Distinguish Describe Explain Describe demonstrate Slide 2 of 29

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2 Distinguish between a solvent and a solute. Describe what happens in the process of solvation. Explain why all ionic compounds are electrolytes. Describe hydrates and demonstrate how the formula of a hydrate is written. 2 of 29

3 15.2 Homogeneous Aqueous Systems An ordinary dill pickle from the deli can be a source of light! Iron or copper electrodes are inserted into the ends of the pickle and connected to a source of alternating electric current. You will learn what kind of solution conducts electricity. 3 of 29

4 Solutions: Are homogeneous mixtures: Are stable Gases and solids can also form solutions Aqueous Solutions Water containing dissolved substances 4 of 29

5 Solvent: The dissolving substance: Solute: The dissolved particles Can t be filtered out Can be small molecules, ions or gases 5 of 29

6 15.2 Homogeneous Aqueous Systems > Solvents and Solutes If you filter a solution through filter paper, both the solute and the solvent pass through the filter. 6 of 29

7 A general rule for solubility: like dissolves like Water will dissolve other polar molecules and ions Water will not dissolve non-polar molecules 7 of 29

8 15.2 Homogeneous Aqueous Systems > The Solution Process Oil and water do not mix. 8 of 29

9 Solvation The process of dissolving by which positive and negative parts of substances become surrounded by the solvent molecules 9 of 29

10 15.2 Homogeneous Aqueous Systems > The Solution Process Solvation of an Ionic Solid 10 of 29

11 Electrolytes: Compounds that conduct electric current when in the aqueous state All ionic compounds that dissolve are electrolytes Strong electrolytes: almost all of the compound dissolves - exists as ions in solution Weak electrolytes: only a fraction of the compound dissolves - exists as ions 11 of 29

12 Nonelectrolytes Compounds that do not conduct electricity when dissolved in water Non- ionic compounds such as the sugar glucose (C 6 H 12 O 6 ) 12 of 29

13 15.2 Homogeneous Aqueous Systems > Electrolytes and Nonelectrolytes The bright glow shows that sodium chloride is a strong electrolyte because nearly all the dissolved sodium chloride exists as separate Na + and Cl ions. 13 of 29

14 15.2 Homogeneous Aqueous Systems > Electrolytes and Nonelectrolytes A weak electrolyte conducts electricity poorly because only a fraction of the solute in the solution exists as ions. 14 of 29

15 15.2 Homogeneous Aqueous Systems > Electrolytes and Nonelectrolytes A compound that does not conduct an electric current in either aqueous solution or the molten state is called a nonelectrolyte. 15 of 29

16 Hydrates A compound that has a specific # of water molecules bound to each formula unit Water molecules are part of the solid crystalline structure Heating the hydrate releases the water molecules 16 of 29

17 15.2 Homogeneous Aqueous Systems > Hydrates Blue crystals of CuSO 4 5H 2 O crumble to a white anhydrous powder that has the formula CuSO of 29

18 Naming & writing hydrates Use a dot to connect the formula of the compound to the number of water molecules per formula unit Use prefixes to name them Example: MgSO 4 7H 2 O = magnesium sulfate heptahydrate 18 of 29

19 Some hydrates change colors: When blue CoCl 2 forms CoCl 2 6H 2 O, it turns pink 19 of 29

20 15.2 Homogeneous Aqueous Systems > Hydrates When treated paper is exposed to moist air, it turns pink because of the formation of the hydrate cobalt(ii) chloride hexahydrate (CoCl 2 6H 2 O). 20 of 29

21 What is the correct formula for the following hydrates? Iron(II) sulfate heptahydrate A. FeSO 4 6H 2 O B. Fe 2 SO 4 7H 2 O C. Fe(SO 4 ) 2 7H 2 O D. FeSO 4 7H 2 O 21 of 29

22 What is the correct formula for the following hydrates? Calcium chloride dihydrate A. CaCl 2 2H 2 O B. CaCl 2H 2 O C. Ca 2 Cl 2 2H 2 O D. Ca 2 Cl 2H 2 O 22 of 29

23 Name the following hydrate: FePO 4 4H 2 O A. iron(ii) phosphate heptahydrate B. iron(iii) phosphate tetrahydrate C. iron phosphate tetrahydrate 23 of 29

24 Hygroscopic hydrates Absorb water from moist air to form higher hydrates CaCl2 H 2 O + H 2 O CaCl 2 2H 2 O Can be used to keep things dry 24 of 29

25 15.2 Section Quiz. Choose the correct words for the spaces. In any solution, the material that is dissolved is called the and the material in which the substance is dissolved is called the. A. solid, liquid B. solvent, solute C. solute, solvent D. crystal, disperser 25 of 29

26 15.2 Section Quiz. In the solution process, the A. solvent molecules are surrounded by positive and negative ions. B. solvent molecules become dispersed in an ionic crystal. C. ions become emulsified in the solvent. D. positive and negative ions are surrounded by solvent molecules. 26 of 29

27 15.2 Section Quiz. All ionic compounds are electrolytes because they A. conduct electricity in the solid state. B. dissociate into ions in the aqueous and/or the molten state. C. remain as positive-negative pairs even when dissolved. D. only conduct electricity in the molten state. 27 of 29

28 15.2 Section Quiz. The formula for iron(ii) sulfate heptahydrate is A. FeSO 4 (H 2 O) 7 B. FeSO 4 (H 2 O) 7 C. Fe 2SO 4 7H 2 O D. FeSO 4 7H 2 O 28 of 29

29 Q's 31-35, 42, 43 (465) Read 16.1, pg of 29