Help pawezzzee

[OnlyDrilling]

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PCl5 (Solid) + 4H20 (L) -----> H3PO4 (aq) + 5HCl (aq) DH = -527kJ

if you increase the temperature, topscore says the reaction will go to the left.

I thought it only shifts if we have gas compounds. I thought solid, aq, and liquids dont matter. Can someone please explain this? 😕

 

[illbirz]

http://forums.studentdoctor.net/showthread.php?t=596958:):thumbup:

 

[khakwanit1]

I think the phase only matters if you are talking about pressure.

 

[iwannabadentist]

^^^
thats correct. the s, l, g stuff only matters when you are talking about pressure. in this case, you are talking abt temperature. DH is negative, meaning the reaction is exothermic, meaning the reaction will release heat. now consider heat as a product of the reaction, and write it on the right side of the equation. now add heat (increase temperature) and see for yourself which way the equilibrium shifts. 🙂

 

[OnlyDrilling]

Is it also tru that if you increase the concentration of a solid in the equation it wont affect anything ( It wont shift left or right because increasing conc of solid doesnt matter)????

 

[iwannabadentist]

Is it also tru that if you increase the concentration of a solid in the equation it wont affect anything ( It wont shift left or right because increasing conc of solid doesnt matter)????

thats not true at all! dont confuse pressure with temperature with concentration. increasing the concentration of either the products or the reactants will shift the equilibrium in the opposite direction, regardless of what the state of the products or reactants is. ex. A + B --> C. in this equation, increasing the concentration of either A or B will shift the reaction to the right, regardless of if one is a solid, liquid or a gas. Also, you gotta keep in mind the limiting reagent. I'm not sure if the actual test would complicate it so much, but its something you need to consider. So for instance, in the same example, if B is the limiting reagent, increasing the concentration of A as much as you want but the equilibrium will be established at a point where all of the B is used up. After this point, A will just remain in solution and hang out there. Hope that helps!

 

[khakwanit1]

thats not true at all! dont confuse pressure with temperature with concentration. increasing the concentration of either the products or the reactants will shift the equilibrium in the opposite direction, regardless of what the state of the products or reactants is. ex. A + B --> C. in this equation, increasing the concentration of either A or B will shift the reaction to the right, regardless of if one is a solid, liquid or a gas. Also, you gotta keep in mind the limiting reagent. I'm not sure if the actual test would complicate it so much, but its something you need to consider. So for instance, in the same example, if B is the limiting reagent, increasing the concentration of A as much as you want but the equilibrium will be established at a point where all of the B is used up. After this point, A will just remain in solution and hang out there. Hope that helps!

You are right about limiting reagent.

 

[toothgyal]

temperature is being produced in this reaction so an increase in temperature would shift to the left by le chatelier's principle.. hope that helps..