03 Madison Kothari
docx
keyboard_arrow_up
School
University of Houston, Clear Lake *
*We aren’t endorsed by this school
Course
CHEM-131
Subject
Chemistry
Date
Feb 20, 2024
Type
docx
Pages
3
Uploaded by MegaInternetWallaby38
CHEM1112-
section#
Experiment #3
Your Name
Date
Qualitative Analysis of Anions
Lab Partner: Lab Partner’s Name
Procedure (3 pts) First obtain 9 test tubes with labels. Add the solution (known or unknown) to one of the test tubes and then add acetic acid till the solution is acidic. Add .1 M AgNO3 to the solution and then put in the centrifuge and pour off supernatant liquid. After wash the precipitate with distilled water and centrifuge again pour off water. Add NH3 to the
precipitate in the test tube and centrifuge. Pour the supernatant liquid into test tube 3 and add 6M HNO3 if it’s not acidic add more HNO3. Discard contents in test tube. Add the solution (known or unknown) to test tube 4 add 6M HNO3 until acidic and .1 M Fe (NO3)3 and mineral oil. Shake the solution if the oil turns purple there are I- ions present. Take out the mineral oil with a dropper and add more, shake, and take it out again, repeat until the oil is clear. Add KMnO4 to test tube 4 until the solution is pink. Add mineral oil cover and shake the liquid. If the mineral oil is brown, there are Br- ions present. Add the solution (known or unknown) to test tube 6 as well as 6M HNO3 then place in a hot water bath. If/ when bubbles form transfer to a test tube with Ba (OH)2 if a white cloudy precipitate forms there is CO3 2- present. Add the solution (known or unknown) to test tube 7 add acetic acid until acidic then add .1 M BaCl2 if a white precipitate forms SO2- is present. Add the solution (known or unknown) to test tube 8 along with 6M NaOH until basic add aluminum granules to the test tube and put a small cotton ball about halfway down the tube where it’s not touching the liquid add a piece of pH paper above the cotton ball. Place the test tube in a hot water bath until the liquid starts forming bubbles if the pH
paper changes colors to blue/ green then NH3 is present.
Data and Observations (12 pts) (be mindful of units and significant figures)
1
CHEM1112-
section#
Experiment #3
Your Name
Date
Qualitative Analysis of Anions
Lab Partner: Lab Partner’s Name
Procedure
Known Solution
Unknown Solution
Results
Conclusions
Results
Conclusions
Example)
Add AgNO
3
to solution in Test Tube 2. Example) White precipitate forms.
Example) Cl
-
, Br
-
or
I
- are present.
White precipitate forms Cl-,Br- or I- are present
Add HNO3 to test tube 3
White precipitate forms
Cl- present
nothing
Cl- Not present
Add Fe(NO3)3 to test tube 4
Mineral oil pink/purple
I-
Ions presen
t
Purple mineral oil I-
Presen
t Add KMnO4 to test
tube 4
Mineral oil brown
Br- present
nothing
Not present
Add HNO3 to test tube 6
Bubbles form
CO3 2- is present
Bubbles formed
CO3 2- present Add BaCl2 to test tube 7
Percipitate forms
SO4 2- is present Percipitate forms
SO4 2- present
Add NaOH to test tube 8
pH paper turns green/ blue
NO3- is present
pH paper turned green
NO3- is present
U
n
k
n
o
w
n
s
o
l
u
t
i
o
n
#
_
Identified presence of the following anions:
SO4 2-, NO 3-, I-, CO3 2-
Identified absence of the following anions:
Br- , Cl-
2
CHEM1112-
section#
Experiment #3
Your Name
Date
Qualitative Analysis of Anions
Lab Partner: Lab Partner’s Name
_
_
c
_
_
Potential Error Sources
One source of error that could have struck was that there could have been a reaction that we didn’t notice happen because it happened too quickly, and we didn’t catch it on our initial known solution so when we did the same test for the unknown, we may have seen something we didn’t see before or thought we saw something we didn’t see. Another source of error could have been when we took out parts of the supernatant liquid, we could have gotten some precipitant in it that could have potentially change our results. Post-Lab Questions (5 pts)
1)
Write oxidaiotn and reduction half-reaction equations that describe the test for identifying NO
3
–
(NO
3
is reduced to NH
3
(gas) witht the presence of Al). Oxidation: Al(s)+ OH- (aq) => Al(OH)- (aq)+ 3 e-
Reduction NO3- + 6H2O+8e- => NH3 (g)+ 9 OH- (aq)
2)
Explain why the test for I
–
must be done before testing for Br
–
.
