At a hydroelectric power plant, potential energy is changed into kinetic energy. The kinetic energy is then transformed into ele
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Answer: The percent yield of this combination reaction is 41.3 %
Explanation : Given,
Mass of = 5.0 g
Mass of = 10.0 g
Molar mass of = 23 g/mol
Molar mass of = 71 g/mol
First we have to calculate the moles of and
.
and,
Now we have to calculate the limiting and excess reagent.
The balanced chemical equation will be:
From the balanced reaction we conclude that
As, 2 mole of react with 1 mole of
So, 0.217 moles of react with
moles of
From this we conclude that, is an excess reagent because the given moles are greater than the required moles and
is a limiting reagent and it limits the formation of product.
Now we have to calculate the moles of
From the reaction, we conclude that
As, 2 mole of react to give 2 mole of
So, 0.217 mole of react to give 0.217 mole of
Now we have to calculate the mass of
Molar mass of = 58.5 g/mole
Now we have to calculate the percent yield of this reaction.
Percent yield =
Actual yield = 5.24 g
Theoretical yield = 12.7 g
Percent yield =
Percent yield = 41.3 %
Therefore, the percent yield of this combination reaction is 41.3 %
The freezing point depression of a solution containing 30.7 g of glycerin is calculated as -1.65°C
Equating :
It is given that,
Given mass of glycerin is = 30.7 grams (Solute)
Volume of water = 376 mL
or molar -freezing-depression point is = 1.86°C/m
Molar mass of glycerin = 92.09 g/mole
Now, to work out the value, the mass of water should be known. Thus, to calculate, the formula used will be:
Mass = Density X Volume
Mass = 1.0 g/mL X 376 mL
Mass = 376 g or 0.376 Kg
Using the formula of melting point depression, the equation becomes:
Δ = i ×
×m
T⁰- =
in which,
Δ = change in freezing point
Δ = freezing point of solution that has to be find
ΔT° = freezing point of water ()
Since, glycerin is a non-electrolyte, the Van't Hoff factor will be 1.
Substituting the values in the above equation:
0⁰C₋T = 1 ×1.86°C/m ×
= -1.65°C
Thus, the freezing point depression of a solution is -1.65°C
<h2 />Freezing point depression
Freezing point depression is a colligative property observed in solutions that results from the introduction of solute molecules to a solvent. The freezing points of solutions are all less than that of the pure solvent and is directly proportional to the molality of the solute
Is melting point elevation or depression?
Boiling point elevation is that the raising of a solvent's boiling point due to the addition of a solute. Similarly, melting point depression is the lowering of a solvent's freezing point due to the addition of a solute. In fact, because the boiling point of a solvent increases, its melting point decreases
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