A halothane-oxygen mixture (C2HBrClF3 + O2) can be used as an anaesthetic. A tank containing such a mixture has the following partial pressures: P (halothane) = 170 mmHg and P (O2) = 570 mmHg. If the tank contains 160 g of O2, calculate the mass of C2HBrClF3 present.

Question

aaronq · Answer

how many moles of O2 do you have?

multiply the moles of O2 by the ratio of Phalothane and PO2 (since P is proportional to moles)

anonymous · Answer

ok man

anonymous · Answer

my plan was to convert the partial pressures to atm then find the total pressure....so it would be partial pressure of O2 = total pressure * ( number of moles of O2 / total number of moles) .....i thought working out the total number of moles would help me get the number of moles of the other substance

what do you think about this

aaronq · Answer

yeah that would work too, subtract the moles of O2 from the total moles.
The only problem is that to use PV=nRT you need to use temp and pressure, but i guess you can assume them to be standard.

anonymous · Answer

no not that way..... i'd use ... Partial pressure of X = (number of moles of X / Number of moles of X+Y) * total pressure

its, Dalton's law of partial pressures......

and in this equation i already have the total amount of pressure, the partial pressure of both and the number of moles of oxygen so i can get the total number of moles.

aaronq · Answer

ohhh right, like this

$$P _{O _{2}}=P _{T}*\chi _{O _{2}}  $$

$$X _{O _{2}}=\frac{ n _{O _{2}} }{n _{T} }$$