Chem Exam 2

chp 6,7,9

What are the different types of intermolecular forces?

1. Ionic bond

2. Hydrogen bond

3. dipole-dipole attractions

4. dispersion forces

Describe an Ionic bond

• strongest

• between METAL and NONMETAL

Describe dispersion forces

• Weakest

• Between NONMETAL and NONMETAL

• between NONPOLAR molecules caused by temporary dipoles

• Ex. F2

Describe Dipole-dipole attractions

• between NONMETAL and NONMETAL

• 2nd to last for weakness

• Between POLAR molecules

describe hydrogen bonds

• 2nd strongest

• Dipole-dipole attraction involving H atoms BONDED TO F, O, or N that are very electronegative

• between POLAR molecules

What is the melting point of an IONIC bond like and why?

• large amount of energy required to break apart so HIGH melting Point.

• solids at room temp

What is the melting point of a Hydrogen bond like and why?

• require more energy than reg dipole-dipole attraction

What is the melting point of a DISPERSION FORCES like and why?

• very weak

• very little energy is needed.

what forms a cation and why?

• metals

• give away Valence electrons to nonmetals

• have fewer electrons than protons so + charged.

• group 1 have +1 charge

• group 2 have +2 charge

• group 3 have +3 charge

what forms an ANION and why?

• nonmetals form anions

• take valence electron away from metals

• more electrons than protons so negatively charged

• first syllable then -ide ending

How do you name an IONIC formula?

• The metal is first followed by nonmetal with -ide ending.

• total pos charge = total neg charge

  1. write charge of each ion

     Mg is +2 Cl is - 1 - need 2 Cl

  2. balance charges

     MgCl2

what are the polyatomic ions?

• OH- Hydroxide

• NO3 - Nitrate

• CO3 -2 Carbonate

• CN- Cyanide

• SO4-2 Sulfate

• PO4 -3 Phosphate

• NH4 + Ammonium

• *charge balance must equal 0

• *put parenthesis around polyatomic when more than one ion is used

What is a mole?

• Avogandros number= 6.02 X 10 ²³

• moles → atoms/ molecules

• 1 mole of carbon = 6.02 X 10 ²³ atoms of C

• IF YOU SEE ATOMS USING A#

How can you use chemical subscripts?

• can be used to go from moles in an element to moles in an element

• ex. C9H8O4

• 9 moles of C = 1 mole C9H8O4

• can also put as atoms/molecules

what is molar mass?

• mass in grams of 1 mole

• grams → molar mass

• can find on the periodic table

• If you see GRAMS using MOLAR MASS

what is a chemical reaction?

• gives the chemical formula of the reactants on the left and the products on the right

• reactants → products

• old bonds are broken and new ones are formed

• reactant atoms rearrange to make products

what is visible evidence of a chemical reactant?

• change in color

• formation of a gas (bubbles)

• formation of a solid (precipitate)

• heat (or a flame) produced or heat absorbed

what are different types of reactions?

1. combination

2. decomposition

3. single replacement

4. double replacement

5. combustion

6. oxidation-reduction

what is combination?

2 or more substances combine to form 1 product

what is decomposition?

1 substance splits into two or more parts

what is the single replacement?

1 element takes the place of another in a reacting compound

what is double replacement

2 elements or ions exchange places

what is combustion?

fuel containing C + H2 react with oxygen to produce CO2, H20 and energy.

what is an oxidation-reduction reaction?

1. provides energy from food

2. provides electrical energy

3. occurs when iron rust

   • transfer of electrons from one reactant to another

   • oxidation is the loss of electrons OIL (electrons are product)

   • reduction is gain of electrons RIG (electrons are reactant)

   • In product (+) is being oxidized, (-) is being reduced

How is oxidation and reduction shown in biological systems?

• oxidation- Gain of O (gains bonds to oxygen) , loss of H

• reduction- gain of H, loss of O

what is theoretical yield?

maximum amount of product (g), which is calculated using the balanced equation.

• when going from grams A → moles A → Moles B → grams B

what is actual yield?

the amount of product obtained when the reaction takes place. *given in problem

what is a limiting reactant?

• the reactant that is used up during a reaction and limits the amount of product that can form.

• Limiting reactant produces the smaller amount

what does a chemical reaction require?

1. collision (reactants must collide)

2. orientation ( bonds break and form new bonds)

3. energy (collision must provide the energy of activation)

what happens in an exothermic reaction?

• energy of products is less than the enrgy of the reactants

• heat of reaction is released

• heats is a PRODUCT

• EXo → product is exiting

what is an endothermic reaction?

