Answer:
116 g
Explanation:
From the question given above, the following data were obtained:
Number of mole of calcium = 2.9 moles
Mass of calcium =.?
The mole and mass of a substance are related according to the following formula:
Mole = mass / molar mass
With the above formula, we can obtain the mass of calcium. This can be obtained as follow:
Number of mole of calcium = 2.9 moles
Molar mass of calcium = 40 g/mol
Mass of calcium =.?
Mole = mass / molar mass
2.9 = mass of calcium / 40
Cross multiply
Mass of calcium = 2.9 × 40
Mass of calcium = 116 g
Therefore, the mass of 2.9 moles of calcium is 116 g.
Answer:
a)
b) entropy of the sistem equal to a), entropy of the universe grater than a).
Explanation:
a) The change of entropy for a reversible process:
The energy balance:
If the process is isothermical the U doesn't change:
The work:
If it is an ideal gas:
Solving:
Replacing:
Given that it's a compression: V2<V1 and ln(V2/V1)<0. So:
b) The entropy change of the sistem will be equal to the calculated in a), but the change of entropy of the universe will be 0 in a) (reversible process) and in b) has to be positive given that it is an irreversible process.
The energy absorbed may be calculated using:
Q = mcΔT
Where Q is the energy absorbed, m is the mass of water, c is the specific heat capacity of the water and ΔT is the change is the temperature of the water. Substituting the values,
Q = (435)(4.18)(100-25)
Q = 136,372 J
The energy absorbed is 136.4 kJ
Answer should be 20% so 1/5
The current needed to deposit all of the nickel in 5 hours is 2.219 A
<h3>
What is Faraday's Law of electrolysis?</h3>
According to the first law of Faraday, the amount of substance liberated at an electrode is directly proportional to the quantity of charge passed through an electrolyte.
m = zq , where z = electrochemical equivalent
An electrochemical equivalent is the mass of the substance liberated at an electrode when 1 Columb of charge is passed through the electrolyte.
For the nickel,
z = 2
The molar mass of NiS0₄ = 154.75 g
154.75 g of Ni needs 2 x 96485 C
32 g of Ni needs
32 g of Ni needs 39944.79 C
We know,
q = It
Where q = charge
I = current and t = time in seconds
q = 39944.79 C and t = 5 x 60 x 60 = 18000 s
= 2.219 A
Hence, the current needed to deposit all the nickel is 2.219 A in 5 hours
Learn more about Faraday's law of electrolysis:
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