Chapter 7 Flashcards
strength of acids g7 (binary)
increases down the group
atomic radius increases down the group, the more weakly electrons in outer levels are held to the nucleus, more easily ionised, stronger dissociation constant, stronger acid
strength of acid accross period
increases, increasing electronegativity, polarity increases, more easily iniosed, higher dissociatoin constant, stronger acid
with number of oxygen atoms`
more electronegativity, the more acidic the h atom becomes
down group 7 oxyacid
electronegativity decreases, for oxyacids withthe same numebnr of o atoms, electronegtivity influemces strength
with an increase in negative charge
the weaker the acid as the more negative the charge on a compound, the more strongly it holds onto its h proton, more weakly ionised
the region where the [HA]:[A-] ratio has more [HA]
-(mention the strengths of the analyte/titrand and titrants and how that affects the subseuqent conjugate and the pH at the equivalence point)
-prior to the equivalence point there is more HA than A- uin the solution as there is more acid than base prior to the equiavlence point and so less A- (conjugate base/acid) will have been produced as a result of neutralisation.
-as the equivalence point approaches the amount of A- equalizes with the amount of HA, and after it, the amount of A- will exceed the amount of HA
the region where the [HA]:[A-] ratio has more [A-]
-After the equivalence point there are more A- than HA in the solution as there is excess titrant added and thus more dissociation. At the equivalence point HA and A- are equal, and beyond that additional titrant added from the buret shifts the balance to an excess in A-
pop test
Hydrogen ignites in air. If hydrogen is present in a test tube, a lighted splint held near its mouth ignites with a squeaky pop.
limewater test
Carbon dioxide reacts with calcium hydroxide solution to produce a white precipitate of calcium carbonate.
Limewater
is a solution of calcium hydroxide. If carbon dioxide is bubbled through limewater, the limewater turns milky or cloudy white.
using a thermometer
-exothermic neutralisation
-point a: temp increases as more reaction occurs. the temperature is rising as the reaction takes place. neutralisation is an exothermic reaction, thus, as the acid and base react to forma neutral solution of salt and water, the overall temperature increases
-point b: at neutralisatoin point, temp stops rising when all (original solution) is used up in neutralisation. the tempersture stops riisng as all availible moclules have been used up in the formation of salt and water over the course of the neutralisation reaction. the point of complete neutralisation has been reached and so the temperature cannot rise anymore as no more reaction can take place due to the absence of reaction molcules
-point c: temp drops as more unnecessary cold (additional solution) is added
using a conductivity meter
-point a: conductivity falls as faster (hydorxide or hydronium) ions are replaced with slower ()ions.
-point b: neutralisation point, no availible ions for condcuivity as all have been used up in the formation of salt and water and the new ions do not make up for this loss as they are slower moving
-point c: conductivity rises due to the presence of excess (hydroxide/hydornium)ions.
conductivity
the conductivity of solution is a measure of how well it conducts electricty. slutions conduct electrviity because of how mnay ions they contain. how well they conduct depends on the number and size of ions present as smaller ones move faster thanm bigger ones and so can help cpnduct electricity better
Relative atomic mass
The relative atomic mass of an element is the weighted average mass or the isotopes of the element
- measured on a scale in which a carbon-12 atom weighs exactly 12 units
