4 AlF3 + 3 O2 ----------> 2Al2O3 + 6 F2
1 answer:
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Answer:
(1) -12 Kcal/mol
Explanation:
Our answer options for this question are:
(1) -12 Kcal/mol
(2) -13 Kcal/mol
(3) -15 Kcal/mol
(4) -16 Kcal/mol
With this in mind, we can start with the chemical reaction (Figure 1). In this reaction, <u>two bonds are broken</u>, a C-H and a Br-Br. Additionally, a C-Br and a H-Br are <u>formed</u>.
If we want to calculate the enthalpy value, we can use the equation:
<u>ΔH=ΔHbonds broken-ΔHbonds formed</u>
If we use the energy values reported, its possible to calculate the energy for each set of bonds:
<u>ΔHbonds broken</u>
<u />
C-H = 94.5 Kcal/mol
Br-Br = 51.5 Kcal/mol
Therefore:
105 Kcal/mol + 53.5 Kcal/mol = 146 Kcal/mol
<u>ΔHbonds formed</u>
C-Br = 70.5 Kcal/mol
H-Br = 87.5 Kcal/mol
Therefore:
70.5 Kcal/mol + 87.5 Kcal/mol = 158 Kcal/mol
<u>ΔH of reaction</u>
<u />
ΔH=ΔHbonds broken-ΔHbonds formed=(146-158) Kcal/mol = -12 Kcal/mol
I hope it helps!
<u />
Answer 1:
Correct Answer: T<span>he average kinetic energy of the gas decreases.
</span>Reason:
From the ideal gas equation, we know that PV = nRT
where, P = pressure, V = volume, n = number of moles of gas, R = gas constant and T = temperature.
From above equation, it can be seen that, Temp. as a direct relation with Pressure and Volume. Hence, as temperature of the gas in a balloon decreases, pressure and volume also decreases.
Also, from kinetic theory of gases, we know that, kinetic energy of gas increases with increasing temp. Hence, average kinetic energy of the gas decreases with decreasing temp.
Answer 2:
Correct answer: Out
Reason:
From the ideal gas equation, we know that PV = nRT
where, P = pressure, V = volume, n = number of moles of gas, R = gas constant and T = temperature.
Therefore, when a sealed syringe is heated, it's temp. will increase. This, will result in expansion of gas i.e volume will increase. Hence, <span>syringe plunger move in outwards direction.
Answer 3: Volume = 6046 L
Reason:
</span>From the ideal gas equation, we know that PV = RT
where, P = pressure, V = volume, R = gas constant and T = temperature.<span>
Given: P1 = 99 kPa, V1 = 3000 L, T1 = 312 K, P2 = 45.5 KPa and T2 = 289 K.
Therefore, we have: </span>
Thus,
Hence, V2 = 6046 L
Answer 4:
Correct Answer: It increases
Reason:
We know that, pressure of gas, it directly proportional to temp. Hence, when the temp. of as is increases. Total pressure of gas mixture increases. This is because, partial pressure of individual component (in present case oxygen) increases.
Answer 5:
Correct answer: 18.5 kPa
Reason:
We know that, total pressure is the sum of the partial pressures of the gases present in it. Mathematically, it can be expressed as:
Ptot = PO2 + PHe + PCO2
Correct Answer: T<span>he average kinetic energy of the gas decreases.
</span>Reason:
From the ideal gas equation, we know that PV = nRT
where, P = pressure, V = volume, n = number of moles of gas, R = gas constant and T = temperature.
From above equation, it can be seen that, Temp. as a direct relation with Pressure and Volume. Hence, as temperature of the gas in a balloon decreases, pressure and volume also decreases.
Also, from kinetic theory of gases, we know that, kinetic energy of gas increases with increasing temp. Hence, average kinetic energy of the gas decreases with decreasing temp.
Answer 2:
Correct answer: Out
Reason:
From the ideal gas equation, we know that PV = nRT
where, P = pressure, V = volume, n = number of moles of gas, R = gas constant and T = temperature.
Therefore, when a sealed syringe is heated, it's temp. will increase. This, will result in expansion of gas i.e volume will increase. Hence, <span>syringe plunger move in outwards direction.
Answer 3: Volume = 6046 L
Reason:
</span>From the ideal gas equation, we know that PV = RT
where, P = pressure, V = volume, R = gas constant and T = temperature.<span>
Given: P1 = 99 kPa, V1 = 3000 L, T1 = 312 K, P2 = 45.5 KPa and T2 = 289 K.
Therefore, we have: </span>
Thus,
Hence, V2 = 6046 L
Answer 4:
Correct Answer: It increases
Reason:
We know that, pressure of gas, it directly proportional to temp. Hence, when the temp. of as is increases. Total pressure of gas mixture increases. This is because, partial pressure of individual component (in present case oxygen) increases.
Answer 5:
Correct answer: 18.5 kPa
Reason:
We know that, total pressure is the sum of the partial pressures of the gases present in it. Mathematically, it can be expressed as:
Ptot = PO2 + PHe + PCO2
Therefore, partial pressure of oxygen, <span>PO2:</span>
PO2 = Ptot − PHe − PCO2
= 101.4 − 82.5 − 0.4
=18.5 kPa.
Answer 6:
Correct Answer: Argon
Reason:
<span>Inert gases are the best choice for inflating a balloon that must remain inflated for a long period of time. Among given options, both neon and argon are inert gas, But, atomic weight of Ar is 40g/mol, while is more than that of neon (20 g/mol). Hence,. Argon gas is preferred over neon gas. </span>