Chemistry Honors 2nd Semester Final

law of conservation of mass

Balancing questions obeys the

Valence electrons

The electrons involved in the formation of a covalent bond are

diatomic molecules

describes the bonding of two atoms between the same element for the purpose of becoming more stable, for example: Cl2, N2, H2, O2

Polar covalent

When the electrons are shared unequally between atoms
Electronegativity Difference: 0.3 - 1.7

Nonpolar covalent

The atoms in the bond are shared equally
Electronegativity Difference: 0 - 0.29

Ionic

a TRANSFER of valence electrons between two or more atoms

Covalent

requires a SHARING of valence electrons between two or more atoms

properties of covalent bonds

Low boiling points
Bad conductors of electricity
Low melting points
solids liquids or gases at room temp

properties of ionic bonds

form salts
solids at room temp
good conductors of electricity
high melting point

Coordinate covalent bond

a covalent bond in which one atom contributes both bonding electrons

Resonance structures

structures that occur when it is possible to draw two or more valid electron dot formulas with the same number of electron pairs for a molecule or ion

A skeleton equation does NOT show

the relative amounts of reactants and products

symbol after the formula

The state of matter for a reactant or a product in a chemical equation is indicated by a

dissolved in water/solution

What does the symbol (aq) in a chemical equation mean?

Above or below the arrow

Catalyst is always shown by writing it ________________________ in a chemical equation

reversible reaction

This symbol ⇔ (double sided arrow) indicates

Combination/ Synthesis Reaction

When two or more substances react to form a single new substance

Decomposition Reaction

a single compound breaks down to form two or more simpler products

single replacement reaction

a chemical change in which one element replaces a second element of the same type in a compound
(Cation with cation and anion with anion)

double replacement reaction

a chemical change that involves an exchange of positive ions between two compounds
- doesn't dissolve in water and forms a precipitate
- is aa gas that bubbles out
- is a molecular compound

Combustion reaction

a chemical reaction that occurs when a substance reacts with oxygen, releasing energy in the form of heat and light
-Complete if produces CO2 and H2O
- Incomplete if produces CO (or just C) and H2O

Spectator Ion

an ion that appears on both sides of an equation and is not directly involved in the reaction

net ionic equation

an equation for a reaction in solution showing only those particles that are directly involved in the chemical change

gases change with temperature and pressure

We use STP to calculate for gases because

Avogadro's number

6.02x 10^23

22.4 L/mol

What is the molar volume of a gas at standard temperature and pressure?

Mole

Is a unit to measure very big numbers

0 C and 1 atm

Which of the following defines standard temperature and pressure?

Density

How much matter is packed in a given sapce

Molar Mass

Mass in grams of one mole of a substance

1:1

In the reaction Ca + Cl2 ---- > CaCl2, what is the mole ratio of chlorine to calcium chloride?

The reactant that has the smallest given mass is the limiting reagent.

Which of the following is NOT true about limiting and excess reagents?
-A balanced equation is necessary to determine which reactant is the limiting reagent.
-The reactant that has the smallest given mass is the limiting reagent.
-The amount of product obtained is determined by the limiting reagent.
-Some of the excess reagent is left over after the reaction is complete.

Theoretical yield

the maximum amount of product that could be formed from given amounts of reactants

Actual yield

the amount of product that is actually formed in the lab

Percent yield

Measure of efficiency of a reaction carried out in the lab
(actual / theoretical) x 100

Collision theory

molecules must collide and with enough intensity and collisions must be correctly oriented

Temperature and Reaction Rates

Temperature increases number of particles with enough kinetic energy to react when they collide.

