properties And Uses Of Substances

Question 1

define atmospheric

Answer 1

Substance that can act as both an acid and a base

Question 2

Define acid

Answer 2

Compound containing hydrogen that dissociates in water forms hydrogen ions

Question 3

Define base

Answer 3

Compound reacts with an acid to form salt and water

Question 4

Define alkali

Answer 4

Base that dissociated in water to form hydroxide ions

Question 5

List key points of the oxide ion

Answer 5

Basic anion, small size and high (2-) charge. reacts w h20 produce hydroxide ions. hydroxide ions are the strongest base to persist in water

Question 6

Define desiccant

Answer 6

A substance used to remove moisture I.e magnesium oxide preserving books in the library

Question 7

which substance is produced at the anode or cathode from molten sodium chloride (electrolysis)

Answer 7

Sodium Na+ —> cathode positive electrode
Chlorine Cl- —> anode negative electrode

Question 8

chlorine produced at anode but h2 gas at cathode rather than Na+ why?

Answer 8

Only one type of ion disgraces at an electrode. Position of ion in electrochemical series affects ease of discharge.

Question 9

when metals reacts in water what happens?

Answer 9

They lose electrons to water to become positive ions. Attracts negative electrons back to the metal. This is an equilibrium process

Question 10

the lower the metal in the electrochemical series…

Answer 10

the more likely it is to be discharged

Question 11

give two reasons that increase the likelihood of which metal is discharged

Answer 11

lower in the electrochemical series, more concentrated ions in solution

Question 12

why do transition atoms lose electrons to form positive ions

Answer 12

Lose their 4s electrons before their 3d electrons. Form compounds with metal ions in +2 oxidation state

Question 13

in solution what do transition metal compounds form

Answer 13

Complex ions

Question 14

what is a complex ion and a ligand

Answer 14

Consists of central metal ion surrounded by ligands. Ligand is molecule/ion donates pair electrons to central transition metal ion forming dative covalent bond

Question 15

What are transition metal complexes used for?

Answer 15

industrial catalysts

Question 16

iron used as catalyst in Hager process synthesis of ammonia, what does it do?

Answer 16

Speeds up reaction by lowering activation energy, N2 bonds and H2 bonds can be broken readily

Question 17

why does Haber process reduce energy demands

Answer 17

Less fuel needs, fossil fuels conserved n fewer co2 emissions. ammonia is used for making fertilisers crop yield

Question 18

alumina ( aluminium oxide) is a refractory material define

Answer 18

material that is physically and chemically stable at high temperatures e.g over 3000C

Question 19

define calcination

Answer 19

Heating to high temperature to remove free and chemically bonded water from the condensate ( liquid collected by condensation)

Question 20

What’s the Bayer process name the steps

Answer 20

Digestion, clarification, precious toon and calcination to produce a product of alumina

Question 21

What’s the hall heroult main aim?

Answer 21

To extract aluminium from alumina

Question 22

What are inert platinum electrodes used for in electrolysis of brine?

Answer 22

Prevent reaction with the gases produced

Question 23

What specialised cells are needed if the products are chlorine and sodium hydroxide jn brine electrolysis

Answer 23

Diaphragm and membrane cell

Question 24

why can’t titanium be extracted using carbon?

Answer 24

Titanium carbide (TiC) will form and carbide makes titanium brittle

Question 25

why are products used based on the properties they have?

Answer 25

Physical or chemical properties. E.g aluminium is reactive so it’s extracted using electrolysis cannot be extracted using cheaper reduction carbon method

Question 26

define electrolysis

Answer 26

Decomposition of an electrolyte by an electric current.

Question 27

When brine is electrolysed 4 products are formed name them

Answer 27

Hydrogen, chlorine and sodium hydroxide