When iron fillings is added into a test tube of dilute nitric acid, iron(||) nitrate forms at first but gets changed into iron (|||) nitrate.
What color changes occur?
When iron filings are added to a test tube of dilute nitric acid, a series of color changes occur as the reaction progresses.
1. Initially, the iron filings reacts with the nitric acid to form iron(II) nitrate, which is green in color. The test tube may appear greenish.
2. As the reaction continues, the iron(II) nitrate undergoes oxidation in the presence of air to form iron(III) nitrate. This causes the color to change from green to a yellow-brown color. The test tube may appear to have a more yellowish-brown hue.
So, the color changes observed are from green (iron(II) nitrate) to yellow-brown (iron(III) nitrate).
Is dilut nitric acid an oxidizing agent or a reducing agent? Explain
Dilute nitric acid (HNO3) is an oxidizing agent. An oxidizing agent is a substance that facilitates oxidation reactions by accepting electrons from other substances. In the case of dilute nitric acid, it contains the nitrate ion (NO3-) which has a high affinity for electrons.
When dilute nitric acid reacts with other substances, it readily donates oxygen or accepts electrons to increase its own oxidation state. This is evident in the reaction between dilute nitric acid and iron filings mentioned in the previous question. In this reaction, the iron begins with an oxidation state of 0 and is oxidized to +3 in the resulting iron(III) nitrate (Fe(NO3)3). The nitric acid, on the other hand, is reduced from an oxidation state of +5 in nitrate (NO3-) to +3 in nitric oxide (NO) or other reduced nitrogen compounds.
Furthermore, dilute nitric acid can also oxidize nonmetals, such as sulfur, phosphorus, and carbon, as it can provide oxygen or accept electrons from these elements during reactions. Overall, the ability of dilute nitric acid to induce oxidation reactions demonstrates its role as an oxidizing agent.
Why is dilute nitric acid an oxidizing agent?
Dilute nitric acid is considered an oxidizing agent due to its ability to readily donate oxygen or accept electrons from other substances, leading to the oxidation of those substances.
The oxidizing properties of nitric acid stem from the presence of the nitrate ion (NO3-) within the acid. The nitrate ion is a polyatomic ion with a formal charge of -1. Nitrate (NO3-) has a high affinity for electrons due to its electronic configuration and molecular structure. Its oxygen atoms have a partial negative charge, creating a strong electrostatic attraction for electrons.
During a reaction, dilute nitric acid can release oxygen or accept electrons, leading to an increase in its own oxidation state. For example, when nitric acid reacts with metals like iron, it accepts electrons from the metal, resulting in the oxidation of the metal to a higher oxidation state. In the case of the reaction with iron filings, the iron is oxidized from an oxidation state of 0 to +3 in iron(III) nitrate (Fe(NO3)3).
In addition to metal reactions, dilute nitric acid can also oxidize nonmetals by accepting electrons or providing oxygen. This ability to facilitate oxidation reactions distinguishes dilute nitric acid as an oxidizing agent.
However, it's worth noting that the oxidizing ability of nitric acid decreases as the concentration decreases. Dilute nitric acid contains less nitrate ion compared to concentrated nitric acid, resulting in a weaker oxidizing ability.
Write an equation to explain this result
Certainly! Here is an equation that explains the result of the reaction between iron filings and dilute nitric acid, showcasing the oxidizing properties of the acid:
Fe (s) + 8 HNO3 (aq) → Fe(NO3)3 (aq) + 3 H2O (l) + 2 NO2 (g)
In this equation, iron (Fe) reacts with dilute nitric acid (HNO3) to produce iron(III) nitrate (Fe(NO3)3), water (H2O), and nitrogen dioxide (NO2) gas. The iron undergoes oxidation, increasing its oxidation state from 0 to +3. The nitric acid acts as the oxidizing agent, accepting electrons from the iron and facilitating the oxidation reaction.
The formation of nitrogen dioxide gas is also indicative of the oxidizing nature of the nitric acid. Nitric acid can undergo reduction, converting nitrate ions (NO3-) to reduced nitrogen compounds such as nitrogen dioxide (NO2) during the reaction.
Overall, this equation depicts the oxidizing properties of dilute nitric acid, as it oxidizes the iron and leads to the formation of iron(III) nitrate.