Zn + HNO3 = Zn(NO3) + NO2 + H2O

balance this equation by oxidation number method step wise 

Asked by govtsecschoolnayaganv051 | 14th Aug, 2018, 06:06: PM

Expert Answer:

Zinc reacts with conc. nitric acid to produce zinc nitrate, nitrogen dioxide and water.
 
 begin mathsize 20px style Skeleton space reaction
Zn space plus space HNO subscript 3 space rightwards arrow Zn left parenthesis NO subscript 3 space end subscript right parenthesis subscript 2 space plus space NO subscript 2 space plus space straight H subscript 2 straight O
Step space 1
Oxidation space numbers comma
Zn with 0 on top space space space plus space space straight H with plus 1 on top left parenthesis straight N with plus 5 on top stack straight O subscript 3 with negative 2 on top right parenthesis subscript 3 space rightwards arrow Zn with 2 plus on top left parenthesis straight N with plus 5 on top stack straight O subscript 3 with negative 2 on top right parenthesis subscript 2 space plus space straight N with plus 4 on top stack straight O subscript 2 with negative 2 on top space plus stack straight H subscript 2 with plus 1 on top straight O with negative 2 on top space
From space above space equation comma space it space is space clear space that comma space straight N space retains space its space oxidation space state space in space zinc space nitrate space while space changes space in space NO subscript 2.
This space means space that space some space nitric space acid space molecules space act space as space acid space while space some space of space them space act space as space oxidising space agents.
Step space 2
Equation space in space ionic space form comma
Zn space plus space straight H with plus on top space plus space straight N with plus 5 on top straight O with blank on top subscript 3 space to the power of minus space rightwards arrow space Zn with 2 plus on top space plus space straight N with plus 4 on top stack straight O subscript 2 with blank on top space space space plus space straight H subscript 2 straight O
Step space 3
Equalise space decrease space or space increase space of space oxidation space state space by space multiplying space Zn space by space 1 space and space NO subscript 3 to the power of minus space by space 2.
Zn space plus space 2 NO subscript 3 to the power of minus space plus space straight H to the power of plus space rightwards arrow space Zn to the power of 2 plus end exponent space plus space NO subscript 2 space plus space straight H subscript 2 straight O
Step space 4
Balance space atoms space other space than space straight O space and space straight H
Zn space plus space 2 NO subscript 3 to the power of minus space plus space straight H to the power of plus space space rightwards arrow space Zn to the power of 2 plus end exponent space plus space 2 NO subscript 2 space plus space straight H subscript 2 straight O
Step space 4 space
Balance space atoms space other space than space straight O space and space straight H
Zn space plus space 2 NO subscript 3 to the power of minus space plus space straight H to the power of plus space rightwards arrow space Zn to the power of 2 plus end exponent space plus space 2 NO subscript 2 space plus space straight H subscript 2 straight O
Step space 5
Balance space straight O space atoms
Zn space plus space 2 NO subscript 3 to the power of minus space plus space straight H to the power of plus space rightwards arrow space Zn to the power of 2 plus end exponent space plus space 2 NO subscript 2 space plus space 2 straight H subscript 2 straight O
Step space 6
balance space straight H space atoms
Zn space plus space 2 NO subscript 3 to the power of minus space plus space 4 straight H to the power of plus space rightwards arrow space Zn to the power of 2 plus end exponent space plus space 2 NO subscript 2 space plus space 2 straight H subscript 2 straight O
Step space 7
Changing space the space equation space to space molecular space form space from space ionic space form
Zn space plus space 2 HNO subscript 3 space plus space 2 straight H to the power of plus space plus space 2 NO subscript 3 to the power of minus space rightwards arrow space Zn left parenthesis NO subscript 3 right parenthesis subscript 2 space plus space 2 NO subscript 2 space plus space 2 straight H subscript 2 straight O
Or
Zn space plus space 4 HNO subscript 3 space rightwards arrow space Zn left parenthesis NO subscript 3 right parenthesis subscript 2 space plus space 2 NO subscript 2 space plus space 2 straight H subscript 2 straight O



end style

Answered by Ramandeep | 15th Aug, 2018, 06:15: PM