The Behavior of Gases
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• 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.
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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. © Copyright Pearson Prentice Hall
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• Solutions: – Are homogeneous mixtures: – Are stable – Gases and solids can also form solutions
• Aqueous Solutions – Water containing dissolved substances
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• Solvent: – The dissolving substance:
• Solute: – The dissolved particles – Can’t be filtered out – Can be small molecules, ions or gases
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15.2
Homogeneous Aqueous Systems
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Solvents and Solutes
If you filter a solution through filter paper, both the solute and the solvent pass through the filter.
Slide 6 of 29 © Copyright Pearson Prentice Hall
• A general rule for solubility: “like dissolves like” − Water will dissolve other polar molecules and ions − Water will not dissolve non-polar molecules
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15.2
Homogeneous Aqueous Systems
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The Solution Process
Oil and water do not mix.
Slide 8 of 29 © Copyright Pearson Prentice Hall
• Solvation – The process of dissolving by which positive and negative parts of substances become surrounded by the solvent molecules
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15.2
Homogeneous Aqueous Systems
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The Solution Process
Solvation of an Ionic Solid
Slide 10 of 29 © Copyright Pearson Prentice Hall
• 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
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– Nonelectrolytes • Compounds that do not conduct electricity when dissolved in water • Non- ionic compounds such as the sugar glucose (C6H12O6)
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15.2
Homogeneous Aqueous Systems
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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.
Slide 13 of 29 © Copyright Pearson Prentice Hall
15.2
Homogeneous Aqueous Systems
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Electrolytes and Nonelectrolytes
A weak electrolyte conducts electricity poorly because only a fraction of the solute in the solution exists as ions.
Slide 14 of 29 © Copyright Pearson Prentice Hall
15.2
Homogeneous Aqueous Systems
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Electrolytes and Nonelectrolytes
A compound that does not conduct an electric current in either aqueous solution or the molten state is called a nonelectrolyte.
Slide 15 of 29 © Copyright Pearson Prentice Hall
• 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
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15.2
Homogeneous Aqueous Systems
>
Hydrates
Blue crystals of CuSO4·5H2O crumble to a white anhydrous powder that has the formula CuSO4.
Slide 17 of 29 © Copyright Pearson Prentice Hall
– 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: MgSO4 • 7H2O = – magnesium sulfate heptahydrate
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– Some hydrates change colors: When blue CoCl2 forms CoCl2 • 6H2O, it turns pink
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15.2
Homogeneous Aqueous Systems
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Hydrates
When treated paper is exposed to moist air, it turns pink because of the formation of the hydrate cobalt(II) chloride hexahydrate (CoCl2·6H2O).
Slide 20 of 29 © Copyright Pearson Prentice Hall
What is the correct formula for the following hydrates? Iron(II) sulfate heptahydrate
A. FeSO4 • 6H2O B. Fe2SO4 • 7H2O C. Fe(SO4)2 • 7H2O D. FeSO4 • 7H2O
Slide 21 of 29 © Copyright Pearson Prentice Hall
What is the correct formula for the following hydrates? Calcium chloride dihydrate
A. CaCl2 • 2H2O B. CaCl • 2H2O C. Ca2Cl2 • 2H2O D. Ca2Cl • 2H2O
Slide 22 of 29 © Copyright Pearson Prentice Hall
Name the following hydrate: FePO4 • 4H2O
A. iron(II) phosphate heptahydrate B. iron(III) phosphate tetrahydrate C. iron phosphate tetrahydrate Slide 23 of 29 © Copyright Pearson Prentice Hall
• Hygroscopic hydrates – Absorb water from moist air to form higher hydrates CaCl2 • H2O + H2O → CaCl2 • 2H2O – Can be used to keep things dry
Slide 24 of 29
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 © Copyright Pearson Prentice Hall
Slide 25 of 29
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. © Copyright Pearson Prentice Hall
Slide 26 of 29
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. © Copyright Pearson Prentice Hall
Slide 27 of 29
15.2 Section Quiz.
The formula for iron(II) sulfate heptahydrate is A. FeSO4(H2O)7
B. FeSO4•(H2O)7 C. Fe•2SO4•7H2O D. FeSO4•7H2O Slide 28 of 29 © Copyright Pearson Prentice Hall
• Q's 31-35, 42, 43 (465) • Read 16.1, pg. 471-479
Slide 29 of 29
• 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.
