General Chemistry: Solutions and their Properties

Solutions and their Properties

1. Solutions and their Properties General Chemistry 2 by: Mr. Christian Nel R. Dominguez

2. Read the statements intelligently and identify what is being asked. ________1. The method calculates the quantities of reactants and products in a chemical reaction. ________2. The concentration unit defined as the number of moles of solute per liter of solution. ________3. The concentration of a solution is expressed as grams of solute per 100 grams of solution. ________4. A colligative property where the freezing point decreases as solute concentration increases. ________5. A phenomenon where the boiling point rises when a solute is added. CHECK YOUR KNOWLEDGE

3. Read the statements intelligently and identify what is being asked. ________1. The method calculates the quantities of reactants and products in a chemical reaction. ________2. The concentration unit defined as the number of moles of solute per liter of solution. ________3. The concentration of a solution is expressed as grams of solute per 100 grams of solution. ________4. A colligative property where the freezing point decreases as solute concentration increases. ________5. A phenomenon where the boiling point rises when a solute is added. CHECK YOUR KNOWLEDGE STOICHIOMETRY MOLARITY PERCENT BY MASS FREEZING POINT DEPRESSION BOILING POINT ELEVATION

4. By the end of the learning session/s, you should be able to: LEARNING TARGETS use different ways of expressing the concentration of solutions: percent by mass, mole fraction, molarity, molality, percent by volume, percent by mass, ppm; describe the effect of concentration on the colligative properties of solutions; and elaborate the use of beneficial solutions in addressing global challenges to target SDG 9: Industry, Innovation, and Infrastructure.

5. A solution is a homogeneous mixture of one or more solutes dissolved in a solvent. A solute is a substance that can be dissolved into a solution by a solvent. A solvent is a substance in which a solute is dissolved. SOLUTIONS

6. TYPES OF SOLUTIONS Solute Solvent Solution Examples Gas Gas Gas Air, Natural Gas, Oxygen-Acetylene Mixture Solid Gas Particulates, Dust, Naphthalene in Air Liquid Gas Perfume in Air, Humid Air, Mist Gas Liquid Liquid Froth, whipped cream, Soft drinks Solid Liquid Salt Solution, Tincture of Iodine, Pancake Syrup Liquid Liquid Mouthwash, Liquid Soap, Ethanol in Water Gas Solid Solid Hydrogen in Palladium, Pumice, Foam Rubber Solid Solid Alloys, Bronze (Copper +Tin), Steel Liquid Solid Gelatin, Amalgam (Mercury + Sodium)

7. ENERGY OF SOLUTION FORMATION The energy of solution formation refers to the overall energy change associated with the process of dissolving solute particles in a solvent to form a solution. The energy changes associated with solution formation can be categorized as either exothermic or endothermic.

8. The concentration of a solution is the quantity of a solute that is contained in a particular quantity of solvent or solution. There are 5 main ways to describe the concentration of solutions: 1) Weight Percent 2) Mole Fraction 3) Molarity; 4) Molality; and 5) Parts Per Million or Billion. CONCENTRATION OF SOLUTIONS

9. Percent by Mass It is the ratio of the mass of the solute with the mass of the solution. Sample Problem: What is the percent by mass of 5.0 g of iron (II) sulfate dissolved in 75.0 g of water? Answer: The percent by mass of iron(II) sulfate in the solution is 6.25%.

10. You Try This: A solution is made by dissolving 30 g of sodium chloride (NaCl) in 120 g of water. What is the percent by mass of NaCl in the solution? Ans: The percentage of NaCl in the solution by mass is 20%.

11. Percent by Volume It is the ratio of the volume of the solute with the volume of the solution. Sample Problem: A solution is prepared by dissolving 20 mL of pure hydrogen peroxide (H2O2) in enough water to make 200 mL of solution. What is the concentration of the H2O2 ? Answer: The concentration of hydrogen peroxide in the solution is 10%.

12. You Try This: Calculate the percent by volume of calcium nitrate (CaNO 3 ) in a solution by dissolving 10.0 mL of CaNO 3 in 150.0 mL of water (H₂O). Ans: The percent by volume of calcium nitrate is 6.25%.

13. Mole Fraction The number of molecules of a particular component in a mixture divided by the total number of moles in the given mixture. Sample Problem: Calculate the mole fraction of each component of a solution containing 65 g of ethanol (C2H6O) in 350 g of water. Answer: The mole fraction of ethanol in the solution is 0.0677 and the mole fraction of water is 0.9323.

14. You Try This: Calculate the mole fraction of calcium chloride ( CaCl ₂) in a solution by dissolving 10.0 g of CaCl ₂ in 150.0 g of water (H₂O). Ans: The mole fraction of calcium chloride ( CaCl ₂) is 0.0081.

15. Molality The amount of a substance dissolved in a certain mass of solvent. Sample Problem: Calculate the molality of 25.0 grams of KBr dissolved in 750.0 mL pure water. Answer: The molality of KBr is 0.280 mol/kg.

16. You Try This: What is the molality of a solution prepared by dissolving 20 grams of magnesium chloride ( MgCl ₂) in 250 grams of water? Ans: The molality of the MgCl ₂ solution is 0.840 mol/kg.

17. Molarity The ratio of the moles of a solute to the total liters of a solution. Sample Problem: Determine the molarity of a solution containing 2.80 moles of ethyl alcohol (C2H6O) in 500 mL of solution. Answer: The molarity of the solution containing 2.80 moles of ethyl alcohol in 500 mL of solution is 5.60 mol/L

18. You Try This: What is the molarity of a solution prepared by dissolving 10 grams of potassium hydroxide (KOH) in 500 mL of water? Ans: The molarity of the KOH solution is 0.356 M.

19. Parts by Million (ppm) The quality of performance or concentration of a substance in a larger mixture. Sample Problem: If there is 0.551 g of As in 348 g of solution, what is the As concentration in ppm? Answer: The concentration of arsenic in the solution is 1583.33 ppm.

20. You Try This: What is the concentration in ppm of a solution that contains 0.5 grams of sodium sulfate ( Na₂SO ₄) dissolved in 1000 grams of water? Ans: The Na₂SO ₄ solution concentration is about 500 ppm..

21. COLLIGATIVE PROPERTIES OF SOLUTION Colligative Property Effect of Solute in Concentration Example Boiling Point Elevation As solute concentration increases, the boiling point increases. Adding salt (NaCl) to water raises its boiling point. Freezing Point Depression As solute concentration increases, the freezing point decreases. Adding salt (NaCl) to water lowers its freezing point.

22. ECOFRIENDLY TECHNOLOGY Ecofriendly technology reduces environmental impact through renewable energy , efficiency , and sustainable materials , promoting sustainability despite challenges like cost and infrastructure. How important is incorporating eco-friendly actions in our daily lives to achieve SDG 9: Industry, Innovation, and Infrastructure?

23. A solution is a homogeneous mixture of two or more substances. It comprises a solute (present in smaller amounts) and a solvent. The concentration of solution measures the amount of solute in a given amount of solvent or solution. It can be expressed in percent by mass, percent by volume, percent by mass-volume, mole fraction, molality, molarity, or part per million. As solute concentration increases, the boiling point increases while the freezing point decreases. LESSON SUMMARY

24. MY LEARNING TAKEAWAYS How do you feel about today’s lesson? I need more practice. I am getting better at it. I can do it on my own. I can explain it to others. One thing I did well today is _________________________________________ One thing I need to improve is ________________________________________