The ceric ammonium nitrate test is a way to test a solution for the presence of alcohol or phenol. In solution, orange-yellow ceric ammonium nitrate forms a complex with the alcohol or phenol, resulting in a color change. Alcohol causes a red color change, while phenols cause a dark-red to dark-brown color change, depending on the phenol used. The Labster theory page of ceric ammonium nitrate test represents the reaction as follows:
Although this is a very simple type of test to determine the presence of alcohol or phenol in a solution, many students do not understand the science behind it. Students familiar with the test often have difficulty learning its details, underlying principles, and real-world applications. Even teachers who are involved in the subject sometimes fail to convey the essence of the subject and its essence.
Figure 1: Demonstration of ceric ammonium nitrate test at Labster's virtual lab. Image Source
At Labster, we understand the complexities of these biochemical tests. This article can provide some help as it tries to identify the main problems faced by students studying this subject. It also lists practical solutions that teachers and educators can implement to improve the situation. Finally, we will convince you why virtual lab simulations are beneficial for your students and you as an educator to convey concepts more effectively.
Why Can Ceric Ammonium Nitrate Test Be Tricky To Teach Or Learn?
There are 3 reasons why students become anxious and confused about the topic of ceric ammonium nitrate test. Recognizing these blocks is the first step to making topics more accessible
1. It feels abstract
The reaction of the ceric ammonium nitrate test happens at the molecular level, students cannot fully appreciate how the elements will react with each other. Not being able to visualize the processes, and not seeing their relevance to the real world can frustrate learning, and make it hard for students to stay motivated.
2. It requires a solid basic knowledge
It involves compounds with complex structures. A brief introduction to Alcohol and Phenolic compounds.
Alcohols are the most common organic compounds and abundantly produced industrial chemicals. The alcoholic organic compound can also be said to be characterized by the presence of one, two, or more hydroxyl groups (-OH) bonded to the carbon atom of an alkyl group or hydrocarbon chain. Alcohols are organic compounds in which the molecules are made up of one or more hydroxyl groups. Besides, these hydroxyl group(s) are bonded to carbon atoms. Alcohols are generally classified into primary, secondary, and tertiary types. Such a classification is usually made depending on which alkyl carbon is attached to the hydroxyl group. OH alcohol is present in carbohydrates and other natural compounds such as steroids.
Phenol is also a type of alcohol that has a hydroxyl group attached to a ring atom. It is an exception to the rule that the hydroxyl group must be attached to a saturated carbon. Phenol and its chemical derivatives are the main components for other compounds such as nylon, detergents, herbs, and drugs. Although phenols are more acidic compared to alcohol, we can say that phenols are considered a subset of alcohol. The fact is that alcohol and phenols both contain hydroxyl groups. Phenols can also be referred to as carbolic acids. They also exhibit unique physical and chemical properties, mainly due to the presence of hydroxyl groups. See examples of alcohol and phenol in Figure 2 below
Note that phenol is both the name of the functional group and it is the simplest compound within this group.
3. The challenge of spotting the difference
Few differences between alcohol and phenol
Acidity:Alcohols are less acidic than phenols because the removal of H ions from alcohol is very difficult. Phenol can easily lose ions because the formed phenoxide ion is somewhat stabilized by resonance.
Structure:Ethanol has the structure, C H 3, C H 2, O H. Phenol is a 6-membered carbon ring with an alcohol side group, C 6, H 5, O H. Phenol has 3 carbon double bonds.
Appearance: Alcohols are usually colorless liquids at room temperature while phenols are mostly colorless crystals at room temperature.
Here, we will study the ceric ammonium nitrate identification test for alcohol.
Objective: Identification of functional groups present in certain organic compounds (alcohol group test).
Theory: The alcohol replaces the nitrate ion in ceric ammonium nitrate, turning the solution from yellow to red.
Result: The formation of complex compounds and the reaction of ammonium nitrate, alcohol, or ceric ammonium nitrate produces a pink or red precipitate.
