chemistry part 5

Chemistry Regents Reference Tables

All questions are based on Tables A–T

Table T

Contains equations and must be used for all calculations

Table F

Solubility rules for predicting precipitates

Table G

Solubility curves used for temperature vs solubility questions

Table H

Vapor pressure curves used for boiling point and pressure questions

Table I

Heat of reaction values used for thermochemistry

Table J

Activity series used for single replacement reactions

Table K

Common acids list

Table L

Common bases list

Table P

Organic compound names

Table Q

Organic functional groups

Table S

Electromagnetic spectrum

Table T

Equations and constants

Common Regents Trick

Use reference tables instead of memorizing values

Most Missed Topic

Stoichiometry and mole conversions

Second Most Missed Topic

Table G solubility curve questions

Third Most Missed Topic

Net ionic equations

Stoichiometry Setup Always

Balance → Convert to moles → Ratio → Convert back

Mole Ratio Source

Coefficients in balanced equation

Limiting Reactant Step

Convert both reactants to product, lowest wins

Gas Law Strategy

Always convert °C to K first

Gas Law Trick

Match variables to correct equation

STP Shortcut

1 mol gas = 22.4 L

Table G Reading Rule

Locate temperature then read solubility in g/100g water

Table G Saturation

If point is above curve → supersaturated

Table G Unsaturated

If point is below curve → unsaturated

Table G Saturated

If point is on curve → saturated

Table F Rule

Nitrates, Group 1, and ammonium are always soluble

Table F Exception Chlorides

Ag+, Pb2+, Hg2+ are insoluble chlorides

Table F Exception Sulfates

Ba2+, Pb2+, Ca2+ are mostly insoluble

Net Ionic Equation Step 1

Write full ionic equation

Net Ionic Equation Step 2

Cancel spectator ions

Net Ionic Equation Step 3

Write remaining ions only

Spectator Ions

Do not change during reaction

Precipitate Formation

Occurs when two insoluble ions combine

Lewis Dot Structure Rule

Atoms want 8 valence electrons

Hydrogen Rule

Hydrogen only wants 2 electrons

Polarity Rule

If electronegativity difference > 0.5 bond is polar

Molecular Polarity Depends

On shape + bond polarity

Shape Effect on Polarity

Symmetrical molecules are usually nonpolar

Example Nonpolar Molecules

CO2, CH4

Example Polar Molecules

H2O, NH3

Intermolecular Force Strength

Hydrogen bonding > dipole-dipole > dispersion

Stronger IMF Effect

Higher boiling point

Heating Curve Flat Parts

Phase change (no temperature change)

Heating Curve Sloped Parts

Temperature change

Specific Heat Trick

Water has high specific heat → heats slowly

q = mCΔT Use

Must always show units

Endothermic Sign

Positive ΔH

Exothermic Sign

Negative ΔH

Bond Energy Rule

Bond breaking absorbs energy

Bond Formation

Releases energy

Nuclear Stability Rule

More neutrons needed for large nuclei

Alpha Decay Change

Mass −4, atomic number −2

Beta Decay Change

Atomic number +1, mass unchanged

Half-Life Trick

After each half-life, divide by 2

Exponential Decay Pattern

Sharp drop at first, then levels off

Electrolyte Rule

Only aqueous ionic compounds conduct

Strong Electrolyte

Completely dissociates in water

Acid Base Shortcut

Acids start with H, bases end with OH

Neutralization Products

Always salt + water

Experimental Design Rule

Write hypothesis before experiment

Independent Variable

What you change

Dependent Variable

What you measure

Control Group

Baseline for comparison

Constants

Everything kept the same

Graphing Rule

X-axis = independent variable

Y-axis = dependent variable

Best Fit Line Rule

Draw smooth line, not dot-to-dot

Significant Figures Rule

Least precise measurement determines answer

Rounding Rule

Look at next digit (5 or higher round up)

Percent Error Trick

Lower percent error = more accurate

Density Shortcut

Mass ÷ Volume always