Atomic mass silicon = 28.085 u
1 mol Si ---------------- 28.085 g
? ------------------------ 245 g
245 x 1 / 28.085 => 8.72 mol
answer A
Answer:
a. Kp=1.4
![P_{A}=0.2215 atm](https://tex.z-dn.net/?f=P_%7BA%7D%3D0.2215%20atm)
![P_{B}=0.556 atm](https://tex.z-dn.net/?f=P_%7BB%7D%3D0.556%20atm)
b.Kp=2.0 * 10^-4
![P_{A}=0.495atm](https://tex.z-dn.net/?f=P_%7BA%7D%3D0.495atm)
![P_{B}=0.00995 atm](https://tex.z-dn.net/?f=P_%7BB%7D%3D0.00995%20atm)
c.Kp=2.0 * 10^5
![P_{A}=5*10^{-6}atm](https://tex.z-dn.net/?f=P_%7BA%7D%3D5%2A10%5E%7B-6%7Datm)
![P_{B}=0.9999 atm](https://tex.z-dn.net/?f=P_%7BB%7D%3D0.9999%20atm)
Explanation:
For the reaction
A(g)⇌2B(g)
Kp is defined as:
![Kp=\frac{(P_{B})^{2}}{P_{A}}](https://tex.z-dn.net/?f=Kp%3D%5Cfrac%7B%28P_%7BB%7D%29%5E%7B2%7D%7D%7BP_%7BA%7D%7D)
The conditions in the system are:
A B
initial 0 1 atm
equilibrium x 1atm-2x
At the beginning, we don’t have any A in the system, so B starts to react to produce A until the system reaches the equilibrium producing x amount of A. From the stoichiometric relationship in the reaction we get that to produce x amount of A we need to 2x amount of B so in the equilibrium we will have 1 atm – 2x of B, as it is showed in the table.
Replacing these values in the expression for Kp we get:
![Kp=\frac{(1-2x)^{2}}{x}](https://tex.z-dn.net/?f=Kp%3D%5Cfrac%7B%281-2x%29%5E%7B2%7D%7D%7Bx%7D)
Working with this equation:
![x*Kp=(1-2x)^{2} - -> x*Kp=4x^{2}-4x+1- - >4x^{2}-(4+Kp)*x+1=0](https://tex.z-dn.net/?f=x%2AKp%3D%281-2x%29%5E%7B2%7D%20-%20-%3E%20x%2AKp%3D4x%5E%7B2%7D-4x%2B1-%20-%20%3E4x%5E%7B2%7D-%284%2BKp%29%2Ax%2B1%3D0)
This last expression is quadratic expression with a=4, b=-(4+Kp) and c=1
The general expression to solve these kinds of equations is:
(equation 1)
We just take the positive values from the solution since negative partial pressures don´t make physical sense.
Kp = 1.4
![x_{1}=\frac{(1.4+4)+\sqrt{(-(1.4+4)^{2}-4*4*1)}}{2*4}=1.128](https://tex.z-dn.net/?f=x_%7B1%7D%3D%5Cfrac%7B%281.4%2B4%29%2B%5Csqrt%7B%28-%281.4%2B4%29%5E%7B2%7D-4%2A4%2A1%29%7D%7D%7B2%2A4%7D%3D1.128)
![x_{1}=\frac{(1.4+4)-\sqrt{(-(1.4+4)^{2}-4*4*1)}}{2*4}=0.2215](https://tex.z-dn.net/?f=x_%7B1%7D%3D%5Cfrac%7B%281.4%2B4%29-%5Csqrt%7B%28-%281.4%2B4%29%5E%7B2%7D-4%2A4%2A1%29%7D%7D%7B2%2A4%7D%3D0.2215)
With x1 we get a partial pressure of:
![P_{A}=1.128 atm](https://tex.z-dn.net/?f=P_%7BA%7D%3D1.128%20atm)
![P_{B}=1-2*1.128 = -1.256 atm](https://tex.z-dn.net/?f=P_%7BB%7D%3D1-2%2A1.128%20%3D%20-1.256%20atm)
Since negative partial pressure don´t make physical sense x1 is not the solution for the system.
With x2 we get:
![P_{A}=0.2215 atm](https://tex.z-dn.net/?f=P_%7BA%7D%3D0.2215%20atm)
![P_{B}=1-2*0.2215 = 0.556 atm](https://tex.z-dn.net/?f=P_%7BB%7D%3D1-2%2A0.2215%20%3D%200.556%20atm)
These partial pressures make sense so x2 is the solution for the equation.
We follow the same analysis for the other values of Kp.
Kp=2*10^-4
X1=0.505
X2=0.495
With x1
![P_{A}=0.505atm](https://tex.z-dn.net/?f=P_%7BA%7D%3D0.505atm)
![P_{B}=1-2*0.505 = -0.01005 atm](https://tex.z-dn.net/?f=P_%7BB%7D%3D1-2%2A0.505%20%3D%20-0.01005%20atm)
Not sense.
With x2
![P_{A}=0.495atm](https://tex.z-dn.net/?f=P_%7BA%7D%3D0.495atm)
![P_{B}=1-2*0.495 = 0.00995 atm](https://tex.z-dn.net/?f=P_%7BB%7D%3D1-2%2A0.495%20%3D%200.00995%20atm)
X2 is the solution for this equation.
Kp=2*10^5
X1=50001
![X2=5*10^{-6}](https://tex.z-dn.net/?f=X2%3D5%2A10%5E%7B-6%7D)
With x1
![P_{A}=50001atm](https://tex.z-dn.net/?f=P_%7BA%7D%3D50001atm)
![P_{B}=1-2*50001=-100001atm](https://tex.z-dn.net/?f=P_%7BB%7D%3D1-2%2A50001%3D-100001atm)
Not sense.
With x2
![P_{A}= 5*10^{-6}atm](https://tex.z-dn.net/?f=P_%7BA%7D%3D%205%2A10%5E%7B-6%7Datm)
![P_{B}=1-2*5*10^{-6}= 0.9999 atm](https://tex.z-dn.net/?f=P_%7BB%7D%3D1-2%2A5%2A10%5E%7B-6%7D%3D%200.9999%20atm)
X2 is the solution for this equation.
Answer:
Yes
Explanation:
The tilt of the Earth means the Earth will lean towards the Sun (Summer) or lean away from the Sun (Winter) 6 months later. In between these, Spring and Autumn will occur. The North pole always points the same way as the Earth revolves around the Sun.
Erm, I think when they are little. When they are just born.