(NH4)2 [Ce(NO3)6] + 3ROH → [Ce(NO3)4(ROH)3] + 2NH4NO3 (NH4)2 [Ce(NO3)6] + 3CH3OH → [Ce(NO3)4(CH3OH) 3] + 2NH4NO3
The formation of esters and hydrogen chloride is the result of the reaction of alcohol with acetyl chloride
R-OH + CH3-CO-Cl → CH3-COOR + HCl HCl + NH4OH → NH4Cl + H2O.
5 Ways To Make Ceric Ammonium Nitrate Test A More Approachable Topic
With those points in mind, here are five things you can incorporate into your chemistry class to make it more engaging, accessible, and fun for you and your students.
1. Show the people behind the science
The son of a wealthy Parisian lawyer, Lavoisier (1743–1794) graduated law at the request of his family. However, his real interest was in science, which he pursued with passion and at the same time led to a fulfilling public life. He equipped an excellent laboratory, which attracted young chemists from all over Europe to learn about the “Chemical Revolution '' that was taking place at the time. An important peculiarity of Lavoisier’s chemistry was his systematic determination of the weights of reactants and products involved in a chemical reaction, including the gaseous components, and his underlying belief that matter—identified by weight—is conserved by each reaction (The Law of Conservation of Mass).
2. Outline the technique and safety measures carefully
1. Test tubes
2. Rack for the test tubes
3. Ceric ammonium nitrate solution
4. Compound to be tested
Ceric Ammonium Nitrate: Take 20gm of orange crystals of ceric ammonium nitrate and dilute in 200ml of warm dilute nitric acid.
Prepare a solution of the organic compound dissolved in a suitable solvent. The organic compound with a weight of 50mg must be dissolved in 1-2 ml of water or dioxane.
Put 1 mL of the dissolved compound in a test tube.
Add a few drops of ceric ammonium nitrate solution and shake the solution well.
Observe the color change immediately.
Result: If the solution turns red, the organic compound contains an alcohol group.
Note: that if the unknown is not soluble in water, two layers will be present. A red color in any of the layers indicates a positive test.
The red color disappears if:
You store the reaction mixture for some time.
You add an excess of ceric ammonium nitrate solution. Therefore, avoid using an excessive solution of ceric ammonium nitrate.
Use freshly prepared nitric acid.
If dioxane has been used as a solvent for the unknown compound, a blank test should be performed.
Some alcohols give a temporary red color, so look for red when mixing.
Some amines also give various colors in this test.
Ceric ammonium nitrate is a strong oxidizing agent, corrosive, irritant, and harmful to the environment. Contact with other materials may cause a fire. Harmful if swallowed and eye contact may cause permanent eye damage. It causes eye, skin, and respiratory tract irritation. So when performing this test, one should be very careful to avoid direct contact and wear protective gear including goggles, face mask or shield, and gown.
3. Relate it to the real world:
Measurement of blood alcohol concentrations is often required in clinical toxicology laboratories. The tests form a large part of forensic autopsies and are the basis of most driver testing laws. Blood is rarely used for forensic examinations of drivers, the media commonly used are urine or breath. Since the alcohol content of these substances does not always reflect blood concentrations, direct measurement of a blood sample makes sense. However, most of the available methods are complex, lengthy, or use unavailable materials. This is where our ceric ammonium nitrate test comes in. In this method, the blood sample is distilled, ceric ammonium nitrate is added to the distillate as a color reagent, and the color change is measured spectrophotometrically. This method is accurate but, like most methods, is not specific to ethanol. Samples that test positive should be further tested to determine the presence of possible contaminants.
4. Make it stick with word-play:
Memorization can be very helpful in understanding the process of ceric ammonium nitrate test. An example of a memory aid is:
CANOR, which simply means: Ceric Ammonium Nitrate: Orange to Red
5. Encourage them to use virtual lab simulations
A unique way to teach ceric ammonium nitrate tests is through a virtual laboratory simulation. The Labster virtual lab simulation allows teachers to make more insightful points, giving students better visual options to follow different concepts freely.
Check out the Labster ceric ammonium nitrate test simulation that allows students to learn about the reaction through active, inquiry-based learning. In the simulation, students will deduce which of the two samples provided contains alcohol groups by performing the test themselves!