Daily TAKS Connection: Water as the Universal Solvent Factors Influencing Solubility

1. Daily TAKS Connection:Water as the Universal SolventFactors Influencing Solubility IPC(9): The student knows how solution chemistry is a part of everyday life. The student is expected to: (A) relate the structure of water to its function [as the universal solvent]. (D) demonstrate how various factors influence solubility including temperature, pressure, and nature of the solute and solvent.

2. Construct a two tab foldable Materials: Foldable handout Scissors Pen Colored pencils/crayons Instructions: Hamburger fold the paper along the solid fold line Cut the paper along the center dashed line Record your name, date and period on the reverse Color the front of the foldable Water Foldable Instructions

3. Polarity is the Key! Record the following notes under the flap labeled “Water is the Universal Solvent” – • Water is a “polar” molecule • Slightly negative at the oxygen atom • Slightly positive at the hydrogen atoms • Like dissolves like • Polar molecules dissolve polar molecules • Most substances in nature are polar; thereforewater dissolves most substances

4. Question Which factor makes water an effective solvent? a. The presence of molecular oxygen b. Its lack of covalent bonds c. The polar nature of its molecules d. Its abundance on Earth’s surface

5. Question The structure of pure water makes it a good — a. solvent b. catalyst c. conductor d. nutrient

6. Question Which characteristic of water best explains its ability to dissolve a great variety of materials? a. Its transparency in light b. Its electrical conductivity c. Its physical state of matter d. Its molecular arrangement

7. Question The graph shows the concentration of ions found in the water of the Dead Sea. Which property of water is responsible for the dissociation of salts that produces the ion concentrations shown in the graph? a. Chemical stability b. High polarity c. Low melting point d. High freezing point

8. Question The diagram above shows water molecules and ions from an NaCl crystal. What is the most likely reason that each water molecule is arranged so that the oxygen part of the molecule faces a sodium ion? a. The oxygen in a water molecule contains a partial negative charge. b. Gravity rotates the oxygen atoms to face the more-massive sodium ions. c. Hydrogen atoms create repulsive forces with chloride ions. d. Oxygen atoms form covalent bonds with sodium ions.

9. Structure and Unique Properties Record the following notes under the flap labeled “Properties of Water that Never Change” – • Water always contains two hydrogen atoms bonded to one oxygen atom • 2:1 ratio • Formula: H20 • Water expands when frozen • Becomes less dense • Ice floats!! Very important to aquatic life!!

10. Question If the properties of water were to change so that the solid form was denser than the liquid form, organisms living in a cold pond environment would be less likely to survive because water would no longer — a. dissolve enough oxygen from the air b. produce solutions containing vital nutrients c. remain neutral, instead becoming highly acidic d. produce a floating insulating layer of ice

11. Question Fish survive through severe winters because of the property of water that allows water to — a. form chemical bonds as it freezes, raising the water temperature below the ice b. increase in density while it freezes, dissolving more oxygen from the air c. expand when it freezes, creating a floating and insulating layer of ice d. precipitate vital nutrients when it freezes, increasing the food supply

12. Construct a two tab foldable Materials: Foldable handout Scissors Pen Colored pencils/crayons Instructions: Fold bottom paper along fold line at bottom edge Hamburger fold along center fold line Cut along the dotted line from edge to peak Tuck the flaps into the bottom flap Color “Solids Dissolved in Liquids” Color “Gases Dissolved in Liquids” Solubility Foldable Instructions

13. Factors of Solids Dissolved in Liquids Record the following notes under the flap label “Solids Dissolved in Liquids” - 3 factors: • temperature • Example: heat water to dissolve sugar when making iced tea • stirring/shaking • Example: mixing Kool-Aid with a spoon • surface area of solid (particle size) • Example: granulated sugar dissolves more quickly than sugar cubes

14. Question A 0.2 g crystal of gypsum dissolves very slowly in 100 mL of water while the water is stirred. Which of these would cause the gypsum to dissolve faster? a. Increasing the water temperature b. Raising the air pressure c. Stopping the stirring d. Use larger crystals

15. Question The table shows temperature and pressure in four containers holding the same amount of water. According to the table, in which container will the least sodium chloride be dissolved in the water? a. Q b. R c. S d. T

16. Question 3 A pharmaceutical company makes the claim that their caplet formulation of a pain reliever is “fast acting”. It is probable that this formulation – a. is a solid caplet b. consists of a gel cap containing finely ground crystals of the pain medication c. reduces fever in the user, aiding digestion d. reduces the gas pressure in the user’s stomach

17. Factors of Gases Dissolved in Liquids • Record the following notes under the flap label “Gases Dissolved in Liquids” – • 2 factors: • temperature • Example: a soda on ice will not go “flat” as quickly as a soda without ice. • pressure • Example: When soda is opened, carbon dioxide gas begins coming out of solution (bubbles rising)

18. Question Over time an open soft drink will lose carbonation (dissolved CO2). Which of these allows the CO2 to remain in solution the longest? a. Reduced air pressure b. Increased air currents c. Exposure to direct sunlight d. Refrigerate the soda

19. Question Abnormally hot summers can have a negative effect on aquatic life. This is because the higher temperatures — a. increases the pressure of rivers, ponds and lakes b. decreases sediment solubility in rivers, ponds and lakes c. increases the pH value of rivers, ponds and lakes d. decreases the dissolved oxygen in rivers, ponds and lakes

20. Question MTBE is a gasoline additive that has entered some groundwater supplies. According to the table shown, which of the following water temperatures would allow 35 grams of MTBE to dissolve in 1 liter of water? a. 15°C b. 35°C c. 40°C d. 50°C