• heat is absorbed

• the energy of the product is greater than the energy of the reactants

• heat is REACTANT

what is rate of reaction?

• speed at which reactants form products

what is the equation for rate of reaction?

ROR = change in concentration / change in time

what are the factors that effect rate of reaction?

1. temperature- high temp= high kinetic energy = more collisions

2. concentration - high= more likely

3. catalyst - speed up the reaction by lowering the activation energy

what are the components in a solution?

1. solvent - present in greatest amount; dissolves solute ‘

2. aqueous - solvent in water

3. solute - present in lesser amount

what is a solute?

• spread evenly throughout the solution

• cannot be separated by filtration

• can not be separated by evaporation

• are not visible by can give color to the solution

what does “like dissolves like” correlate to?

when two substances form a solution the solute and solvents are ALIKE
- polar solvents dissolve polar and ionic solutes

-nonpolar solvents dissolve nonpolar solutes

• THIS MEANS A SOLUTION WILL FORM, IF NOT A LIKE SOLUTION WILL NOT FORM

what are nonelectrolytes?

• covalent/ molecular compounds

• NONMETALS

• dissolve as molecules in water

• no ion produce

• no electric current conducted

what is a strong electrolyte?

• ionic compounds/ strong acids or bases

• dissociate into ions in water

• fully ionize

• will conduct electricity

what are weak electrolytes?

• weak acids or bases

• partially dissociate into ions in a solution

• partially ionize

• weakly conducts electricity

• DOUBLE HEADED ARROW

• mostly molecules and few ions

what is an equivalent?

amount of electrolyte or an ion that provides 1 mole of electrical charge

• ex. 1 mole Na + = 1 EQ , 1 mole Fe+3 = 3 Eq

what is solubility?

max amount of solute that dissolves in a specific amount of a solvent

what affects solubility?

1. type of solute

2. type of solvents

3. temperature

how is solubility expressed?

g of solute / 100 g of water

what is an unsaturated solution?

contains LESS than the maximum amount of solutes

• ex. - MgCl2 threshold is 60/ 100

  40/100 is unsaturated, so it 25/50

what is an saturated solutuion?

max or more solute that can be dissolved

• undissolved salt at the bottom of the container

• ex. 60/100 is threshold

  80/100 and 22/25 are saturated

what does soluability depend on?

temperature

• solubility of gas DECREASES as TEMP INCREASES

  ex. fish may die in warm water bc O2 is less soluble in warm water

what is henry law?

solubility of a gas is directly related to the pressure of the gas above the liquid

ex. at high pressure more CO2 dissolved in liquid

what are the steps to get a net Ionic equation?

1. double replacement

2. formulas correct

3. balanced

4. states (full equation shows the formulas of the compounds)

5. Break all and CHARGES (aq) into ions (need a charge on everything) (this shows IOnic equation)

6. cross out all spectators (ones that stay the same)

7. Rewrite

   NET IONIC EQUATION shows only ions that change in product

what is the concentration of a solution?

describes how much solute is present in the solution

• small concentration = small amount of solutes

• concetration= amount of solute/ amount of solution

equation for concetration?

mass percent = mass of solute (g) / mass of solute (g) + mass of solvent X 100

mass percent = mass of solute (g) / mass of solution (g) X 100

these show m/m, m/v, v/v

equation for Molarity

molarity (M) = moles of a solute/liters of solution

can use molarity as a conversion factor too

FIRST find amount of MOLES using MOLAR MASS

what is dilution of a solution?

• solvent is added

• volume increases

• concentration of solute increases

• C1 V1 = C2 V2

what is a colloids?

• Medium-shaped particles

• cannot be separated by filtration

• CAN be separated by semipermeable membrane

• scatter light

• ex. fog, smoke, homogenous milk

what is a suspension?

• large particles

• settle out

• can be seperated by filtration

• must be stirred to stay suspended

• ex, calamine, lotion, muddy water

what is osmosis?

flow of water low to high

what is osmotic pressure?

the pressure that prevents the flow of additional water into the more concentrated solution

explain osmosis in blood cells

hypertonic - crenation (shrinks)

isotonic - normal

hypotonic- hemolysis (explodes)

what is dialysis?

• solvent and small solute pass-through

• large particles stay inside

• waste products such as urea from blood are removed using hemodialysis

What electron groups are usually nonpolar?

linear , triginal planar, tetreahedral

what electron groups are polar?

bent, trigonal pyramidal,