help please help me Chemestry

timer Asked: Jun 4th, 2015

Question description

Points: 24

Answer the questions below. When you have finished, submit this assignment to your teacher.

Please remember to record the number of drops of Reagent D needed to turn the solution light blue in each phase.

Part 1: Lab set up:

(1 point)

1) Which phase is the control phase?

Answer: MEASURE, ANALYZE, and IMPROVE phases

(1 point)

2) What variable is controlled and stays the same in all 3 phases?

Answer:the molecule?

(1 point)

3) What is the independent variable (the one are we changing to see if it impacts the dependent variable)?


(1 point)

4) What is the dependent variable (the one we are measuring)?


Part 2: Experiment


Amount of water
mL or drops

Amount of yeast
mL or drops
(20 drops = 1 mL)


6 mL



6 mL

10 Drops or 0.5 mL


6 mL

20 drops or 1 mL

(3 points)

5) Complete the data table. You can use our data from class or your own.


Phase 1

Phase 2

Phase 3

O2 concentration in ppm (parts per million) = number of drops of Reagent D added to reach blue color (when it is blue this means the oxygen has been completely depleted) and observations

Number of drops:


Number of drops:


Number of drops:


(3 points)

6) Regarding Phase 3 of the experiment:

·  Were more or less drops of Reagent D (sodium hydroxide) were needed to get the same blue color as in Phase 1 and 2?


·  What does this tell us about the available amount of dissolved oxygen in the water compared to Phase 1 and 2?


(3 points)

7) In this lab, you continued to add Reagent D to each solution until it turned blue. The purpose was to remove the oxygen to measure how much was left.

·  In which phase(s) did the solution turn blue before you added Reagent D?


·  What do you think that means?


(3 points)

8) What would happen to the dissolved oxygen in the Chesapeake Bay if large amounts of waste were dumped into it? (Make sure you read and use the information from Lesson 5.07 when putting together your answer to this question).


(2 points)

9) Is this demonstration a good example of eutrophication in the Chesapeake Bay? Why or why not?


(2 points)

10) Does the Chesapeake Bay have uniform dissolved oxygen content throughout the different areas of the bay? If not, where would you expect to find higher levels of nitrogen and lower levels of dissolved oxygen?


(2 points)

11) Which Phase represents the Chesapeake Bay BEFORE human impact? Why? Which Phase represents the Chesapeake Bay after? Why?


(2 points)

12) What other human impacts have negatively influenced the biodiversity of the Chesapeake Bay watershed? Explain using the food webs discussed in class.


Tutor Answer

(Top Tutor) Studypool Tutor
School: UC Berkeley
Studypool has helped 1,244,100 students
flag Report DMCA
Similar Questions
Hot Questions
Related Tags

Brown University

1271 Tutors

California Institute of Technology

2131 Tutors

Carnegie Mellon University

982 Tutors

Columbia University

1256 Tutors

Dartmouth University

2113 Tutors

Emory University

2279 Tutors

Harvard University

599 Tutors

Massachusetts Institute of Technology

2319 Tutors

New York University

1645 Tutors

Notre Dam University

1911 Tutors

Oklahoma University

2122 Tutors

Pennsylvania State University

932 Tutors

Princeton University

1211 Tutors

Stanford University

983 Tutors

University of California

1282 Tutors

Oxford University

123 Tutors

Yale University

2325 Tutors