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Gasoline
A complex mixture of mainly alkanes (single bonded hydrocarbons) with 7-9 carbon atoms.
Branching
The process of changing a hydrocarbon by removing a carbon atom to create a new branch.
Octane rating
A measure of how controlled the explosion of a fuel is.
Ethanol
A type of alcohol made from corn.
Stoichiometry
The study of quantitative relationships in chemical reactions.
Limiting reactant
The reactant that is fully consumed in a chemical reaction.
Excess reactant
The reactant that remains after a chemical reaction has completed.
Impurities
Substances that hinder reactions from reaching their theoretical yield.
Percentage yield
A calculation of the efficiency of a reaction, expressed as (actual yield / theoretical yield) x 100%.
Titration
A technique used to determine the concentration of a substance by limiting the limiting reactant.
NO2
Nitrogen dioxide, a primary pollutant from cars.
Reactive free electron
An electron that contributes to the reactivity of a molecule, often causing problems in reactions.
Gas properties
Characteristics of gases, including expansion to fill volume, low density, variable density, thorough mixing, and dramatic volume changes with temperature.
Universal gas constant (R)
A constant used in gas equations, with values of 0.08206 L atm mol-1 K-1 and 8.314 J mol-1 K-1.
Pressure
The force exerted per unit area.
Units of pressure
Measurements including 1 torr = 1 mm Hg, 1 atm = 760 torr, and 1 atm = 101,325 Pa.
Trace analysis
The detection of chemicals at extremely low levels.
Non-destructive testing
Techniques that do not damage or decompose samples.
Microscopy and spectroscopy
Techniques used in trace analysis that exploit the unique properties of different elements.
Speed of light (C)
A constant value of 3 x 10^8 m/s.
Wave equation
The relationship C = frequency * wavelength.
Photoelectric effect
The phenomenon where light striking a metal surface causes the ejection of electrons.
Energy transfer
The process by which energy from light is transferred to electrons in a metal, allowing them to break free.
Ideal Gas Law
The Ideal Gas Law is a fundamental equation in chemistry that describes the behavior of ideal gases. It is expressed as:
[ PV = nRT ]
Where:
( P ) = Pressure of the gas
( V ) = Volume of the gas
( n ) = Number of moles of the gas
( R ) = Ideal gas constant (8.314 J/(mol·K))
( T ) = Temperature in Kelvin
This law combines Boyle's, Charles's, and Avogadro's laws, providing a comprehensive relationship between pressure, volume, temperature, and amount of gas.
1 torr ≈ atm (atmospheres)
1 torr is approximately equal to 0.000987 atmospheres (atm).
1 torr ≈ mm/inHg (millimeters / inches of mercury)
1 torr = 1 mmHg (millimeter of mercury)
1 torr is approximately equal to 0.7500616 inches of mercury (inHg).
torr
Torr is a unit of pressure, defined as 1/760 of an atmosphere, equivalent to approximately 133.322 pascals.
c to kelvin
To convert Celsius (°C) to Kelvin (K), use the formula:
[ K = °C + 273.15 ]
For example, to convert 25°C to Kelvin:
[ K = 25 + 273.15 = 298.15 , K ]
celsius to farenheit
To convert Celsius to Fahrenheit, use the formula:
[ F = 9/5C + 32 ]
Where:
( F ) = temperature in Fahrenheit
( C ) = temperature in Celsius
moles to grams to molar mass relationship
The relationship between moles, grams, and molar mass is defined by the formula:
[ grams = moles x molar mass ]
Where:
Moles (n) is the amount of substance.
Grams (g) is the mass of the substance.
Molar Mass (M) is the mass of one mole of a substance (g/mol).
STP conditions (standard temperature and pressure)
STP Conditions:
Standard Temperature: 0 degrees Celsius (273.15 K)
Standard Pressure: 1 atmosphere (101.325 kPa or 760 mmHg)
STP is commonly used as a reference point in chemistry for gas calculations.
