Lab 1: Separation Of a Three-Component Mixture
- Page ID
- 514061
\( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)
\( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)
\( \newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\)
( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\)
\( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\)
\( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\)
\( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\)
\( \newcommand{\Span}{\mathrm{span}}\)
\( \newcommand{\id}{\mathrm{id}}\)
\( \newcommand{\Span}{\mathrm{span}}\)
\( \newcommand{\kernel}{\mathrm{null}\,}\)
\( \newcommand{\range}{\mathrm{range}\,}\)
\( \newcommand{\RealPart}{\mathrm{Re}}\)
\( \newcommand{\ImaginaryPart}{\mathrm{Im}}\)
\( \newcommand{\Argument}{\mathrm{Arg}}\)
\( \newcommand{\norm}[1]{\| #1 \|}\)
\( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\)
\( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\AA}{\unicode[.8,0]{x212B}}\)
\( \newcommand{\vectorA}[1]{\vec{#1}} % arrow\)
\( \newcommand{\vectorAt}[1]{\vec{\text{#1}}} % arrow\)
\( \newcommand{\vectorB}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)
\( \newcommand{\vectorC}[1]{\textbf{#1}} \)
\( \newcommand{\vectorD}[1]{\overrightarrow{#1}} \)
\( \newcommand{\vectorDt}[1]{\overrightarrow{\text{#1}}} \)
\( \newcommand{\vectE}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash{\mathbf {#1}}}} \)
\( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)
\( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)
\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)The purpose of this experiment is to
- To separate a three-component mixture of sand, sodium chloride (salt), and ammonium chloride by utilizing their distinct physical properties.
- To determine the mass percentage of each component in an unknown mixture of three solids, which has two water-soluble components and one water-insoluble component (sand, sodium chloride, and ammonium chloride).
INTRODUCTION
This experiment demonstrates the separation of a mixture containing sand, sodium chloride, and ammonium chloride using various techniques based on their physical properties.
Mixtures are combinations of two or more substances that retain their individual properties and can be separated through physical processes.
The separation strategy for this experiment involves the following principles:
- Sublimation: Ammonium chloride \(\ce{(NH₄Cl)}\) undergoes sublimation, transitioning directly from a solid to a gas upon heating without passing through a liquid phase. This property separates it from non-sublimate, such as sand and sodium chloride. The gaseous ammonium chloride can be cooled to obtain pure solid ammonium chloride. Other substances that sublime include camphor, naphthalene, anthracene, and iodine.
- Solubility: Sodium chloride \(\ce{(NaCl)}\) is soluble in water, whereas sand \(\ce{(SiO₂)}\) is not. By adding water to the mixture, sodium chloride dissolves, allowing it to be separated from the insoluble sand through filtration.
- Filtration or Decantation: This process involves separating the sodium chloride from the sand by pouring the liquid away from the solid.
- Evaporation: Heating the sodium chloride solution causes the water to evaporate, leaving behind solid sodium chloride.
1. Always wear safety goggles to protect your eyes.
2. To avoid inhaling ammonium chloride fumes, perform the sublimation step in a fume hood.
3. Use caution when handling hot equipment such as evaporating dishes, hot plates, and Bunsen burners. Use tongs or heat-resistant gloves, and allow the equipment to cool down before handling it.
4. Thoroughly wash all used glassware and equipment with soap and water at the end of the experiment.
5. Avoid direct contact with chemicals and wash your hands thoroughly after the experiment.
6. Keep flammable materials away from the Bunsen burner.
7. Clean up your work area and return all equipment and glassware to their designated places.
8. Dispose of any chemicals properly per your instructor's guidelines before leaving.
CHEMICAL DISPOSAL
Dispose of the recovered sand in the Recovered Sand container after the sand is cooled.
The recovered ammonium chloride should be scraped from the glass funnel and deposited into the appropriate waste container. Wash the funnel with soap and water.
Wash the recovered sodium chloride in the evaporating dish in the sink with plenty of water.
- Dispose of any remaining solutions according to the instructor's guidelines.
