CHEM 112 Exam 1 Questions And Answers All Correct

things tend to go _______________ in energy - correct answers downhill concentration - correct answers how much you can dissolve and how much you put in it formula for molarity (M) - correct answers moles of solute/liters of solution; unit is mol/L formula for mole fraction (X) - correct answers moles of solute/(moles of solute+moles of solvent); unit is moles? formula for molality (m) - correct answers moles of solute/kilograms of solvent; unit is mol/kg what is the molality of 7.75g of urea ((NH3)2CO) in 203 g of water? - correct answers 0.617 mol/kg What are the four colligative properties? - correct answers boiling point, freezing point, vapor pressure, and osmotic pressure if the chemical energy of a substance is low, then i wont make a good ______? - correct answers fuel nature wants to go ____________ in chemical energy (downhill or uphill). - correct answers downhill anytime you dissolve something into another substance, you are _____________ the chemical energy (decreasing or increasing). - correct answers decreasing is a higher or lower chemical energy more stable? - correct answers lower calculate the mole fraction of 25g of NaCl dissolves into 100g of H2O. - correct answers 0.0715 moles what are the rules that apply to the Van't Hoff Factor (i)? - correct answers if you have a non-electrolyte, it will not come apart and i=1, if you have an electrolyte, then i=the number of ions in the formula what is the Van't Hodd Factor of -NaCl -MgCl -Fe(NO3)3 -C2H5oH - correct answers -i=2 -i=3 -i=4 -i=1 (not an ion) if the molecule has a lot of C's, H's, and O's, then it is probably___________ (ionic or not ionic) - correct answers not ionic formula for boiling point elevation - correct answers ∆Tb=ikbm ∆Tb=change in boiling point i=Van't Hoff Factor kb=boiling point elevation constant m=molality what is the new boiling point for a 1.5 m NaCl solution in water? - correct answers 101.536 degrees Celsius formula for freezing point depression - correct answers ∆Tf=ikfm ∆Tf=change in freezing point(goes down by) i=Van't Hoff Factor kf=freezing point depression constant what is the new freezing point for 1.5 m NaCl solution in water? - correct answers -5.58 degrees Celcius formula for vapor pressure lowering - correct answers Pa=(Xa)(Pa*) Pa=partial of solution Xa=mole fraction of the SOLVENT -moles of solvent/total moles (opposite of before) Pa*=vapor pressure of pure solvent you have 100.0 g of H2O and 10.0 g of NaCl, the pure vapor pressure at these conditions is 350 torr, what is the new vapor pressue? - correct answers 339.548 torr osmotic pressure - correct answers pressure needed to prevent osmosis osmosis flows from a _____ concentration to a _____ concentration. - correct answers low-high examples of colloids - correct answers gels, sols, and emulsions what is the difference between dispersion and condensation? - correct answers dispersion is grinding big particles into small ones, while condensation is the opposite, and build up big molecules from many small ones. molecules with many C's and Hs are _________. - correct answers nonpolar colloids - correct answers particles that are bigger than molecules and disturb light, they will not settle out. emulsion - correct answers a mixture of two immiscible liquids energy - correct answers the capacity to do work potential energy - correct answers energy of position kinetic energy - correct answers energy of motion what are the two types of kinetic energy? - correct answers -all particles moving in the same direction(somewhat like velocity) -particles moving randomly (basically temperature) what does temperature measure? - correct answers average kinetic energy what is heat? - correct answers transferring thermal energy from a hot object to a cold one. calorie - correct answers amount of energy needed to raise temperature 1 gram of water 1 degree C Calorie vs. calorie - correct answers Calorie=food calorie=energy 1 Calorie=1,000 calories equation for heat transfer - correct answers q=(C)(ΔT) q=symbol for heat C=heat capacity ΔT=change in temp heat capacity - correct answers how much thermal energy it takes to raise the temperature of a system extensive value _________ depend(s) on the amount (does/does not). - correct answers does; mass intensive value _________ depend(s) on the amount (does/does not). - correct answers does not; color, temperature, etc. formula for total heat capacity - correct answers q(J)=(total heat capacity (J/degrees Celsius))(ΔT (degrees Celsius)) formula for specific heat capacity - correct answers q (J)=(specific heat capacity (J/g*degrees Celsius))(amount (g))(ΔT (degrees Celsius)) it takes 95 J of energy to change the temperature of a small rock by 4.5 degrees Celsius, what is the heat capacity of the rock? - correct answers 21 J/degrees Celcius how much energy is needed to