# Chem 1c – Chemistry Test Questions Patsy Brent
question

 factors that influence reaction rate

 concentration, physical state, temperature
question

 reaction rate in terms of products

 rate= -Δ[A]/Δt
question

 rate law

 rate=k[A]^m[b]^n *m and n are the stoichimetric coefficients if the reaction is elementary… otherwise you have to find them experimentally
question

 reaction orders

 how the rate is affected by reactant concentration.
question

 rate constants

 are specific for a particular reaction AT A PARTICULAR TEMPERATURE!!!
question

 units for rate constant k for an overall zeroth order reaction

 mol/L s
question

 units for a rate constant k for an overall 1st order reaction

 1/s
question

 units for rate constatnt k for an overall second order reaction

 L/mol s
question

 use of integrated rate laws

 used to solve for concentrations, times, or rate constants when you want to consider time a factor
question

 integrated rate law in straight line form for zeroeth order reaction

 [A]=-kt + [A]0
question

 Integrated rate law in straight line form for a 1st order reaction

 ln [A]=-kt + ln[A]0
question

 Integrated rate law in straight line form for a 2nd order reaction

 1/[A]=kt+1/[A]0
question

 half life for a zeroeth order reaction

 [A]0/2k
question

 half life for a 1st order reaction

 (ln2)/k
question

 half life for a 2nd order reaction

 1/k[A]0
question

 Arrhenius equation

 k=Ae^(-Ea/RT) A=frequency factor
question

 What happens as T increases, according to the Arrhenius equation?

 k increases, and therefore the rate increases.
question

 If the Ea forward is larger than the Ea reverse, is the process endothermic or exothermic?

 endothermic
question

 If the Ea reverse is larger than the Ea forward, is the reaction endothermic or exothermic?

 exothermic
question

 According to the Arrhenius equation, as Ea increases, what happens to k and rate?

 k decreases, which leads to a decreased rate.
question

 what is a spontaneous reaction?

 one proceeding towards equilibrium.
question

 what is the sign of ΔS for the following rxns:solid–>liquid–> gascrystalline solid + liquid-> ionscrystaline solids-> gases + ions

 ΔS>0
question

 microstate (W)

 each quantized state of a system (energy levels)
question

 equations for ΔS of a system

 ΔS (sys)=q/T ** RECAll q= cmΔT!!!!!!
question

 Entropy in similar compounds

 for similar compounds, entropy increases with molar mass
question

 determining spontaneity using entropy

 ΔS (universe)>0 means spontaneous ** note… must take into consideration ENTIRE univers, so ΔS sys+ ΔS surr
question

 entropy in relationship to equilibrium

 ΔS (univ)=0 therefore ΔS (sys)=-ΔS (surr)
question

 phase changes in relationship to equilibrium

 phase changes occur at equilibrium
question

 exothermic reactions

 ΔH0
question

 endothermic reactions

 ΔH>0, so ΔS(surr)<0
question

 free energy equation

 ΔG=ΔH-TΔS **WOrd of Caution– if rxn is not at 298 k, then you MUST use this formula, because the tables are made at 298 K!!!!
question

 spontaneity in relation with gibbs free energy

 ΔG<0 spontaneousΔG>0 nonspontaneousΔG=0 equilibrium
question

 4.18 joules is…

 the heat required to heat one gram of water by 1 C.
question

 does vapor pressure for a liquid increase as the temperature increases?

 why yes, it does.
question

 do fast reactions have large equilibrium constants?

 not necessarily. Keq=K1/K(-1), and the reaction could occur quickly in both directions.
question

 are activation energies for forward and reverse reactions the same?

 nope. draw some pictures.
question

 will the equilibrium constant for a reaction increase if a catalyst is added?

 nope, catalysts only affect the activation energy.
question

 are the rates of forward and reverse reactions equal at equilibrium?

 yes, this is the definition of equilibrium
question

 equilibrium

 when the reaction rates for the forward and reverse processes are equal
question

 H2O2

 hydrogen peroxide
question

 definition of enthalpy

 ΔH=ΔE+PΔV
question

 1st law of thermodynamics

 ΔE=q+w
question

 ethanol

 C2H5OH
question

 octane

 C8H18
question

 combustion

 adding oxygen gas to form carbon dioxide and water
question

 molality

 mol/kg
question

 ΔH(soln) without ions

 ΔH(soln)=ΔH(solute) + ΔH(solvent) + ΔH(mix)
question

 ΔH(soln) with ions

 ΔH(soln)=ΔH(lattice)+ΔH(hydration)
question

 Osmotic pressure

 pi=MRT M=molarityR=gas constantpi=osmotic pressure
question

 charge density: periodic trends

 charge density increases as you move across the periodic table, and decreases as you move down inc——–>||| dec/
question

 miscible

 solute and solvent are soluble in each other in any proportion.
question

 list these major types of intermolecular forces in order of decreasing strength: dipole-dipole, H bond, ion-induced dipole, dipole induced dipole, ion-dipole, dispersion

 ion-dipole, H bond, Dipole-dipole, ion-induced dipole, dipole-induced diole, dispersion.
question

 what kind of intermolecular forces are seen with the use of soap to remove grease?

 dipole-induced dipole
question

 hydroxyl

 -OH group
question

 methanol

 CH3OH
question

 ethanol

 CH3CH2OH
question

 how is charge density related to heat of hydration?

 the higher the charge density,the more negative ΔH (hydration) is
question

 entropy