How many grams of nickel (+2) are required to replace all of the silver when 15.55 grams of agno3 are present?

2AgNO3 + Ni2+  = Ni(NO3)2 + 2Ag+

From the reaction, it can be seen that AgNO3 and Ni2+ has following amount of substance relationshep:

n(AgNO3):n(Ni)=2:1

From the relationshep we can determinate requred moles of Ni2+:

n(AgNO3)=m/M= 15.5/169.87=0.09 moles

So, n (Ni)=n(AgNO3)/2=0.045 moles

Finaly needed mass of Ni2+ is:

m(Ni2+)=nxM=0,045x58.7=2.64g

o conteúdo de calor de um sistema é igual à entalpia apenas para um sistema que é constante