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alejandra216
27.08.2020 •
Chemistry
A reaction between 7.0 g of copper(II) oxide and 50 mL of 0.20 M nitric acid produces
copper(II) nitrate, Cu(NO3)2 and water.
(c) Determine the limiting reactant.
(d) Calculate the mass of excess reactant after the reaction.
(ANS: 6.6068g)
(e) Determine the percentage yield if the actual mass of copper (II) nitrate obtained from
the reaction is 0.85 g.
(ANS: 90.64%)
How to get the mass of HNO3 from here? I only managed to get mass of NO3 based on the molarity formula. thanks!
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Ответ:
(c) The limiting reactant is HNO₃
(d) The mass of the excess reactant after the reaction is approximately 6.6 grams
(e) The percentage yield of copper (II) nitrate from the reaction is approximately 90.64%
The reason the above values are the correct values is as follows;
The given parameters are;
The mass of copper(II)oxide in the reaction = 7.0 g
The volume of the 0.20 M nitric acid, HNO₃ = 50 mL
(c) Concentration of the reactants
The molar mass of CuO = 79.545 g/mol
Number of moles = Mass/(Molar mass)
The number of moles of CuO = (7 g)/79.545 g/mol ≈ 0.088 moles
50 mL of 0.20 M HNO₃, contains 50/1000 × 0.2 = 0.01 moles of HNO₃
The chemical equation for the reaction is CuO + 2HNO₃ → Cu(NO₃)₂ + H₂O
Therefore;
One mole of CuO reacts with two moles of HNO₃ to produce one mole of Cu(NO₃)₂ and one mole of H₂O
Therefore, 0.088 moles of CuO reacts with 2 × 0.088 = 0.176 moles of HNO₃
Given that there is only 0.01 moles of HNO₃, the limiting reactant is the HNO₃, which is not enough to completely react with the CuO which is the excess reactant
(d) The mass of the CuO that reacts with the 0.01 moles of HNO₃ is given as follows;
1 mole of CuO reacts with 2 moles HNO₃
0.01 moles of HNO₃ will react with 0.01/2 = 0.005 moles of CuO
Mass = Number of moles × Molar mass
The mass of 0.005 moles of CuO = 0.005 moles × 79.545 g/mol = 0.397725 grams
The mass of the CuO left = Initial mass - Reacting mass
∴ The mass of the CuO left = 7 grams - 0.397725 grams = 6.602275 grams
The mass of the excess reactant (CuO) after the reaction ≈ 6.6 grams
(e) The theoretical number of moles of copper (II) nitrate, Cu(NO₃)₂ produced = Half the number of moles of HNO₃ in the reaction
The number of moles of HNO₃ in the reaction = 0.01 moles
∴ The theoretical number of moles of copper (II) nitrate, Cu(NO₃)₂ produced = (1/2) × 0.01 moles = 0.005 moles
The molar mass of Cu(NO₃)₂ = 187.56 g/mol
The theoretical mass of Cu(NO₃)₂ produced = 0.005 moles × 187.56 g/mol = 0.9378 grams
The actual yield of copper (II) nitrate is 0.84 g
Therefore;
The percentage yield of copper (II) nitrate, %yield ≈ 90.64%
Learn more about percentage yield from chemical reactions here:
link
Ответ:
(c) Nitric acid
is the limiting reactant.
(d) Approximately
of
will be in excess.
(e) The percentage yield of
is approximately
. (Rounded to two significant figures, as in other quantities in the question.)
Explanation:
Start with the balanced chemical equation:
Look up relevant relative atomic mass data on a modern periodic table:
Calculate the formula mass of the species:
There are two reactants in this reaction:
and
. Assume that
is the limiting one. In other words, assume that all the
is consumed before
was.
Consider: how many moles of
would be required to convert all that
of
to
?
Calculate the number of moles of
formula units in
of
Note the ratio between the coefficients of
and
:
Therefore:
On the other hand, how many moles of
are actually available?
Convert the volume of that
solution to the standard unit (liter.)
Calculate the number of moles of
in that
solution:
Apparently, the quantity of
required exceeded the quantity that is available. Therefore, the assumption is invalid, and
cannot be the limiting reactant. At the same time,
Mass of the reactant in excessSince it is now known that all that
of
will be consumed, apply that coefficient ratio again to obtain the quantity of
consumed in this reaction:
It was already shown that the formula mass of
is (approximately)
. Therefore, the mass of that
formula units of
would be:
Before the reaction,
of
is available. Therefore, all that
of
would be in excess.
Percentage YieldSimilarly:
Apply this ratio to find the theoretical yield of
:
Find the mass of that
of
formula units using its formula mass:
Calculate the percentage yield given that the actual yield is
:
(Rounded to two significant figures.)
Ответ:
2Fecl
2Na2(OH)2
AlSO4 + H
Explanation:
metal and salt gives a metalsalt and gas