Methods of Evaporation and Filtration Used
to Separate Mixtures
Juan Cuara
Diego Reynoso
March 07, 2023
Purpose:
In this experiment we used physical means, such as: evaporation, gravity filtration, and vacuum
filtration to separate homogeneous mixtures.
Theory:
There is concern among people regarding how safe drinking faucet water truly is. In this
experiment we set out to find whether it would be safe to drink purified sewage water by
analyzing how effective, if at all, it would be if we could separate water from unwanted
substances using three filtration techniques: evaporation, gravity filtration, and vacuum filtration.
Evaporation allows us to remove a liquid from a solution to leave a solid material by
using heat. In this experiment we used a bunsen burner to dispose of the liquid in NaCl. Through
direct heat we were able to remove the liquid in our sample of NaCl. Through the use of vacuum
filtration we placed a filter paper inside a Buchner funnel attached to a Buchner flask. Attaching
a vacuum line allowed us to use suction to separate the mixture. Using gravity filtration we
placed a filter paper inside a funnel that was suspended above an Erlenmeyer flask. When we
poured the mixture into the filter paper we were able to trap the large solid particles while liquid
molecules, dissolved ions, and any small particles able to pass through the filter paper were
dropped into the Erlenmeyer flask due to gravity.
We had different outcomes in each part. Namely, in Part 1 NaCl was separated from the
NaCl solution by evaporation. We then calculated the mass percent of NaCl in our saturated
NaCl solution. To do so we used Equation 1.
𝑚𝑎𝑠𝑠 % 𝑁𝑎𝐶𝑙 =
𝑀𝑎𝑠𝑠 𝑁𝑎𝐶𝑙𝐷𝑟𝑦
𝑀𝑎𝑠𝑠 𝑁𝑎𝐶𝑙𝑆𝑜𝑙𝑢𝑡𝑖𝑜𝑛
(E1. 1)
In order to find the weight of the solution in its dry and wet state we used the following
equations, respectively. The values for Equation 2 and 3 were obtained when we measured the
weight of the objects.
𝑀𝑎𝑠𝑠𝑁𝑎𝐶𝑙 𝑆𝑜𝑙𝑢𝑡𝑖𝑜𝑛 = 𝑊𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑑𝑖𝑠ℎ 𝑤𝑖𝑡ℎ 𝑁𝑎𝐶𝑙 − 𝑊𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑑𝑖𝑠ℎ𝑤𝑖𝑡ℎ𝑜𝑢𝑡 𝑁𝑎𝐶𝑙
(Eq. 2)
𝑀𝑎𝑠𝑠𝑁𝑎𝐶𝑙 𝑆𝑜𝑙𝑢𝑡𝑖𝑜𝑛 𝐷𝑟𝑦 = 𝑊𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑑𝑖𝑠ℎ𝑎𝑓𝑡𝑒𝑟 𝑒𝑣𝑎𝑝 - 𝑊𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑑𝑖𝑠ℎ𝑤𝑖𝑡ℎ𝑜𝑢𝑡 𝑁𝑎𝐶𝑙
(Eq. 3)
For Part 2 we wrote a balanced chemical reaction equation when we mixed the Sodium
Carbonate and Calcium Chloride, and a balanced chemical reaction equation for the observed
reaction after adding HCl. Equation 5 is our balanced equation of Sodium Carbonate and
Calcium Chloride. Equation 6 is our balanced equation for the mixture when we added Hydro
Chloride.
𝑁𝑎+1 𝐶𝑂3−2 + 𝐶𝑎+2 𝐶𝑙 −1
(Eq. 4)
𝑁𝑎2 𝐶𝑂3(𝑎𝑞) + 𝐶𝑎𝐶𝑙2(𝑎𝑞) → 2𝑁𝑎𝐶𝑙(𝑎𝑞) + 𝐶𝑎𝐶𝑂3(𝑠)
(Eq. 5)
Ca𝐶𝑂3(𝑠) + 2𝐻𝐶𝑙(𝑎𝑞) → 𝐶𝑎𝐶𝑙2(𝑎𝑞) + 𝐻2 𝑂(𝑎𝑞) + 𝐶𝑂2(𝑔)
(Eq. 6)
To balance the yield of Calcium Chloride plus Sodium Carbonate (Eq. 4) we added the
atoms on each side of the equation. We had twice as many Sodiums and twice as many Chlorines
on the reactant side. We added a coefficient of 2 in front of NaCl and were able to balance the
equation. We performed a similar process for balancing Equation 6.
