What are the variables (Independent, dependent and controlled) in this experiment?

Question

Title:

Does carbon dioxide heat up the globe faster than oxygen?

Purpose:

The purpose of this experiment is to find out if carbon dioxide (from cars etc) causes the earth’s temperature to rise. Scientists often suggest that carbon dioxide is causing a flux in temperature which is causing global warming. This experiment will try to see if carbon dioxide actually causes a rise in temperature.

Apparatus:

• Data logger

• Two temperature probes (if we don’t have those, we will use an electronic thermometer)

• Two 2 litre plastic pop bottles

• Two clamp stands

• Carbon dioxide & air

• Two lamps

• Plasticine

If you know the 3 variables, it would be greatly appreciated?

Answer 1

Independent : concentration of CO2

Dependent: Temperature change

Control: air? ( it's not a true control)

Answer 2

It helps to know the experimental method that you're using.  Look at that and make sure that what I'm listening makes sense to you.  Basically, the independent variable is the one that you alter throughout the experiment.  The dependent variable is the one that you measure.  The controlled variables are ones that you keep the same.  My guesses:

Independent:  The amount of CO2 versus air in the different bottles.

Dependent:  The temperature of the two different bottles.

Controls:  Anything you're keeping the same, such as identical lamps, identical starting temperatures, identical bottles and volumes and pressures in the bottles, identical distance from lamp to bottle, identical angle of lamp to bottle, that sort of thing.  Anything you purposefully make the same between the two different bottles counts as a controlled variable.

Alternate meaning of control:  This is the experiment that you do to make sure that your experiment works.  An example here would be to set up another bottle without a lamp on it to measure how much temperature fluctuates in the bottles anyway, or to set one up with a different gas mix (one that shouldn't affect temperature) to prove that it's the addition of extra carbon dioxide causing the change, instead of there just being less of some other gas in the air.

Note:  You aren't really comparing CO2 and O2 here.  You're comparing CO2 and air.  To compare CO2 and O2 effects, you'd have to do mixes of air and CO2, AND similar mixes of air and O2.