diploma studying Flashcards by bridget Ng

thermochemistry

what is Q=mcΔt mean, and what do the individual elements represent?

-used to calculate heat transferred in a process with no phase change
- Q = quantity of heat transferred into the system
m = mass (g)
c = specific heat capacity
Δt = temperature change

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thermochemistry

what is the origin of chemical bond energy?

(majority of biosphere) is derived from solar energy
- energy required to break bonds
- energy released when bonds break

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thermochemistry

what is enthalpy?

change in potential energy between reactants and products
represented by ΔH (or ΔrH)

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thermochemistry

what is molar enthalpy?

enthalpy per mole of specified substance
represented by ΔH, or ΔHm
units in kJ/mol

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thermochemistry

how do you find amount of energy released or absorbed in reaction (equation)

ΔH = nΔrH
ΔH = enthalpy change
n = #of moles of specific substance
ΔrH = molar enthalpy

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thermochemistry

how do you find standard enthalpies of formation

ΔrHº = Σ(nΔfHº)products - Σ(nΔfHº) reactants
Σ = “sum of”

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thermochemistry

what is calorimetry, the equation, and individual representations?

energy lost/gained by system observed by (equal to) changes in water temperature
ΔH = -Q = -mcΔt
m = mass of water
c= specific heat capacity of water
=Δt is change in water temperature

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thermochemistry

what is a bomb calorimeter

different material other than polystyrene used
heat absorbed must be accounted for
formula: nΔrH = CΔt
C=constant, heat capacity of calorimeter
no need for mass

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thermochemistry

states of water in organic reactions

photosynthesis and cellular respiration both produce/consume LIQUID water (closed systems)
in open systems (e.g. combustion), GASEOUS water will be produced

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thermochemistry

ΔH, endothermic and exothermic

ΔH positive = endothermic
ΔH negative = exothermic
photosynthesis is endothermic, while combustion and cellular respiration is exothermic

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thermochemistry

what is activation energy

Ea, minimum collision energy to produce a successful reaction
(KMT) = need sufficient speed and orientation to occur through collisions

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thermochemistry

breaking/forming bonds in relation to endothermic and exothermic reactions

exothermic = products contain less potential energy than reactants
-endothermic = products contain more potential energy than reactants, require more kinetic energy to create activated complex (extra energy stored in bonds of products)

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thermochemistry

catalysts and their effects

cause rate of reactions to increase by providing an alternate pathway (less energy needed)
does NOT affect value of ΔH, change reactants/products, or get consumed

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electrochemical changes

what is oxidation and reductions

oxidation: loss of electrons, substance is oxidized
reduction: gain of electrons, substance is reduced

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electrochemical changes

what is a redox reaction

two processes do not occur in isolation
net reaction, “reduction-oxidation reaction”

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electrochemical changes

what are oxidizing and reducing agents?

oxidizing agent: GAINS electrons (reduced), causes another substance to get oxidized
reducing agent: LOSES electrons (oxidized), causes another substance to get reduced

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electrochemical changes

what is disproportionation?

redoc reaction where the SAME substance functions as both the RA and the OA

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electrochemical changes

what is an oxidation #, and relation to oxidation and reductions

positive or negative number, allows you to determine the movement of electrons in a reaction
increase: substance is being oxidized
decrease: substance is being reduced
H is ALWAYS +-1, O is always -2
*easiest way to determine if a reaction is a redox rxn or not

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electrochemical changes

what is the rule of spontaneity?

if the OA is above the RA on a table of half-reactions, the reaction is spontaneous. If not, it is non spontaneous

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electrochemical changes

balance out redox reactions
(from half reactions)

write half reactions
multiply coefficients to balance electrons
add half reactions to obtain balanced net reaction

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electrochemical changes

balance out redox reactions (creating own half reactions)

balance all molecules except O and H
Add H2O to balance O
Add H to balanced H
Balance electrons
write out half reactions
multiply one half reactions to match electrons in other half reaction
add together to obtain net reaction

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electrochemical changes

balance out redox reactions (from OA and RA)

identify OA and RA
balance electrons
balance primary atom
balance oxygen with H2O
balance H

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electrochemical changes

what is a voltaic cell

-spontaneously reaction to produce electricity
E net: positive

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electrochemical changes

what is an electrolytic cell

uses electricity to cause non spontaneous reaction (electrical>chemical energy)
E net: negative

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# electrochemical changes what is the electrode

solid in half cell

# electrochemical changes what is the anode

electrode where oxidation occurs (SRA reacts) voltaic: negative charge electrolytic: positive charge

# electrochemical changes what is the cathode

where reduction occurs (SOA reacts) voltaic: positive charge electrolytic: negative charge