IF KMnO4 was used first it would have taken out the I- and Br- so we wouldn’t be able to know
which one is in the solution. Fe(NO3)3 is only strogn enough to take out the I- while leaving the
Br- behind
3)
Which one of the iodine species dissolved in the mineral oil, and why ? I2 is dissolved because non-polar molecules dissolve other non-polar molecules. “like dissolves
like” 1. Iodine
2. Iodide
3
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
- Access to all documents
- Unlimited textbook solutions
- 24/7 expert homework help
Related Documents
Related Questions
Table of chemicals and reagents with their physicochemical properties (name,
molecular formula, molecular weight, pKa, melting point, boiling point, etc.)
Write a short outline or a flow diagram of the procedure
List and safety issues
Read and understand the MSDS information for each chemical used in this practical
Experimental procedure
Please do not scratch the clear sides of the UV cuvettes as this will invalidate your results.
Part 1: Preparation of a calibration curve
A calibration curve should be constructed using at least five concentrations of the pure paracetamol standard
supplied in the range 3-15 ug/mL as follows:
Weigh about 150 mg of paracetamol accurately and transfer to a 200 mL volumetric flask. Add 50 mL of o.1 M
NaOH and dilute to about 100 mL with deionised water (DI). Shake and make up to volume with DI water. Dilute
10 mL of the resulting solution to 100 mL (volumetric flask) with DI water (= stock solution). Prepare standard
solutions containing 3, 6, 9, 12 and 15…
arrow_forward
I need help on questions 2-8?
arrow_forward
Pre Lab Questions: (Each answer is to be written as a complete sentence)
What is the reason for washing the precipitate with water in Step 9?
Define precipitate. Define filtrate.
In Step 2, what is the purpose for rinsing the stirring rod?
read the Procedure to answer the questions
Using a balance, mass between 1.50 – 2.00 grams of sodium carbonate in a pre-massed 150mL beaker.
Add 20 mL of distilled water and stir thoroughly to make sure all the crystals are dissolved. Rinse the stirring rod with a little distilled water after stirring.
Using a balance, mass between 1.50 – 2.00 grams of calcium chloride dihydrate in a pre-massed 50 mL beaker.
Repeat Step 2 for the solution in the 50 mL beaker.
Pour the calcium chloride solution into the 150mL beaker containing the sodium carbonate solution and stir.
Mass a piece of filter paper. Fold the filter paper and place it into the funnel. Wet it with a little distilled water to ensure that it is stuck to the sides of the funnel.
Slowly…
arrow_forward
I need help on questions 2-7?
arrow_forward
Hello! Could you please answer this with one long dimentional analysis like I am supposed to do it? Thank you!
arrow_forward
1. Answer the following questions based on the table:
Pickling Vinegar
Conc NaOH (M)
0.1005
Trial #1
Trial #2
Trail #3
Trial #4
Volume Vinegar (mL)
2.00
2.00
2.00
2.00
Initial Volume NaOH (mL)
0.32mL
0.22
1.02
0.44
Final Volume (mL)
24.25mL
24.20
25.00
24.45
Volume NaOH added (mL)
23.93mL
23.98mL
23.98mL
24.01mL
a) Calculate the Average Volume NaOH used...show the trials that have %difference
within 1% of each other. If you need to discard any trials- make sure to note this.
b) Mass percentage of acetic acid in vinegar using your average volume of NaOH from
Q1: (include a balanced reaction equation and show all work)
c) % error calculation. Show ybur work in full. See Appendix B for details. (Reminder:
Regular vinegar is 5.25% listed on bottle, pickling vinegar is 7.34% listed on bottle)
d) In the titration of vinegar, a student uses 12.36 mL of NaOH(aq) (Molarity 0.100 M) to
titrate a 2.00 mL sample of vinegar. If the student used lithium hydroxide (Molarity:
0.200 M) instead, what…
arrow_forward
For each of the following scenarios, determine if the error will cause the molarity of the hydrochloric acid to be greater than, less than, or the same as the initial value.
