2Aqueous Reactions Water Solvent Solutions

Set 2

What are the two factors responsible for the solvent power of water

uneven charge distribution

bent geometry

What do these two factors of water combine to render H2O as

polar molecule

Besides at the macroscale, where else does water have tremendous power at

molecular level

How are electrons shared in bonds between identical atoms

equally

What does it mean when the electron sharing in covalent bonds between different nonmetals are uneven

one atom attracts electrons more than the other

Where are the shared electrons in an O-H bond closer to, what does this result in

O, polar bond

Explain whether or not polar bonds are enough to make a molecule polar

no, the geometry matters

Explain what can happen to polar bonds in linear molecules

equal and opposite will cancel

What shape does H2O take on, what does this make water?

bent, polar bonds+bent=polar

Using water as a solvent, explain what happens during ion-dipole forces

dissolved ionic compounds

Using water as a solvent, explain what happens during hydrogen bonding

dissolves polar nonionic compounds

Using water as a solvent, explain what happens during dipole-induced dipole and dispersion forces

dissolves nonpolar atmospheric gases

Explain the 5 key properties of water

highest heat capacity of any liquid

very high heat of vaporization

high surface tension

high capillarity

solid water has a hexagonal organization making water the most dense as a liquid

What are ionic compounds held together by

electrostatic attractions between oppositely charged particles

Explain how water separates (ionizes) ionic compounds

by replacing the electrostatic attractions with several water-ion interactions

Explain how ionic compounds can dissolve in water

when the sum of the several interactions is energetically more favorable than the single electrostatic attraction

What is the negative center of water (oxygen) attracted to

positively charged ions, cations

What are the positive ends of water (Hydrogen atoms) attracted to

negatively charged ions, anions

Explain how a substance dissolves

when attractions between each type of ion and several water molecules is stronger than the attraction between the ions themselves

What does it mean to be solvated

when ions separate and get surrounded by water

Describe the movement of solvated ions

move freely

How does the solubility of ionic compounds in water vary

based on the types of ions (cation and anion)

How is solubility influenced by temperature

higher temperature increase solubility of ionic compounds

What is the solubility of NaCl in 20ºC

365 grams per liter of H2O

What is the solubility of AgCl in 20ºC

0.0009 grams per liter of H2O

What do we consider NaCl in water

soluble

What do we consider AgCl in water, why?

insoluble because very little AgCl ionizes to form Ag⁺ and Cl^- ions

True or false. Pure water is a great conductor of electricity

False

When ionic compounds dissolve in water, what does the resulting solution have

a dramatically increased conductivity

What is the enhanced conductivity due to

the movement of solvated ions in solution

Define electrolytes

substances that conduct electricity when dissolved in water

What does the formula of a soluble ionic compound give

number of moles ions in solution

What does one mole of KBr ionize to give

one mole of K+ ions and one mole of Br- ions

What does one mole of KBr dissociate into

two moles of ions

How many moles of each ion are produced when CaCl₂ dissolves? How many total moles of ions?

1 mole of Ca and 2 moles of Cl, 3 moles

In addition to ionic compounds, what does water dissolve many of (give 3 examples)

covalent compounds

1. table sugar (sucrose)

2. beverage alcohol (ethanol)

3. automobile antifreeze

What do covalent compounds contain

polar bonds that interact with water

Explain covalent compounds properties

do not ionize and do not conduct electricity

Explain what happens to covalent compounds without polar bonds come in contact with water

do not appreciably dissolve in water

If a compound is non-polar, do they love or hate water

hate water

What are the 3 types of equations used to represent ionic reactions

molecular

total ionic

net ionic

What do molecular equations reveal

the least information about species present in solution

How do molecular equations treat all reactants and products

fully associated complexes

What do total ionic equations show

all soluble ionic compounds dissociated into ions (much more accurate)

For total ionic equations, what must the charge on the left and right be

balanced

What do net ionic equations eliminate

spectator ions from the equation and only show the actual chemical change