partial pressure question

[Smooth Operater]

---

Members don't see this ad.

when heated, solid mercury oxide decomposes into gaseous mercury and oxygen gas, reaching equilibirum at a temperature of 740K and pressure of 15 atm, as the following rxn equation shows

2HgO (s) + heat ---> 2Hg (g) + O2 (g)


At equilibrium, the partial pressure would be pHg(g) : pO2(g) ??


the correct answer is 1 atm: 0.5 atm .

But I am not sure how to derive to this answer. I first throught it's 2:1 since the mole ratio of Hg and O2 is 2:1. Anyone know how to solve it correctly?

 

[PDizzle]

The answer is 4. It's always 4. Remember that! 🙂


P.S. post this on the DAT forum for a better response. 🙂

 

[harjay]

when heated, solid mercury oxide decomposes into gaseous mercury and oxygen gas, reaching equilibirum at a temperature of 740K and pressure of 15 atm, as the following rxn equation shows

I assume you meant 1.5 atm ^^

There is 2 moles of Hg gas per mole of O2 gas produced (2:1 reaction coefficient, you are correct). However, it was looking for actual pressures of each
2x+1x=1.5atm -> x=.5 atm
2x= 1atm (Hg)
1x= .5atm (O2)
1atm : 0.5atm

 

[Dr. Dai Phan]

Hello,

I am moving this to DAT section where it may be given the attention it needs. DP

 

[jamminjimmy21]

I would use the formula for partial pressure. I too am assuming total pressure of 1.5 atm.

Total Pressure=PHg+PO2

PHg= X*Total Pressure= (2/3)(1.5)= 1 atm

PO2= X*Total Pressure= (1/3)(1.5)= 0.5 atm


X=mole fraction (moles of particular gas/moles of total gas)
P=Partial Pressure


Hope this helps.