heat the rock from 25 to 100 degrees Celsius? - correct answers 1,575 J how much how much energy is needed to heat 203 g of iron by 57 degrees Celsius? - correct answers 5,195.38 J if it is cooling off, then ΔT is ___________ - correct answers negative system - correct answers what you're looking at, the rock, the mineral, etc. surroundings - correct answers the surroundings of the system, everything else around the system. if energy flows into the system, the energy is _____ - correct answers (+) if evergy flows out of the system, the energy is _____ - correct answers (-) heat always flows from _______objects to ______ objects - correct answers hot to cold calorimetry - correct answers measurement of heat flow in calorimetry, if the temperature goes up, then it is an ___________________ reaction - correct answers exothermic formula for heat of a reaction - correct answers q(surroundings)=(heat capacity)(ΔT) in an endothermic reaction, q is___ - correct answers (+) in an exothermic reaction, q is ___ - correct answers (-) if a system is gaining energy, the surroundings are ____________ energy. - correct answers losing if a system is losing energy, the surroundings are ______________ energy. - correct answers gaining a calorimeter has a total heat capacity of 875 J/degrees Celsius, you run a reaction that raises the temperature from 25.0 to 28.3 degrees Celsius, what is the heat of the surroundings? - correct answers -2887.5 J Enthalpy (H) - correct answers a type of energy storage. state functions depend on ____________ - correct answers where you are; example: elevation path functions depend on ______________ - correct answers how you got there, and which path you take. ΔH is the ____________________ - correct answers change in enthalpy formula for change in enthalpy - correct answers ΔH=(sum ΔH products)-(sum ΔH reactants) what is the ΔH of 2H2(g) + O2(g) = 2H2O(g) - correct answers ΔH=-483.6 kJ/mol what is the ΔH of H2(g) + 1/2 O2(g) = H2O - correct answers ΔH=-241.8 kJ/mol from the previous reaction, if you have 8 moles of H, how many moles of O do you need to react? - correct answers 4 moles of O, because if 1 mole of H=1/2 mol of O, then 8 moles of H=4 moles of O how much energy is released when you burn 6.0 g of H2? - correct answers -725.4kJ what are standard conditions? - correct answers 25 degrees Celsius, 1 atm, and the solution is 1 molar the stronger the bond, the _____________ the bond length. - correct answers shorter what determines the strength of bonds? - correct answers the charges on the ions, if the charges are the same, than the one with the smaller atomic radius has a stronger bond. formula for energy - correct answers Δu=q+w Δu=change of internal energy q=heat w=work if a system absorbs 25 J of heat energy and does 99 J of work on the surroundings, what is Δu? - correct answers -74 J spontaneous reactions occur _____________ outside energy - correct answers without Entropy (S) - correct answers measure of disorder microstates and macrostates - correct answers microstates are individual, and determine what each outcome will be, and macrostates are the overall observation, it doesn't depend on how many microstates there are. relative entropy - correct answers solidliquidgas 6! - correct answers 6x5x4x3x2x1 ΔS(universe)0(positive) means that the reaction is _______________. - correct answers spontaneous ΔS(universe)0(negative) means that the reaction is _______________. - correct answers nonspontaneous ΔS(universe)=0 means that the reaction is _______________. - correct answers at equilibrium formula for ΔS - correct answers ΔS=(sum of ΔS for products)-(sum of ΔS for reactants) true or false: You can convert 100% of heat/energy into useful work. - correct answers false predict the entropy (+ or -) for 2H2(g) +O2(g)=2H2O(l) - correct answers negative formula for Gibb's free energy - correct answers G=H-TS or ΔG=ΔH-TΔS when is the ΔG equation at equilibrium? - correct answers when 0=ΔH-TΔS if a reaction is exothermic, and the ΔH is positive, then it is ____________________ - correct answers always spontaneous if a reaction is endothermic, and the ΔS is negative, then it is ____________________ - correct answers never spontaneous if a reaction is exothermic and ΔH is negative, then it is ____________ - correct answers spontaneous at low temperatures if a reaction is endothermic and ΔH is positive, then it is ________________ - correct answers spontaneous at high temperatures formula for Gibb's free energy of a reaction - correct answers ΔG=(sum of ΔG products)-(sum of ΔG reactants) coupled reactions - correct answers pairs of chemical reactions that make a nonspontaneous reaction spontaneous, by coupling it with a spontaneous reaction if you have 1.5 L of water and gas at 0.5 atm, how much gas is dissolved? - correct answers (Kh)(1.5L)(0.5atm)=answer Kh will be given in the problem.