REAL CHEMISTRY FINAL STUDY GUIDE...

Which three molecular shapes are always nonpolar

linear, trigonal planar, and tetrahedral

Which two molecular shapes are always polar

bent or seesaw

If the central atom is surrounded by two different elements and one is polar but the other is nonpolar the molecule is most likely

POLAR

Common ways to tell if a molecule is polar

if there is a hydrogen bonded to a N, O, or F / lacks symmetry / arrows all point in one direction / arrows don’t cancel / electro negativity difference between 0.5 and 1.7

Common ways to tell if a molecule is nonpolar

diatonic molecule / only mad eup of carbon and hydrogen / symmetrical / electronegativity difference of 0.5 or less

delta -

represents the more electronegative atom of a polar bond

delta +

represents the less electronegative atom of a polar bond

True or False: A double and tripple bond only act as one electron domain

True

1 mole is = to how many atoms/molecules

6.022×10²³ atoms

How to calculate percent composition

mass of sample (atomic mass) /total mass (molar mass) x 100

How many decimal points should percent composition go to

1

how many decimal points should molar mass go to

2

how to calculate molar mass

take the atomic mass of each element and multiply it by the number of that element present. Then add.

How to make an empirical formula

convernt grams to moles. Then divide the moles by the smaller amount of moles

if it tells you the molar mass is 5x oxogen gas or nitrogen gas or hydrogen gas what do you do

because they are DIATONIC gasses, you multiply the atomic mass of H,N,O, or the group 17 elements by 2 and then by the multiplier it gives you

how to find the molecular formula

1. find the empirical formula

2. find the MM of the empirical formula

3. divide the molar mass of the compound given by the empirical formula molar mass

4. multiply empirical formula by that number

What is the ideal gas law

PV=nRT

What does p stand for in the ideal gas law

pressure

pressure

What does V stand for in the ideal gas law

Volume

volume

amount of space taken up by an object

what does t represent in the ideal gas law

temperature

temperature

measures the average kinetic energy of the particles

moles

meausres the number of particles

n

moles

indirect

variables on the same side of the equation. As one goes up the other goes down

direct

variables on different sides of the equation

value for r when pressure is in atm

0.08206

value for r when pressure is in kPa

8.314

value for r when pressure is in torr or mmHg

62.36

what are the values at STP

273.15 K / 1 atm / 22.4 L per mole

1 atm is equal to…

760 torr, 760 mmHg, and 101.3 kPa

Acids

substance with a ph less than 7/ the concentration of H+ ions is greater than the concentration of hydroxide (OH-) ions

Strong Acids

HCl

HI

HBr

HSO₄

HNO₃

HClO₃

What is the most common weak acid?

Vinegar (HCH₂COO)

Bases

substance with a ph greater than 7/ the concentration of H+ ions is less than the concentration of OH- ions

True or False: Strong Acids and Bases Completely disassociate from a solution

True

True or False: weak Acids and Bases only partially separate from a solution

True

Bases

substance with a ph greater than 7/ the concentration of H+ ions is less than the concentration of OH- ions

What is the most common weak base

ammonia, NH₃

Strong bases

LiOH

NaOH

KOH

RbOH

CsOH

Ca(OH)₂

Sr(OH)₂

Ba(OH)₂

SNAP Ions

Sodium, nitrate, ammonium, and potassium

Lewis acid theory

Acids accept electron pairs

Bronsted-Lowry acid theory

Acids donate H⁺ (protons)(H₃0⁺)

Arrhenius acid theory

Acids donate H⁺ (H₃0⁺)

Neutralization Reaction

A chemical reaction between an acid and a base that form a salt and water/ The point where the number of acid moles is equal to the number of base moles. / Neutralized limiting acid with excess base or neutralizing the limiting base with excess reactions.

Conjugate Acid

originally the base with an extra H+ ion/ when the base gains a hydrogen ion

Conjugate Base

When an acid loses a hydrogen ion

What would the conjugate base be for this acid- HCN

CN-

What would the conjugate acid be for this base- NH₃

NH₄

Identify the acid and base in this reaction and 

NH₃ + HNO₃→ NO₃^1- + NH₄¹⁺

NH₃ - base

HNO₃ - acid

NO₃^1- - conjugate base

NH₄¹⁺ - conjugate acid

True or false: Conjugate acids and bases are weak

TRUE

Mantissa

everything to the right of the decimal point

when calculating the molarity/concentration of acid or bases, what equation do you use?

H+=10^-pH

when calculating the molarity/concentration of acid or bases, do you use the mantissa or just count sig figs

sig figs

True or false: IF YOU ARE GIVEN THE PH AND ARE TOLD TO FIND THE MOLARITY-SIG FIGS ARE WHAT IS TO THE RIGHT OF THE DECIMAL POINT

True

diprotic (can donate 2 protons per molecule )

multiply the concentration of the acid/base by 2

triprotic

multiply the concentration of the acid/base by 3

if you are given the pH and are told to find the concentration of H+ ions, but you are also told the acid is diprotic, what do you do?

divide the 10^-pH by 2

When solving for pH and you are told the acids and bases are either mono-, di-, or triprotic, what do you do?

multiply H+ by 1,2, or 3

to find the pH of an acid/base reaction with excess acid or base what do you do?