Ideal Gas Constant (R)
The Ideal Gas Constant (R) is a fundamental constant used in the ideal gas law, which relates pressure, volume, temperature, and the number of moles of a gas. Its value is:
R = 8.314 J/(mol·K) (joules per mole per kelvin)
R = 0.0821 L·atm/(mol·K) (liters atmospheres per mole per kelvin)
R = 62.36 L·torr/(mol·K) (liters torr per mole per kelvin)
The appropriate value of R depends on the units used in the calculations.
1 mol of Ideal Gas, volume at STP
1 mol of an ideal gas has a volume of 22.7 L at STP.
Kinetic Molecular Theory
Definition: A theory that explains the behavior of gases in terms of particles in constant motion.
Key Points:
Gas particles are in continuous, random motion.
The volume of gas particles is negligible compared to the volume of the container.
Collisions between gas particles are elastic, meaning no energy is lost.
Average kinetic energy is directly proportional to the temperature of the gas in Kelvin.
Gay-Lussac's Law
Gay-Lussac's Law states that the pressure of a gas is directly proportional to its absolute temperature when the volume is held constant. Mathematically, it can be expressed as:
[ P1/T1 = P2/T2 ]
where ( P ) is pressure, ( T ) is the temperature in Kelvin, and the subscripts 1 and 2 refer to two different states of the gas.
Avogadro's Law
Definition: At constant temperature and pressure, equal volumes of gases contain an equal number of molecules.
Formula: ( V1/n1= V2/n2 ) (where ( V ) is volume and ( n ) is the number of moles).
Implication: This law implies that the volume of a gas is directly proportional to the number of moles of the gas, provided temperature and pressure remain constant.
Boyle's Law
P1⋅V1=P2⋅V2
P1 is the initial pressure (30.0 psi),
V1V_1V1 is the initial volume (1.55 mL),
P2P_2P2 is the final pressure (643.6 psi),
V2V_2V2 is the final volume (which we need to calculate).
bar (unit of pressure)
1 bar is equal to 100,000 pascals (Pa) or approximately 0.9869 atmospheres (atm).
Conversion:
1 bar = 100 kPa
1 atm ≈ 1.01325 bar
Summary:
1 bar ≈ 0.9869 atm
1 atm ≈ 1.01325 bar
kinetic energy formula
The formula for kinetic energy (KE) is:
[ KE = 1/2mv^2 ]
Where:
( KE ) = kinetic energy
( m ) = mass of the object (in kilograms)
( v ) = velocity of the object (in meters per second)
Limiting reactant
The limiting reactant in a chemical reaction is the substance that is completely consumed first, limiting the amount of product formed. It determines the maximum yield of the reaction. To identify it:
Calculate moles of each reactant.
Use stoichiometry to determine how much product can be formed from each reactant.
The reactant that produces the least amount of product is the limiting reactant.
Percent yield
Percent Yield is a measure of the efficiency of a chemical reaction. It is calculated using the formula:
[Percent Yield=(Actual Yield/Theoretical Yield)×100]
Actual Yield: The amount of product obtained from a reaction.
Theoretical Yield: The maximum amount of product that could be formed based on stoichiometry.
A percent yield of 100% indicates a perfect reaction with no losses.
Planck's constant
Planck's Constant
Symbol: ( h )
Value: ( 6.626 x 10^-34 J*s )
Significance: Fundamental in quantum mechanics, relates energy of a photon to its frequency:[ E = h \nu ]where ( E ) is energy, ( h ) is Planck's constant, and ( \nu ) is frequency.
The Dilution Equation
The dilution equation is used to calculate the concentration of a solution after dilution. It is expressed as:
[ C1V1 = C2V2 ]
Where:
( C1 ) = initial concentration
( V1 ) = initial volume
( C2 ) = final concentration
( V2 ) = final volume
This equation helps in determining how much solvent to add to achieve a desired concentration.
Boyle’s law
Boyle's Law states that for a fixed amount of gas at constant temperature, the pressure of a gas is inversely proportional to its volume.
Formula:
P1V1 =P2V2
Where:
P1 and P2 are the initial and final pressures.
V1 and V2 are the initial and final volumes.
Key Point: As volume increases, pressure decreases, and vice versa, assuming constant temperature.
Note
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