2. Suppose a student introduces an object to aid in stirring the solution but does not rinse the object and places it directly on their countertop. They notice a white powder that resides on the stirrer. How will their calculation for percent error be affected? Explain. Momci saat bag
2. Suppose a student introduces an object to aid in stirring the solution but does not rinse the object and places it directly on their countertop. They notice a white powder that resides on the stirrer. How will their calculation for percent error be affected? Explain. Momci saat bag
Chapter31: Introduction To Analytical Separations
Section: Chapter Questions
Problem 31.19QAP
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Chemical Reactions and Equations
When a chemical species is transformed into another chemical species it is said to have undergone a chemical reaction. It consists of breaking existing bonds and forming new bonds by changing the position of electrons. These reactions are best explained using a chemical equation.
Question
Please help with question 2
Transcribed Image Text:ber 1 of prelab (see
inder.
agitation. You may also
et so all solution stays in
f you overfill the
ding,
and has a uniform
12 in number 2 of prelab
duated cylinder.
agitation. You may also
so all solution stays in
you overfill the
ng,
and has a uniform
this mass for the second
mL of 0.250M CaCl2 into
nt or a graduated
fore measuring a new
ixing. The mixture will
- is
f
the
This Photo by Unknown Author is licensed und
supernatant until it is
of passes.
cipitate a few times
cipitate. This ensures
Chem 105 Online
that all the spectator ions are rinsed off the filter paper and precipitate and not
recrystallize-which would add an additional mass on the filter paper when dried,
7. Carefully remove the filter paper (it will still be very moist) and place it on a paper towel
to dry overnight.
a. If you are cramped for time, an oven will work set at 200-225°F. Set the wet filter
paper on a baking sheet and place in the oven. Check it regularly to not burn
the filter paper.
b. A sunny window is a happy medium for wet filter paper as well. Ⓒ
8. Repeat the process one more time for a second trial. This time you will measure 10.0mL
of 0.750M Na2CO3 and 50.0mL of 0.250M CaCl2 into a new plastic cup..
Don't forget your documentation!
Data Table
Data Entry
Quantities Used
Theoretical Yield of
Precipitate (record
here, show calculations
below table)
Mass of Filter Paper
BEFORE experiment
Mass of DRY Filter Paper
and Precipitate (day 2)
Mass of Calcium
Carbonate
(Precipitate, day 2!
Percent Yield
Trial 1
Trial 2
30.0mL of 0.250M CaCl₂
15.0mL of 0.750M Na₂CO3
.53g
Trial 2
50.0mL of 0.250M CaCl₂
10.0mL of 0.750M Na2CO3
.53g
Calculations
For each trial, show the theoretical yield of Calcium Carbonate produced based on your limiting
reactant and amounts of each reactant used.
Trial 1
Transcribed Image Text:Chem 105 Online
Post Laboratory Questions:
1. What is the purpose of rinsing the precipitate at the end of the reaction? How would
your calculation for percent yield be affected if this were not rinsed thoroughly?
2. Suppose a student introduces an object to aid in stirring the solution but does not rinse
the object and places it directly on their countertop. They notice a white powder that
resides on the stirrer. How will their calculation for percent error be affected? Explain.
The percent error would be incorrect because
we wouldn't
3. Why must the filter paper be dried before obtaining the final mass?
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