4: LAB 4 - SEPARATION OF SALT AND SAND
- Page ID
- 506142
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)The purpose of this experiment is to:
- Separate a mixture containing an unknown composition of sand and salt.
- Calculate the percentage of sand and salt in the unknown mixture.
INTRODUCTION
Matter can be classified as a pure substance or a mixture. Pure substances include elements and compounds. Elements are the simplest forms of matter that cannot be decomposed into other types of matter. They are found on the periodic table. A compound is a chemical combination of elements. Mixtures can be either homogeneous, meaning they are uniform throughout, or heterogeneous, meaning they are non-uniform in composition.
Mixtures can be separated by physical methods such as filtration, decantation, distillation, and evaporation. In this experiment, you will use filtration and evaporation to separate a mixture of sand and salt. Once the mixture is separated, you will be asked to determine the percentage of sand and salt. The following example illustrates how to perform these calculations.
A mixture of sand and salt had a mass of 10.750 g. Once separated, the mass of sand was determined to be 5.550 g. The mass of recovered salt was
5.200 g. Using this information, determine the percentage of sand and salt in the mixture.
Solution
We find the percentage of a component in a mixture using the formula.
x 100
The percentage of sand would be 
x 100 = 51.63 %
and the percentage of salt would be 
x 100 = 48.37%
- Always wear chemical splash goggles during the experiment.
- Gloves are provided for those who wish to wear them.
- Be cautious when handling glassware, both while it is being heated and after it has cooled, as it will remain hot. Allow all hot glassware to cool to room temperature before touching it.
- At the end of the experiment, dispose of the sand in the “recovered sand jar” on the lab cart.
- At the end of the experiment, wash the watch glass and the evaporating dish containing the recovered salt in the sink with plenty of soap and water.
- Ensure all glassware is clean, and all equipment is returned to its designated place.
- Clean the lab benches and verify all equipment is in your lab drawer before leaving.
- Wash your hands as soon as you leave the lab.
EQUIPMENT* AND CHEMICALS NEEDED
| Equipment | Equipment | Chemicals |
|---|---|---|
| Milligram balance | 50.0 mL beaker | Filter paper |
| Spatula | Watch glass (2) | 125 mL Erlenmeyer flask |
| Bunsen burner | Wire gauze pad | Beaker tongs |
| Ring stand | Hot plate | Deionized Water |
| Ring clamp | Stirring rod | Wash bottle |
| Matches, a striker, or a lighter | Glass funnel | Evaporating dish |
| Unknown mixture |
* Images of equipment needed in this lab can be found in the appendix (the equipment may differ or be subject to changes; follow your instructor’s directions).
EXPERIMENTAL PROCEDURE
1. Using a milligram balance, weigh an empty 50.0 mL beaker and record its Mass.
2. Using a spatula, add approximately 1.000 - 2.000 g of an unknown mixture (record the mixture number or letter) to the 50.0 mL beaker.
3. Obtain the mass of the mixture and the beaker and record the total mass. (Subtracting the mass of the empty beaker from the total mass will give you the mass of the mixture.)
4. Using a wash bottle, add enough deionized water to the 50.0 mL beaker to completely cover the mixture. Continue stirring the mixture with a stirring rod for approximately five minutes to dissolve the salt.
5. Using a glass funnel, a 125 mL Erlenmeyer flask, and filter paper, set up gravity filtration (following the instructions provided by your instructor) to separate the sand from the saltwater. A wash bottle can ensure the sand is completely removed from the beaker. Continue to rinse the beaker's contents into the filter until the beaker is empty.
To recover the sand, follow steps 6 through 9. To recover the salt, follow steps 10 through 14. These steps may be performed simultaneously depending on the number of members in your lab group.
6. After filtration, remove the filter paper from the funnel. Using a wash bottle, wash the sand from the filter paper back into the 50 mL beaker, being sure to remove all the sand.
7. Decant any excess water in the 50.0 mL beaker, then place the beaker on a hot plate with a low setting to dry the sand.
Note: Once the beaker warms, the sand may start to bubble. Hold the beaker with tongs and use a stirring rod to move the sand particles around it to prevent this.
8. Once the sand is completely dry and does not clump together (it will appear like beach sand on a hot summer day), turn off the hot plate and allow the beaker to cool.
