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# CO² concentration over time

## CO² concentration over time

(OP)
Hi all,

I don't know how to calculate following problem:

Problem:
I have a room with a certain concentration of CO2. There is a leak which causes the concentration to fall over time.

Known:
CO2 concentration start = 43.0%
CO2 concentration after 10 minutes = 22.2%
CO2 concentration air outdoors = 0.04%

What should the initial CO² concentration be to have the minimal CO2 concentration after 10 minutes = 38% ?

Any help?

*edit*

### RE: CO² concentration over time

You need two readings at two different times inside the room to establish the leak rate.

### RE: CO² concentration over time

(OP)
Now you have all the information.

### RE: CO² concentration over time

This is comically ill defined for me, if the answer is to matter in some way. Why does the concentration change? Does the leak selectively permit C02 to leave? Is the CO2 diluted by infill? Is it a leak at the bottom of a chamber where C02 sinks to the bottom? These possibilities give different meanings and solutions to the problem.

A common engineering assumption would be that dC/dT is constant and that C(t) is linear and determine dC/dT from 2 points where the change in C and the change in time is known, and you're doing 7th or 8th grade math in the US, or 5th grade math in many other countries. That's as simple as it gets. Beyond that responsibility for passing on this, getting this right or wrong is yours.

### RE: CO² concentration over time

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