EQUIPMENT AND CHEMICALS NEEDED
| Chemicals and Equipment | Equipment | Equipment |
|---|---|---|
| Unknown mixture (sand, sodium chloride, ammonium chloride) | Ice Bath | Tongs |
| Evaporating dishes (2) | Graduated cylinder | Bunsen Burner |
| Ring stand | Stirring rod with Rubber policeman | Beaker |
| Ring clamp | Watch glass | Deionized Water |
| Clay triangle | Hot Plate | Glass Funnel |
EXPERIMENTAL PROCEDURE
1. Obtain two evaporating dishes, and clean and dry them.
2. Record the weight of the first clean, dry evaporating dish (label "first") in the data table.
3. Obtain an unknown mixture and record the unknown ID in the data table.
4. Add 2 to 3 grams of this unknown mixture to the first previously weighed evaporating dish from step 2. Accurately record the combined weight of the evaporating dish and the unknown sample.
5. Obtain a glass funnel that covers the mixture inside the first evaporating dish. Insert a small piece of cotton into the opening of the funnel's stem. Record the mass of the glass funnel with the cotton ball.
Figure 1: An Evaporating Dish Containing the unknown hydrate mixture covered with a glass funnel with the stem plugged with cotton
Sublimation of the Ammonium Chloride Component
6. Set up a ring stand with a ring clamp and a clay triangle in a fume hood. Place the evaporating dish containing the unknown mixture on the clay triangle.
7. Cover the mixture with the previously weighed inverted glass funnel, with a cotton plug at the opening, over the evaporating dish.
8. Continue heating the evaporating dish with a Bunsen burner until you no longer observe any white fumes. When the fumes are no longer visible, continue heating for an additional five minutes before turning off the Bunsen burner. Allow the evaporating dish and funnel to cool to room temperature for 10 - 15 minutes.
9. Weigh the evaporating dish with the remaining sample (sand and sodium chloride) and record the weight.
10. Calculate the mass of ammonium chloride (mass by difference) from the sublimed sample collected by subtracting the weight of the evaporating dish and sample after heating from the weight of the evaporating dish and sample before heating.
11. Weigh the glass funnel with the sublimated ammonium chloride and cotton ball.
12. Calculate the mass of ammonium chloride using the sublimed sample by subtracting the weight of the glass funnel, the cotton ball, and the sample after heating from the weight of the glass funnel and the cotton ball before heating.
13. Clean the glass funnel by scraping off the ammonium chloride and depositing it into the ammonium chloride solid waste container as instructed by your instructor
14. Add 25 mL of deionized water to the evaporating dish containing the remaining mixture and gently stir using a glass rod for 5 minutes to dissolve the sodium chloride.
15. Weigh a second (label second) clean, dry evaporating dish along with a watch glass and record the weight.
16. Carefully decant the liquid (sodium chloride solution) from the first evaporating dish into the second evaporating dish, trying not to disturb the sand.
17. Repeat the decantation with two additional 10 mL portions of water.
Separation and Isolation of Sodium Chloride Component
18. Place the second evaporating dish (containing the sodium chloride solution) on a hot plate and heat the solution to evaporate the water.
19. Avoid splattering. When the volume reduces to approximately 5 mL, or if the solution splatters, cover the evaporating dish with the previously weighed watch glass to prevent further splattering.
20. Continue heating until all the liquid evaporates, and the watch glass droplets are dry.
21. Allow the evaporating dish and watch glass to cool to room temperature. Weigh the cooled evaporating dish, watch the glass, and record the weight.
22. Calculate the mass of sodium chloride recovered by subtracting the weight of the evaporating dish and watch glass before evaporation from the weight of the evaporating dish and watch glass after evaporation.
Recovery of Sand Component
23. Dry the original first evaporating dish containing the wet sand on a hot plate by heating it gently and stirring it occasionally to avoid popping or cracking.
24. Allow the evaporating dish to cool. Weigh the evaporating dish with the dried sand and record the weight.
25. Calculate the mass of the recovered sand by subtracting the weight of the empty evaporating dish from the weight of the evaporating dish with the dried sand.