A: A student adds 50 mL of water to the reaction flask with unknown hydrochloric acid instead of the 25 mL sated in the procedure.
B: A student adds 50 mL of water to the reaction flask with unknown hydrochloric acid instead of the 25 mL stated in the procedure.
C: A student doesn't notice the some of the HCL has dripped out from the volumetric pipet when transferring to the reaction flask
arrow_forward
I need help constructing graph I m not sure where to put values
On the graph paper plot a graph of your reaction rates vs. concentration by using
vertical scale or Y-axis representing reaction rate and a horizontal scale or X-axis
representing mls of solution #1(KIO3).
arrow_forward
Procedure:
Step 1: Pipet 25 mL of prepared sample solution, which has been prepared into a 250 mL
Erlenmeyer flask.
Step 2: Add 3-5 drops of phenolphthalein indicator solution to the sample solution in the 250
mL Erlenmeyer flask.
Step 3: Rinse the buret with three 10 mL portions of standardized 0.1 M HC1 acid solution,
before fill this acid solution into the buret and record the initial volume of this acid solution in
the burette.
Step 4: Titrate the sample solution with the standardized 0.1 M HC1 to the endpoint and record
the final volume of this acid in the burette. (Note: phenolphthalein endpoint is from pink color
to colorless)
Step 5: Repeat the titration for two more times.
Step 6: Repeat the same procedure from step 1 to step 5 by using methyl orange as an indicator
rather than phenolphathelein. (Note: methyl orange endpoint is from orange to red color).
Calculate the alkalinity of the sample for both the indicators and potentiometric method using
the following equation:
[Alk]…
arrow_forward
You obtain an Unknown Sample from the Stockroom. You begin testing the solution through the steps outlined in the flowchart of the experiment’s PDF file. You first add HCl and centrifuge your mixture. You observe the formation of a white precipitate in the bottom of the test tube. After pouring off the supernatant liquid, you add hot water to the white precipitate. Addition of the hot water dissolves some of the precipitate, but some white precipitate still remains on the bottom of the test tube. You pour off the supernatant liquid, and add ammonia (NH3) to the remaining precipitate. You now observe the formation of a gray-black precipitate.
Which of the following is a valid conclusion to draw at this point?
Select one:
Hg22+ is definitely present.
Pb2+ is definitely present.
Ag+ could be present, or Hg22+ could be present, or BOTH could be present.
Ag+ is definitely present
arrow_forward
You obtain an Unknown Sample from the Stockroom. You begin testing the solution through the steps outlined in the flowchart of the experiment’s PDF file. You first add HCl and centrifuge your mixture. You observe the formation of a white precipitate in the bottom of the test tube. After pouring off the supernatant liquid, you add hot water to the white precipitate. Addition of the hot water dissolves some of the precipitate, but some white precipitate still remains on the bottom of the test tube.
Which of the following is a valid conclusion to draw at this point?
Pb2+ is definitely present.
Hg22+ is definitely present.
Ag+ could be present, or Hg22+ could be present, or BOTH could be present.
Ag+ is definitely present
arrow_forward
7
Solid lead (II) nitrate is slowly added to 125 mL of a 0.190 M potassium hydroxide solution until the concentration
of lead ion is 0.0547 M. The percent of hydroxide ion remaining in solution is
%.
Submit Answer
$
4
R
LLO
%
5
[Review Topics)
[References
Use the References to access important values if needed for this question.
