Chem/Phys Study Concepts Flashcards by Jacki Leigh

An isothermal process occurs when?

The systems temperature is constant. If U=0 then Q=W

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An adiabatic process occurs when?

No heat is exchanged between the system an enviroment Q=0 then U=-W

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An isobaric process occurs when?

The systems pressure is constant. Does not alter first law so U=Q-W

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An isovolumetric process occurs when?

The system has no change in pressure. With no change in pressure W=O and U=Q

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What are standard conditions for state functions?

25 deg C (298 K), 1 atm Pressure, 1 M concentration

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What are the State Functions?

Pressure, Density, Temp, Volume, Enthalpy, Internal Energy, Free energy

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Mneumonic for State Functions?

When I am under Pressure and feeling dense, I watch TV and get HUGS

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What state change is vaporization?

Liquid to gas

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What state change is condensation?

Gas to liquid

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What state change is sublimation?

solid to gas

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What state change is deposition?

Gas to solid

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Enthalpy is?

the thermal energy of the substance

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What is the symbol for Enthalpy?

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What is the Q value for Endothermic Processes?

♦Q>0

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What is the Q value for Exothermic Processes?

♦Q<0

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What is Hess’s Law?

That since Enthalpy is a State function its not path-depended therefore all enthalpy changes in a rxn are additive.

H=H1+H2+H3….etc

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What is the formula for the enthalpy of a reaction, when bond dissociation comes into play?

Hrxn=Sum H(bonds broken)-SumH(bonds formed)

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Bond dissociations:

What is the energy of bonds dissociating?

What is the energy of bonds formed?

Bonds dissociation energy >0

Bond Formation energy <0

*Breaking bonds requires energy

Forming bonds releases energy

Combustion:

How do alkane reactant size effect number of combustion products?

The larger the alkane reactant=more numerous the combustion sizes

What is the definition of Entropy?

It is a measure of spontaneous dispersal of energy at a specific temp: How much energy is spread out, and how widley spread out energy becomes

What is the change in free energy?

The maximum amount of energy released by a process at a constant temperature and pressure that is available to perform useful work

What is the formula for Gibb’s free energy?

DeltaG=DeltaH-TDeltaS

Gibb’s Free Energy:

If DeltaG<0 the reaction is?

G<0 the reaction is spontaneous

Gibb’s Free Energy:

If DeltaG=0 the reaction is?

The rxn is at equilibruim

Gibb's Free Energy: If DeltaG\>0 the reaction is?

The reaction is non-spontaneous

Delta G is ____________ \_\_\_\_\_\_\_\_\_\_\_\_ when both delta H and delta S have the same sign.

Delta G is temperature dependent when both delta H and delta S have the same sign. \*The temp dependence is equal to the sign they have Negative delta H and delta S are temp dependent at low temps. Positive delta H and delta S are temp dependent at high temps

Gibb's Free Energy: What sign for Delta H and Delta S means the reaction is nonspontaneous?

A positive Delta H and a negative Delta S is a nonspontaneous reaction

How does Keq relate to Gibbs Free Energy?

A high Keq=more positive natural log=more negative delta G=more spontaneous rxn.

You have to switch equations for Delta G when a reaction is in progess, why?

Because once a reaction begins to progress, it is no longer in the standard state condition of 1*M* and the value must be replaced by another number that reflects its path towards equilibrium.

When a reaction is in progress for delta G, what variable is added to the equation? What is the new equation

The reaction quotient *Q.* Delta Grxn=DeltaGºrxn+RTlnKeq=RT(*Q*/Keq)

Keq and Gibb's Free Energy: How do ratios of *Q* and Keq affect whether a rxn is spontaneous or nonspontaneous

(*Q*

(Q>Keq)=Ratio>1=DeltaG>0=Reverse Spontanous

(Q=Keq)=reaction is at equilibrum=DeltaG equals 0

The saturation point of a compound is also known as the?

equilibrum point

What is the formula for K_sp?

A_mB_n(s)→mA^N+(aq)+nB^M-(aq) With this in mind- K_sp=[A^N+]^m[B^m-]ⁿ

K_sp is ________ and _________ dependent.

Temperature and pressure (for gasses only)

How does temperature affect K_sp values?

Higher temp=higher K_sp value Lower temper=lower K_sp value

What is ion product?

how to tell where the system is in relation to equilibrum

How do Ion Product (I.P) and Ksp relate?

I.P

I.P=Ksp =equilibrium

I.P>Ksp = supersaturated

When the I.P\>Ksp and the solution is supersaturated, what occurs?

Precipitation because the solution is trying to get back to equilibrum

What is the formula for Ion Product?

With this in mind: A_mB_n(s)→mAⁿ⁺(aq)+nB^m-(aq) Forumula for Ion Product is: I.P=[Aⁿ⁺]^m[B^m-]ⁿ

What are the steps in solving a molar solubility problem?

1) Write out equation 2) Use K_sp formula 3) Use x to figure out the amounts that dissociate 4) Plug x's into K_sp equation 5) Plug in molar solubility 6) Simplify and reduce to proper SI notation

What are the molar solubility shortcuts?

MX=x² MX₂=4x³ MX₃=27x⁴

K_f represents?

The formation constant: When aqueous ions find stability in an aqueous complex

What is the common ion effect?

Molar solubility is *reduced* by the presence of one of it's constituent ions in solution