Flashcards
CHMB31 2nd Midterm part 1
Cards in this deck (51)
- 1What if entropy (∆Sº) is <0 or >0?<0, the system is in high order after reaction (less randomness)>0, the system s in less order after the reaction (high randomness)
- 2What if enthalpy (∆Hº) is <0 and >0?<0, reaction releases energy (exothermic)
>0, reaction takes up energy (endothermic) - 3What if K >1? What if K is <1?If K>1 equllibrium is shifted towards the products
If K<1 the equilibrium is shifted towards the reactants - 4What if the reaction quotient (Qc) is =0, QK or Q=K. (K being the equilibrium constant)Q=0, proceeds ot the products
QK, proceeds to the reactants
Q=K, Reaction is in equilibirum - 5What is equilibriumIt is when two opposing process take place at the same rate, the system is in dynamiic equillibrium. it can be between phsyical states or chemical species or reactant/products.
- 6What is le Châtelier's principle?It describes what happens to a system already in an equilibrium position under the influence of external factors
- 7What is reaction Quotient? (Qc)?It is the ration of inital concentrations (activities) having the same mathematical form as the equilibrium constant.
- 8Which 3 changes in conditions are part of le chatliers principle?Changes in pressure, temperature, concentration of the reacting species
- 9What is the difference between kinetically and thermodynamically controlled reactions?Kinetically products are determined by mechanistic factors while thermodynamically the products are determined through Gibbs energy change
- 10What is a lewis acid and lewis base?Lewis acid is an electron pair acceptor, while lewis base is an electron pair donor.
- 11How is the strength of acids and bases determined?Through: Ka= products/reactants, and pKa =-log(Ka). same goes for Kb
- 12What are the four types of acids in water?Binary (no oxygen),
Oxoacids (has oxo and OH groups), Hydroxoacids (only OH group), and
Aqua acids (water + metal ion). - 13What factors influence Oxoacid strength?Inductive effect (presence of oxygen increases acidity)
Resonance (more resonance stabilizes conjugate base making acid more acidic) - 14What makes aqua brønsted acids acidic?The small and highly charged cations strongly attract the lone pairs on the oxygen in water, making the hydrogen atom increasingly positive = acidic.
- 15Are metallic oxides or non-metallic oxides acidic?Metallic oxides are basic due to water transferring its protons
Non-metallic oxides are acidic oxides, they bind to water molecules and release hydrogen. - 16What is a reducing agent vs oxidizing agent?Reducing agent- supplies electrons for redox
Oxidizing agent- receives electrons from the reducing agent - 17Oxidation state vs oxidation number. What is the differenceOxidation number- an imagined state of the ionic character of any bond
Oxidation state- is the true physical state oof the atom or ion in a compound - 18Which of the two cells, galvanic and electrolytic is spontaneous?Galvanic cell is a spontaneous reaction, while electrolytic is non spontaneous
- 19what if EºCell potential>0 or <0If Ecell is >0 then oxidation is strong and has the tendency to gain electrons
If Ecell is <0 then reduction is strong and has the tendency to lose electrons - 20How do you calculate Eºcell?Eºcell= Eºreduction - Eºoxidation
- 21What is disproportionation?It is the redox reaction when oxidation number of one element is raised and lowered at the same time, it is both oxidizing and reducing agent.
- 22What is comproportionationredox where two oxidation states become one.
- 23If pH is increased what happens to the reduction potential?It becomes more negative
- 24Why does pH matter in reduction/latimer diagram?pH matters in the diagram because it affects oxidation state can occur in that condition
- 25What is a frost diagramIt shows the stability of an element's redox states relative to the free element, oxidation state vs free energy.
- 26What if free energy is less than 0 in a frost diagramIf they are below 0 they are the most stable
- 27what if free energy is large in a frost diagram?It means it is the most unstable and that it is a good oxidizing agent
- 28What is the hexagonal length of sides and its angles?Sides: a=b≠c
Angles: aº=bº, yº=120º - 29What is hexagonal close packingIt is alternating layers of atoms, where one atom would have 12 neighbours and a pair of three atoms are eclipsed
- 30What is cubic close packingThe unit cell is a cube with atoms at each corner and middle of each face of the cube.
- 31What are the two types of holes in a lattice structure?octahedral and tetrahedral
- 32What is body-centred cubic lattice (BCC)the corners and centre of the cube
- 33Simple cubic latticespheres only on the corners of the cube
- 34How do bands form and what do they representthey form when different atomic orbitals can overlap, it represents antibonding and bonding orbitals at an infinite scale
- 35How are insulators, conductors and semiconductors portrayed in bandsInsulators- have a large band gap not allowing electrons to jump over
Conductors- have small band gap or overlapping filled and empty bands
Semi-conductors- have a small band gap - 36What is the NaCl structure?Halite also known as rock salt, it is cubic unit cell
- 37What is CaF2 structures (AX2)Cubic unit cell, fluorite
- 38What is antifluorite?It is the same structure as fluorite but the positions of the cation and anion is reversed
- 39What are zinc sulfide's structures?Sphalerite also known as zinc blend with a cubic unit cell
Wurtzite, it is composed of two intermeshed hexagonal closed packed structures, unit cell is hexagonal - 40Define polymorphSame formula but different structures
- 41What is the structure of TiO2Rutile, with a tetragonal unit cell (it also is a polymorph but other structures aren't mentioned in lecture)
- 42What is CaTiO3's structure?Perovskite, with a cubic unit cell
- 43what is the born-harder cycleThe Born Haber cycle is a cycle of enthalpy change of process that leads to the formation of a solid crystalline ionic compound from the elemental atoms in their standard state and of the enthalpy of formation of the solid compound such that the net enthalpy becomes zero
- 44what is coulombic attractionsCoulombic attraction is the force of attraction between positive and negative charges
- 45What is the born-lande equation aboutIt is an equation to estimate lattice energy based on the repulsive and attractive forces
- 46Why was the born-mayer equation made, how is it different from the born-landemayer replaced one part of the equation for better and more accurate results to better define the repulsive interactions and magnitude to better predict lattice energy.
- 47In the born-mayer equation, what happens if d increases?∆Hlat decreases as d increases
- 48If there is an increase in charge, how does it affect ∆Hlat in the born-mayer equation?∆H lat increases as the charge increases
- 49What is the kapustinskii equation used forit describes lattice energy in a more simple equation but it is not as precise as born-mayer. It can also determine the thermodynamic radii of cations and anions.
- 50What is the lewis-langmuir equation used forit is used to estimate the partial charges on bonded atoms
- 51what are the consequences of being in between covalent and ionic compoundsweak and non bonding interactions hold covalent molecules in the solid state, and having an in-between covalent and ionics for melting and boiling points