Retry Entire Group
T
Cengage Learning | Cengage Technical Support
^
6
*
8 more group attempts remaining
MacBook Pro
G H
2
&
7
A
J
* 0
8
(
9
UD
U
K
F
0
)
O
◆
P
|
Previous
Email Instructor
{
[
+ 11
=
Next>
Save and Exit
}
]
arrow_forward
No plagiarism Please!
Station #9 = HC2H3O2 (aq)
For this acid, what does the white bead represent?________ blue bead? __________ 3rd Color Bead? _________
Record your observations in the particulate drawing.
How many acid molecules have broken into ions?
Determine the % ionization for the acid.
Write the ionization reaction for this acid. ________ ↔ ______ + _______
arrow_forward
How do I calculate the first table ?
arrow_forward
Help with the CHEM Lab report please! It is about Volumetric Analysis
There is also a Burn trail please make sure for that!
arrow_forward
>
1
arrow_forward
What is the concentration of hydrochloric acid? Find the concentration using the information given below.
Equipment used in the lab:
50 mL burette
X M H2SO4 solution (aq) • Two 50 mL beakers
0.10 M NaOH (aq)
Procedure:
25 mL volumetric pipette • Bromothymol blue indicator • Pipette pump
• 250 mL Erlenmeyer flask
Observations from the Titration Lab.
Trial 1
Trial 2
Trial 3
Final burette reading
14.6 mL
27.85 mL
40 mL
Initial burette reading
0 mL
14.5 mL
27.85 mL
Volume of H2SO4 (aq) added
25 mL
14.6mL
13.35 mL
12.15 mL
arrow_forward
16
You need to make an aqueous solution of 0.237 M cobalt(II) fluoride for an experiment in lab, using a 250 mL volumetric flask. How much solid cobalt(II)
fluoride should you add?
grams
Submit Answer
Review Topics]
[References]
Use the References to access important values if needed for this question.
Retry Entire Group
8 more group attempts remaining
Cengage Learning Cengage Technical Support
Previous
Next>
Save and Exit
arrow_forward
I need help with one of my pre-lab questions which I want to understand. Its question number 2, the one that highlighted. I don't want to make it over-complicated, I want something that I can understand.
arrow_forward
i) How many moles of hydrochloric acid were there in the volume of acid added in the titration?
ii) How many moles of calcium hydroxide were there in the 25 cm sample of solution that the student used in the titration?
iii) What was the concentration of the calcium hydroxide solution in mol/dm?
arrow_forward
1.What is the volume of NaOH?
And the
2.concantration of NaOH?
arrow_forward
Please answer fast i give you upvote.
arrow_forward
Color BEFORE adding
Color AFTER adding
Intensity of color AFTER
adding FeCl3
Test Tube #
FeCl3
FeCl3
#1 (salicylic acid)
clear
lilac
100%
#2 (commercial aspirin A) clear
slightly pink
50%
#3 (commercial aspirin B) clear
lilac
95%
#4 (aspirin from your
clear
pink
20%
synthesis above)
#5 (control)
clear
clear
0%
Based on this data and the melting point of Aspirin, how pure is the synthesized product?
arrow_forward
Reactions of Na₂CO3
* Reactions with a carbonate salt and acid are gas evolving!
I
Na₂CO3(aq)
Na* CO3²-
Na2CO3(aq)
Na₂CO3 (aq)
Na₂CO3(aq)
Na₂CO3 (aq)
Na₂CO3 (aq)
Na2CO3 (aq)
Na₂CO3 (aq)
Na₂CO3 (aq)
Na₂CO3 (aq)
+
+
+
+
2
Pb(NO3)2 (aq)
H* CI
HCl (aq)
Na3PO4 (aq)
KI (aq)
CuSO4 (aq)
H₂SO4 (aq)
NaOH (aq)
AgNO3(aq)
CaCl2 (aq)
HNO3(aq)
→>>
→>
→>>>
➜>>
↑
↑
Na Cl + H* CO3²-
NaCl (aq) + [H₂CO3 (aq)] → NaCl (aq) + H₂O (1) + CO2 (s)
2 NaCl (aq) + H2₂O (1) +
PAGE 123 OF 232
(g)
arrow_forward
Hi, I am having trouble understanding how to do dilution factors for these tubes can you show me how to get the DF please?
arrow_forward
All changes save
7. When two solutions are mixed, a color change occurs. The data tables show the time between mixing and the color change for two sets of conditions. For
Condition One, the solution concentrations were constant and temperature varied. For Condition Two, the temperature was constant and concentrations varied.