# electrochemical changes what is an anion and cation

anion: negative ion, moves to anode cation: positive ion, moves to cathode

# electrochemical changes what is a salt bridge/porous cup

- barrier which keeps solutions of voltaic cells apart, but allows ion flow

# electrochemical changes what is an electrolyte

- substance that conducts electricity when dissolved in water - solutions in both cells

# electrochemical changes what is a power supply

electronic device that replaces a battery - drives electrolysis reactions

# electrochemical changes what is the external circuit

wires (and voltmeter) that are used to connect anode to cathode electron flow from the anode to the cathode

# electrochemical changes what is the line notation for cells

anode|anode electrolyte||cathode electrolyte|cathode

# electrochemical changes what is the chloride anomaly

when H2O ( in presence of CL) is both the SRA and SOA, chloride will become the SRA (anode rxn)

# electrochemical changes what are standard reduction potentials

Erº, measured to the standard hydrogen half cell (Erº=0.00V)

# electrochemical changes how to calculate standard cell potential

Eºnet = Erºcathode - Erºanode positive: spontaneous negative: non spontaneous

# organic chemistry what are organic compounds, and exceptions?

- molecular compounds of carbon exceptions: oxides, and ionic compound containing carbon

# organic chemistry organic compound nomenclature

1-meth 2-eth 3-prop 4-but 5-pent 6-hex 7-hept 8-oct 9-non 10-dec

# organic chemistry difference between unsaturated and saturated hydrocarbons

saturated: single bonds unsaturated: double/triple bonds

# organic chemistry hydroxyl functional group

R-O-H alcohol

# organic chemistry carboxyl functional group

- carboxylic acid r-(o=c-o)-h *where r is bonded to the c atom

# organic chemistry ester linkages`

-SINGLE bonded oxygen bonds to another hydrocarbon (cutoff!) -r1(o=c-o)-r2 *where r1 is bonded to the c atom

# organic chemistry halogens

-halogen atom (G17) bonds to hydrocarbon - R-X, x= halogen

# organic chemistry what is a structural isomer

- same molecular formula, but different structure - similar chemical properties but different physical properties

# organic chemistry what is an addition reaction

-diatomic molecules added across double/triple bond - becomes more saturated (e.g. double-->single)

# organic chemistry what is a substitution reaction

- atom replaces another atom in a molecule - often require the presence of light

# organic chemistry what is an elimination reaction

- molecule is removed, create double bond - water or hydrogen halide is commonly produced -(reverse addition)

# organic chemistry what is an esterification reaction

- water is eliminated (created) to make an ester - carboxylic acid + alcohol = ester + water

# organic chemistry what is a combustion reaction

- hydrocarbon or alcohols react with oxygen to produce CO2 and water

# organic chemistry polar vs non-polar structure

polar = asymmetrical nonpolar = symetrical

what is the haber process

production of ammonia n2 + 3h2 <-> 2NH3

what does shift left/right mean

right: more products formed left: more reactants formed

le chatliers principle: temperature

increase: shift endothermic right, exothermic left decrease: shift endothermic left, exothermic right

le chatlier's principle: concentration

shift right. (add to right): increase reactant, decrease product shift left (add to left): increase product, decrease reactant

le chatlier's principle: volume/pressure

increase: shift to side w more moles of gases decrease: shift to side w less moles of gases

what is the equilibrium constant?

kc, for aA+bB=cC+dD [C]c[D]d/[A]a[B]b affected by temperature

kc generalizations

kc >1 = products favoured kc = 1, relatively the same concentration kc < 1, reactants favoured

what is a bronsted-lowry acid and base

acid: proton donor base: proton acceptor

what does polyprotic mean

conjugate base can continue to give away protons (H+), can be determined by # of H's

equilibrium position in relation to acid base strength

check side with stronger acid/base, weaker side will be favoured

conjugate acid/base pairs + equilibrium position

- all reactions have two conjugate acid-base pair differ by one proton - if acid higher than base, favours products (>50%) - if acid lower than base, favours reactants(<50%)

what is an amphiprotic substance

can act as an acid or a base

what is a buffer

-mixture of weak acid and conjugate base - addition of acid/base will be neutralized to water, by the opp (acid/base, base/acid)

what is the equivalence point

same # of mole of titrant added a tere were moles of sample >7 = SB-WA <7 = SA-WB =7, SA-SB

ph and h3O formula

ph=-log[H3O] [H3O]=10^-ph responsible for acidic properties

pOH and OH formula

pOH=-log[OH] OH=10^-pOH responsible for basic properties

what is Kw

-equilibrium constant for ionization of water -kw=1.00x10^-14. (=[h3O][OH])

what is Ka

- equilibrium constant for reaction of acid with water Ka = [H3O][A-]/HA (prod/reactant)

what is Kb

- equilibrium constant for reaction of base with water - kb = [OH][HA]/[A] (prod/reactant