Qualitative analysis is the process that is used to identify the compositions of the given sample. Generally, it provides nonnumerical information about the specimen. Qualitative analysis of elements helps to identify whether certain atoms, functional groups, or ions are present in the sample or not. In the qualitative analysis method, the sample compound's chemical properties can be determined using several reagents. The process can be highly effective because it can separate up to 20 metal cations from a sample of solution.
Qualitative analysis can identify the elements of the sample but cannot determine the amount. There are two main branches of qualitative analysis; organic qualitative analysis and inorganic qualitative analysis. Organic qualitative analysis is helpful in determining the functional groups, chemical bonds, and types of molecules. In Inorganic qualitative analysis, the ionic composition and elemental composition of inorganic compounds can be determined.
Sometimes, some aspects of the introduction to qualitative analysis of the elements can be difficult for students to understand. At Labster, we compiled all the complexities that students experience during learning about the introduction to qualitative analysis of elements. We provide five methods that help them while learning. In the end, we will convince you why a virtual lab simulation is effective for teachers to convey the topic, like the introduction to qualitative analysis of elements.
Figure: An image of the periodic table from the Labster virtual laboratory of introduction to qualitative analysis of elements.
Three main reasons make the introduction to qualitative analysis of elements a difficult topic to understand.
Introduction to qualitative analysis of elements consists of several abstract concepts. Students need to learn about the atoms, electrons, chemical reactions, valence shells, excitation state, and de-excitation state. For instance, when an electron absorbs energy, it will go into an excited state. The size of the electron is too small that you cannot see it with the naked eye. So, it is difficult for students to understand abstract concepts.
For qualitative analysis of elements, several tests are used to identify organic and inorganic substances. Every test is performed following a different procedure. Additionally, there are chemical reactions between the compound sample and the reagent. It is hard for students to remember the procedures of several tests present in the qualitative analysis.
When you need to learn about the introduction to qualitative analysis of elements, it is important to learn about the periodic table. There are more than a hundred elements present in the periodic table. Students should need to learn about the structure of the periodic table. They do not like learning about the periodic table. It makes the introduction to qualitative analysis of elements a complicated and time-consuming topic.
Since we are familiar with the difficulties that students may experience during learning of introduction to qualitative analysis of elements. There are five ways that can help students to understand this topic.
Izaak Maurits Kolthoff was an analytical chemist who contributed to the qualitative analysis of elements. He was known as the “Father of modern analytical chemistry.” He published his research related to the separation, identification, and qualification of chemical substances. He introduced the world to the modern methods that are used for the qualitative analysis of the elements. Additionally, he published a paper on pH in 1915. He was the one who worked on analytic chemistry and enhanced the interest of other scientists in the qualitative analysis of substances.
Introduction to qualitative analysis of elements consists of chemical tests used to determine elements present in the substance. For instance, we use the iodine test for the organic qualitative analysis, while the Kastle Meyer test is performed in the inorganic qualitative analysis.
Before starting the learning about the tests, students should know the periodic table and some basic terms used in the introduction to qualitative analysis of elements. A periodic table is a tabular display of elements according to their atomic numbers, chemical properties, and electron configuration. The elements are arranged in periods and groups. The groups are the columns of the periodic table. In groups, all the elements have the same number of electrons in the valence shell. Periods are the horizontal rows present in the periodic table. The periodic table consists of seven periods.The elements are classified into metals, metalloids, and nonmetals.
Metals are those elements that are solid, shiny, malleable and good conductors of heat and electricity.
Metalloids have some properties of metals as well as some properties of nonmetals.
Nonmetals are those elements that do not have metallic properties. Additionally, they are poor conductors of heat and electricity.
Qualitative analysis of elements can help measure the changes in color, odor, reactivity, melting points, boiling points, and precipitation of the compounds. Several methods are used in the qualitative analysis of elements; extraction, chromatography, distillation, and precipitation. Let’s discuss the tests for the identification of simple salt.
Flame test: A flame test is a common analytic method used to differentiate between metal ions. The metal ion solution is mixed with concentrated hydrochloric acid HCl in this test. Then, the sample is placed on the nickel or chromium wire and heated in a flame. The flame causes a change in color because I can excite the electrons of the valence shell of the metal. When the electrons go back to their normal state, they emit certain wavelengths. For example, lead metal shows pale bluish color, calcium shows brick red, and sodium shows bright yellow in the flame test.
The reaction of a substance with sodium hydroxide: In this test, add sodium hydroxide (NaOH) to the solution and stir it well. Now, observe the reaction of sodium hydroxide with the solution and check the precipitate formation.
The reaction of substances with ammonia: You should add drops of ammonia to the given solution. For metal hydroxide, you may need to add more drops of ammonia to dissolve the solution fully. Ammonia can make complex structures with different substances and show different colors in the test. For instance, the Ni2+ complex with ammonia can give a violet color. Additionally, the Zn2+ reaction with ammonia shows a colorless solution. When adding ammonia in a Cu2+ solution, it gives blue color.
Since students know different tests used for the identification of salts. They should also learn about the tests used for the qualitative analysis of the organic substances.
Sodium fusion test: The sodium fusion test is also known as Lassaigne’s test. It is an effective test to check the presence of nitrogen, halogens, and sulfur in a sample of organic compounds. For detection, it is important to convert the sample into inorganic substances.
Tollen’s test: Tollen’s test is used for the identification of aldehydes present in the sample. For this test, you can add 3 to 4 drops of Tollen’s solution to the sample and heat it. If shiny silver precipitates are formed, it confirms the presence of aldehyde in the solution.
Figure: An image representing the electrons excitation and de-excitation in flame tests from Labster theory.
Color diagrams make the learning introduction to qualitative analysis of elements a more interesting topic for learners. When they see color images, it will help to store them in their memory. Additionally, the use of diverse colors makes the topic simpler for students to understand. In the qualitative analysis of elements, there are several tests that can be performed for the identification of elements. Virtual diagrams play an important role in making the identification of substances easier for students.
The image presented below explains the procedure of the flaming test in the laboratory. The blocks show the metals including calcium, sodium, copper, phosphorus, and neon. The flame test is used to identify the colors of these elements.
Figure: An image of flame test from the Labster virtual laboratory of introduction to qualitative analysis of elements.
Virtual lab simulation is an effective method to learn about difficult topics like introduction to qualitative analysis of elements. It helps to explain the topic in a simpler way that every student can understand. At Labster, we provide a 3D simulation that has gamification elements like storytelling and a scoring system.
Labster virtual simulation of introduction to qualitative analysis of elements explains the periodic table's structure, trends among periods and groups, differentiate metals from other element classes, and flame test.
Check out Labster simulation of introduction to qualitative analysis of elements here, or get in touch to find out how you can start using virtual lab simulation with your students.
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