Hno3 Cr

HNO3 & Cr: A Study of Nitric Acid and Chromium Reactions

This article explores the chemical reactions between nitric acid (HNO₃) and chromium (Cr), focusing on the diverse outcomes depending on the concentration of the acid and the oxidation state of chromium. Understanding these reactions is crucial in various fields, including chemistry, materials science, and industrial processes. We will delve into the different reaction pathways and their implications.

1. Understanding the Reactants: HNO₃ and Cr

Nitric Acid (HNO₃): A strong oxidizing acid, HNO₃ readily donates its nitrate ion (NO₃⁻) which acts as an oxidizing agent. Its oxidizing power significantly depends on its concentration. Dilute HNO₃ acts as a weaker oxidant compared to concentrated HNO₃. The concentration affects the final oxidation state of chromium in the products.

Chromium (Cr): A transition metal, chromium exhibits multiple oxidation states, the most common being +2, +3, and +6. The initial oxidation state of chromium greatly influences the reaction pathway with nitric acid. Metallic chromium (Cr⁰) will undergo oxidation, while chromium compounds with lower oxidation states can be further oxidized.

2. Reactions of Dilute HNO₃ with Chromium

Dilute nitric acid reacts with chromium to form chromium(III) nitrate [Cr(NO₃)₃] and release nitric oxide (NO) gas. This reaction demonstrates the weaker oxidizing power of dilute nitric acid, which is not strong enough to oxidize chromium to its higher oxidation states (+6).

The balanced chemical equation for this reaction is:

6HNO₃(aq) + 2Cr(s) → 2Cr(NO₃)₃(aq) + 3NO(g) + 3H₂O(l)

This reaction is relatively slow, and the formation of nitric oxide can be observed as a brown gas due to its immediate oxidation to nitrogen dioxide (NO₂) in air.

Scenario: Imagine immersing a chromium strip into dilute nitric acid. You would observe a gradual dissolution of the chromium, accompanied by the evolution of a brown gas, indicating the formation of NO and its subsequent oxidation.

3. Reactions of Concentrated HNO₃ with Chromium

Concentrated nitric acid is a much stronger oxidant. Its reaction with chromium results in the formation of chromium(III) nitrate and nitrogen dioxide (NO₂) gas. The higher concentration allows for a more complete oxidation of chromium.

The balanced chemical equation for this reaction is:

6HNO₃(conc.) + Cr(s) → Cr(NO₃)₃(aq) + 3NO₂(g) + 3H₂O(l)

Unlike the reaction with dilute acid, concentrated nitric acid's strong oxidizing power prevents the formation of nitric oxide. The produced NO₂ gas is a reddish-brown gas, easily distinguishable from the brown gas formed in the dilute acid reaction.

Scenario: If a chromium strip is added to concentrated nitric acid, the reaction is much more vigorous, with a rapid dissolution of chromium and the evolution of a dense reddish-brown gas. The heat generated from the exothermic reaction may be significant.

4. Reactions with Chromium Compounds

The reactions of HNO₃ with chromium compounds depend on the initial oxidation state of chromium. Chromium(II) compounds, for instance, will be readily oxidized to chromium(III) by both dilute and concentrated nitric acid. Similarly, chromium(III) compounds may not react further with dilute nitric acid but could react with concentrated HNO₃ under specific conditions, though such reactions are less common.

5. Passivation: A Unique Phenomenon

A notable characteristic of chromium's interaction with nitric acid is the phenomenon of passivation. Under specific conditions, particularly with concentrated nitric acid, a thin, protective layer of chromium oxide (Cr₂O₃) forms on the surface of the chromium. This passive layer prevents further reaction, rendering the chromium resistant to further attack by the acid. This passivation is crucial in the use of chromium and chromium-containing alloys in various applications where corrosion resistance is essential.

