical-equation-essay
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