For Part 3 we wanted to determine the percent of vanillin recovered. To accomplish this
we used Equation 2. The actual mass recovered was calculated from Equation 5. Taking the
difference of the final weight of the watch glass, weight of the glass, and weight of the filter
paper gave us the mass recovered.
% 𝑅𝑒𝑐𝑜𝑣𝑒𝑟𝑒𝑑𝑣𝑎𝑛𝑖𝑙𝑙𝑖𝑛 =
𝑀𝑎𝑠𝑠 𝑜𝑓 𝐴𝑐𝑡𝑢𝑎𝑙𝑟𝑒𝑐𝑜𝑣𝑒𝑟𝑒𝑑
𝑀𝑎𝑠𝑠𝐼𝑛𝑖𝑡𝑖𝑎𝑙
𝑀𝑎𝑠𝑠𝑎𝑐𝑡𝑢𝑎𝑙 𝑟𝑒𝑐𝑜𝑣𝑒𝑟𝑒𝑑 = 𝑊𝑒𝑖𝑔ℎ𝑡𝑓𝑖𝑛𝑎𝑙 − 𝑊𝑒𝑖𝑔ℎ𝑡𝑤𝑎𝑡𝑐ℎ 𝑔𝑙𝑎𝑠𝑠 − 𝑊𝑓𝑖𝑙𝑡𝑒𝑟 𝑝𝑎𝑝𝑒𝑟
(Eq. 7)
(Eq. 8)
Procedures:
Part Ⅰ. Separation of mixtures by evaporation
1. Use an analystical balance to weigh and record the mass of a clean and dry evaporating
dish
2. Use 5 mL of a saturated NaCl solution and reweigh the dish with NaCl.
3. Setup a heating apparatus and choose an appropriate size beaker that will hold the
evaporating dish.
4. Add boiling chips into the beaker to avoid bumping.
5. Fill the beaker half full with tap water.
6. Place dish with NaCl on top of beaker and heat it until dry.
7. Allow the evaporating dish to cool and reweigh dish. Repeat process until constant mass
achieved.
8. Finally, calculate the mass percent of NaCl in the saturated solution.
Part Ⅱ. Separation of Mixtures by Gravity Filtration
1. Add 10 mL of 1.0 M sodium carbonate into a 150 mL beaker.
2. Add 10 mL of 1.0 M calcium chloride and stir the mixture with a glass stirring rod.
3. Write a balanced chemical equation for this mixture.
4. Set up a gravity filtration system. Wet the filter paper with deionized water to ensure that
it sticks well to the funnel.
5. Pour the sodium carbonate and calcium chloride mixture directly into the center of the
funnel. (Remove when dry).
6. Transfer some solids to a watch glass.
7. Add 3 drops of 6 M HCl to the solids on the watch glass.
8. Write a balanced chemical reaction for the observed reaction.
Part Ⅲ. Separation of Mixtures by Vacuum Filtration
1. Place and tare a 250 mL Erlenmeyer flask on an analytical balance.
2. Weigh and record the mass of 0.8 g to 1 g of vanillin.
3. Remove the Erlenmeyer flask from the balance and add approximately 50 mL of
deionized water and vigorously stir to dissolve as much vanillin as possible.
4. Heat the solution in the flask until all the solids dissolve.
5. Put the Erlenmeyer flask into an ice bath to produce crystallization of the solution.
6. Once crystallization is complete, setup a vacuum filtration setup.
7. Weigh a filter paper using an analytical balance. Place the filter paper at the bottom of the
Büchner funnel and wet it with deionized water.
8. Turn on the water line to create a suction effect.
9. Rinse the crystals in the Erlenmeyer flask with approximately 5 mL of ice-cold water and
pour crystals into the center of the Büchner funnel.
