unit 2 test 3
how to find ppm (parts per million)
conc in gL^-1 = (mass of solute (g))/(volume of solution (L))
can also be ug g^-1 lr mgL^-1
conc in %(m/m)
(mass solute (g) / mass of solution (g)) x 100
conc of %(m/n)
(mass of solute (g) / solution (mgL^-1)) x 100
molac conc (M or molL^-1)
moles/vol solution (L)
ionic lattice does what in solution
dissociates
how they deal with hard water
create precipitates using the ions and fish out all solids
what is hard water
water with dissolved ions (shit in it)
what is turbidity
measure of how cloudy water is
what turbidity caused by
fine particles in suspension (like clay) or bacteria
why remove phosphate ions
because they can cause eutrophication
what is wastewater (heavy metal)
byproduct of industrial and mining processes
heavy metal ion contamination
can lead to birth defects/organ damage etc
what solubility measure
how much solute will dissolve in given amt of H2O at given temp
what solubility depend on
attraction of solute particles to the H2O
(high attraction forms low energy bonds with it) (thus high solubility)
also temp
how does temp affect solubility
(diff for diff substances)
as temp increases, particles more kindtic energy
thus easier to overcome activation energy (break initial bonds/possibly dissolve)
most solids more soluble higher temp
agitation/mixing affect
not increase solubility
increase SA of solid where dissolving can take place
this more mix=more dissolve
(tea stirring?)
solubility of gasses/liquids
like dissolve like
polar liquids dissolve (miscible)
non polar form liquid (immiscible)
gasses less soluble as increase temp
homogenous mixture meaning
a mixture
all mixed together (combined)
heterogenous mixture meaning
called solution
not necessarily combined (can be diff things together)
saturated solution meaning
confains max amt of solute for the vol of solution (at particular temp)
unsaturated solution meaning
contains less than max amt of solute could be added to solution
supersaturated solution meaning
unstable solution
when solution contains more than max solute at given temp
how supersaturated solution occur
when saturated solution slowly cooled down
causes small crystal seeds or dust
(excess solute crystallises)
what if above the line (curve on graph)
super saturated
what if below the line (on graph)
unsaturated
what does curve show on graph
mass of solute in saturday solution at given temp
what is crystallisation
process of dissolved salts precipitating out of solution as solid
crystallisation caused how?
cooling supersaturated solution
evaporating solvent (less solute can dissolve)
reducing pressure (evap at lower temp)
what is stochiometry
calculations based on chemical equations (moles)
what does stochiometry determine
moles of smt
important to use molar ratios detailed in the questions (balance)
what does a chemical equation not tell us
rate of reaction
endo/exo thermic
specific pathways for molecules
what is a volumetric analysis
measuring of vol of solutions
thus finding uninown conc
thus using c=n/v
what is a standard solution
substabce with known conc
used to find conc of unknowns accurately
what are the qualifications of a primary standard
solid w/high state of purity and soluble in any solvent used
accurate known formula
stable (composition mustnt change over time (or h2o or co2))
cheap/readily available
relatively high molar mass (weighing errors)
qualifications of primary standard
solid w/high state of purity and soluble in any solvent used
accurate known formula
stable (composition mustnt change over time (or h2o or co2))
cheap/readily available
relatively high molar mass (weighing errors)
secondary standard
can be prepared standardusing it (conc) against primary standard
anhydrous meaning
no h2o
what is a titrant
solution in rhe burette
usually primary stabdard (solvent 1)
what is the first solution used for is columetrci technique
to find the unknown conc of solution 2 (usually the analyte)
what should glassware be washed with
distilled H2O prior
so no contaminatoom
what should the piperte be primed with
the solution that is going to be used in the task
what is an end point of an indicator
when the indicator triggers (permanent colour change occurs)
what is the equivelanve point
when there is the correct stoichiometric ratio
usually at abt pH 7
alternatives to indicatirs
pH meter
potentiometer
measuring conductivity
what are uncertanties in equipment
glassware has uncertanties
intolerance at higher temp (thus quote tolerance)
usually one tenth uncertantie of wtv the lowest number is on a scale