Concentration and Reaction Rates

Higher density increases collision frequency

Particle Size and Reaction Rates

A smaller particle size = larger surface area

Characteristics of a system in equilibrium

the rates of the forward and reverse are equal, the concentrations of components on both sides may not be equal

the equilibrium favors reactants

Keq = <1
Keq less than 1

Stresses on Equilibrium

concentration, temperature, pressure/ volume

Changes in Concentration at Equilibrium

Adding more reactant produces more product.
Adding more product produces more reactant
Removing a reactant produces more reactant
Removing a product produces more product

Changes in Temperature at Equilibrium

Increasing temperature shifts equilibrium position to shift in direction that absorbs heat
- Heating exothermic produces more reactant and cooling it produces more product
- Heating endothermic produces more product and cooling produces more reactant

Endothermic

Absorbs heat

Exothermic

Releases heat

Changes in Pressure at Equilibrium

Only affects gaseous.
Increasing pressure (decreasing volume) shifts to direction with less moles
Decreasing pressure (increasing volume) shifts to direction with more moles
No change if both sides are equal

Le Chatelier's Principle

States that if a stress is applied to a system at equilibrium, the system shifts in a way that relieves the stress.

the equilibrium favors products

Keq = >1
Keq greater than 1

more NH3 molecules

N2(g) + 3H2(g) ↔ 2NH3(g) + heat
Putting pressure on the above system leads to

Transition state/ Activated Complex

An unstable arrangement of atoms that forms momentarily

Keq

the ratio of product concentration to reactant concentration at equilibrium

Could not explain Ammonia

What was the problem with Arrhenius theory of acids and bases?

Boyle's Law

States that a given amount of gas at a constant temperature varies inversely with the pressure.
P1V1 = P2V2

Charles Law

States that the volume of a fixed mass of gas is directly proportional to its kelvin temperature, if pressure is constant
V1/T1 = V2/T2

Gay-Lussac's Law

the pressure of a gas is directly proportional to the Kelvin temperature, if the volume is constant

The combined gas law

Combination of gas laws given that the amount of gas (mol) is kept constant
P1V1/T1 = P2V2/T2

Ideal Gas law

PV=nRT
n is moles
R = gas constant

Ideal gas molecules

ideal gas molecules do not attrract or repel, take up no volume, and move rap

blue, red

Acids turn __________ litmus paper __________

pH of bases

7.0 - 14

pH of Acids

0 - 6.9

rate

measure of the speed of any chemical change that occurs within an interval of time is called

Bronsted-Lowry

Acid is H+ ion donor. Base is H+ ion acceptor

Lewis Acid and Bases

acid: electron pair acceptor
base: electron pair donor

Acid rain

gases mix and react with water and other chemicals to acid rain.

Salt and water

Neutralization reaction will always produce

Hydrogen Gas

Acids react with metals to form

Arrhenius

Acids are substances that dissociate in water to produce H+ ions and bases are substances that dissociate in water to produce OH- ions. This was the definition given by

OH- ions and bitter taste

bases are recognized by

H+ ions and sour taste

Acids are recognized by

solubility depends on the amounts of solute and solvent present

In 100 mL of cold water, 35 g of NaCl will dissolve, but 70 g will not. Just this observation ALONE would means that

in an unopened bottle in the refrigerator

Under which conditions is more CO2 dissolved in a carbonated beverage?

False

Increasing pressure and decreasing temperature decreases the solubility of a gas in a liquid. (T/F)

You add 2 teaspoons of granulated sugar crystals to a glass of hot tea and stir with a spoon.

Which of the following scenarios would the sugar dissolve the fastest?
-You add 2 sugar cubes to a glass of cold tea and let it sit.
-You add 2 teaspoons of granulated sugar crystals to a glass of cold tea and let it sit.
-You add 2 teaspoons of granulated sugar crystals to a glass of hot tea and let it sit.
-You add 2 teaspoons of granulated sugar crystals to a glass of hot tea and stir with a spoon.

The one at 33 degrees F

You have two bottles of Coke. One is at 37 degrees F. The other is at 33 degrees F. Which one will be more fizzy - that is, which one will have more CO2 bubbles dissolved in it?

Salt can stick to the flask and change the molarity

Why do we add a little solvent before you put the salt in the flask for dilution?

saturated

A solution cannot dissolve any more solute at room temperature. This solution is

Immiscible

Liquids that do not mix are called

Ionic

In the Lab 7, what kind of compounds conducted electricity?

Homogenous mixture

Gatorade is an example of a
-Heterogenous mixture
-Homogenous mixture

Precipitate

What was the sign that a double replacement happened in the lab

Al

What metal replaced copper in the single replacement reaction

It did not take part in the reaction and was retrieved at the end

Why was MnO2 a catalyst in the lab

Lead because it was very dense

What was the heaviest element in your Mole lab? why?