5.1: Covalent & Ionic Compounds Lab

4.1: Forces of Attraction

INTRAmolecular forces - think BONDS WITHIN molecules (ie ionic bond)

• Ionic, Covalent, Metallic

INTERmolecular forces - think interactions BETWEEN molecules (hydrogen bond) 3 types

1. Dipole-Dipole

• 2 poles (positive/negative)

• Attractive forces between the positive end of the POLAR molecule and the negative end of the POLAR molecule

• Between POLAR molecules

2. Hydrogen Bonding

• Type of Dipole-Dipole between positive Hydrogen molecule to an opposing molecule of an adjacent compound

• IE: H -> N,O,F

3. London Dispersion Forces

• ALL MOLECULES HAVE THIS (especially non-polar)

• Attraction of weak dipoles that form at any given time when molecules are close 

• Temporary induced molecules 

5.5: Properties of Water

Hydrogen bonding 

• In a water molecule, hydrogen ends have a slight positive charge and oxygen has a slight negative charge

• Cause the hydrogen to attract to oxygen in another molecule

• Bonds formed between water is called hydrogen bonds

Surface tension

• Hydrogen bonds cause water to stick together which creates high surface tension

• High surface tension is what causes water to bead up on leaves or pennies and that allows bugs to walk on water 

Specific Heat 

• The quantity of energy needed to raise temp of 1g of water by 1C

• Water has a specific heat of 4.18 Joules

• Takes 4.18 J of energy to raise temp of water by 1C

Freezing/Boiling Point

• Hydrogen bonds cause water to have a high freezing point

• Hydrogen bonds also cause water to have a high boiling point

• More forces between molecules = higher the BP/FP

Polarity

• Unequally sharing of electrons that result in partial charges

• Hydrogen side of water is partially positive

• Oxygen side is partially negative

Density

• Density is ratio of mass to volume, how tightly packed things are

• Mass/volume, g/cm^3, kg/m^3, g/mL (GET THE EQUATIONS RIGHT)

• Ice floating vs oil sinking

• Oil more dense than water AS A SOLID (as liquid it is less dense), and ice has hydrogen bonding which expands and creates more space when solid

5.6: Properties of Solutions

Homogeneous mixtures 

• A blend of two or more substances that are evenly distributed throughout, so that the composition is uniform (homogeneous 🥶)

Solute

• The substance that is being dissolved

Solvent

• The substance that dissolves the solute

How to predict what will dissolve

“Like dissolves like” (Like = polarity) 

• Polar solvents dissolve polar molecules

• Ex: H2O(polar) can dissolve NaCl (polar) & C₂H₆O (ethanol/alcohol; polar)

• Nonpolar solvents dissolve nonpolar molecules

• Ex: CCl₄ (nonpolar) can dissolve methane, CH₄ (nonpolar), hydrocarbons, C_xH_y (nonpolar), & CO₂ (nonpolar)

Hahaahhah funni joke qiuerawiojfdsn

The polar bear is dissolving because he’s in water, which is a “polar” substance

5.6?: Solubility curves

Solubility - amount of solute that can be dissolved in a solvent at a specific temp and pressure

Solubility curve is a graph used to show how much solute can dissolve in a given quantity (100g) of solvent (water) at a given temperature

DEGREES OF SATURATION

SATURATED

• Contains the MAX AMOUNT of solute per solven at that particule temperature

• Falls ON THE LINE of solubility

UNSATURATED

• Contains less than the maximum amount of solute per solvent

• More solute can be dissolved

• Falls BELOW the line of solubility

SUPERSATURATED

• More salute than expected for that temp is dissolved in a solution

• Falls ABOVE the line of solubility

Dot on the top = Supersaturated           Dot on the line = Saturated

Dot below the line = Unsaturated

FACTORS THAT AFFECT SOLUBILITY

For a solid

• Increase in temp = increase in solubility 

• Decrease in temp = decrease in solubility

• Agitation = stir it!  

• Increase in Surface area = crush it 

For a gas

• Decrease in temp = increase in solubility

• Increase in temp = decrease in solubility 

• Increase in pressure = increase in solubility

HOW DOES IT DISSOLVE?

Dissociate = “To separate”

Ionic compounds are dissociated (pulled apart) to form IONS in water

Positive end (H+) will surround the ANION (METAL)

Dissolution is for IONIC 

Negative end (O-2) will surround the CATION (NONMETAL)

think of the hydrogen atoms as arms

The arms are positive and hug the anion (which in this case is Cl)

The “body” or the oxygen atom is negative and is attracted to the cation

HYDRATION

For Covalent compounds

Water surrounds the entire compound