9. Once the beaker is cool, obtain the mass of the 50.0 mL beaker and sand. (Subtracting the mass of the empty beaker from the combined mass of the beaker and sand will give you the mass of sand.)
10. Obtain the mass of an empty evaporating dish and a watch glass.
11. Pour the salt water from the 125 mL Erlenmeyer flask into the evaporating dish. Rinse the flask with deionized water from the wash bottle and pour this into the evaporating dish.
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You can use a Bunsen Burner or a hot plate to evaporate the saltwater. See the steps below for either. Your instructor may decide which type of evaporation you need to use.
Using a hot plate:
12. Place the Evaporating dish on the hot plate, drying the sand. Heat the mixture, and when the saltwater starts to boil, place a watch glass partially, and later entirely, on top of the evaporating dish to avoid splattering the saltwater into a crucible or beaker. Use a crucible or beaker tong for this purpose.
13. Heat the mixture until all the water evaporates and there is no condensation on the watch glass. Then, turn off the hot plate, and allow the evaporating dish to cool.
Or
Using a Bunsen Burner:
12. Under the hood, set up a ring stand containing a ring clamp and wire gauze pad. Place a Bunsen burner a few inches below the wire gauze pad. (Note: Your instructor will demonstrate how to set up this apparatus. Once you have set up your apparatus, ensure that your instructor approves it before proceeding with the next step.
13. Place the evaporating dish on the wire gauze pad and cover it with the watch glass. Light the Bunsen burner under the wire gauze pad and heat the mixture until all the water evaporates and there is no condensation on the watch glass. Then, turn off the burner and allow the evaporating dish to cool.
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14. Once the evaporating dish is cool, weigh the evaporating dish, watch glass, and salt. (By subtracting the mass of the empty evaporating dish and the watch glass from the mass of the evaporating dish, watch glass, and salt, you will find the mass of salt.)
15. Clean up all equipment as specified in the Safety Precautions and Clean-Up section. Transfer all data to the assignment loaded in Blackboard and complete the lab calculations as instructed by your instructor.
PRE-LAB QUESTIONS
Name: ____________________________________
- Imagine you are presented with a mixture of sand and salt. Based on previous knowledge, please describe how you would separate the mixture into its components.
- Classify the following matter samples as a homogeneous mixture, a heterogeneous mixture, an element, or a compound.
Part A: red wine
Part B: carbon dioxide
Part C: pepperoni pizza
Part D: silver
Part E: brass
- The Mass of a sand and salt mixture is 7.500 g. After separating the mixture, the mass of recovered sand was determined to be 5.473 g, and the mass of salt was 1.350 g. Calculate the percentage of sand and salt in the mixture.
- Refer to pre-lab question 3. What is the total percent recovery of the components of the mixture? (Add the percent of sand and the percent of salt.)
DATA OBSERVATIONS AND CALCULATIONS
Name: ___________________________ Lab Partner(s):____________________________________
Unknown Letter / Number =
Components |
Mass (g) (Show calculations where possible) |
|---|---|
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1. Mass of an empty 50 mL beaker |
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2. Mass of the beaker and the mixture |
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3. Mass of mixture |
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4. Mass of the beaker and sand |
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5. Mass of sand |
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6. Mass of empty evaporating dish and watch glass |
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7. Mass of evaporating dish, watch glass, and salt. |
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8. Mass of salt |
Percentage of sand in the mixture (show calculations):
Percentage of salt in the mixture (show calculations):
Percent recovery (show calculations):
POST LAB QUESTIONS
- Explain why the percent recovery of your mixture may not have been equal to 100%.
- Classify the substances encountered in this experiment as a homogeneous mixture, a heterogeneous mixture, an element, or a compound.
Deionized water:
Sand and salt mixture:
Sand:
Salt:
Saltwater:
- Imagine you are provided with a mixture of ammonium chloride (which sublimes when heated), sand, and salt. Outline a procedure for separating the mixture into its components.
- Chromatography is another separation method. What is chromatography, and how can it be used to separate the components of a mixture?
Please click here to access the Pre-Lab, Data Tables, and Post-Lab in Word or PDF format. Complete them and upload according to your instructor's instructions.