3.1.3 group 7
No description yet. This curated deck is ready for daily study.
Card preview (19)
describe the properties of the first 4 halogens
F2 pale yellow gas Cl2 greenish gas Br2 red liquid I2 shiny grey solid
state and explain the trend of melting points down the halogens
increases • molecules become larger • more electrons so more attraction to nucleus • stronger london forces between molecules so more energy needed to overcome
state and explain the trend of electronegativity down the halogens
decrease • shielding increases as there are more shells • electrons in the covalent bond are further from nucleus so attraction decreases to the nucleus
give the basic equation of a halogen acting as an oxidising agent
X2(?) + 2e- —> 2X-(aq)
state and explain the trend of oxidising power down the halogens
decrease • shielding increases as shells increase • electrons are further away from nucleus so less attraction • so less likely to gain an electron
give the basic equation of a halide acting as a reducing agent
2X-(aq) —> X2(?) + 2e-
state and explain the trend of reducing power down the halides
increases • number of shells in the ions increases so shielding increases • less attraction of outer electrons to nucleus so they are more easily lose
give an equation and state the observations of Cl2 reacting with KBr
colourless —> yellow solution 2KBr(aq) + Cl2(aq) —> 2KCl(aq) + Br2(aq)
give an equation and state the observations of Cl2 reacting with KI
colourless —> brown solution 2KI(aq) + Cl2(aq) —> 2KCl(aq) + I2(aq)
give an equation and state the observations of Br2 reacting with KI
colourless —> brown solution 2KI(aq) + Br2(aq) —> 2KBr(aq) + I2(aq)
what are the changes in displacement reactions of halogens if an organic solvent is added
Cl - colourless Br -yellow I -purple
give the method of reacting halide ions with AgNO3
1) make solution of halide 2) acidity with dilute nitric acid to prevent formation of insoluble silver salts 3) add AgNO3 solution 4) if ppt is formed add dilute NH3 5) if still ppt add concentrated NH3
give the colour ppt that is formed when cl, br and i react with AgNO3
AgCl white AgBr cream AgI yellow
how can you tell the difference between AgCl AgBr and AgI
AgCl dissolves in dilute ammonia whereas AgBr and AgI do not AgBr dissolves in concentrated ammonia whereas AgI does not
define disproportionation
when an element is simultaneously oxidised and reduced
define electronegativity
the relative tendency of an atom in a covalent bone in a molecule to attract electrons in a covalent bond to itself
give the reaction of chlorine with water and give the colour change when indicator is added
Cl2(g) + H2O(l) —> HClO(aq) + HCl(aq) will first turn red then colourless as HClO bleaches the colour
give the equation of Cl with NaOH and give the colour change
Cl2(aq) + 2NaOH(aq) —> NaCl(aq) + NaClO(aq) + H2O(l) colourless
what is a use of NaClO
bleach to kill bacteria