GEORGIA MILLITARY COLLEGE
NATURAL SCIENCE DEPARTMENT
ONLINE CAMPUS
CONCENTRATION, TEMPERATURE AND THE SOLUBILITY OF SALTS
STUDENT NUMBER
Introduction
This laboratory measures and compares the water solubility of salts, and analyzes the effect of temperature increases on solubility. Concentration is the amount of solute contained in a given amount of solution. Molar concentration is defined as the quantity of solute in moles present in a liter of water. The experiment investigates the solubility of three salts/solutes: Cobalt (II) Nitrate (Co (NO3)2), potassium permanganate (KMnO4), and sodium chloride (NaCl). Solubility is defined as the amount of solute in grams that completely dissolves in 100 grams of solvent at a given temperature. A solution is considered saturated if it contains the maximum quantity of solute that completely dissolves in 100grams of solvent at any given temperature. A solution is unsaturated if it contains less solute than is needed to completely dissolve in 100g of solvent, and supersaturated if it contains more solute than is needed to dissolve completely in 100g of solute at a given temperature.
The solubility of solutes is influenced by multiple factors, including molar mass and temperature. Solutes with higher mass are likely to have bigger particles and are likely to be less soluble in liquids. At the same time, some solutes exhibit huge increases in solubility with temperature increases, while others show little variation. For this reason, it is important to measure the solubility of different solutes to see how they compare. The general hypothesis is that solutes with higher atomic mass will exhibit lower solubility, and that solubility will increase with increases in temperature.
The objectives of this laboratory are summarized as follows:
i) To enhance ones ability to calculate a solutes molar concentration at different temperatures.
ii) To increase ones familiarity with the solubility curve.
iii) To enhance ones understanding of solubility.
Materials and Methods
Preparing the Lab
1. Access the simulation environment on the course home page and click on the Concentration Link.
2. Once the Simulation environment loads, click on the bottom faucet to set the solvent volume at 0.1L.
3. If necessary, click on the top faucet to add solvent.
Performing the Environment
1. Select the saltshaker containing Cobalt (II) Nitrate from the solute category and shake it gently to add the salt to the solvent.
2. Keep adding the solute until the solution is saturated and record the molar concentration (M) of the solute at the saturation point in mol/L.
3. Repeat the procedure for sodium chloride (NaCl) and potassium permanganate (KMnO4).
Data Analysis
1. Calculate the quantity of solute that dissolved in...
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= 93.16g/100g of water.
Conclusion
The laboratory sought to compare the solubility of Cobalt (II) Nitrate, Potassium Permanganate, and Sodium Chloride. The procedure involved using the molar concentrations of the available solutions (1.5M, 0.8M, and 1.2M respectively) to calculate the number of moles of solute using the formula; Number of moles (n) = Molarity (M) x Volume. The number of moles of solute (n) was then multiplied by the calculated atomic molar mass (MM) to obtain the mass of the solute (m) in grams based on the formula: n = m/MM. Since the density of water is 1g/mL, the obtained mass was equated to solubility in grams/per 100g of water for the three solutes. Cobalt (II) Nitrate exhibited the highest water solubility, while sodium chloride exhibited the lowest solubility. This negated the experiments hypothesis that sodium chloride would exhibit the highest solubility due to its low molar mass relative to both Cobalt (II) Nitrate and Potassium Permanganate. The accuracy of the procedure could be improved by using more concentrated solutions to increase the accuracy of molar mass measurements, leading to more precise mass calculations. The simulation showed that as hypothesized, the solubility of Cobalt (II) Nitrate increased with increases in temperature. The solubility increased slowly between…
