- #1
krootox217
- 51
- 2
Homework Statement
Hi, I tried the following task:
I tried to solve it, but apparently it's not correct:
Can someone show me the right way to do this?
Homework Equations
See above
The Attempt at a Solution
see above[/B]
The quoted K is based on partial pressures expressed in bars. The equilibrium constant is dimensionless because the standard state of each species is 1 bar.epenguin said:OK got that - I was reading rapidly and imagined it was some mixup deriving from the 3 in PCl3.
Also I had to check back because I had a queasy moment of wondering whether I had ever understood right. But I was reassured by the Wikipedia article https://en.m.wikipedia.org/wiki/Equilibrium_constant#Pressure_dependence
You see I am coming from biochemistry/biophysics where it is usual to give units when stating equilibrium constants. This is very convenient for visualisation (whether a 'binding constant' is mM, μM, or nM speaks to you immediately of how tight a binding is. If talking of binding of oxygen to respiratory proteins mm Hg or atm is also suggestive.) And you always know what you are talking about if you use such units. So it was only here that I realized that a lot of people use K's without any units, and officially when no units are quoted, molarities (to an appropriate power) are intended. I hate this convention.
But I guess that is the convention being used here, so I suggest convert your atm into molarities, assume the quoted K is for molarities, and see if you get the right answer.
(About half the time this is not an issue, for equilibria like A ⇔ B or A + B ⇔ C + D the equilibrium constant would be dimensionless.)
Second opinions welcome.
If x is the number of moles that dissociate, the total number of moles increase to 1+x, so the final mole fractions are x/(1+x), x/(1+x), and (1-x)/(1+x). If the pressure is held constant at 3 bars, then the final partial pressures are 3x/(1+x), 3x/(1+x), and 3(1-x)/(1+x). Try the problem again with these substitutions and see what you get.krootox217 said:Oh i thought that the 3 bar were at the beginning, so I converted everything in SI units and used p*V=n*R*T to get the volume. Then i converted the volume in liters, and divided the starting amount of moles to get the mol/l which I used to calculate the values
A dissociation reaction is a chemical reaction in which a compound breaks apart into smaller molecules or ions. This process is also known as ionization.
The purpose of solving dissociation reaction homework is to practice and apply the principles of chemistry and chemical reactions. It also helps to develop problem-solving skills and deepen understanding of dissociation reactions.
To solve a dissociation reaction homework problem, first write out the balanced chemical equation for the reaction. Then, identify the reactants and products and determine the type of reaction (e.g. acid-base, precipitation, etc.). Next, use the appropriate formulas and equations to calculate the molar mass and concentration of the reactants and products. Finally, check your answer and make sure it is balanced and follows the laws of conservation of mass and charge.
Some common mistakes to avoid when solving dissociation reaction homework include forgetting to balance the chemical equation, using incorrect formulas or equations, and not paying attention to units and significant figures. It is also important to double check your calculations and answer to ensure accuracy.
Yes, solving dissociation reaction homework can be applied to real-world situations. Many chemical reactions involve dissociation, such as the dissociation of acids and bases in our bodies and the dissociation of compounds in the environment. Additionally, understanding dissociation reactions is important in fields such as pharmaceuticals, environmental science, and industrial chemistry.