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CHY 103
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Gas Equations (moles at STP and RTP) ** 1 mole of any gas at STP has the same volume Percent Yield *To find theoretical yield, use the limiting reagent equation Mass, Moles, Molar Mass o STP = Standard conditions (273 K / 0 C, 101.3 kPa) STP/RTP RTP= Room Conditions (293 K / 20 C, 101.3 kPa) The conversion of a solid to a vapor sublimation Moles, Avogadro’s constant, number of particles * 6.02 X 103 as volume increases (doubles) Gas Relationships: Pressure/ Volume pressure decreases (halves) Pressure, Temperature, Volume P Pressure/ atm n moles Ideal Gas Equation V Volume 5 R 8.31 JK/mol 1.01X10 Pa T Temperature/ K Density, mass, volume Concentration, moles, volume cm  dm 3 Mass number (A) A= mass number Atomic number (Z) Z= atomic number X= element Is defined in the number of protons Definition of: Atomic Number NOT electrons Definition of: Isotopes of an Element Atoms of the same element with different mass numbers Calculate the number of protons, electrons, neutrons protons= 13 neutrons= 27-13=14 electrons= 13-3=10 Mass Spectrometer Is used to measure the masses of different isotopes and their relative abundance RAM= average mass of the element taking into account all of its Relative Atomic Mass (RAM/A ) r isomers The range of wavelengths or frequencies over Electromagnetic Spectrum which electromagnetic radiation extends. - longer wavelengths= infrared (less energy) - shorter wavelengths= ultraviolet (more energy) - produced when white lights passes through a prism. Continuous Spectrum - Colours merge into each other Cation/Anion Loss of electrons / Gain of electrons The sample is vaporized and injected into the Mass Spectrometer: Step 1  Vaporization instrument. Allows the individual atoms to be analyzed Atoms are hit with high energy electrons which knock Mass Spectrometer: Step 2  Ionization out other electrons causing positively charged ions - positive ions are attracted to negatively charges Mass Spectrometer: Step 3  Acceleration plates - are accelerated by electric fields and pass through a hole in the plate - deflected by a magnetic field placed at right Mass Spectrometer: Step 4  Deflection angles on their path - amount of deflection is proportional to the ions charge/mass ratio Mass Spectrometer: Step 5  Detection The machine measures the number and mass of the positively charged ions - light passes through hydrogen gas, an Line Spectrum / Emission Line Spectra absorption spectrum is produced; the lines of the unabsorbed elements are shown - Emission spectra shows the absorbed colours Is the amount of energy needed to remove an Define: Ionization Energy electron from the ground state of a gaseous atom, ion or molecule Hydrogen Spectrum Element Arrangement Increasing atomic number (number of protons) Group: Period: - columns - rows Group / Period - number of valence - energy levels electrons Chemical Properties - are determined by the number of electrons in the outer shell - distance from the nucleus to the outermost Definition of: Atomic Radii electron (increase down, and to the left) - The radius decreases as electrons are lost and Definition of: ionic radii increases as electrons are gained. - the amount of energy required to remove one Definition of: First Ionization Energy mole of electrons from one mole of gaseous atoms (increases up, and to the right) - measure of the attraction between the nucleus and its outer electrons Definition of: Electronegativity (increases up, and to the left) if an ionic compound will result, the difference in two values must be 1.8 or more Trends in: atomic radii Trends in: ionic radii Trends in: ionization energies Trends in: electronegativity Trends in: melting/boiling points - increase up group 1 - increase down group 7 Bonding: - oxides of Al and Na have large ionic structures Period Three Elements: Bonding  ionic character depends on electronegativity  decreases from left to right (as they approach 3.5 [Oxygen]) - become more ionic down a group - oxide of silicon has a large covalent structure - ionic compounds are formed between metallic and non-metallic Ionic Compounds - have a lattice structure - covalent bonds are made between two non- Covalent Compounds metals (share electrons) Na2O MgO A2 O3 SiO 2 P 4 10 SO 3 Cl2O7 Period Three Elements: Acid-Base Basic amphoteric acidic Amphoteric Can act as both a acid/base Basic  soluble in water and form hydroxide ions in aqueous solution Acid/Base: Alkalis Of Metals: Ionic AND Basic Acid/Base: Oxides Of Non-Metals: covalent AND Acidic single double triple Bond length and Strength decreasing length, increasing strength - result from unequal sharing Polar Bonds - bonds are more polar when the difference in electronegativity is greater Valence Shell Electron Pair Repulsion VESPER - electron pairs found in the outer energy level / valence shell of atoms repel each other and this position themselves as far apart as