Law of equivalence [closed]








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100g mixture of nitrates two metals a and b is heated to constant weight containing corresponding 50g oxides of the metals
{i.e METAL NITRATES(100g) --->OXIDES(50g) +(some nitrogen oxide gases) } . 
The equivalent weight of a and b are 103 and 31 respectively .What is the percent composition of a and b in the mixture? 


In this question book has given that 


equivalent weight of nitrate of a= equivalent weight of a + equivalent weight of nitrate ion 


And similarly, 
equivalent weight of oxide of a= equivalent weight of a + equivalent weight of oxide


How to find EQUIVALENT WEIGHTS of nitrate and oxide.Can you tell me how should i calculate it or where am i going wrong?Or can you just solve this question?


![enter image description here](https://i.stack.imgur.com/96JUE.jpg)




Finally your problem reads correctly! Do you recall how equivalent weights are calculated for redox species and anions? What is the charge on NO$\_3^-$ ? It is -1, so equivalent weight is "molecular weight"/ absolute value charge. = Anything divided by 1 stays the same.


Coming to the oxide, O$^{2-}$, the charge is -2. So equivalent weight is 16/2=8.


Keep in mind that equivalent weights are highly dependent on the reaction to reaction. Don't apply these rules without understanding the nature of the reaction. Hope it is clear now. 


As an exercise, calculate the equivalent weight of KMnO$\_4$, when it reduces to Mn$^{2+}$ in acidic medium. This time, you have to check how many electrons are involved.


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