(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A syringe of volume 20 ml has just been used and now lies empty on the doctor's desk. The pressure in the office is 100,000 Pa. Assume that the air is an ideal gas consisting of nitrogen N2 (80%) and oxygen O2 (20%) molecules. k=1.38×10-23 J/K and the molar mass of oxygen is 32 g/mol.

The syringe must be heated to high temperatures to sterilize it. When the syringe is at its maximum temperature, the number of oxygen molecules is 6.5 x 1019 (but the pressure, volume, and percent oxygen remain the same), what is the rms speed of the oxygen molecules?

2. Relevant equations

PV=nkT

KE=1/2 m v^2=3/2kT

3. The attempt at a solution

Hi ok so I'm new here! Sorry if I'm doing anything incorrectly. I've been working on this problem for quite some time and I have a feeling that the answer is staring at me in the face, but I can't seem to catch my mistake. I'm literally solving for the variable v. I'm so close! Please help me!

1) Find the total # of gas molecules: 6.5*10^19 (100/20)= 3.25*10^20

2) Solve for temperature: PV=nkT: (100,000) (0.02)= (3.25*10^20)* (1.38*10^-23)T

T=445.93088K

3) 32g/mol * 6.022*10^23=1.92704*10^25grams=mass of O2

4) Solve for Vrms: .5(1.92704*10^25)v^2= 3/2(1.38*10^-23)(445.93088)

Vrms= 3.09519902*10^-23

HELP PLEASE!

xxoo

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# Homework Help: Syringe: probably a really simple mistake that I can't seem to catch!

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