Summary

The reactions between nitric acid and chromium are complex and depend heavily on the concentration of the acid and the oxidation state of the chromium. Dilute HNO₃ oxidizes chromium to Cr(III), producing nitric oxide, while concentrated HNO₃ typically oxidizes chromium to Cr(III), producing nitrogen dioxide. Passivation can occur with concentrated acid, forming a protective oxide layer and inhibiting further reaction. Understanding these reactions is vital in various chemical and industrial processes.

FAQs

1. Q: Why is the reaction with concentrated HNO₃ more vigorous than with dilute HNO₃?
A: Concentrated HNO₃ possesses a higher concentration of oxidizing species (NO₃⁻), leading to a faster and more complete oxidation of chromium.

2. Q: What is the color difference between the gases produced in the two reactions?
A: Dilute HNO₃ produces nitric oxide (NO), which rapidly oxidizes to brown NO₂ in air. Concentrated HNO₃ directly produces reddish-brown NO₂ gas.

3. Q: Can chromium be oxidized beyond Cr(III) by nitric acid?
A: While it is possible under highly specific and controlled conditions, typically involving very high concentrations of nitric acid and elevated temperatures, it is not the usual outcome of these reactions. Other strong oxidizers are generally needed to achieve higher oxidation states of chromium.

4. Q: What is the practical significance of chromium passivation?
A: Passivation is crucial for corrosion resistance in stainless steel, which contains chromium. This protective oxide layer prevents rusting and enhances the durability of stainless steel components.

5. Q: Are there any safety precautions to consider when working with HNO₃ and chromium?
A: Yes, nitric acid is a corrosive and potentially hazardous substance. Appropriate safety measures, including eye protection, gloves, and a well-ventilated area, should always be employed when handling it. The reactions can also be exothermic, generating heat. Therefore, careful control of the reaction conditions is vital.

Search Results:

Cr2(SO3)3 + HNO3 = Cr(NO3)3 + H2SO3 - Balanced chemical … 1 Cr 2 (SO 3) 3 + 1 HNO 3 = 1 Cr(NO 3) 3 + 1 H 2 SO 3 For each element, we check if the number of atoms is balanced on both sides of the equation. Cr is not balanced: 2 atoms in reagents and 1 atom in products. In order to balance Cr on both sides we: Multiply coefficient for Cr(NO 3) 3 by 2 1 Cr 2 (SO 3) 3 + 1 HNO 3 = 2 Cr(NO 3) 3 + 1 H 2 SO 3

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Cr + 4 HNO3 → Cr(NO3)3 + NO + 2 H2O - Balanced equation Cr + 4 HNO3 → Cr (NO3)3 + NO + 2 H2O - Balanced equation | Chemical Equations online! HNO3 is an oxidizing agent, Cr is a reducing agent. Appearance: Grey powder ; Blue-white to steel-gray, lustrous, brittle, hard, odorless solid.

Chemical Equations online! Application for completing products and balancing equations of chemical reactions.

Cr(NO3)2 + HCl = HNO3 + CrCl2 - Balanced chemical equation, … 1 Cr(NO 3) 2 + 1 HCl = 1 HNO 3 + 1 CrCl 2 For each element, we check if the number of atoms is balanced on both sides of the equation. Cr is balanced: 1 atom in reagents and 1 atom in products.

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Cr(OH)3(s) + HNO3(aq) = Cr(NO3)3(s) + H2O(l) - Balanced … 1 Cr(OH) 3 (s) + 3 HNO 3 (aq) = 1 Cr(NO 3) 3 (s) + 3 H 2 O(l) O is balanced: 12 atoms in reagents and 12 atoms in products. All atoms are now balanced and the whole equation is fully balanced:

Cr + HNO3 = Cr(NO3)3 + H2 - Chemical Equation Balancer Cr + HNO3 = Cr(NO3)3 + H2 is a Single Displacement (Substitution) reaction where two moles of solid Chromium [Cr] and six moles of aqueous Nitric Acid [HNO 3] react to form two moles of aqueous Chromium Trinitrate [Cr(NO 3) 3] and three moles of Dihydrogen [H 2] gas

6 HNO3 + Cr → 3 H2O + 3 NO2 + Cr(NO3)3 - Balanced equation … Solved and balanced chemical equation 6 HNO3 + Cr → 3 H2O + 3 NO2 + Cr(NO3)3 with completed products. Application for completing products and balancing equations.

