Exam 2 Flashcards
Limiting reagent
the reactant that gets consumed first in a chemical reaction and therefore limits how much product can be formed
Percent yield
the actual yield divided by the theoretical yield times 100
Solubility
the ability of a solid, liquid, or gaseous chemical substance (referred to as the solute) to dissolve in solvent (usually a liquid) and form a solution.
Solvation
the interaction of a solvent with the dissolved solute—in the case of water, solvation is often referred to as hydration.
Dissociation
a general process in which molecules (or ionic compounds such as salts, or complexes) separate or split into other things such as atoms, ions, or radicals, usually in a reversible manner.
Ionization
Ionization is the process by which an atom or a molecule acquires a negative or positive charge by gaining or losing electrons, often in conjunction with other chemical changes.
Electrolytes
a substance that dissociates in water into charged particles called ions. Positively charged ions are called cations. Negatively charged ions are called anions. Simply, an electrolyte is a substance that can conduct an electric current when melted or dissolved in water.
Molarity
Amount of moles of a substance in a certain volume of solution.
M=n/v
Concentration
The quantity of solute present in a given quantity of solution.
Dilution
the addition of solvent, which decreases the concentration of the solute in a solution.
Acid
A molecule or other species which can donate a proton or accept an electron pair in reactions.
Base
A substance that can neutralize an acid by reacting with (accepting) hydrogen ions.
Polyprotic acid
Polyprotic means “many protons”
Specific acids that are capable of losing more than one single proton (ionizable H+) per molecule in acid-base reactions.
Monoprotic acid
An acid that will only donate one proton (ionizable H+)
Neutralization
The reaction of an acid and a base, which forms water and salt
Gas-evolution reaction
A gas evolution reaction is a chemical reaction in which one of the end products is a gas such as oxygen or carbon dioxide
Precipitation
The formation of a solid from a solution
Redox reaction
Reaction that involve the transfer of electrons from one species to another
Oxidizing agent
A chemical species that tends to oxidize other substances.
Oxygen, hydrogen peroxide, halogens
Reducing agent
a substance that is oxidized by donating electrons
Potassium, calcium, barium, sodium, and magnesium
Oxidation
a process in which a chemical substance changes because of the addition of oxygen.
Reduction
the process of an atom or compound gaining one or more electrons
Combustion reaction
occur when a compound, usually one containing carbon, combines with the oxygen gas in the air. This process is commonly called burning. Heat is the most-useful product of most combustion reactions.
*Oxidation identification rules
Gases under normal conditions
He, Ar, Ne, N2, H2, O2, O3, F2, Cl2, Kr, Xe.
*Pressure
the force exerted per unit area.
Measured using barometer or manometer.
Pressure & volume
Inverse = when volume increases, pressure decreases (constant temp)
Temperature & volume
Directly proportional = volume increases as temperature increases (constant pressure)
Moles & volume
Directly proportional at constant temperature and pressure.
Ideal Gas Equation
PV=nRT
P = pressure
V = volume
n = moles
R = Gas constant
T = temperature
Dalton’s Law of Partial Pressure
the total pressure by a mixture of gases is equal to the sum of the partial pressures of each of the constituent gases
Ptotal = Pg1 + Pg2 + Pg3 …
Kinetic Molecular Theory of Gases
Gases consist of particles (molecules or atoms) that are in constant random motion.
Gas particles are constantly colliding with each other and the walls of their container.
These collisions are elastic; that is, there is no net loss of energy from the collisions.
Graham’s Law to find the molar mass of an unknown gas
the rate of diffusion or of effusion of a gas is inversely proportional to the square root of its molecular weight.
Using the given effusion rates of the known reference gas (Rate₁) and the unknown gas (Rate₂) along with the molar mass of the known reference gas (M₁), substitute these values into the equation: M₂ = (Rate₁ / Rate₂)² * M₁ Calculate M₂ to determine the molar mass of the unknown gas.
Real vs. ideal gases
Real gases follow Ideal Gas Law only under conditions of high temperature and low pressure
An ideal gas is a theoretical gas composed of many randomly moving particles that are not subject to interparticle interactions. A real gas is simply the opposite; it occupies space and the molecules have interactions.
Energy
the capacity to supply heat or do work. The ability to do work.
Potential energy
the energy stored in the bonds of chemical compounds
PE = Fx
F = opposing force
x = distance moved
PE=mgh
m = mass
g = gravity acceleration
h = object’s height
Kinetic energy
energy possessed by an object in motion. The earth revolving around the sun, you walking down the street, and molecules moving in space all have kinetic energy. Kinetic energy is directly proportional to the mass of the object and to the square of its velocity:
KE=1/2mv^2
m = mass
v = velocity
Thermal energy
refers to the energy contained within a system that is responsible for its temperature. Heat is the flow of thermal energy.
q = mcΔT
Chemical energy
the energy stored in the bonds of chemical compounds
Heat
The flow of thermal energy. The amount of energy that is transferred from one system to its surroundings because of a temperature difference.
q = mcΔT
Work
the energy needed to move against a force.
a change in volume against a pressure. ( Pressure is force divided by area, so convince yourself that P x V has the same units as F x d.) For instance, atmospheric pressure is constant at ~1 atm.
System
our chemical reaction. That includes the reactants, products, catalysts, transition states, intermediates, solvents, and anything else. The surroundings are everything else.
Surroundings
Everything that surrounds and potentially reactions with the system itself.
Endothermic
endothermic reactions absorb energy from the surrounding that is in the form of heat.
Exothermic
releases energy into the surrounding of the system.
Enthalpy
the heat change occurred when one mole of substance is formed from its constituent elements in their standard state,
Specific heat
the amount of heat that must be added to one unit of mass of the substance in order
Heat capacity
physical property of matter defined as the amount of heat needed to cause a unit change in temperature in a given mass of material
Calorimetry
the process of measuring the amount of heat released or absorbed during a chemical reaction. By knowing the change in heat, it can be determined whether or not a reaction is exothermic (releases heat) or endothermic (absorbs heat).
First Law of Thermodynamics
energy cannot be created or destroyed; it can only be converted from one form to another. The First Law is used to categorise ‘the performance of cyclic conversion systems like fossil-fired, steam power cycles or geothermal cycles.
Hess’s Law
If a chemical equation can be written as the sum of several other chemical equations, the enthalpy change of the first chemical equation equals the sum of the enthalpy changes of the other chemical equations.
if a process can be expressed as the sum of two or more steps, the enthalpy change for the overall process is the sum of the ΔH values for each step.
