Module 5 Keywords Flashcards
zero order
the concentration of the reactant has no effect on the rate
first order
the rate of the reaction depends on the concentration of the reactant raised to the power one
*any change you make to the concentration of the reactant gives the same change to the rate
second order
The rate of the reaction depends on the concentration of the reactant raised to the power 2
initial rate
instantaneous rate at the beginning of an experiment when t=0
- the change in concentration per unit time at the start of the reaction
half life
the time taken for the concentration of a reactant to decrease by half
rate of reaction
the change in concentration of a reactant or product per unit time
order of reaction
the magnitude that a reactant affects the reaction
overall order
The sum of the individual orders
reaction mechanism
A series of steps that make up the overall reaction
rate-determining step
the slowest step in a multi-step reaction sequence. provides evidence for rejecting or accepting a proposed reaction mechanism
*this makes up the rate equation. but orders and species must match. catalysts aren’t allowed but intermediates are, just have to show how they’re made
stoichiometry
gives you the relative amounts of the species in the reaction (must b balanced)
Heterogeneous equilibrium
Contains equilibrium species with different states of phases
Homogeneous equilibrium
Contains equilibrium species that all have the same state or phase
Mole fraction
Moles divided by total moles in gas mixture
- Same as the gas’s proportion by volume to the total volume of gas in a gas mixture
- sum must equal 0
Partial pressure
The contribution that a gas makes towards the total pressure
Mole fraction times total pressure.
*Sum of partial pressure is total pressure.
Voltaic cells
Covert chemical energy into electrical energy. For this you need chemical reactions that transfer electrons from one species to another. Redox reactions!
Connect two half cells to make the cell.
Standard electrode potential
The emf of a half cell compared to the standard hydrogen half cell under standard conditions of 100KPa 1moldm3 and 298K
Primary cells
Non rechargable
Designed to be used once only.
Secondary cell
Rechargeable
Eg.
-Lead acid batteries in car batteries
-Nickel cadmium NiCd
Cells and Nickel metal hydrides NiMH the cylindrical batteries used in radios and torches etc
-lithium ion and lithium ion polymer cells used in modern appliances. Laptops tablets cameras mobiles etc. Also being developed for cars
Fuel cells
Use the reaction of a fuel with O2 to make a voltage. Constant supply of O2 and fuel enables the cell to operate continuously.
Nah have to be recharged
Electrolyte
a solution of ions
Lattice Enthalpy
Enthalpy change that accompanies the formation of one mole of an ionic compound from its gaseous ions under standard conditions
- measuring strength of an ionic bond
- exothermic
Standard enthalpy change of formation
enthalpy change that takes place when one mole of a compound is formed from its elements under standard conditions with all products and reactants in their standard states
-exo
standard enthalpy change of atomisation
enthalpy change that takes place for the formation of one mole of gaseous atoms from the element in its standard state under standard conditions
- endo cuz bonds broken to make gaseous atoms
- then element being atomisaised is already a gas, delta at is related to bond enthalpy of the bond being broken
First ionisation energy
energy required to remove an electron from each atom of one gaseous mole of an element to make one gaseous mole of 1+ions.
*endo because energy needed to overcome the attraction between the electron and the positive nucleus
first electron affinity
the enthalpy change that takes place when one electron is added to each atom in one mole of gaseous atoms to make one mole of 1- ions.
-exothermic as electron being added is attracted to the nucleus
standard enthalpy change of solution
the enthalpy change that takes place when one mole of a compound is completely dissolved in water under standard conditions.
-can be endo or exo
standard enthalpy change of hydration
enthalpy change that takes place when one mole of isolated gas ions is dissolved in water forming one mole of aq ions under standard conditions
-exo
ionic liquids
ionic compounds that are liquid are room temperature
feasibility /spontanuous
the reaction is energetically feasible. if delta g is negative
transition elements
d block elements that form at least one ion with a partially filled d orbital
coordinate bond
a type of covalent bond when one of the bonded atoms provides both the electrons for the shared pair
ligand
molecule or ion that donates a pair of electrons to a central mental ions to form a coordinate bond
coordination number
indicates the number of coordinate bonds attached to the central metal ion
Monodentate ligand
can donate one pairof electrons to the central metal ion forming 1 coordinate bond
bidentate ligand
can donate two pairs of electrons to the central metal ion forming 2 coordinate bonds
Ligand substitution
one ligand in a complex ion is replaced by another ligand
ppt reaction
two aq solutions contain ions react to make an insoluble ionic solid
Buffer solution
system that minimises the change in pH when a small amount of acid or base is added. made of an acid and its conjugate base
end point
indicator contains equal con of HA and A-
equivalence point
he volume of one solution that exactly reacts with the volume of the othe solution. the centre of the verticle section
bronsted lowry acid
proton donor
bronsted lowry base
proton acceptor
conjugate acid base pair
comtains two species that be interconverted by the transdfer of a proton
kw the ionic product of water
1x10-14 at room temp mold2dm-6. [OH-][H+]
standard entropy
the entropy of one mole of substance understandard conditions
