A 5.0 g sample of a pesticide was decomposed with metallic sodium in alcohol, and the liberated chloride ion was precipitated with AgCl. Express the results of this analysis in terms of percent DDT (C14H9Cl5, molar mass, 354.72 g/mol)) based on the recovery of 0.1606 g of AgCl

1.59%

Explanation:

First, we convert 0.1606 g of AgCl into moles, using its molar mass:

Then we convert the calculated moles of Cl (equal to AgCl moles) into moles of DDT:

Now we convert 2.24x10⁻⁴ moles of DDT into grams, using its molar mass:

Finally we calculate the percentage of DDT in the sample:

answer: c. the experiment shows that the red substance experienced a chemical change.

explanation: chemical change is the change in which chemical composition of the substance changes. physical change is the change in which there is no change in chemical composition.

chemical changes are accompanied by following changes:

a) precipitate formation

b) energy is released or absorbed

c) formation of bubbles

d) change in color

as it is given that the red color has disappeared and there is production of gas, it means the red substance has undergone a chemical change.

e