Answer:
The mass of water to be added is 2 pounds
Explanation:
The given parameters are;
The mass of the given solution = 2 pounds
The concentration of the given solution = 30%
The desired concentration of the solution = 15%
The mass, m of the acetic acid in the given solution = 30% × 2 pounds
m = 30/100 × 2 pounds = 0.6 pounds
To make a 15% acetic acid solution of acetic acid, the mass X of the required volume, is given as follows;
15% of X = 0.6 pounds
15/100 × X = 3/20 × 0.6 pounds
∴ The mass of the solution required X = 0.6 × 20/3 = 4 pounds
The mass of the solution that will contain 0.6 pounds of acetic acid giving a 15% acetic acid solution is 4 pounds
Therefore, the mass of water to be added to the original solution to make the a 15% acetic acid solution is 2 pounds.
Most atoms do not. For those atoms that do not have a full valence shell (which usually would contain eight electrons, except for hydrogen and helium, where it would contain two), something has to change. So nature's tendency toward a full valence shell will lead to one of two things: The gain or loss of electrons.
Mn metal can be used as a sacrificial electrode to prevent the rusting of an iron pipe. So, the correct option is (c) Mn.
Commonly, sacrificial electrodes are employed to stop another metal from corroding or oxidising. A metal that is more reactive than the metal being shielded must serve as the sacrificial electrode. Magnesium, aluminium, and zinc are the three metals most frequently used in sacrificial anodes.
Manganese-Magnesium (Mn-Mg) electrode is more suited for on-shore pipelines where the electrolyte (soil or water) resistivity is higher since it has the highest negative electropotential of the three. In order to replenish any electrons that could have been lost during the oxidation of the shielded metal, the highly active metal offers its electrons.
Therefore, Mn metal can be used as a sacrificial electrode to prevent the rusting of an iron pipe. So, the correct option is (c) Mn.
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The Reaction is spontaneous when temperature is 430 K. Hence, Option (C) is correct.
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What is Spontaneous reaction ?</h3>
Reactions are favorable when they result in a decrease in enthalpy and an increase in entropy of the system.
When both of these conditions are met, the reaction occurs naturally.
Spontaneous reaction is a reaction that favors the formation of products at the conditions under which the reaction is occurring.
According to Gibb's equation:
ΔG = ΔH - TΔS
ΔG = Gibbs free energy
ΔH = enthalpy change = +62.4 kJ/mol
ΔS = entropy change = +0.145 kJ/molK
T = temperature in Kelvin
- ΔG = +ve, reaction is non spontaneous
- ΔG = -ve, reaction is spontaneous
- ΔG = 0, reaction is in equilibrium
ΔH - TΔS = 0 for reaction to be spontaneous
T = ΔH / ΔS
Here,
T = 500K
Thus the Reaction is spontaneous when temperature is 500 K.
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