# Chemistry

posted by .

Phosphorus pentachloride decomposes according to the chemical equation
PCl5(g) -----> PCl3 (g)+ Cl2(g)
Kc= 1.80 at 250 degrees C

A 0.206 mol sample of PCl5(g) is injected into an empty 3.30 L reaction vessel held at 250 °C. Calculate the concentrations of PCl5(g) and PCl3(g) at equilibrium.

• Chemistry -

I don't know what to do after I set up the Kc equation. How do you isolate x from 1.80=(x^2)/(.062-x)

• Chemistry -

First, I would check that 0.206/3.30. You shouldn't drop that last number; you are allowed three significant figures in 0.206 and 3.30 and that means you can have three s.f. in the answer. I have 0.0624. Second, your chemistry is right; you've done the hard part. Now it's just algebra. Here is what you start with.

(x^2)
--------- = 1.80
0.0624-x

Multiply both sides by 0.0624-x like this.
(0.0624-x)(x^2)
---------------- = 1.80*(0.0624-x)
(0.0624-x)

You see (0.0624-x) term on the left cancels since it is in the numerator and denominator and you are left with
x^2 = 1.80(0.0624-x)
Note: You could have done the same thing by cross multiplying but I don't know that you've seen that way.
Now multiply the right side to remove the parentheses, move all the terms to the left and you are left with a quadratic which you can solve for x. Let me know if you get stuck. Thanks for showing your work.

• Chemistry -

I was able to figure it out! Thank you very much for your help(:

## Similar Questions

1. ### chemistry

Phosphorus pentachloride decomposes according to the chemical equation PCl5(g) -----> PCl3 (g)+ Cl2(g) Kc= 1.80 at 250 degrees C A 0.463 mol sample of PCl5(g) is injected into an empty 4.80 L reaction vessel held at 250 °C. Calculate …
2. ### Chemistry

Phosphorus pentachloride decomposes according to the chemical equation PCl5(g) <-> PCl3(g)+Cl2(g) Kc=1.80 at 250 degrees Celsius A 0.222 mol sample of PCl5(g) is injected into an empty 3.25 L reaction vessel held at 250 °C. …
3. ### Chemistry

Phosphorus pentachloride decomposes according to the chemical equation: PCl5(g)<--> PCl3(g)+Cl2(g) Kc = 1.80 at 250 degrees Celsius A 0.352 mol sample of PCl5(g) is injected into an empty 4.45 L reaction vessel held at 250 °C. …
4. ### Chemistry

Phosphorus pentachloride decomposes according to the chemical equation PCl5(g) ⇌ PCl3(g) + Cl2(g) A 0.304 mol sample of PCl5(g) is injected into an empty 4.75 L reaction vessel held at 250 °C. Calculate the concentrations of …
5. ### chemistry

A 0.411 mol sample of PCl5(g) is injected into an empty 4.65 L reaction vessel held at 250 °C. Calculate the concentrations of PCl5(g) and PCl3(g) at equilibrium.kc=1.80 at 250c
6. ### CHEM

A 0.229 mol sample of PCL5 is injected into an empty 3.20 L reaction vessel held at 250 degrees celsius. Calculate the concentration of PCl5 and PCl3 at equilibrium. Kc=1.80 M PCl5 -------> PCl3 + Cl2
7. ### Chem 2

Phosphorus pentachloride decomposes according to the chemical equation PCl5<-->PCl3 +Cl2 A 0.260 mol sample of PCl5(g) is injected into an empty 2.75 L reaction vessel held at 250 °C. Calculate the concentrations of PCl5(g) …
8. ### Chemistry

PCl5 --> PCl3 + Cl2 A 0.318 mol sample of PCl5(g) is injected into an empty 4.15 L reaction vessel held at 250 °C. Calculate the concentrations of PCl5(g) and PCl3(g) at equilibrium.
9. ### chemistry

A 0.239 mol sample of PCl5(g) is injected into an empty 2.85 L reaction vessel held at 250 °C. Calculate the concentrations of PCl5(g) and PCl3(g) at equilibrium.
10. ### Chemistry: Equilibrium

So, I think I'm doing everything right and even checking my math, but it keeps showing up as wrong. If someone can help me and go into detail,including the quadratic formula, I would appreciate it: Phosphorus pentachloride decomposes …

More Similar Questions