# Activity series and element oxidized and reduced

dana
Tue, 04/16/2013 - 11:27

oxidation state, identify whats reduced & oxidized, balance half reactions for K + CaCl2 = KCl +Ca

Also activity series for A, C, X, M AND Y

ELEMENT C REACTS WITH X+ AND M+ BUT NOT WITH A+

ELEMENT M REACTS WITH Y2+ BUTNOT WITH X+

ELEMENT A REACTS WITH C+ M+ X+ AND Y2+

I miss class that day so I'm so confused

the activity series you need for the single replacment reaction like the one mentioned here in your problem,,

K + CaCl2 = KCl +Ca

go to this you tube video to uinderstand this

http://www.youtube.com/watch?v=BHdV3-s3JmY

as K is in elemental form its oxidation no = 0

The oxidation number of all Group 2A metals = +2 (unless elemental).So, Ca has +2 in CaCl2 and Cl o.n can be found using the rule that : The sum of the oxidation numbers of all atoms (or ions) in a neutral compound = 0.So,

let say x is the oxidation number of Cl and +2 is oxidation number of Ca then

+2 + x *2 = 0

x* 2 = -2

x = -1

so Cl oxidation number of -1

now , on the product side

Ca is in elemental form so it has 0 oxidation number

The oxidation number of all Group 1A metals = +1 (unless elemental).So, K which is group 1 element have +1 oxidation number ,and using the rule that The sum of the oxidation numbers of all atoms (or ions) in a neutral compound = 0 we will find the oxidation number of Cl

+1 + x = 0

x = -1

so, Cl = -1 oxidation number

so, you see now how the oxidation number is changeing of each eleemt

Ca from +2 -------> 0

K from 0 ---------> +1

Cl -1 ( no change )

so, as

Oxidation is loss of electrons. ( charge increases)Reduction is gain of electrons.(charge decreases)K is oxidised and Ca is reduced