Find the moles of acid and base

Subtract to find leftover

Divide by total volume

Then do pH square

IF YOU HAVE OH- IN EXCESS YOU HAVE TO SOLVE FOR pOH FIRST AND THEN USE pH+pOH=14

true or false: pH and pOH have a direct relationship

true

what are strong electrolyes

Ionic compounds that contain SNAP ions, strong acids/bases. Dissolves and completely ionizes and conduct electricity

example of strong electrolytes

NaCl and HCl

what are weak electrolytes

Ionic compounds, weak acids and bases. Partially dissolves and ionizes or dissolves and partially ionizes and can conduct electricity to an extent

Examples of weak electrolytes

AgCl, HCH₃COO, HF

Nonelectrolytes

Covalent Compounds, do not dissolve or dissolves but does not ionize

Examples of nonelectrolytes

glucose, paraffin wax, Iron, Ethanol, Sand

Concentration

measures the amount of a solute (substance) dissolved in a given amount of solvent or total solution

Dilute

describes a solution with a small amount of solute dissolved and has not molarity /. not a lot of material/ is used if there is a small amount of solute particles

Concentrated

describes a solution with a large amount of solute dissolved and has a high molarity

Unsaturated

the solution can dissolve more solute

Saturated

The maximum amount of dissolved solute

Molarity

Moles (mol) / volume (L)

Solute

the substance that is being dissolved

solvant

the substance that does the dissolving

How to find the concentrations of ions in solution

Determine the Molarity of the Compound, write disassociation equation, use stoichiometry to find the number of moles

Mole Fraction

Moles of solute / total moles of mixturee

mole percent

moles of solute/total moles of mixture x 100

How do you calculate the amount of grams (mass) needed to prepare specific concentrations of solutions?

M1V1=M2V2

How do you create a stock solution from power

1. Calculate the moles of solute that you will need. Convert the moles to mass using the molar mass.

2. Weigh the calculated mass of solute. Place the weigh boat on the balance and tare to subtract the mass of the weigh boat, then add solute to the desired mass.

3. Add approximately half of the solvent to a beaker. Then dissolve the solute in some of your solvent. Stir with a glass stirring rod to dissolve.

4. Using the funnel, carefully transfer all of the solution to a volumetric flask.

5. Rinse the beaker, stirring rod, and funnel with more solvent and add the rinse to the volumetric flask. Repeat.

6. Make sure that the solution is at room temperature and then fill the volumetric flask so that the bottom of the meniscus is at the calibration line on the neck of the volumetric flask. Stopper and shake to ensure that the solution is homogeneous.

How do you make the creation of a dilution from a stock solution

1. Calculate the Volume Needed

Calculate the volume of the stock solution needed. You can do this with dimensional analysis or you can use the dilution equation:

The Dilution Equation:Since the moles of solute remains constant before and after dilution and we know that molarity times liters gives us the number of moles, we can state that:

M1V1 = M2V2

Where 1 is the original stock solution and 2 is the new diluted solution.

2. Procedure:

1. Measure your desired volume of stock solution. To do this as accurately as possible, use a graduated pipette or the smallest graduated cylinder that will fit your sample.

2. Add approximately half of the solvent to the volumetric flask. Then add your measured stock solution.

3. Rinse the pipette or graduated cylinder with more of your solvent and add that to the volumetric flask. Mix and repeat.

4. Make sure that the solution is at room temperature and then fill the volumetric flask so that the bottom of the meniscus is at the calibration line on the neck of the volumetric flask. Stopper and shake to ensure that the solution is homogeneous.

Enthapy

the amount of heat exchanged

if heat is being removed from the system is enthapy positive or negative

negative

entropy

measure of disorder measured by Delta S

Gibbs free energy

How spontaneuous a system is measured in Delta G

Endothermic

heat is transferred from the surrounding to the system (enthalpy is positive) (q+)

Exothermic

heat is lost from the system and transfered to the surroundings. (enthalpy is negative) (q-)

system

the specific part of the universe that we are studying

surroundings

what is outside the system

universe

the system and it surroundings

the effect of entropy and temperature

When heat is removed from the universe (endothermic) there is a decrease in entropy / entropy is temperaure dependent/ low temperature = low energy

open system

heat and matter can be exchanged (example heta pack)

closed system

heat can be exchanged (example = sealed soda can)

isolated system

no heat or matter exchanged

What type of reaction is shown in this diagram?

Endothermic because the heat of the product is greater than the reactants

What type of reaction is shown in this diagram?

Exothermic because the heat of the product is less than that of the reactant

True or false, an exothermic system would make the surroundings feel hotter

true

an endothermic reaction would make the surroundings feel…

colder

sublimation is an example of

endothermic