An emulsifiable concentrate herbicide contains 20% a.i. How much of the product would be needed to create 5 gallons of spray mixture at 0.5 a.i. per gallon?

To determine how much emulsifiable concentrate herbicide is needed to create a spray mixture at a specific active ingredient (a.i.) concentration, it's essential to understand the relationship between the concentration of the formulation and the desired concentration in the mixture.

In this scenario, the emulsifiable concentrate contains 20% a.i. This means that for every 100 ounces of the concentrate, 20 ounces are active ingredient. You want a spray mixture that contains 0.5 a.i. per gallon, and you are preparing 5 gallons of this mixture.

First, calculate the total amount of active ingredient required for 5 gallons:

• Since there are 128 ounces in a gallon, 5 gallons will equal 640 ounces of the spray mixture.

• At 0.5 a.i. per gallon, you need 0.5 ounces of a.i. per gallon for all 5 gallons:

[

0.5 , \text{oz/gallon} \times 5 , \text{gallons} = 2.5 , \text{oz of a.i.}

]

Now you need to find out how much of the herbicide concentrate you need to obtain 2.5 ounces