CALCULATIONS
1. Mass of the Original Sample
\[\text{Mass of Original Sample} = \text{(Mass of the First Evaporating Dish with Original Sample)} - \text{(Mass of the First Evaporating Dish)} \nonumber \]
2. Mass of the Ammonium Chloride from the Difference
\[\text{Mass of Ammonium chloride \(\ce{(NH₄Cl)}\) } = \text{(Mass of First Evaporating Dish with Original Sample Before Heating)} - \text{(Mass of First Evaporating Dish with Original Sample after Heating)} \nonumber \]
3. Mass of the Ammonium Chloride from the Sublimated Sample
\[\text{Mass of Ammonium chloride \(\ce{(NH₄Cl)}\) from the Sublimated Sample} = \text{(Mass of Funnel and Cotton Plug with the Sublimated Sample)} - \text{(Mass of Funnel and Cotton Plug)} \nonumber \]
4. Mass of the Sodium Chloride
\[\text{Mass of Sodium Chloride \(\ce{(NaCl)}\)} = \text{(Mass of Second Evaporating Dish, Watch Glass, and Dried Sodium Chloride)} - \text{(Mass of Second Evaporating Dish with Watch Glass)} \nonumber \]
5. Mass of the Sand
\[\text{Mass of Sand} = \text{(Mass of the First Evaporating Dish with Sand)} - \text{(Mass of the First Evaporating Dish (g))} \nonumber \]
Mass of Sand = (Mass of First Evaporating Dish with Dried Sand (g)) - (Mass of the First Evaporating Dish (g))
6. Calculate the Total Mass Recovered
\[\text{Mass of Original Sample} = \text{(Mass of the First Evaporating Dish with Original Sample)} - \text{(Mass of the First Evaporating Dish)} \nonumber \]
Total Mass Recovered = Mass of Ammonium Chloride + Mass of Sodium Chloride + Mass of Sand
7. Calculate the Percent Mass Recovered
\[\text{Percent Mass Recovered } = \frac{\text{Total Mass Recovered(g)}}{\text{Mass of Original Sample(g)}} \times 100\ \nonumber \]
8. Calculate the Mass Percent of Each Component
\[\text{Mass Percent of each Component } = \frac{\text{Mass of Component(g)}}{\text{Total Mass Recovered(g)}} \times 100\ \nonumber \]
PRE-LAB QUESTIONS
NAME:
1. Define the following terms:
a) Mixture:
b) Decantation:
c) Sublimation:
d) Evaporation:
e) Freezing:
f) Melting:
2. List three examples of mixtures you encounter in everyday life.
3. Explain the difference between decantation and filtration. When is one separation technique used over the other?
4. Describe the safety precautions when working with a Bunsen burner. Why should you not weigh hot objects?
5. Classify the following as a pure substance or a mixture. State whether it is an element, compound, heterogeneous, or homogeneous mixture.
a) Salt (Sodium chloride \(\ce{(NaCl)}\)) and sand mixture:
b) Sugar water:
c) Ammonium chloride \(\ce{(NH₄Cl)}\)
d) Iron:
DATA AND OBSERVATIONS
Name: ___________________________ Lab Partner(s): ______________________________________
UNKNOWN ID: _____________
OBSERVATIONS:
Record any observations during the experiment, such as changes in appearance, color, or texture.
Data |
Show your work where possible. |
|---|---|
| 1. Mass of the First Evaporating Dish (g) | |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
CALCULATIONS
- Show all calculations for the mass of each component recovered and all the percentage calculations.
POST-LAB QUESTIONS
- Please explain how the differences in physical properties of sand, sodium chloride, and ammonium chloride allow for their separation.
- What could be the source of errors in this experiment that would lead to a low percent recovery?
- Suggest additional methods for separating the mixtures.
- Why is it essential to use a fume hood when heating the mixture?
Please click here to access the Pre-Lab, Data Tables, and Post-Lab in Word or PDF format. Complete them and upload the lab report according to your instructor's instructions.