Solubility Lab Report
CHM-101L Solubility

Materials

Obtain the following:

  • 8 small (approximately 8 oz) clear plastic cups
  • 8 plastic straws or wooden splints (popsicle sticks/skewers) to use as stirring rods
  • Microwave safe Pyrex (or similar) measuring cup
  • Microwave
  • Hot glove or pot holder
  • Approximately ½ cup of each of the following:
  • Sugar
  • Salt
  • Calcium tablet (or white chalk or TUMS®)
  • Cornstarch
  • Flour
  • Baking soda
  • Vegetable oil
  • Drain opener

Part A – Will it Dissolve?

Fill one cup ¾ full with water. Into the first cup, add approximately a dime-sized sample (approximately 1/8 tsp) of sugar and stir. Observe the mixture, did the sample dissolve? Record your observations in the table below. Repeat for each of the subsequent samples in fresh samples of water. For the calcium tablet (or chalk) crush the sample before adding it to the water. Record all observation on the table below. Include a labeled image of each mixture in your final submission. Once completed, dispose of all liquids down the sink and discard the cups. Caution: Do not reuse cups that had chalk or drain opener in them for drinking.

SampleObservationsWater solubility (Yes/No)Hydrophobic or Hydrophilic
Sugar
Salt
Calcium (or chalk)
Cornstarch
Flour
Baking soda
Vegetable oil
Drain opener
  1. What does it mean when someone states that Vitamin C is water soluble?

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  1. For vitamins, if they are not soluble in water, they would be fat soluble. So rather than any excess being able to be dissolved and excreted in urine, it is stored in the liver and fatty adipose tissue. Fiber is another nutrient that can be subcategorized as soluble or insoluble. Describe the difference between these two types of fiber and how they are utilized by the body.

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  1. For the substances that were water soluble, what effect do you think raising the temperature of the water would have on the solubility of the substance? Discuss both the effects on rate and quantity in your response.

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Part B – Effect of Temperature on Solubility

Using the sugar from Part A of the lab and the microwave safe measuring cup, fill the measuring cup with 2/3 of a cup of water. Slowly add sugar while stirring, until you reach the point at which no more sugar will dissolve in the water. Take the measuring cup and place in a microwave. Heat for 1 minute. Using a hot glove or potholder, remove the measuring cup from the microwave and stir. What happened to the sugar that did not dissolve at room temperature? Is it now dissolved? While the water is hot, can you add any additional sugar to the water and still have it dissolve? What does this tell us about the solubility of sugar in hot water versus the solubility of sugar in room temperature water?

  1. Write a paragraph summarizing your results that includes responses to the above-mentioned questions.

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Solids and liquids will generally have increased solubility when heated, but for gases, the opposite is true. As temperature increases, solubility of gases in an aqueous (water based) solution decreases. You might have experienced this phenomenon if you have ever left a can of soda in your car on a hot summer day. As the temperature increases, the carbon dioxide (CO2) becomes less soluble in the liquid, forcing it into the small air space at the top of the can. When enough CO2 leaves the liquid and the pressure becomes too great, the can will explode. The videoDiet Coke Explodes in Back of My Jeep Wrangler” demonstrates this specific circumstance!

Use the solubility curve below to answer questions 2 and 3.

https://sites.prairiesouth.ca/legacy/chemistry/chem30/graphics/4_graphics/sol_curve.jpg

Solubility Curve (Lawson, 2006)

  1. What is the solubility difference for a sample of potassium chlorate (KClO3) at 30°C to that of a sample at 80°C?

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  1. To which compound does temperature have the greatest effect on solubility? Explain how you know this using specific values from the solubility curve.

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  1. Coenzyme Q10 (CoQ10) is an antioxidant that your body produces naturally. However, levels can decrease with age, and so some find it beneficial to take CoQ10 as a supplement. CoQ10 is used by the cells for growth and maintenance. Different brands claim to be more water soluble than others. If you were taking it in pill form versus an injection, would it more beneficial to take the version that is more water or more fat soluble? How does a drug’s solubility influence its effectiveness?

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Part C – Predicting Solubility

The solubility rules are a set of guidelines that allow for the prediction of solubility of ionic compounds in water.

Solubility Rules
Soluble Ionic Compounds
1. All nitrates are soluble.
2. Most alkali earth metals are always soluble.
3. Most halides are soluble (except Ag+, Pb+, Hg22+, Cu+).
4. Most sulfates (SO42-) are soluble (except Sr2+, Ba2+, Pb2+).
Insoluble Ionic Compounds
5. Most PO43-, CO32-, SO32- are insoluble (except alkali metal ions, NH4+).
6. Most OH are insoluble except KOH and NaOH

(GCU, 2016)

  1. Using the solubilty rules provided above, classify each substance as being solubule or insoluble in water.
SubstanceSoluble / Insoluble
KBr
Hg2SO4
Ca(OH)2
NH4NO3
CuI

References

Grand Canyon University. (2016). Qualitative analysis. CHM 101L Laboratory Manual for General and Organic Chemistry and Biochemistry. Retrieved from https://lc.gcumedia.com/chm101l/laboratory-manual-for-general-and-organic-chemistry-and-biochemistry/v2.1/#/chapter/5

Lawson, P. (2006). Solubility curve. Chemistry 30: Saskatchewan Evergreen Curriculum. Retrieved from https://sites.prairiesouth.ca/legacy/chemistry//chem30/graphics/4_graphics/sol_curve.jpg

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