Chapter 12 - Redox reactions Flashcards
define redox reaction
reaction where both oxidation and reduction takes place
define oxidising agent
assists other substances to oxidise
define reducing agent
assists other substances to reduce
table for OXIdation
OXYgen (+)
OXYdising agent (+)
hydrogen (-)
electrons (-)
common non redox reactions
- neutralisation
- decomposition
- double displacement
common redox reactions
- single displacement
- combustion
- synthesis
test for oxidising agent and observations
add aqueous potassium iodide
= potassium iodide turns from colourless to brown
test for reducing agent and observations
add acidified potassium manganate
= acidified potassium manganate turns from purple to colourless
examples of oxidising agents (4)
- acidified potassium manganate
- halogens
- oxygen
- acidified potassium dichromate
examples of reducing agents (5)
- aqueous potassium iodide
- carbon monoxide
- carbon
- group one metals and hydrogen - sulfur dioxide
examples of both oxidising and reducing agent
water and hydrogen peroxide
observation when oxidising agent is being reduced
acidified purple potassium manganate turns colourless
observation when reducing agent is being reduced
colourless potassium iodide turns brown
element / compound rule for oxidation
0
ion rule for oxidation
see charge of ion
hydrogen rule for oxidation
+1
oxygen rule for oxidation
-2
transition metal rule for oxidation
see roman letter
group 1 elements rule for oxidation
+1
group 2 elements rule for oxidation
+2
group 3 elements rule for oxidation
+3
rules in calculating oxidation state
the total has to be zero and individual elements can be solved with the rules
4 types of doing redox reactions
- oxygen transfer
- hydrogen transfer
- electrons transfer
- oxidation state
explanation for oxidation in oxygen transfer
CuO + H2 = Cu + H2O
CuO + H2 = Cu + H2O
= hydrogen has become oxidised
= it gained oxygen to become water
= copper (ll) oxide is the oxidising agent
explanation for oxidation hydrogen transfer
2HCl + F2 = 2HF + Cl2
2HCl + F2 = 2HF + Cl2
= hydrochloric acid has become oxidised
= it lost hydrogen to become chlorine gas
= fluorine is the oxidising agent
explanation for oxidation electrons transfer
Zn + Cu2+ = Zn2+ + Cu
Zn + Cu2+ = Zn2+ + Cu
= zinc metal has been oxidised
= it lost two electrons to become Zinc ion
= copper ion is the oxidising agent
explanation for oxidation oxidation state
K + NaCl = KCl + Na
K + NaCl = KCl + Na
= potassium has been oxidised
= its oxidation state increased from o in K to +1 in KCl
= sodium chloride is the oxidising agent
explanation for reduction in oxygen transfer
CuO + H2 = Cu + H2O
CuO + H2 = Cu + H2O
= copper (ll) oxide has been reduced
= it lost oxygen to become copper metal
= hydrogen is the reducing agent
explanation for reduction hydrogen transfer
2HCl + F2 = 2HF + Cl2
2HCl + F2 = 2HF + Cl2
= fluorine has been reduced
= it gained hydrogen to become hydrogen fluoride
= hydrochloric acid is the reducing agent
explanation for reduction electrons transfer
Zn + Cu2+ = Zn2+ + Cu
Zn + Cu2+ = Zn2+ + Cu
= copper ion has been reduced
= it gained 2 electrons to become copper metal
= Zn is the reducing agent
explanation for reduction oxidation
K + NaCl = KCl + Na
K + NaCl = KCl + Na
= Sodium chloride is being reduced
= its Oxidising agent decreased from +1 in NaCl to 0 in Na
= potassium is the reducing agent
theory : how to test for reducing agent like SO2
use acidifies potassium manganate (Vll), place on a filter paper and if gas evolved turns purple potassium manganate (Vll) colourless, gas is sulfur dioxide
theory : how do you test for oxidising agent like F2
use aqueous potassium iodide and bubble gas evolved through KI if it turns colourless potassium iodide brown, the gas is a halogen
theory : explain how potassium iodide can be used to test for an oxidising agent
When colourless aqueous potassium iodide is added to added to an oxidising agent, it turns brown due to iodine solution produced
