- #1

PerenialQuest

- 10

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This is a homework problem for my CHE345 class. Not sure what to do here, please at least let me know if I'm in the right ballpark.

## Homework Statement

A student decomposes KCLO

_{3}and collects 35.2 cm^3 of O

_{2}over water at 23.0°C. The laboratory barometer reads 751 Torr. The vapor pressure of water at 23.0°C is 21.1 Torr. Find the volume the oxygen would occupy at 0.0*C and 1.2atm (= 912 Torr).

## Homework Equations

not exactly sure what is relevant here. Perhaps these:

(1) PV = nRT

(2) P

_{j}= partial pressure

(3) x

_{j}= mole fraction

(4) P

_{j}= x

_{j}P

(5) P

_{j}= n

_{j}RT/V

(6) P

_{total}= P

_{A}+ P

_{B}+...

## The Attempt at a Solution

My problem I think, is in interpreting the question, but here goes an attempt:

using eq. (6):

P

_{total}= P

_{water}+ P

_{O2}

751 Torr = 21.1 Torr + P

_{O2}

P

_{O2}= 729.9

from here I'll use eq. (1) to solve for n

_{O2}

PV = nRT

n = PV/RT

n = (729.9 Torr)(0.0352 L)/(62.634 L Torr K

^{-1}mol

^{-1})(296.15 K)

n = 1.385 x 10

^{-4}

Now to solve for the V at T

_{final}

V = nRT/P

V = (1.385E-4 moles)(62.634 L Torr K

^{-1}mol

^{-1})(273.15 K) / 912 Torr)

__V = 0.002598 L = 2.598cm__

^{3}How'd I do?