ES 6 Flashcards
(27 cards)
how do you make hydrochloric acid HCl
(simple way)
use hydrogen gas and chlorine gas to form hydrogen chloride gas
H2 (g) + Cl2 (g) —- 2HCl (g)
then dissolve HCl gas into water
what is the equation for atom economy
R formula mass of the desired product/ R formula mass of all reactants used X 100
R = relative
what reactions always have 100% atom economy and why
addition reactions as they only form one product
preparation of HCl as a co product (2 steps)
ethene + chlorine —- 1,2-dichloroethane
650K
1,2-dichloroethene ——— chloroethene + HCl (g) (undergoes thermal cracking)
then pass HCl through water to make hydrochloric acid
why is phosphoric acid used in reactions to make HBr and HI
it makes pure HBr and HI
what is the equation for making the hydrogen halide HCl using sulfuric acid
NaCl (s) + H2SO4 (aq) —- NaHSO4 (aq) + HCl (g)
how can hydrochloric acid be made form sodium chloride + sulfuric acid
HCl gas will be made and the moist air creates droplets of hydrochloric acid
what is the equation when making the hydrogen halide HBr using sulfuric acid
NaBr (s) + H2SO4 (aq) —- NaHSO4 (aq) + HBr (g)
what makes the products of the reaction of the hydrogen halide HBr impure
bromide ions are strong enough reducing agents to reduce sulfuric acid to sulfur dioxide which makes the product impure
what is the equation when making the hydrogen halide HI using sulfuric acid
NaI (s) + H2SO4 (aq) —- NaHSO4 (aq) + HI (g)
what makes the products of the reaction of the hydrogen halide HI impure
iodide ions are strong reducing agents so reduce sulfuric acid to hydrogen sulfide making the product impure
what acid is used to make the hydrogen halides sodium chloride and fluoride
sulfuric acid
what acid is used to make the hydrogen halides sodium bromide and iodide
phosphoric acid
what is the trend in thermal stability of hydrogen halides
decreases down the group since bond enthalpy decreases down group 7
HI is easiest to break down
what is the trend and features of acidity of the hydrogen halides
trends-
acidity increases in the hydrogen halides down the group
features-
HCl, HBr and HI almost completely dissociate to form oxonium ions
e.g. H20 + HCl —- H3O+ + Cl-
results of the reaction of hydrogen halides with ammonia
salts are formed
white cloud of ammonium halide is formed
results of the reaction of hydrogen halides with sulfuric acid
HF and HCl do not react with sulfuric acid
HBr makes sulfur dioxide (SO2)
HI makes hydrogen sulfide (H2S)
what can be seen + created when adding sulfuric acid to potassium chloride
white fumes
HCl + KHSO4
what can be seen + created when adding sulfuric acid to potassium bromide
brown fumes
HBr + Br2 + SO2
what can be seen + created when adding sulfuric acid to potassium iodide
purple fumes
HI + H2S
what are the results of the addition of ammonia solution to KCl, KBr and KI
white fumes are created
NH4Cl, NH4Br, NH4I
what is the effect potassium halides KCl, KBr, and KI have on damp blue litmus paper
litmus paper turns red
what is the effect of KCl, KBr and KI on potassium (VIII) manganate solution
KCl stay purple
KBr goes from purple to colourless (test for sulfur dioxide)
KI stays purple
what is the effect of lead ethanoate solution on KCl, KBr and KI
KCl has no change
KBr has no change
KI turns black (positive test for hydrogen sulfide)
