Chapter 4 Solutions and Chemical Reactions I. Water A. Importance 1. Life (as we know it) depends on water 2. Human civilization requires water for many purposes 3. Many important chemical reactions occur in Aqueous Solutions, where other compounds are dissolved in water B. The nature of water 1. Bent shape and unequal sharing of electrons makes water polar 2. This aids water in dissolving ionic compounds (cations and anions) 3. Water hydrates the ions by interacting with its oppositely charged ends
Chapter 4 Solutions and Chemical Reactions. Water Importance Life (as we know it) depends on water Human civilization requires water for many purposes Many important chemical reactions occur in Aqueous Solutions , where other compounds are dissolved in water The nature of water - PowerPoint PPT Presentation
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Chapter 4 Solutions and Chemical ReactionsI. Water
A. Importance
1. Life (as we know it) depends on water
2. Human civilization requires water for many purposes
3. Many important chemical reactions occur in Aqueous Solutions, where other compounds are dissolved in water
B. The nature of water
1. Bent shape and unequal sharing of electrons makes water polar
2. This aids water in dissolving ionic compounds (cations and anions)
3. Water hydrates the ions by interacting with its oppositely charged ends
4. The ionic substance breaks up into independent cations and anions
5. Nonionic compounds can also dissolve in water if they are polar
6. Nonpolar substances generally don’t dissolve in water: grease, oils, skin
II. ElectrolytesA. Solutions
1. A solution is a homogeneous mixture the same throughout
2. We can vary the composition by adding more or less of the components
3. Solvent = usually a liquid; the most abundant component of a solution
4. Solute = the lesser abundant component(s) of a solution
Ethanol
NaCl(s) -----> Na+(aq) + Cl-(aq)
B. Solutions and Electrical Conductance
1. A substance allowing current to flow through it is electrically conductive
2. Pure water does not conduct electricity
3. Different solutes dissolved in water help it to be conductive
a. Strong electrolyte = completely ionized; strongly conductive solution
b. Weak electrolyte = partially ionized; somewhat conductive solution
c. Nonelectrolyte = not ionized; nonconductive solution
Arrhenius (1859-1927) foundthat the more ions present, thebetter the conductivity
C. Strong Electrolytes
1. Completely ionized when dissolved in water
2. Many salts (ionic compounds) are strong electrolytes
3. Strong Acids are strong electrolytes
a. Acid = substance that produces H+ when dissolved in water
b. Strong Acids completely ionize in solution
i. Hydrochloric Acid HCl(g) -------> H+(aq) + Cl-(aq)
ii. Nitric Acid HNO3(g) -------> H+(aq) + NO3-(aq)
iii. Sulfuric Acid H2SO4(l) -------> H+(aq) + HSO4-(aq)
4. Strong Bases are strong electrolytes
a. Base = substance that produces OH- when dissolved in water