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

Answer:

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

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