what are concordant titres
three or more titres within 0.1ml
what is miscible
substances that can form homogenous solution (no layers, completely dissolved)
what is immiscible
substances that do not dissolve, instead separating to form distinct layers
minerals
rocks/soil found
soluble salts are ions
commonly sodium chloride
organometallic compounds
ionic compounds
heavy metals
do not degrade in humans, cause cancer
can be converted to organometallic compounds and fatty tissue
salinity/eectrical conductivity
when salts dissolve in H2O, dissociate and produce ions which carry electrical charge
thus salinity = electrical conductivity
to find empirical formula of salts
weigh sample of hydrated salt
heat sample to remove water of crystallisation
weight resultant anhydrous (repeated until same multiple times)
calc using chem formula
saline meaning
containing salt
what is the limiting reactant
the reactant completely used up in the reaction
excess reactant
reactant left over when limiting used up (molar ratio explains how much)
what is colorimetry
intensity of colour correlates to conc
physically see the colour
amt of light absorbed correlates to ingrediants ratio
(thus use calibration curve)
dilution implies what equation
c1V1=c2V2
properties of gas
particles moving constantly and at random
particles very dad apar, volum of particles very small compared to volume gas occupies
force of attaction and repulsion between particles practically zero
particles collide with eachother and contained walls, exerting pressure (collisions perfectly elastic(no energy lost))
higher temp = faster bc more kinetic energy
properties of gas
particles moving constantly and at random
particles very dad apar, volum of particles very small compared to volume gas occupies
force of attaction and repulsion between particles practically zero
particles collide with eachother and contained walls, exerting pressure (collisions perfectly elastic(no energy lost))
higher temp = faster bc more kinetic energy
what is gas pressure
force exerted on a unit area of a surgace bu psrticles of gas as they collide with each other and walls of container
pressure of fixed amount is independant of actual gas considered
gas pressure equation
P is defined as force exerted per unit area
or P(pascal/Pa)=force/area
or Nm^-2= N/m^2
what is atmospheric pressure
measured air pressure is sum of individual gas pressures
measured by barometer
1 bar = 100,000 pa
standar lab conditions
25 degrees celcius
100kPa
Boyles Law
is volume of fixed amt of gas at constant temp is halved, pressure doubled, i.e P1V1=P2V2
Charles Law
if temp of fixed amr of gas at constant pressure doubled, volume also double, i.e. V1/T1=V2/T2
Avagadros law
if number of mole of a gas at constant pressure and temp is doubled, volume also double i.e. V/n =K
what is molar gas volume
volume occupied by a mole of a substance at a given temp and pressure
at SLC one mole of gas occupies 24.8 litres
what is molar gas volume
volume occupied by a mole of a substance at a given temp and pressure
at SLC one mole of gas occupies 24.8 litres
equation for molar gas volume
at given temp and pressure
n=V/Vm
meaning at SLC
nslc = V/24.8 (which is one mole of any gas at slc)
what is the universal gas equation
PV= nRT
R has a value of 8.31 J K^-1 mol^-1 when:
Pressure is measured in kPa
volume is in Litres
Temp is in Kelvin
quantity of gas is in moles (n)
what is the ideal or universal gas equation
PV= nRT
R has a value of 8.31 J K^-1 mol^-1 when:
Pressure is measured in kPa
volume is in Litres
Temp is in Kelvin
quantity of gas is in moles (n)
what is ideal or unjversal gas equation
PV= nRT
R has a value of 8.31 J K^-1 mol^-1 when:
Pressure is measured in kPa
volume is in Litres
Temp is in Kelvin
quantity of gas is in moles (n)
celcius to Kelvin
C+ 273 =K
conversion for atmospheric pressure
100kPa = 0.987 atm
what is GWP
global warming potential is the energy of one tonne of gas will absorb compared to one tonne of carbon dioxide (which has 1GWP over a 100 year period)
CH4 >20
H2O not measured this way bc levels not directly linked with human activity
greenhouse effect
natural process that warms eaths surface as the suns energy reaches earths atmoshpere and some is retained/absorbed
enhanced greenhouse effect
effect of increasing concentrations of greenhouse gases in atmosphere as a result of human activity
global warming
gradual increzse in overall temp of earths atmosphere
climate change
long term shifts in temp and weather pattern (more bc of humans that global warming)