Balancing redox reactions by oxidation number change method In the oxidation number change method the underlying principle is that the gain in the oxidation number (number of electrons) in one reactant must be equal to the loss in the oxidation number of the other reactant. Enter an equation of a chemical reaction and click 'Submit' (for example: so32-+cr2o72- -->cr3++so42- ).

HNO3 + Cr = H2O + NH4NO3 + Cr(NO3)3 - Chemist Hunter Construct the equilibrium constant, K, expression for: HNO_3 + Cr H_2O + NH_4NO_3 + CrN_3O_9 Plan: • Balance the chemical equation. • Determine the stoichiometric numbers. • …

Chromium Standard: Cr @ 1000 µg/mL in 5% HNO3 Chromium Standard: Cr @ 1000 µg/mL in 5% HNO3 reference standards available online at LGC Standards, for food and beverage analysis.

Question: enter a balance redox equation for the reaction that Correct HNO4 oxidizes metals through the lollowing reduction hat-rescion: NO2−(aq)+4H′(aq) Because this hat-reaction is above the reduction of H+ in the libic.

Cr(OH)3 + HNO3 = Cr(NO3)3 + H2O - chemiday.com 3 Apr 2015 · Chromium (III) hydroxide react with nitric acid to produce chromium (III) nitrate and water. Chemical reaction. Balancing chemical equations.

HNO3 + Cr = CrNO3 + NO2 + H2O - Balanced chemical … 1 hno 3 + 1 cr = 1 crno 3 + 1 no 2 + 1 h 2 o For each element, we check if the number of atoms is balanced on both sides of the equation. H is not balanced: 1 atom in reagents and 2 atoms in products.

HNO3 + Cr = Cr2O3 + NO2 + H2O - Balanced chemical … a HNO 3 + b Cr = c Cr 2 O 3 + d NO 2 + e H 2 O Now we write down algebraic equations to balance of each atom: H: a * 1 = e * 2 N: a * 1 = d * 1 O: a * 3 = c * 3 + d * 2 + e * 1 Cr: b * 1 = c * 2 Now we assign a=1 and solve the system of linear algebra equations: a = e * 2 a = d a * 3 = c * 3 + d * 2 + e b = c * 2 a = 1 Solving this linear ...

acid base - What's the simplest way to etch Nickel and Chromium ... 28 May 2015 · Cr is easy to etch in my experience, we have a simple commercial acetic acid based one that works well. Yes at RT, I did this etching a lot of times. I was etching 200 nm Ni layer by diluted HCl and it worked perfectly well for microstructures preparation on glass. If HCl does not work, then there is something different than Nickel.

HNO3 + Cr = Cr(NO3) + H2 - Balanced chemical equation, … 1 hno 3 + 1 cr = 1 cr(no 3) + 1 h 2 For each element, we check if the number of atoms is balanced on both sides of the equation. H is not balanced: 1 atom in reagents and 2 atoms in products.

Cr + HNO3 - Balanced chemical equation, limiting reagent and … Cr + HNO3 = Cr(NO3)3 + H2. Cr + HNO3 = Cr(NO3)3 + H2O + NO. Cr + HNO3 = Cr(NO3)2 + H2O + NO. Instructions and examples below may help to solve this problem You can always ask for help in the forum. Instructions on balancing chemical equations: Enter an equation of a chemical reaction and click 'Balance'. The answer will appear below

Solid chromium (III) hydroxide reacts with nitric acid. Write the ... Cr (OH)3 (s) + 3HNO3 (aq) --> Cr (NO3)3 (aq) + 3H2O (l) This is the correct balanced chemical equation. I have tried entering both: 3OH- (aq) + 3H+ (aq) --> 3H2O (l) 3OH- (s) + 3H+ (aq) --> 3H2O (l) But neither are marked correct. Could someone please tell me what is …