Condition One: Concentration
Time for
Temperature
(°C)
Sample
Color to
Change
1
10°
36 sec
22°
14 sec
Condition Two: Temperature
Time for
Concentration
Sample
Color to
%
Change
1.
100%
15 sec
2.
50%
24 sec
Which of these statements is true according to the data?
O The reaction rate is greater at 22°C than at 10°C.
O Reducing the temperature increases the rate of the reaction.
The reaction is affected by changes in temperature
not by changes in concentration.
O Decreasing the concentration increases the reaction rate.
PREVIOUS
17 of 25
NEXT
SAVE & EXIT
arrow_forward
SEE MORE QUESTIONS
Recommended textbooks for you
Related Questions
- Table of chemicals and reagents with their physicochemical properties (name, molecular formula, molecular weight, pKa, melting point, boiling point, etc.) Write a short outline or a flow diagram of the procedure List and safety issues Read and understand the MSDS information for each chemical used in this practical Experimental procedure Please do not scratch the clear sides of the UV cuvettes as this will invalidate your results. Part 1: Preparation of a calibration curve A calibration curve should be constructed using at least five concentrations of the pure paracetamol standard supplied in the range 3-15 ug/mL as follows: Weigh about 150 mg of paracetamol accurately and transfer to a 200 mL volumetric flask. Add 50 mL of o.1 M NaOH and dilute to about 100 mL with deionised water (DI). Shake and make up to volume with DI water. Dilute 10 mL of the resulting solution to 100 mL (volumetric flask) with DI water (= stock solution). Prepare standard solutions containing 3, 6, 9, 12 and 15…arrow_forwardI need help on questions 2-8?arrow_forwardPre Lab Questions: (Each answer is to be written as a complete sentence) What is the reason for washing the precipitate with water in Step 9? Define precipitate. Define filtrate. In Step 2, what is the purpose for rinsing the stirring rod? read the Procedure to answer the questions Using a balance, mass between 1.50 – 2.00 grams of sodium carbonate in a pre-massed 150mL beaker. Add 20 mL of distilled water and stir thoroughly to make sure all the crystals are dissolved. Rinse the stirring rod with a little distilled water after stirring. Using a balance, mass between 1.50 – 2.00 grams of calcium chloride dihydrate in a pre-massed 50 mL beaker. Repeat Step 2 for the solution in the 50 mL beaker. Pour the calcium chloride solution into the 150mL beaker containing the sodium carbonate solution and stir. Mass a piece of filter paper. Fold the filter paper and place it into the funnel. Wet it with a little distilled water to ensure that it is stuck to the sides of the funnel. Slowly…arrow_forward
- I need help on questions 2-7?arrow_forwardHello! Could you please answer this with one long dimentional analysis like I am supposed to do it? Thank you!arrow_forward1. Answer the following questions based on the table: Pickling Vinegar Conc NaOH (M) 0.1005 Trial #1 Trial #2 Trail #3 Trial #4 Volume Vinegar (mL) 2.00 2.00 2.00 2.00 Initial Volume NaOH (mL) 0.32mL 0.22 1.02 0.44 Final Volume (mL) 24.25mL 24.20 25.00 24.45 Volume NaOH added (mL) 23.93mL 23.98mL 23.98mL 24.01mL a) Calculate the Average Volume NaOH used...show the trials that have %difference within 1% of each other. If you need to discard any trials- make sure to note this. b) Mass percentage of acetic acid in vinegar using your average volume of NaOH from Q1: (include a balanced reaction equation and show all work) c) % error calculation. Show ybur work in full. See Appendix B for details. (Reminder: Regular vinegar is 5.25% listed on bottle, pickling vinegar is 7.34% listed on bottle) d) In the titration of vinegar, a student uses 12.36 mL of NaOH(aq) (Molarity 0.100 M) to titrate a 2.00 mL sample of vinegar. If the student used lithium hydroxide (Molarity: 0.200 M) instead, what…arrow_forward
