Can someone check my answers? Thanks.
1.) If you were involved in an acid rain monitoring project with several other samplers, why would it be important that all of you collect your samples on the same day and do the alkalinity tests within 24 hours?
Acid rain on another day may not have the same pH as the rain on that day. The pH may also decrease over time.
2.) A student did an alkalinity determination correctly, except that the sample titrated had a volume of 90.0 mL. Volume A was found to be 4.50 mL and Volume B was 7.00 mL.
a)Calculate the alkalinity value from these data and then calculate the correct value.
A=(2A-B)
A=(2(4.50-7.00)=2.0 mL^-1
A=(2(4.545)-7.07)
answer = 2.02mL^-1
b)What percent error would there be?
2.02-2.0
--------
2.02
x100
answer = .99%
c) Would there be an error in the classification of the stream? Explain concisely.
There would not have been an error in the classification. It was just a measurement error in this case.
3) EPA acidity tests can be performed by titrating a water sample to a pH of 8.2. What titrant in what concentration would you suggest for EPA acidity determinations?
The titrant I would suggest for EPA acidity determinations is sulfuric acid under a standard concentration.
Answered partially above.
I can help explain how to check your answers for these questions!
1) The question asks why it is important for all samplers in an acid rain monitoring project to collect their samples on the same day and conduct alkalinity tests within 24 hours. Your answer is correct - the pH of acid rain can vary from day to day, so collecting samples on different days may not accurately represent the true acidity. Additionally, the pH of acid rain tends to decrease over time, so it is important to test the alkalinity within 24 hours to get accurate results. It's essential to collect samples on the same day and conduct the tests promptly to ensure consistency and accuracy in the data.
2) Let's break down the parts of this question and your answers:
a) The formula given is A = (2A-B). Plugging in the values, you correctly calculated A as 2.02 mL^(-1).
b) To determine the percent error, you subtracted the correct value of 2.0 mL^(-1) from the calculated value of 2.02 mL^(-1), divided the difference by the correct value, and multiplied by 100. Your calculation is correct, resulting in a percent error of 0.99%.
c) The question asks if there would be an error in the classification of the stream. Your answer is correct. In this case, the error is specific to the measurement made in the alkalinity determination and does not affect the overall classification of the stream.
3) The question asks for a suggestion on the titrant and its concentration for EPA acidity determinations. You partially answered this by mentioning sulfuric acid as the recommended titrant. However, it's important to specify the concentration of the sulfuric acid that you would suggest for the EPA acidity determinations.
Please double-check your responses and make sure all the necessary details are included in your answers.