CHEMISTRY exam
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Created by:
LilacKhojasteh on May 26, 2012
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94 terms
Terms | Definitions |
|---|---|
 amphoteric | can behave either as an acid or as a base (water is the most common) |
| pH | provides a convinent way to represent solution acidity = -log[H+] |
| buffered solutions | characteristics: 1. the solution contains a weak acid HA and its conjugate base A- 2. the ___ resists changes in pH by reacting with any added H+ or OH- so that these ions do not accumulate 3. any added H+ reacts with the base A- 4. any added OH- reacts with the weak acid HA |
| acids | produce hydrogen ions |
| bases | produce hydroxide ions |
| conjugate base | everything that remains of the acid molecule after a proton is lost |
| conjugate acid | formed when the proton is transferred to the base |
| acid strength | a strong acid contains a relatively weak conjugate base |
| Kw | ion-product constant for water, the product of [H+] and [OH-] must always equal 1.0e-14 |
| acidic | pH<7 |
| solute | other substance or substances; what is dissolved |
| solvent | the substance present in the largest amount; what the substance is dissolved in |
| dilute solution | a relatively small amount of solute is dissolved in a |
| concentrated solution | a relatively large amount of solute is dissolved in a |
| aqueous solution | solutions with water as the solvent |
| electrolytes | any substance containing free ions that make the substance electrically conductive |
| strong electrolytes | when each unit of a substance that dissolves in water produces separate ions, the substance is called a ... |
| weak electrolytes | a electrolyte that does not completely separate in the solution; the solution will contain both ions and moleculs of the electrolyte |
| non-electrolytes | does not provide ions in a solution and therefore current does not flow through such solution |
| mass percent | a common way of describing a solution's composition = mass of solute/mass of solution x 100% = grams of solute/grams of solute+grams of solvent x 100% |
| molarity | the most commonly used expression of concentration; describes the amount of solute in moles and the volume of the solution in liters; the number of moles of solute per volume of solution in liters M=moles of solute/liters of solution |
| standard solution | a solution whose concentration is accurately known |
| dilution | the process of adding more solvent to a solution |
| neutralization reaction | an acid-base reaction; when just enough strong base is added to react exactly with the strong acid in a solution |
| equivalent of an acid | one ... is the amount of that acid that can furnish 1 mole of H+ ions |
| equivalent of a base | one ... is defined as the amount of that base that can furnish 1 mole of OH- ions |
| equivalent weight | the ... of an acid or a base is the mass in grams of 1 equivalent of that acid or base |
| (molar) heat of fusion | the energy required to melt 1 mole of a substance (for ice 6.02 kJ/mole) |
| (molar) heat of vaporization | the energy required to change 1 mole of liquid to its vapor (for water 40.6 kJ/mole) |
| intermolecular forces | the forces that occur among molecules that cause them to aggregate to form a solid or a liquid are ... (between the molecules) |
| dipole-dipole forces | molecules with dipole moments can attract each other by lining up so that the positive and negative ends are close to each other. these forces are typically only about 1% as strong as covalent or ionic bonds, the become weaker as the distance between dipoles increases |
| hydrogen bonding | particularly strong dipole-dipole forces occur between molecules in which hydrogen is bound to a highly electronegative atom, such as nitroge, oxygen or fluorine. so unusually strong because of the great polarity of the bond and the close approach of the dipoles |
| London dispersion forces | occurs in all molecules... the forces that exist among noble gas atoms and nonpolar molecules. instantaneous dipole that occurs accidentally in a given atom and induces a similar dipole in a neighboring atom. significant in large atoms/molecules. |
| volatile | a measure of the tendency of a substance to vaporize |
| triple point | the ... of a substance is the temperature and pressure at which the three phases (gas, liquid, solid) of that substance coexist in thermodynamic equilibrium |
| sublimation | the process of transition of a substance from the solid phase to the gas phase without passing through the liquid phase. occurs at temperatures and pressures below a substance's triple point |
| heating/cooling curve | going from left to right on this graph means energy is being added (heating). going from right to left on the graph means energy is being removed (cooling) |
| dipole moment | molecules with polar bonds often behave in an electric field as if they had a center of positive charge and a center of negative charge |
| crystalline solids | those substances with a regular arrangement of their components |
| ionic solids | crystalline solid- components are ions |