- For each of the following scenarios, determine if the error will cause the molarity of the hydrochloric acid to be greater than, less than, or the same as the initial value. A: A student adds 50 mL of water to the reaction flask with unknown hydrochloric acid instead of the 25 mL sated in the procedure. B: A student adds 50 mL of water to the reaction flask with unknown hydrochloric acid instead of the 25 mL stated in the procedure. C: A student doesn't notice the some of the HCL has dripped out from the volumetric pipet when transferring to the reaction flaskarrow_forwardI need help constructing graph I m not sure where to put values On the graph paper plot a graph of your reaction rates vs. concentration by using vertical scale or Y-axis representing reaction rate and a horizontal scale or X-axis representing mls of solution #1(KIO3).arrow_forwardProcedure: Step 1: Pipet 25 mL of prepared sample solution, which has been prepared into a 250 mL Erlenmeyer flask. Step 2: Add 3-5 drops of phenolphthalein indicator solution to the sample solution in the 250 mL Erlenmeyer flask. Step 3: Rinse the buret with three 10 mL portions of standardized 0.1 M HC1 acid solution, before fill this acid solution into the buret and record the initial volume of this acid solution in the burette. Step 4: Titrate the sample solution with the standardized 0.1 M HC1 to the endpoint and record the final volume of this acid in the burette. (Note: phenolphthalein endpoint is from pink color to colorless) Step 5: Repeat the titration for two more times. Step 6: Repeat the same procedure from step 1 to step 5 by using methyl orange as an indicator rather than phenolphathelein. (Note: methyl orange endpoint is from orange to red color). Calculate the alkalinity of the sample for both the indicators and potentiometric method using the following equation: [Alk]…arrow_forward
- You obtain an Unknown Sample from the Stockroom. You begin testing the solution through the steps outlined in the flowchart of the experiment’s PDF file. You first add HCl and centrifuge your mixture. You observe the formation of a white precipitate in the bottom of the test tube. After pouring off the supernatant liquid, you add hot water to the white precipitate. Addition of the hot water dissolves some of the precipitate, but some white precipitate still remains on the bottom of the test tube. You pour off the supernatant liquid, and add ammonia (NH3) to the remaining precipitate. You now observe the formation of a gray-black precipitate. Which of the following is a valid conclusion to draw at this point? Select one: Hg22+ is definitely present. Pb2+ is definitely present. Ag+ could be present, or Hg22+ could be present, or BOTH could be present. Ag+ is definitely presentarrow_forwardYou obtain an Unknown Sample from the Stockroom. You begin testing the solution through the steps outlined in the flowchart of the experiment’s PDF file. You first add HCl and centrifuge your mixture. You observe the formation of a white precipitate in the bottom of the test tube. After pouring off the supernatant liquid, you add hot water to the white precipitate. Addition of the hot water dissolves some of the precipitate, but some white precipitate still remains on the bottom of the test tube. Which of the following is a valid conclusion to draw at this point? Pb2+ is definitely present. Hg22+ is definitely present. Ag+ could be present, or Hg22+ could be present, or BOTH could be present. Ag+ is definitely presentarrow_forward7 Solid lead (II) nitrate is slowly added to 125 mL of a 0.190 M potassium hydroxide solution until the concentration of lead ion is 0.0547 M. The percent of hydroxide ion remaining in solution is %. Submit Answer $ 4 R LLO % 5 [Review Topics) [References Use the References to access important values if needed for this question. Retry Entire Group T Cengage Learning | Cengage Technical Support ^ 6 * 8 more group attempts remaining MacBook Pro G H 2 & 7 A J * 0 8 ( 9 UD U K F 0 ) O ◆ P | Previous Email Instructor { [ + 11 = Next> Save and Exit } ]arrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you