topic 3 Flashcards
what are alkalis usually
metal hydroxides (solutions)
concentration formula
concentration = moles / volume
how to get from cm^3 to dm^3
divide by 1000
higher concentration of hydrogen IONS means what
more acidic
higher concentration of hydroxide means what
more alkaline
phenolphthalein indicator
alkaline = pink
acidic = colourless
methyl orange indicator
alkaline = yellow
acidic = red
litmus solution indicator
alkaline = blue
acidic = red
blue litmus paper indicator
blue -> red in acidic
stays blue in alkaline
red litmus paper indicator
alkaline: red -> blue
stays red in acidic
what happens if pH decreases by one unit
hydrogen ions increase by a factor of 10
core practical - investigate change in pH on adding powdered calcium hydroxide or calcium oxide to a fixed volume of dilute hydrochloride acid
add dilute HCl to beaker and measure pH
add weighted mass of calcium hydroxide and stir
record pH
keep adding weighted masses of calcium hydroxide until no more change to pH
draw a line graph with mass on horizontal axis with pH on vertical
draw line of best fit
(ignore anomalies)
dilute vs concentrated
concentrated = larger amount of substance in a given volume of solution
dilute = less amount of substance in a given volume of solution
what are bases
metal oxides or metal carbonates (solid)
what’s a strong acid
completely disassociate (separate or ionise) in water
what do weak acids do
partially disassociate (separate or ionise) in water
what’s the test for hydrogen
use a burning splint held at the open of a test tube of the gas
created a squeaky pop of its hydrogen
test for carbon dioxide
bubble the gas through limewater and it will turn cloudy
for any neutralisation reaction with an acid and an alkali the ionic equation is what
H+ + OH- -> H2O
How to prepare a dry insoluble salt
mix two solutions
filter mixture
rinse beaker with distilled water and pour through filter paper
pour distilled water over the
precipitate in the funnel
remove filter paper with solid on and dry in a warm oven
what is soluble in water
all sodium potassium and ammonium salts
all nitrates
most chlorides
most sulfates
sodium carbonate
potassium carbonate
ammonium carbonate
sodium hydroxide
potassium hydroxide
ammonium hydroxide
what’s insoluble in water
silver chloride, lead chloride
lead sulfate, barium sulfate, calcium sulfate
most carbonates
most hydroxides
cooper sulfate core practical udon water bath
add excess of copper oxide (insoluble) to your acid (sulphuric acid since it’s copper sulfate)
use a filter and filter paper to filter off any copper oxide that hasn’t reacted (solution should be blue as copper sulfate solution has formed)
evaporate water by placing final solution in a water bath
why is excess reactant of an insoluble salt added when preparing an acid
to ensure volume of acid reacts completely
excess reactant removed by filtration to only be left with salt and water
titration method used when
both reactants are soluble
titration method
add acid to burette using a funnel
record volume in the brhette
add known volume of alkali to conical flask add some indicator (phenolphthalein)
put conical flask on white tile to see colourchange better
add acid to alkali until solution goes colourless
calculate how much acid been added (titre)
repeat until you get concordat titres
