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# How Ca + HNO3 => Ca (NO3) 2 + N2O + H2O ?

Can anyone explain me how to get this?

4Ca + 10HNO3 = 4Ca (NO3) 2 + N2O + 5H2O

### 1 Answer

- Roger the MoleLv 77 years agoFavorite Answer
Ca + HNO3 → Ca(NO3)2 + N2O + H2O

The only practical way I see is to use simultaneous equations.

Start by assigning algebraic variables to each species:

a Ca + b HNO3 → c Ca(NO3)2 + d N2O + e H2O

Write a balanced equation for each element:

Ca: a = c

H: b = 2e

N: b = 2c + 2d

O: 3b = 6c + d + e

Solve these four equations simultaneously in terms of a, using whatever algebraic method you prefer:

a = a and b = (5a)/2 and c = a and d = a/4 and e = (5a)/4

Substitute these values in a into the original equation:

a Ca + (5a)/2 HNO3 → a Ca(NO3)2 + a/4 N2O + (5a)/4 H2O

Multiply each coefficient by 4/a to eliminate the fractions and the single remaining variable a:

4 Ca + 10 HNO3 → 4 Ca(NO3)2 + N2O + 5 H2O