Question

Dissolving brass requires an oxidizing acid such as concentrated nitric acid. Nitrogen dioxide is produced as a byproduct in this reaction. Write a balanced chemical equation for the reaction of copper metal with concentrated nitric acid to pro­ duce copper(il) nitrate, nitrogen dioxide, and water.

Answer 1

Cu + 4 HNO₃ → Cu(NO₃)₂ + 2 NO₂ + 2 H₂O

Step-by-step explanation:

Step 1: Write down the chemical formulas of given substances,

Copper Metal = Cu

Nitric Acid = HNO₃

Copper (II) Nitrate = Cu(NO₃)₂

Nitrogen Dioxide = NO₂

Water = H₂O

Step 2: Write down the unbalance Chemical equation,

Cu + HNO₃ → Cu(NO₃)₂ + NO₂ + H₂O

Step 3: Balance Cu atoms on both sides;

The number of Cu atoms on both sides are same. Hence, there number will remain the same.

Step 4: Balance N atoms on both sides;

As there is 1 N atom on left hand side and 3 N atoms on right hand side, so we will multiply HNO₃ by 3 to balance N on both sides, hence,

Cu + 3 HNO₃ → Cu(NO₃)₂ + NO₂ + H₂O

Step 5: Balance O atoms on both sides;

As there are 9 O atom on left hand side and 9 O atoms on right hand side, so they are balance.

Step 6: Balance H atoms on both sides;

As there are 3 H atom on left hand side and 2 H atoms on right hand side, so we will multiply H₂O by 2 as,

Cu + 3 HNO₃ → Cu(NO₃)₂ + NO₂ + 2 H₂O

By doing so the number of O atoms got imbalanced, so to balance O atoms again we will multiply HNO₃ by 4 as,

Cu + 4 HNO₃ → Cu(NO₃)₂ + NO₂ + 2 H₂O

Now, The Cu and H atoms are balanced, and the O atoms are greater on left hand side and the N atoms are greater on right hand side, therefore we will multiply NO₂ by 2 to balance both N and O as,

Cu + 4 HNO₃ → Cu(NO₃)₂ + 2 NO₂ + 2 H₂O