(Green) redox Flashcards
(Green) redox
CuO + H2 —-> H2O + Cu
Which substance is being oxidised
Which substance is being reduced
Explain why
Which substance is being oxidised? H
Which substance is being reduced? CuO
Explain why gained an O atom
Explain why lost an O atom
give the definitions of oxidation and reduction
OXIDATION is when a species LOSES one or more ELECTRONS
REDUCTION is when a species GAINS one or more ELECTRONS
describe what oxidation involves
increase in oxidation number
loss of electrons
gain of oxygen or loss of hydrogen
describe what reduction involves
decrease in oxidation number
gain of electrons
loss of oxygen or gain of hydrogen
what is the definition of redox
A chemical reaction that takes place between an oxidizing substance and a reducing substance. The oxidizing substance loses electrons in the reaction, and the reducing substance gains electrons.
is glucose a reducing agent or oxidising agent
reducing agent , remember there reducing sugers
what is the definition of oxidation number
Oxidation Number is the charge the species in a molecule or ion would have if the bonding was 100% ionic.
info card (read and recite)
1) Elements in their uncombined state have an oxidation number of zero.
2) The sum of all the oxidation numbers in an uncharged molecule is zero.
3) The sum of all the oxidation numbers in an ion is the charge on the ion.
4) The oxidation number of hydrogen is +1 except in metal hydrides when it is -1.
5) Being the most electronegative element, fluorine (unlike the other halogens) always has the oxidation number -1, and can bring out the highest oxidation number in any element it reacts with.
6) The oxidation number of oxygen is -2 apart from in compounds with fluorine or in peroxides (-1).
7) The oxidation number of chlorine is -1 apart from in compounds with fluorine or oxygen
8).The oxidation number of all the group one and two metals is +1 and +2 respectively.
9) In any combination of two elements, the more electronegative one has the negative oxidation number.
what is the oxidation number of :
Ba in BaCl2
+2
what is the oxidation number of :
Li in Li2O
+1
what is the oxidation number of :
P in P2O5
+5
what is the oxidation number of :
P in P2O3
+3
what is the oxidation number of :
C in CO
+2
what is the oxidation number of :
I in I2
0
what is the oxidation number of :
C in CCl4
+4
what is the oxidation number of :
I in I-
-1
what is the oxidation number of :
Cr in CrO4-2
+6
what is the oxidation number of :
P in PO43-
+5
what is the oxidation number of :
Cr in Cr2O72-
+6
what is the oxidation number of :
O in H2O2
-1
what is the oxidation number of :
Mn in MnO2
+4
what is the oxidation number of :
Xe in XeF4
+4
what is the oxidation number of :
N in NH3
-3
what is the oxidation number of :
N in N2O4
+4
what is the oxidation number of :
H in LiH
-1
what is the oxidation number of :
S in Na2S4O6
+2.5
What is the problem with the oxidation number of sulfur in Na2S4O6?
S has an oxidation number of +2.5, cannot have ½ electron! But this method works for electron counting purposes
what is the definition of Disproportionation
Disproportionation is the simultaneous oxidation and reduction of atoms of the same element
what is the oxi state and colour of MnO4-
purple
+7
what is the oxi state and colour of MnO4 2-
green
+6
what is the oxi state and colour of MnO2
brown
+4
what is the oxi state and colour of Mn2+
very pale pink
+2
what is the colour of Cu 2+
pale blue
what are the observations of adding CuSO4
to Chloride ions and starch
solution remained pale blue
what are the observations of adding CuSO4
to Bromide ions and starch
solution remained pale blue
what are the observations of adding CuSO4
to Iodide ions and starch
solution turned brown. When starch added it turned blue/black
what observations do you see when adding Fe2+
to hydroxide ions
pale green ppt. starts to turn brown with time Fe(OH)2(s)
what observations do you see when adding Fe2+
to Thiocyanate (SCN-)
No change (turned slightly pink with time)
what observations do you see when adding Fe2+
to Iodide (I-)
No change
what observations do you see when adding Fe2+
to Manganate (MnO4-)
pale pink/slight brown ppt REDOX
what observations do you see when adding Fe2+
to Silver Ag+
sparkly particles appeared Ag(s) REDOX
what observations do you see when adding Fe3+
to OH-
Red/brown ppt. Fe(OH)3(s)
what observations do you see when adding Fe3+
to Thiocyanate SCN-
Blood red solution Fe(SCN)3(s)
what observations do you see when adding Fe3+
to Iodide I-
orange solution I2 turned black with starch REDOX
what observations do you see when adding Fe3+
to Manganate MnO4-
No change
what observations do you see when adding Fe3+
to Silver (Ag+)
No change