What is an independent variable in chemistry?
An independent variable is the variable you have control over, what you can choose and manipulate.
Example: You are interested in how stress affects heart rate in humans. Your independent variable would be the stress and the dependent variable would be the heart rate. You can directly manipulate stress levels in your human subjects and measure how those stress levels change heart rate.
A dependent variable is the variable being tested in a scientific experiment.
The dependent variable is 'dependent' on the independent variable. As the experimenter changes the independent variable, the change in the dependent variable is observed and recorded.
A scientist is testing the effect of number of hours spend in gym on the amount of muscle developed. The independent variable is the number of hours in gym (deliberately changed) and the amount of muscles developed is the dependent variable.