10. Place the filter paper containing the crystals on watch glass and allow it to dry in the lab
drawer.
11. Calculate the percent recovery of vanillin
Data Tables
Measurements Part Ⅰ
Weight of dish without NaCl, (grams)
65.88425
Weight of dish with NaCl, (grams)
71.11445
Weight of dish after evaporation, (grams)
66.7011
WeightNaCl (grams)
5.2302
Table 1. Mass of Solution
Measurements Part Ⅲ
WeightFlask Initial (grams)
125.45
WeightFilter Paper (grams)
0.5657
WeightVanillin (grams)
0.9047
WeightWatch Glass (grams)
17.6153
Weight TotalTheo (grams)
19.08
Weight TotalActual (grams)
18.73
Table 2. Mass of objects
Results and Discussion
Part I. Calculations for finding the mass percent of NaCl using the values in Table 1.
𝑚𝑎𝑠𝑠 % 𝑁𝑎𝐶𝑙 =
0.8169
= 16.62 𝑔
5.2302
𝑀𝑎𝑠𝑠𝑁𝑎𝐶𝑙 𝑆𝑜𝑙𝑢𝑡𝑖𝑜𝑛 = 71.1144 − 65.8842 = 5.2302
𝑀𝑎𝑠𝑠𝑁𝑎𝐶𝑙 𝑆𝑜𝑙𝑢𝑡𝑖𝑜𝑛 𝐷𝑟𝑦 = 66.7011 − 64.8842 = 0.8169
Mass % NaCl, g
16.62
Mass NaCl Solution, g
5.2302
Mass NaCl Solution Dry, g
0.8169
By using the evaporation method we were able to take saturated NaCl solution and
evaporate away the water. In this case, the water is the solvent. Once we accomplished this we
were able to bring out the solute (NaCl crystals) from the solution. After a couple times of
heating and drying the solution the water evaporated and we were able to collect the pure NaCl.
Using the values from table 1 we found the % mass of NaCl in the saturated NaCl solution to be
16.62% by taking the ratio of the mass of the solute to the solution’s mass.
The importance of constant mass is to dry the sample completely. The goal is to dry,
cool, weigh. Then we dry, cool, weigh again and repeat this process until constant weight is
achieved in order to have a constant weight or within reasonable error because we used
analytical balances. Ineed, this was done a couple times in our experiment throughout.
Part III. Calculating the % Recovery of Vanillin by using the values in Table 2.
% 𝑅𝑒𝑐𝑜𝑣𝑒𝑟𝑦 𝑉𝑎𝑛𝑖𝑙𝑙𝑖𝑛 =
0.549
× 100
0.9047
= 60.7% 𝑅𝑒𝑐𝑜𝑣𝑒𝑟𝑒𝑑
From the above calculations we can conclude that the percent recovery calculation helps
us estimate the amount of vanillin recovered.
Conclusion:
In conclusion, in Part I we obtained a low mass percent. This tells us we were able to
evaporate a lot of the liquid. Indeed, after heating and allowing the dish to cool, a gentle flame
was applied to evaporate any remaining residues of liquid. In order to see if our mass percent of
NaCl is accurate we would need a verified sample to have established on. In Part III using the
method of vaccum filtration it is hard to see if we got an acceptable result because we believe we
must have an established procedure upon which to compare. However, if we were to make an
argument as to why only 60.7% was recovered it would be because of some errors on our part
when we performed the experiment. For example, throughout the experiment we were moving
back and forth to weigh the vanillin crystal and could have dropped some. In the end, we believe
physical filtrations are not enough to separate unwanted substances from sewage water. Perhaps
chemical filtration is also needed.
In this experiment I learned the importance of constant mass. As stated above plays a
huge role in determining accuracy of the mass percent. In adittion, I learned of the different
physical methods used for filtration, and the limits to how effective they can be. This is why
chemical filtrations are needed as well. Being able to apply the theory we learn in class through
experiment was very useful in enhancing my understanding of mixtures.
References
Khuu, A. K., & Rivera, A. R. (n.d.). An Inquiry Approach through an Environmental Awareness.