possible repulsion between pairs decreases as follows: lone pair-lone pair > lone pair-bonded > bonded-bonded - in non-polar molecules - a temporary dipole Intermolecular forces: Van der Waals (VDW) - is the WEAKEST bond - have low melting/boiling points because it take little energy to break - occurs in molecules with permeate dipole (HCl) Intermolecular forces: Dipole-Dipole - opposite charges on neighboring molecules attract each other - strongest bond  dipole-dipole Intermolecular forces: Hydrogen Bond (H-Bond) - between H +(F or O or N) - increases as molecular mass increases *are much weaker then ionic and covalent bonds - a chemical bond in which electrons are shared Metallic Bond over many nuclei and electronic conduction occurs. - Ionic: very high melting/boiling points there is a large force electrostatic attraction between ions Melting/Boiling Points that require a lot of energy to break - Covalent: lower melting/ boiling points as the bonds are relatively weak intermolecular forces - the ease at which a solid becomes dispersed through a liquid and forms a solution Solubility ionic Polar Non- covalent polar covalent Polar soluble increases as Non- polarity soluble increases Non-polar Non- increases as soluble soluble polarity - only if the compound contains ions that are able to move and carry a charge Conductivity (metals) - ionic compounds conduct electricity in either a liquid (molten) or aqueous state (water) Release heat (neutralization / combustion) Exothermic Reactions - products have less energy - is negative - Transfer of heat: system  surroundings absorbs heat - products have more energy is positive Endothermic Reactions - transfer of heat: surroundings  system - bringing and breaking particles that are attracted to each other Conditions are: - temperature at 25 C (298K) Standard Enthalpy Change of Reaction - pressure of 101.3 kPa (1atm) - 1 mol concentration for ALL solutions - all substances in their standard state Open system can exchange energy and matter with Open / Closed system the surroundings Closed system can exchange energy but not matter with the surroundings Enthalpy Diagrams Heat Change (j) when heat is absorbed by water, c= 4.18 Heat reaction from temperature change ⁄ The enthalpy change for any chemical reaction is independent of the route, providing the starting and Hess’s Law final conditions, and reactants and products are the same. - breaking bonds is endothermic Bond Enthalpy - bond enthalpy is the energy needed to break one mole of (gaseous) bonds under standard conditions It is an enthalpy change when one mole of the Enthalpy of formation substance is formed from its elements in standard state Rate of reaction - measure of the amount of reactants being converted into products per unit of time - change in volume of gas produced - change in mass How to measure rate of reaction - change in transmission of light (colorimetry) - change in concentration using a) titration b) conductivity - ‘clock reactions’ - temperature (K) is proportional to the average Kinetic theory kinetic energy of the particles in a substance - Activation Energy (E ) Is the minimum value of kinetic energy with particles a must have before they are able to react Maxwell-Boltzmann energy distribution curve: Maxwell-Boltzmann energy distribution curve: Increaseing temperature, increases rate of temperature reaction Maxwell-Boltzmann energy distribution curve: Increasing concentration, increases rate of reaction concentration because it increases the chance for collision Maxwell-Boltzmann energy distribution curve: Increasing pressure increases rate of reaction pressure because higher pressure compresses the gas Is a substance that increases the rate of a chemical Catalyst reaction without itself undergoing permanent change. It lowers activation energy Inserting a catalyst increases the rate of reaction Maxwell-Boltzmann energy distribution curve: because it provides another route for the reaction to catalyst occur Law of conservation of energy: You cant create or destroy energy Solid liquid Gas State vs Kinetic Energy Increasing kinetic energy Increasing temperature Maxwell-Boltzmann energy distribution curve: Decreasing particle size increases rate of reaction particle size because it increases surface area Forward reaction Forward and backward reaction Backward reaction K Cives information about how far a K C1) reaction will go, not the time it will take - a system at equilibrium when subjected to a Definition: Le Chandelier’s Principal change will respond in such a way to minimize the effect of the change Does not change the position of the equilibrium or Effect of Catalyst increase the yield, rather it allows for the equilibrium to be achieved more quickly Although applying Le Chandelier’s principal would achieve the best results, it to too expensive and Industrial Process unproductive to apply all the changes (pressure, temp) Characteristics of chemical system and physical The rate of evaporation is equal to