Chem Things I dont Know

Transition Metals with More Than One Charge

• These can form more than one stable ion.

  • Use Roman numerals to indicate the charge.

    • Iron(II) = Fe²⁺, Iron(III) = Fe³⁺

    • Copper(I) = Cu⁺, Copper(II) = Cu²⁺

Synthesis (Combination)

•  A + B → AB

• Ex: 2Na + Cl₂ → 2NaCl

Decomposition

• AB → A + B 

• Ex: 2H₂O → 2H₂ + O₂

Single Replacement

• A + BC → AC + B

• Ex: Zn + HCl → ZnCl₂ + H₂

Double Replacement

• AB + CD → AD + CB

• Ex: Na₂SO₄ + BaCl₂ → BaSO₄ + 2NaCl

Combustion

• Hydrocarbon + O₂ → CO₂ + H₂O

• Ex: CH₄ + 2O₂ → CO₂ + 2H₂O

Know 3 ways in which matter is measured

• By Mass (grams)

  • Count by tens to an individual number of items 

  • Measured using a balance.

  • Used in labs to weigh substances.

• By Moles

  • Moles by weighing

  • Based on the number of particles (atoms/molecules).

  • 1 mole = 6.022 × 10²³ particles.

• By Volume

  • Volume by finding the space it takes up 

  • For gases at STP (standard temperature and pressure).

  • 1 mole = 22.4 L at STP

Convert between moles and particles, or volume

• To convert between moles and particles

  • Use 6.02x10^23 particles = 1.0 mol conversion factor

  • Ex. 3.2 mol =? Particles

    • 3.2 mol x 6.02x10^23/1 mol = 1.9x10^24 particles

Find % composition

• Add up the masses to the total mass

• Divide each element's mass by the  total

• Multiply by 100%

• If a sample is found to contain 5.4% oxygen and 8.2% sulfur, what is the % composition

  • 5.4+8.2 =13.6

  • 5.4/13.6 = 39.7

  • 8.2/13.6 = 60.3

    • If you know the formula, you can find the percent composition by mass

Find the percent composition of H₂O.

• Percent comp = mass of element of a compound x 100

• Find the molar mass of the total and divide each element by the total, x by 100

  • Molar mass: 18

  • 2/18x100 = 11.19

  • 16/18x100 = 88.889

Calculate both empirical and molecular formulas

1. Empirical

2. change the % sign to grams

3. Divide by the mass of the element to find moles

4.  Divide by the smallest mole amount to find the ratio

5. Molecular: Divide the given molar mass by the empirical molar mass to find a whole number to multiply the empirical formula by

Know how to tell quantities of reactants or products like a recipe

• Coefficients tell you how many moles of each substance react or are produced.

• Example: 2H₂ + O₂ → 2H₂O 2H₂ + O₂ → 2H₂

• This means: 2 moles of hydrogen react with 1 mole of oxygen to make 2 moles of water

Convert between grams and kilograms

• Convert to moles first, then grams given to mol, given to mol, want to g, want

Know how to find the % yield

actual/theoretical × 100

Know the 3 parts to the kinetic theory.

• Particles are small, have insignificant volume, are far apart, and are independent.

• The motion of gas is rapid, chaotic, random, and constant for a given temperature.  

• Collisions with another particle or object are perfectly elastic (no energy lost)

sublimation

• Solid → Gas (skips liquid phase, e.g., dry ice)

depostition

Gas → Solid, e.g., frost

Be able to explain hydrogen bonding.

when H bonds with/ unshared pair of electrons on O from a different

tell why water is unique in surface tension, vapor pressure, boiling point, and density.

• Surface Tension—tends to hold drops in a round shape, with thin skin on the surface

• Vapor Pressure is lower with solute for simple liquids and slowly evaporates

• Boiling Point rises 

• Liquid Density is higher than ice

Dissociation

• strong acid or base completely breaks apart or ionizes in water.

Dissolving

• a solid or liquid solution is formed in a solvent

Know the 3 factors to get something to dissolve faster

• Increase temperature → particles move faster.

• Stir or agitate → more interaction between solute and solvent.

• Particle size → increases surface area.

Properties of acids

• Tastes sour or tart (like lemon juice)

• Are electrolytes (conduct electricity when in water)

• Causes litmus to turn red or pink 

• React with many metals to release H₂.

Properties of bases (also called Alkaline)

• Tastes bitter (ex-soap)

• Feels slippery 

• Are electrolytes

• Turns litmus paper blue

• Not found in food, but found in cleaning supplies

Arrhenius Acid

• contains Hydrogen that becomes a H+ ion in water, must be joined to a more electronegative atom

Arrhenius base

• contains hydroxide that can become an ion in water (OH-)

Bronsted Acid

• hydrogen ion, Donor

Bronsted Base

• hydrogen ion, Acceptor 

Be able to do calculations with K_w

• The ionization constant of water (Kw) represents the equilibrium constant for the autoionization of water. It is defined as:

•  [H+] x [OH-] = 1x10^-14M

Know the pH formula and scale, and be able to do calculations

• 0-7= acidic (closer to 0= more acidic)

• 7-14= basic (closer to 14 = more basic)

Know how to complete a Titration problem

• Used to find the unknown concentration of an acid  or base by using a certain amount and concentration

• Regardless of concentration or amount, the number of moles must be equal

• Ex 25.0 mL of an acid (HXL) with an unknown concentration is titrated with 16.8 mL of a 1.25M solution of NaOH. What is the concentration of the acid?

  • Since it is ml, we need to move the decimal point.

  • 1.25 m=x/0.0168

  • x = 0.021 mol acid

  • Acid = 0.021 mol/0.025 = 0.84M

  • Ma(va) = Mb(Vb) 

Know how to complete a neutralization reaction

• Acids and bases cancel each other out when added together (neutralize)

• Products are water and salt (not necessarily table salt)

• Need to have the right amounts of each

  • A small weak base won't completely neutralize a large amount of strong acid.

  • Ex. HCL + KOH → HOH + KCL (DR 1:1:1:1) (both are strong)

  • Ex. 2HNO₃ + Ca(OH)₂ → 2HOH + Ca(NO₃) ₂

    • For the 2HOH, we don't have 2 h with OH because it is with the O