properties And Uses Of Substances Flashcards
define atmospheric
Substance that can act as both an acid and a base
Define acid
Compound containing hydrogen that dissociates in water forms hydrogen ions
Define base
Compound reacts with an acid to form salt and water
Define alkali
Base that dissociated in water to form hydroxide ions
List key points of the oxide ion
Basic anion, small size and high (2-) charge. reacts w h20 produce hydroxide ions. hydroxide ions are the strongest base to persist in water
Define desiccant
A substance used to remove moisture I.e magnesium oxide preserving books in the library
which substance is produced at the anode or cathode from molten sodium chloride (electrolysis)
Sodium Na+ —> cathode positive electrode
Chlorine Cl- —> anode negative electrode
chlorine produced at anode but h2 gas at cathode rather than Na+ why?
Only one type of ion disgraces at an electrode. Position of ion in electrochemical series affects ease of discharge.
when metals reacts in water what happens?
They lose electrons to water to become positive ions. Attracts negative electrons back to the metal. This is an equilibrium process
the lower the metal in the electrochemical series…
the more likely it is to be discharged
give two reasons that increase the likelihood of which metal is discharged
lower in the electrochemical series, more concentrated ions in solution
why do transition atoms lose electrons to form positive ions
Lose their 4s electrons before their 3d electrons. Form compounds with metal ions in +2 oxidation state
in solution what do transition metal compounds form
Complex ions
what is a complex ion and a ligand
Consists of central metal ion surrounded by ligands. Ligand is molecule/ion donates pair electrons to central transition metal ion forming dative covalent bond
What are transition metal complexes used for?
industrial catalysts
iron used as catalyst in Hager process synthesis of ammonia, what does it do?
Speeds up reaction by lowering activation energy, N2 bonds and H2 bonds can be broken readily
why does Haber process reduce energy demands
Less fuel needs, fossil fuels conserved n fewer co2 emissions. ammonia is used for making fertilisers crop yield
alumina ( aluminium oxide) is a refractory material define
material that is physically and chemically stable at high temperatures e.g over 3000C
define calcination
Heating to high temperature to remove free and chemically bonded water from the condensate ( liquid collected by condensation)
What’s the Bayer process name the steps
Digestion, clarification, precious toon and calcination to produce a product of alumina
What’s the hall heroult main aim?
To extract aluminium from alumina
What are inert platinum electrodes used for in electrolysis of brine?
Prevent reaction with the gases produced
What specialised cells are needed if the products are chlorine and sodium hydroxide jn brine electrolysis
Diaphragm and membrane cell
why can’t titanium be extracted using carbon?
Titanium carbide (TiC) will form and carbide makes titanium brittle
why are products used based on the properties they have?
Physical or chemical properties. E.g aluminium is reactive so it’s extracted using electrolysis cannot be extracted using cheaper reduction carbon method
define electrolysis
Decomposition of an electrolyte by an electric current.
When brine is electrolysed 4 products are formed name them
Hydrogen, chlorine and sodium hydroxide
