Answer:
20 kJ/mol
Explanation:
From ∆G°= -RTlnK
But
Ag2SO4(s)<----------->2Ag+(aq) + SO4^2-(aq)
Ksp= [2Ag+]^2 [SO4^2-]
But Ag+ = 0.032M
Ksp= (2×0.032)^2 (0.032)
Ksp= 1.31072×10^-4
∆G°= -RTlnK
∆G°= -(8.314× 298×(-8.93976))= 20KJmol-1( to the nearest KJ)
Explanation:
Half life is simply the amount of time it takes for half of a substance to decompose.
Options;
- Carbon-14 has a half-life of 5,730 years. A 30 gram sample will be 10 grams after 5,730 years. This is incorrect. After 5730 years, 15g of the sample ought to remain.
- Nickel-59 has a half-life of 76,000 years. A sample would go through 3 half-lives in 228,000 years. This is correct. 3 * 76000 = 228,000
- Hafnium-182 has a half-life of 9 million years. A 38 gram sample would be 4.75 grams in 27 million years. This is incorrect. Mass after 3 half lives (27/9) = 9.5 (38 / 2 / 2)
- Iron-60 has a half-life of 1.5 million years. In 6 million years a 40 gram sample would be reduced to 10 grams. This is incorrect. Mass after 4 half lives (6 / 1.5) = 2.5 gram (40 / 2 / 2 /2 / 2)
- Lead-202 has a half-life of 52,500 years. The original sample must have been 120 grams if you have a 60 gram sample after 105,000 years. This is incorrect. Original sampe = 240 gram. So after 2 half lives (105,000/52500), mass left = 60 (240 / 2 /2)
Answer:
7.46 g
Explanation:
From the balanced equation, 2 moles of Mg is required for 2 moles of MgO.
The mole ratio is 1:1
mole = mass/molar mass
mole of 4.50 g Mg = 4.50/24.3 = 0.185 mole
0.185 mole Mg will tiled 0.185 MgO
Hence, theoretical yield of MgO in g
mass = mole x molar mass
0.185 x 40.3 = 7.46 g
Answer:
A) ∆Suniv >0, ∆G<0, T∆Suniv >0.
Explanation:
The connection between entropy and the spontaneity of a reaction is expressed by the <u>second law of thermodynamics</u><u>: The entropy of the universe increases in a spontaneous process and remains unchanged in an equilibrium process</u>.
Mathematically, we can express the second law of thermodynamics as follows:
For a spontaneous process: ΔSuniv = ΔSsys + ΔSsurr > 0
Therefore, the second law of thermodynamics tells us that a spontaneous reaction increases the entropy of the universe; that is, ΔSuniv > 0.
If we want spontaneity expressed only in terms of the properties of the system (ΔHsys and ΔSsys), we use the following equation:
-TΔSuniv = ΔHsys - TΔSsys < 0
That means that T∆Suniv >0.
This equation says that for a process carried out at constant pressure and temperature T, if the changes in enthalpy and entropy of the system are such that <u>ΔHsys - TΔSsys is less than zero, the process must be spontaneous.</u>
Finally, if the change in free energy is less than zero (ΔG<0), the reaction is spontaneous in the forward direction.
Ideal solutions obey Raoult's law, which states that:
P_i = x_i*(P_pure)_i
where
P_i is the partial pressure of component i above a solution
x_i is the mole fraction of component i in the solution
(P_pure)_i is the vapor pressure of pure component i
In this case,
P_benzene = 0.59 * 745 torr = 439.6 torr
P_toluene = (1-0.59) * 290 torr = 118.9 torr
The total vapor pressure above the solution is the sum of the vapor pressures of the individual components:
P_total = (439.6 + 118.9) torr = 558.5 torr
Assuming the gas phase also behaves ideally, the partial pressure of each gas in the vapor phase is proportional to its molar concentration, so the mole fraction of toluene in the vapor phase is:
118.9 torr/558.5 torr = 0.213