Slide 2 of 29
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. © Copyright Pearson Prentice Hall
Slide 3 of 29
• Solutions: – Are homogeneous mixtures: – Are stable – Gases and solids can also form solutions
• Aqueous Solutions – Water containing dissolved substances
Slide 4 of 29
• Solvent: – The dissolving substance:
• Solute: – The dissolved particles – Can’t be filtered out – Can be small molecules, ions or gases
Slide 5 of 29
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.
Slide 6 of 29 © Copyright Pearson Prentice Hall
• A general rule for solubility: “like dissolves like” − Water will dissolve other polar molecules and ions − Water will not dissolve non-polar molecules
Slide 7 of 29
15.2
Homogeneous Aqueous Systems
>
The Solution Process
Oil and water do not mix.
Slide 8 of 29 © Copyright Pearson Prentice Hall
• Solvation – The process of dissolving by which positive and negative parts of substances become surrounded by the solvent molecules
Slide 9 of 29
15.2
Homogeneous Aqueous Systems
>
The Solution Process
Solvation of an Ionic Solid
Slide 10 of 29 © Copyright Pearson Prentice Hall
• 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
Slide 11 of 29
– Nonelectrolytes • Compounds that do not conduct electricity when dissolved in water • Non- ionic compounds such as the sugar glucose (C6H12O6)
Slide 12 of 29
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.
Slide 13 of 29 © Copyright Pearson Prentice Hall
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.
Slide 14 of 29 © Copyright Pearson Prentice Hall
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.
Slide 15 of 29 © Copyright Pearson Prentice Hall
• 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
Slide 16 of 29
15.2
Homogeneous Aqueous Systems
>
Hydrates
Blue crystals of CuSO4·5H2O crumble to a white anhydrous powder that has the formula CuSO4.
Slide 17 of 29 © Copyright Pearson Prentice Hall
– 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: MgSO4 • 7H2O = – magnesium sulfate heptahydrate
Slide 18 of 29
– Some hydrates change colors: When blue CoCl2 forms CoCl2 • 6H2O, it turns pink
Slide 19 of 29
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 (CoCl2·6H2O).
Slide 20 of 29 © Copyright Pearson Prentice Hall
What is the correct formula for the following hydrates? Iron(II) sulfate heptahydrate
A. FeSO4 • 6H2O B. Fe2SO4 • 7H2O C. Fe(SO4)2 • 7H2O D. FeSO4 • 7H2O
Slide 21 of 29 © Copyright Pearson Prentice Hall
What is the correct formula for the following hydrates? Calcium chloride dihydrate
A. CaCl2 • 2H2O B. CaCl • 2H2O C. Ca2Cl2 • 2H2O D. Ca2Cl • 2H2O
Slide 22 of 29 © Copyright Pearson Prentice Hall
Name the following hydrate: FePO4 • 4H2O
A. iron(II) phosphate heptahydrate B. iron(III) phosphate tetrahydrate C. iron phosphate tetrahydrate Slide 23 of 29 © Copyright Pearson Prentice Hall
• Hygroscopic hydrates – Absorb water from moist air to form higher hydrates CaCl2 • H2O + H2O → CaCl2 • 2H2O – Can be used to keep things dry
Slide 24 of 29
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 © Copyright Pearson Prentice Hall
Slide 25 of 29
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. © Copyright Pearson Prentice Hall
Slide 26 of 29
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. © Copyright Pearson Prentice Hall
Slide 27 of 29
15.2 Section Quiz.
The formula for iron(II) sulfate heptahydrate is A. FeSO4(H2O)7
B. FeSO4•(H2O)7 C. Fe•2SO4•7H2O D. FeSO4•7H2O Slide 28 of 29 © Copyright Pearson Prentice Hall
• Q's 31-35, 42, 43 (465) • Read 16.1, pg. 471-479
Slide 29 of 29
