**Content**

**Content**- How do I know the initial
concentration of CO
_{2}?

The initial concentration of CO_{2}is given in the lab. Re-read the introductory paragraph on the first page of the lab taken from our text. The initial concentration of CO_{2}is given in this paragraph. (The initial concentration is the concentration at dawn, when of course*t*= 0.)

- How can I tell if the CO
_{2}level is increasing or decreasing?

Remember that you have the rate of change of the CO_{2}level, which is its*derivative*. If the derivative of a function is*positive*, this means it has positive slope, so it is sloping upwards and therfore*increasing.*Similarly, a negative derivative means the function is*decreasing*. The sign of the derivative always tells us if the original function is increasing or decreasing.

(Be careful you aren't looking at where the derivative is increasing or decreasing! That's not related to where the function increases or decreases.)

- How do I know the initial
concentration of CO