exam 2 chem 1230 – Flashcards
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| when does a precipitate form? |
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| when the attractive forces between ions are large |
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| what are the exceptions for I, Cl, and Br? |
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| Ag, Hg, Pb, Cu, Ti |
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| what are the exceptions for SO4? |
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| Ca, Sr, Ba, Pb |
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| what are always soluble? |
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| NH4, group 1A, NO3, ClO4, Clo3, C2H3O2 |
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| solution |
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| homogenous mixture of 2+ substances |
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| solvent |
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| major proportion |
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| solute |
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| minor proportion |
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| colligative properties |
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| affected by concentration of particle the solute contirbutes to the solution |
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| what are examples of colligative properties? |
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osmotic pressure vapor pressure lowering boiling point elevation freezing point depression
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| colligative molality |
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| change in freezing point or boiling point of a solvent when solute is added |
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| what is the equation for colligative molality? (Mc) |
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| Mc = i x m |
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| how do you find molality and what are the units? |
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| moles of solute / kg of solvent |
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| what is i? |
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| vant hoff factor; # of particles produced when a solute dissolves |
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| what is the equation for delta T? |
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| delta T = Kf * Mc |
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| what is Kf? |
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| the freezing point depression constant of solvent |
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| what are the properties of lauryl acid? |
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| non hazardous but prolonged contact may cause skin irritation |
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| what equipment is used in experiemnt 8? |
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crystallization dish graduated cylinder beaker thermometer tongs spatula hot plate |
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| when is equilibrium established? |
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| when the rates of the forward and reverse reactions are equal |
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| what are the properties of HCl? |
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| corrosive, irritant, use fume hood, injures eyes and skin |
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| what are the properties of AgNO3? |
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| dark spots |
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| what is the effect of raising temperature with respect to Le Chateliers principle? |
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| equilibirum shifts to the higher energy side |
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| what are the reactions studied in experiment 9? |
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CoCl4^2- + 6 H2O -> Co(H2O)6^2+ + 4 Cl^- Fe^3+ + SCN^- -> FeSCN^2+ |
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| when are reactants favored? products? |
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when K is low when K is high |
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| what are titrations? |
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| stoichiometric volume of one reactant of known concentration (titrant) is required to react with another reactant of unknown concentration (analyte) |
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| how is the concentration of the analyte determined? |
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| from the concentration of the titrant and stoichiometry of reaction between them |
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| what is in the buret? |
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| titrant |
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| what is in the flask? |
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| analyte |
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| what is in indicator |
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| a substance that changes color near the equivalence point |
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| how is an indicator chosen? |
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| when the equivalence point is near the end point |
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| what is the endpoint? |
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| point at which the color change occurs |
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| what should you consider when setting up a titration? |
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buret measured to nearest .01 mL make sure no air bubbles in buret tip condition buret fill buret below 0 mark close stopcock |
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| what happens if you dont condition the buret? |
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the volume of titrant will increase the moles of analyte will be overestimated |
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| what happens if you condition the flask with analyte? |
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increase in volume of titrant overestimation of moles of analyte |
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| mass % |
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| moles of acid / moles of base x 100 |
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| how do u go from moles to mmol |
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| 1 mol = 1000 mmol |
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| what is the difference when doing conjugates? |
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| a H+ |
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| conjugate base of an acid |
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| remove an H+ |
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| conjugate acid of a base |
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| add H+ to base |
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| what subsances are corrosive? |
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acetic Nh3 Hcl Naoh |
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| what substances are irritants? |
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acetic NH3 HC; |
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| how do u find [H3O+] given pH? |
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| H+ = 10^-pH |
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| how do u find pH given [H+] |
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| pH = log[H+] |
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| enthalpy |
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| amount of heat energy absorbed at constant pressure |
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| entropy |
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| number of ways energy can be distributed in a system |
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| system |
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| part of universe being studied |
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| surroundings |
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| part of universe that interacts with system being studied |
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| spontaneous |
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| lowers energy of system |
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| nonspontaneous |
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| amount of energy supplied to cause process to occur |
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| heat of reaction |
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| when reactants react completley at STP |
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| electrodes |
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| metal strips |
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| cathode |
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| reduction |
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| anode |
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| oxidation |
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| saltbridge |
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| allows ions to travel from one 1/2 cell to other |
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| voltmeter |
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| calculates potential difference between oxidizing and reducing agents (mV -> V) |
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| how do you find Ecell |
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| Ecell = Ecathode - Eanode |
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| if H < 0 and S > 0 |
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| spontaneous |
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| if H > 0 and S < 0 |
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| non spontaneous |
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| H < 0 |
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| exo |
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| H > 0 |
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| endo |
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| S < 0 |
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| spontaneous |
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| G > 0 |
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| nonspontaneous |
