Moderate

Consider the following redox reaction. Zn+dil HNO3? Zn (NO3)2 + N2O + H2O The coefficient number of HNO3 in the equation is__________________?

Correct answer: C. 10

  • A. 6
  • B. 8
  • C. 10
  • D. 4

Explanation

Let the equation be aZn + bHNO3 → aZn(NO3)2 + cN2O + dH2O. Hydrogen gives d = b/2, nitrogen gives b = 2a + 2c, and oxygen then gives 3b = 6a + c + d; solving gives a = 4c, b = 10c, and d = 5c. Taking c = 1 gives 4Zn + 10HNO3 → 4Zn(NO3)2 + N2O + 5H2O, so the coefficient of HNO3 is 10. The likely mistake is choosing 8 by balancing nitrogen and oxygen incompletely without checking hydrogen and water.

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About Balancing Redox Equations

Redox equations are balanced by tracking electron loss and gain through oxidation numbers or the ion-electron method. Work includes identifying oxidizing and reducing agents, balancing atoms and charge in acidic or basic medium, and ensuring that electrons lost equal electrons gained.

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