| molecular soilds | crystalline solid- components are molecules |
| atomic solids | crystalline solid- components are atoms |
| partial pressure | the pressure that the gas would exert if it were alone in the container |
| Boyle's Law | PV=PV |
| Charles' Law | V/T=V/T |
| Avogadro's Law | V1/n1=V2/n2 |
| combined Gas Law | PV/T=PV/T |
| absolute zero | -273 degrees C is the lowest possible temperature- this temperature is defined as ___ on the Kelvin scale |
| resonance | a molecule shows this when more than one Lewis structure can be drawn for the molecule |
| electronic geometry structure | use the VSEPR to predict this- look at the bonds-linear, trigonal planar, tetrahedral, trigonal pyramid, bent/v-shaped |
| tetrahedral | 4 electron pairs- 4, 3, 2 bonds (electron pair arrangement)- molecular structure: 4 electron pairs, 4 bonds, same electron pair arrangement |
| trigonal pyramidal | one side is different from the other three- 4 electron pairs- 3 bonds- tetrahedral electron pair arrangement |
| covalent bonds | two identical atoms nuclei share electrons equally |
| linear structure | all atoms are in a line- 2 electron pairs- 2 bonds |
| bent/angular structure | "v-shaped"- 4 electron pairs- 2 bonds- electron pair arrangement: tetrahedral |
| trigonal planar structure | all four atoms in the same plane- 3 electron pairs- 3 bonds- must have this electron pair arrangement to have the molecular structure |
| the polarity of a bond depends on... | the difference between the electronegativity values of the atoms forming the bond. If the atoms have very similar electronegativities, the elctrons are shared almost equally and the bond shows little polarity. if the atoms have very different electronegativity values, a very polar bond is formed. |
| nonpolar | no lone pairs and symmetrical |
| polar | lone pairs and not symmetrical |
| the polarity of the bond increases as | the difference in electronegativity increases |
| the farther apart the elements are on the periodic table | the more polar they are |
| kinetic energy | energy due to the motion of the object and depends on the mass of the object and its velocity =1/2 mv^2 |
| law of conservation of energy | energy can be converted from one form to another bu can be neither created nor destroyed |
| temperature | a measure of the random motions of the components of a substance |
| heat | flow of energy due to a temperature difference |
| system | par of the universe on which we wish to focus attention |
| surroundings | include everything else in the universe |
| exothermic | process results in the evolution of heat, energy flows out of the system |
| endothermic | processes that absorb energy from the surroundings, the heat flow moves into the system |
| first law of thermodynamics | (law of conservation of energy) the energy of the universe is constant |
| internal energy | E can be defined as the sum of kinteic and potential energies of all "particles" in the system E= q + w |
| w | work if the system does work on the surroundings (energy flows out of the system) it is negative if the surroundings do work on the system (energy flows into the system) it is positive |
| calorie | the amount of energy (heat) required to raise the temperature of one gram of water by one Celsius degree |
| joule | 1 calorie=4.184 |
| specific heat capacity | the amount of energy required to change the temperature of one gram of a substance by one Celsius degree |
| Enthalpy | H a special energy function the change is equal to the energy that flows as heat deltaHp=heat |
| calorimeter | a device used to determine the heat associated with a chemical reaction- the reactions is run in it and the temperature change of it is observed |
| greenhouse effect | the effect of carbon dioxide on our climate |
| energy spread | in a given process, concentrated energy is dispersed widely. this distribution happens every time an exothermic process occurs |
| matter spread | the molecules of a substance are spread out and occupy a larger volume |
| entropy | S a function invented to keep track of the natural tendency for the components of the universe to become disordered- a measure of disorder or randomness |
| second law of thermodynamics | the entropy of the universe is always increasing |
| spontaneous process | one that occurs in nature without outside intervention |
| the longer the wavelength | the lower the frequency |
| high-energy photons | short-wavelength light |
| low-energy photons | long-wavelength light |
| ground state of an atom | lowest possible energy state of an atom |
| quantized | energy is absorbed and released in certain amounts |
| valence electrons | the s and p electrons in the outermost principal energy level of an atom |
| long wavelength | low frequency=low energy |
| short wavelength | high frequency=high energy |
| oxidation-reduction | reaction in which one or more electrons are transferred between species |
| oxidation | loss of electrons or increase in the ___ number |
| reduction | gain of electron or a decrease in the oxidation number |
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