4. This experiment used Pb(NO3)2 and Ba(NO3)2 in the past. These chemicals have been removed from this experiment and replaced with others such as Na2CO3 to reflect Green
Chemistry Principles. Explain why these chemicals have been removed from the experiment.
You may need to access other resources (books, internet) to help you answer this question.
Please cite any resources used. In addition, identify which green chemistry principles might
apply to your answer.