the rate of systems in a state of equilibrium condensation Reaction Shift Concentration: Right Pressure: To the side with fewer molecules Le Chandelier’s Principal Temperature*: Low temp favors exothermic High temp favors endothermic *ONLY thing that changes K C Acid Base Define Acids and Bases according to Brønsted- Brønsted-Lowry H donor H acceptor Lowry and Lewis - - Lewis e pair e pair donor acceptor Characteristics of Acids in Water Is an ionic compound that +issolves in water to form H ions Alkalis dissolve in water to form the OH ion Characteristics of Bases in Water Dissociate completely in water Strong Acids (ie: HCL, HNO )3 - higher conductivity - higher rate of reaction Dissociate completely in water (ie: LiOH, NaOH, KOH) Strong Bases - higher conductivity - higher rate of reaction + The lower the pH value, the higher the H concentration pH Scale 1,2,3,4,5,6,7,8,9,10,11,12,13,14  acid neutral base  Parent Acid 1 Acid + Metal  Salt + Hydrogen Neutralization 2 Acid + Base  Salt + Water Dissociate partially in water (ie: CH3COOH, H PO 3 4 Weak Acids - low conductivity - lower rate of reaction Dissociate partially in water (ie: NH 3 C 2 5H ) 2 Weak Bases - low conductivity - lower rate of reaction OIL RIG Definition: Oxidation and Reduction Oxidation is the LOSS of electrons Reduction is the GAIN of electrons A number assigned to an element in chemical combination that represents the number of electrons lost Oxidation Numbers (1) (or gained, if the number is negative) by an atom of that element in the compound Na, K +1 F -1 Oxidation Numbers (2) O -2 Can be -1 in peroxide, or +2 in O2 H +1 Metal hydrides is -1 Cl -1 When it is combined with O or F How to write half equations: 1. assign oxidation numbers to determine which are being Half Equations oxidized and reduced 2. write the half equation: a) Balance the atoms other then H and O b) Balance each O by adding H2O c) Balance each H by adding H as needed d) Balance the others by adding electrons to the more positive side 3. Equalize the number of electrons in the two equations by multiplying 4. Add the two equations together 5. Substance that is reduced is the oxidizing agent Definition: Oxidizing Agent and Reducing Agent The Substance that is oxidized is the reducing agent Is a chemical reaction in which changes in the Redox Reaction oxidation numbers occur Oxidation Occurs when there is an increase in oxidation number of an element Occurs when there is a decrease in oxidation Reduction number of an element More reactive metals are stronger reducing agents Metals (REDOX) and is able to reduce the ions of a less reactive metal Non-Metal (REDOX) More reactive non-metal is able to oxidize the ions of a less reactive non-metal an electrochemical cell that derives electrical energy from spontaneous redox reaction taking place within the cell. It Voltaic Cell generally consists of two different metals connected by a salt bridge, or individual half-cells separated by a porous membrane. Electrode Potential is the electromotive force of a cell built of two electrodes Metal (VOLTAIC) More reactive the metal, the more negative its electrode potential is in its half cell Anode The negatively charged electrode of a device Oxidation always occurs in the anode. Cathode The positively charged electrode of a device Reduction always occurs in the cathode. electrons always flow Voltaic Cell Diagram in the external circuit from anode to cathode Similar to the voltaic cells, but the two metal Electrolytic Cells plates are in the same container. It is non spontaneous (if it is in a different container) A liquid that conducts electricity and undergoes Electrolyte chemical change as a result. Are commonly molten ionic compounds, or aquious solutions of ionic compounds Are always made from a conducting substance Electrodes (metal or graphite) that is immersed in the electrolye and onnected to the power supply. Conductors Wires Connects the power supply to the electrodes At the anode, negative ions lose electrons; at the Anode and Cathode (electrolytic cell) cathode, posative ions gain. V E Voltaic Vs Electrolytic Anode Oxidation (-) Reduction (+) Cathode Reductio (+) Oxidation (-) - members of a homologous series have the fame functional group and can be represented by the Homologues Series same general formula - successive members of the series have an additional CH2group - the members of a series show a gradation in their physical properties - the members of a series have similar chemical properties - increases as you move down a series Boiling Point Trends in Homologous Series - more branches = higher boiling point - functional groups will also vary the BP most least alkane Halogenalkane aldehyde keytone alcohol Carb. acid VDW DIPOLE H-Bond Increaseing strength of inter-mol forces Increasing BP/MP Structural Isomers Are compounds with chane the same molecular formula but different arrangements of atoms Primary: attached to one car
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