Analysis of ions

Question 1

where are galvanic cells in everyday life

Answer 1

they are found in everyday electronic devices, such as mobile phones and calaculators, as a source of electricity

Question 2

in electronic devicezs, where does the electricityy come from?

Answer 2

galvanic cells, the source of energy comes from a spontaneously occuring redox reaction between two metals

Question 3

what are the componenets of a galvanic cell

Answer 3

two half cells and two electrodes (anode and cathode), salt bridge, voltmetre and wire

Question 4

what differs between the two half-cells

Answer 4

one has a negatively charged electrode (anode) so oxidation occurs and the other has a posiitvely charged electrode (cathode) so reduction occurs

Question 5

acronym to remember where reduction/oxidation occurs in galvanic cells

Answer 5

REDCAT and ANOX

Question 6

REDCAT ANOX

Answer 6

reduction occurs at the cathode, anode is the site of oxidation

Question 7

two functions of the salt bridge

Answer 7

prevents build up of charge in each half cells and connects two solutions of the half cells to allow for ion flow

Question 8

how does the salt bridge prevent build up of charge

Answer 8

the anion of the salt in the salt bridge will go to the halfcell of oxidation as it is becomingg positvely charged and the ccation of the salt will go to the site of reduction as it is gaining electrons

Question 9

what are tthe electtrodes

Answer 9

each electrode is a solid metal immersed in a solution of that same metals cations, the electrodes are connected by a wire

Question 10

what is tthe flow of electrons in a galvanic cell

Answer 10

the anode loses electrons, which then travel through the exterrnal circuit and to the cathode which gains the electrons

Question 11

what is the function of the wire in galvanic cells

Answer 11

to connect the electrodes for electricity output

Question 12

how does the mass of the two half-cells change

Answer 12

the half cell will the anode will undergo oxidation, so loses electrons and therefore decreases in mass, whereas the half-cell with the cathode will undergo reduction, so gains electrons and therefore increases in mass

Question 13

what type of reactions are redox reactions

Answer 13

exothermic

Question 14

how do galvanic cells convert energy

Answer 14

they convert chemical energy into electrical energy

Question 15

when is water toxic

Answer 15

when water contains high concentrations of salt ions, it is toxic to plants, animals and humans

Question 16

how is the salinity of water tested

Answer 16

we test the electrical conductivity of a sample of water

Question 17

how does testing the electrical conductivity of water show the salinity

Answer 17

because pure water is a poor conductoe but saline water with a high concentration of ions will have a higher conductivity

Question 18

hydroscopic salts

Answer 18

salts that absorb water from its surroundibngs and have it within their chemical formula

Question 19

water of crystallisation

Answer 19

the molecules of water bonded into the crystals of a salt, which have crystallised out of water, forming a hydrated salt

Question 20

when salt crystals are formed in the absense of water, the salt is considered…

Answer 20

anhydrous

Question 21

the dot between a salt and H2O in a formula represnts

Answer 21

used in hydrated ssssalts and is used to indicate that water of crystalliation molecules are bonded to tthe salt

Question 22

CuSO₄.5H₂O is called

Answer 22

copper (II) sulfate pentahydrate as each copper sulfate molecule is bonded to five water molceules

Question 23

how can the water of crystallisation be removed

Answer 23

by heating the hydrated salt and making it anhydrous