Ana. Chem. Lab Notes
Lab. Experiment #1 “Composition of Hydrates”
Materials:
Crucible & cover
Ring stand
Watch Glass
Alcohol Lamp
Crucible Tongs
Stirring rod
Wire Gauze
Analytical Balance
Dropper
Spatula
Clay Triangle
CuSO4 • 5H2O
Procedure:
1. Measure the mass of empty crucible
2. 2. Tare the balance to zero, add 5.20g of hydrates (CuSO 4 • 5H2O), record exact
mass.
3. Set up ring stand, iron ring, clay triangle, etc.
4. Heat the crucible & content until blue color disappear (Note: slightly tipped
crucible cover leaving a small opening for gases to escape)
5. Remove crucible (use tong), let it cool for a while
6. Find the mass of crucible + anhydrous salt (powdered CuSO 4)
7. Scrape the salt into the watch glass, add drops of H 2O until it reverses back to its
original form.
Questions:
1. Calculate MM of CuSO4 • 5H2O
2. Calculate the theoretical % of H2O in CuSO4 • 5H2O (This is the accepted value)
Mass of H2O
% H2O = ---------------------- x 100
Mass of Hydrate
Note:
Mass of crucible =
Mass of Hydrate =
Mass of crucible + anhydrous salt =
Mass H2O =
Analysis:
1. Determine the mass of the anhydrous salt
2. Determine the mass of H2O that left after heating
3. Using the equation (%H2O), calculate. This is the measured value.
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Lab. Experiment #2 “Making Solutions”
Activity A - Making Solutions of Differing Mass/Volume Concentration
Materials:
CuSO4 Solution
Vortex
Test tubes
Analytical Balance
Graduated Cylinder
Test tube rack
Procedure:
1. Label all the test tubes with the sample name, concentration, and group no.
2. Do calculations needed to prepare the solution in Table 1.
Use the equation: Mass/Volume = Concentration
Volume desired (mL) x Concentration (g/mL) = Mass of solute needed (g)
Table 1
Tube
#
CuSO4
Solution
Total Volume
Concentratio
n mg/mL
Calculations of Mass
needed
1
5.0 mL of 300
5.0
300 mg/mL
mg/mL
2
4.5 mL of 150
mg/mL
3
4.0 mL of 75
mg/mL
4
3.5 mL of 37.5
mg/mL
5
3.0 mL of 18.75
mg/mL
Example: Make a 20 mL of 40 mg/mL solution of glucose.
40 mg
20 mL x -------- = 800 mg = 0.8 g
mL
Observation:
1. Observe and draw the different shades of CuSO 4 (blue color)
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Lab. Experiment #3 “Making Solutions of Differing % Mass/Volume”
Purpose:
 Learn to prepare solution of specific mass/volume
 Prepare different mass & volume one of which is a testing reagent.
Computations:
Rule: a 1% solution means 1 g of solute in 100 mL solvent
Step 1: Convert % to a decimal by dividing by 100 this converts the unit to g/dL
Step 2: Same as with previous equation for M/V Concentration
Volume desired (mL) x Concentration (g/mL) = Mass of solute needed (g)
Procedure:
• Prepare the ff. solutions:
1. 5 mL of 10% NaOH
2. 5 mL of 5% CuSO4
3. 5 mL of each 5%, 2.5%, 1.25% and 0.625% gelatin
Volume
Calculations
Tube label
Solute
(g)
(mL)
5% CuSO4
5% Gelatin
2.5% Gelatin
1.25% Gelatin
0.625%
Gelatin
Perform Biuret test
1. Get 5 tubes with label: 5%, 2.5%, 1.25% and 0.625%, 0%
2. Add 250 uL of NaOH to each tube (use gloves)
3. Add 125 uL of CuSO4 to each tube
4. Add 1mL of the gelatin solution to each tube (for the 0% gelatin, use 1 mL of H 2O
5. Centrifuge for 1 to 2s
6. Observe the color change
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Lab. Experiment #4 “Making Solutions”
Activity B: Making Solutions of Different Molar Concentrations
Objective: Be able to calculate and make solution of molar solution
Materials:
Test tubes (5 each group)
Test tube rack
Spatula
Vortex Mixer
Analytical Balance
Pipettes (Volumetric and Serological)
Aspirator
Procedure:
1. Calculate. See Table 1
2. Label test tubes; weigh needed amount of solute and add 5 ml of solvent (H 2O)
3. Observe different shades of color. Draw.
Molarity Concentration Equation:
Volume desired (L) x Molarity desired (mol/L) x MM of solute (g/mol) = Mass of solute needed (g)
Table 1:
Tube Molarit
Total
Mass of
#
y
Volume solute to use
1
1.0 M
0.99 g
2
0.5 M
0.49 g
5
mL
3
0.1 M
0.09 g
4
0.05 M
0.04 g
5
0.01 M
0.0099 g
Group 2: (NO2)2 C6H3NHNH2
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Calculations
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Lab. Experiment #5 “Making Dilution of Concentrated Solutions”
Purpose and Background:
In this activity you will learn how to make diluted solutions from a much more
concentrated stock solution.
Diluting concentrated solutions:
C1 V1 = C2 V2
C1 = Starting concentration
V1 = Volume to use of the stock solution to make diluted solution
C2 = desired concentration
V2 = desired volume of the diluted sample
Procedure:
1. Use the tube of 5mL of CuSO 4 as stock solution
2. Label 5 tubes with the concentrations listed below and your group no. In your lab
notebook do the calculations.
Concentratio
n
Volume
150x
30x
15x
3x
1x
5mL
7mL
5mL
5mL
6mL
Calculations
0
Vol. of stock
concentration to
use
2.5 mL
0
Volume of
H2 o
2.5 mL
Lab. Experiment #6 “Serial dilution”
Purpose: To learn how to make solution of constantly decreasing concentration.
Materials:
Test tubes (4 each group)
Test tube rack
Spatula
CuSO4
Pipettes (Volumetric and Serological)
Aspirator
Procedure:
1. Make a stock solution of CuSO4 with a concentration of 300 mg/mL
2. Dilute the stock solution 3x using 1:10 dilution (label the test tubes accordingly)
3. Tabulate & record your computations. (Make sure to write your observations)
Table 1
Test
tube
1
2
3
4
Concentration
Vol. H20
300 mg/mL
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0
Volume desired
Lab. Experiment #7 “Semi-Quantitative (Test for Sugars)”
Aim:
1. To make the Benedict’s Test Semi-quantitative
2. To prepare different concentration of glucose using serial dilution
3. To estimate the quantity of glucose in a fruit juice solution
Procedure:
1. Decide on the five concentrations of glucose you will use. (2%, 1%, 0.5%, 0.2%,
0.1%)
2. Label 5 test tubes and 5 beakers with the concentrations
3. Set up a water bath
4. Make dilutions using serial dilution (5mL each)
C1
C2
V1
2
1
0.5
0.2
0.1
5 mL
2.5 mL
1.25 mL
0.5 mL
0.25 mL
Volume of
H2 O
0
V2
5 mL
5. Add 2 mL of Benedict’s solution
6. Then add 0.5 mL of each glucose solution and fruit juice solution to the
appropriate tube
7. Stir
8. Place in water bath 7 minutes
9. Observe and record results.
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