Saturday
April 30, 2016

# Homework Help: Chemistry check

Posted by Joe on Wednesday, March 21, 2007 at 7:25pm.

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)

b)What percent error would there be?
2.02-2.0
--------
2.02
x100

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.