1. Three different chemicals have the following LD 50 for killing mosquito larvae and
minnows in a freshwater ecosystem.

Chemical

LD 50 for mosquito larvae
(mg/L)

LD 50 for minnows
(mg/L)
A 0.200 1.01
B 0.500 2.56
C 0.300 2.11

a) Based on the LD 50 of these chemicals, which chemical would you use to control mosquito larvae populations? Defend your answers by providing sound reasons as to why your chosen chemical is better than the others.

b) You have been told that one of these chemicals is alcohol, one is a carboxylic acid, and one is a halogenated hydrocarbon. You are then given the names and structures of each chemical. For each type of chemical, what would be present in the name and/or structural formula that will help you identify which chemical is which?

c) Identify three other characteristics that you would like to know that would help you make a more informed decision as to which chemical would the best for you to use in controlling the mosquito population while protecting the minnow population. Explain why you would select those characteristics.

2. In agriculture, farmers are pressured to use chemicals such as fertilizers and pesticides to increase crop production and minimize losses. At the same time, they are mindful of the
impact on the environment that using these chemicals can have, and look for ways of increasing crop yields that are safer for the environment

a) Identify three practices that can reduce the number of fertilizers and/or pesticides that a farmer could use.

b) Describe an environmental hazard associated with the improper use of pesticides.

c) Describe an environmental hazard associated with the improper use of fertilizers