An introductory laboratory should help students develop a range of basic skills, understand the role of direct observation, engage each student in meaningful experimental experiences, and develop collaborative learning skills essential to success in many lifelong endeavors.
Personal protective equipment (PPE) in the lab includes gloves, respiratory protection, eye protection, and protective clothing. The need for each type of protection depends on the individual case, the type of operation, the type of chemical, and the amount used.
Protective gloves should be worn when handling irritants, hazardous and corrosive substances, chemicals of unknown toxicity, and very hot or very cold materials. Gloves used in laboratories are usually made of latex, vinyl, or nitrile. Respirators should only be used when ventilation is required.
Glasses are used to protect the eyes from flying particles, glass, or dust. Protective clothing, such as a lab coat, that is resistant to physical and chemical hazards should be worn. Shorts, revealing shoes, and unkempt hair should be avoided. Eating, drinking, smoking, and storing food and beverages in the laboratory refrigerator is prohibited.
Read on to know why this can be a difficult topic for teachers and students, five suggestions for changing it, and thoughts on why virtual labs can make things easier.
Why an introductory laboratory can be complicated
The reaction of strong acids with water can be very dangerous. The dissociated hydrogen ions react with water molecules to form hydronium ions, and this reaction releases a lot of energy. This exothermic reaction can be very strong, causing the acid to boil and splash.
1. It can be challenging
Caustic chemicals appear to damage or permanently alter materials on contact. These chemicals can damage materials ranging from human skin tissue to steel. The main types of corrosives include strong acids, bases, and dehydrating agents.
Protective clothing should be worn when working with corrosive materials, including lab coats, gloves, closed-toe shoes, and long-sleeved clothing. Corrosive materials should be handled in fume hoods where there is a risk of explosion or chemical splash.
It's safest to add acid to the water little by little, not the other way around. In this way, an aqueous solution of the strong acid is initially formed and the exothermic reaction can be controlled.
Whether an acid is strong or weak has nothing to do with the concentration or dilution of the solution. For example, a strong acid such as sulfuric acid does not become a weak acid simply by diluting it. Even if the pH increases, the acid is less concentrated, and the solution appears less reactive, it will still be a dilute solution of a strong acid. Be careful when working with concentrated strong acids!
The chemical can be an acid or base depending on how it reacts in an aqueous solution. According to the Bronsted-Lowry definition, an acid is a proton-donating entity in an aqueous solution while bases are the entity that accepts protons in an aqueous solution. Compare this with the Arrhenius and Lewis definitions. The ability to accept or donate protons depends on the chemical structure of the molecule.
The proton (H+) released by the acid combines with a water molecule to form a hydronium ion (H3O+). Bases accept protons from water molecules. The water molecules are then converted into hydroxide ions (OH-). These two different reactions occur because water is amphoteric— it can donate or accept protons and a pH scale will show how acidic or basic a substance is.
2. It’s content-heavy
Image 1: Sourced from Labster's introductory lab simulation, where your students can participate actively and learn about the different laboratory guidelines.
Dangerous goods (or hazardous materials) are solids, liquids, or gases that can harm humans, other living organisms, or the environment and must be controlled by chemical regulations. These hazards include materials that are radioactive, flammable, explosive, corrosive, oxidizing, biohazardous, toxic, pathogenic, or allergenic. Image 1 is a list of the categories that this hazardous substance belongs to:
Class 1: Explosives (Dynamite, Nitroglycerin)
Class 2: Gases such as flammable gases (acetylene, hydrogen) and non-flammable (nitrogen, neon), or toxic (fluorine, hydrocyanic acid)
Class 3: Flammable liquid (diethyl ether, carbon disulfide, gasoline, acetone)
Class 4: Flammable Solids (Nitrocellulose, Magnesium, White Phosphorus, Sodium)
Class 5: Organic oxidizing agents and peroxides (calcium hypochlorite, ammonium nitrate, hydrogen peroxide, cumene hydroperoxide)
Class 6: Toxic and infectious substances and biological hazards (human materials, viral cultures), potassium cyanide, mercury chloride, pesticides.
Class 7: Radioactive materials (uranium, plutonium)
Class 8: Corrosive substances such as acids (sulfuric acid, hydrochloric acid) and bases (potassium hydroxide, sodium hydroxide).
Class 9: Other (asbestos, airbag inflators, self-inflating life rafts, dry ice)
Each hazard can be identified by a special mark used to identify the risk of using each chemical. It is important to note that acids and bases, especially strong ones, are corrosive and can attack leather and metal.
3. It’s complicated
Diffusion is a transport phenomenon in which particles move from an area where they are highly concentrated to an area where they are less concentrated. The speed at which these particles move is known as the rate of diffusion and is affected by the following factors:
Temperature: As the temperature increases, the kinetic energy of the particles increases, causing the particles to move faster. As a result, the particles are distributed more rapidly in solution and increase the rate of diffusion.
Size of particle: As the particle size increases, the rate of diffusion decreases. Larger particles become less mobile in the solvent, reducing their velocity and thereby reducing the rate of diffusion.
Mass of particle: As the particle mass increases, the rate of diffusion decreases. Like larger particles, heavier particles move less in solution and reduce the rate of diffusion.
In a solution, the solute is the substance to be dissolved and the solvent is the medium that dissolves the solute.
Osmosis is a unique style of diffusion in which the water concentrations of two solutions divided by a partially permeable membrane get to equilibrium. This equilibrium arises when water molecules move from the most concentrated solution to the least concentrated.
Osmosis can occur in cells because the cell membrane is semipermeable. The following three situations can occur:
Hypotonic medium: solute concentration outside the cell is lower than inside the cell. Thanks to osmosis, there is a net movement of water molecules from outside the cell into the cell, causing them to swell.
Isotonic medium: solutes outside the cell have the same concentration as inside the cell. Therefore, there is no net movement of water molecules across the cell membrane in all directions.
Hypertonic medium: solute concentration outside the cell is higher than inside the cell. This results in a net movement of water molecules from inside the cell to the outside, causing it to shrink.
Image 2: Sourced from Labster's introductory lab simulation, where your students can participate fully and learn about the different laboratory guidelines.
The phenomenon of osmosis must be controlled and is very important in the case of blood cells. When erythrocytes are surrounded by a hypotonic solution, there is a net movement of water molecules into the cells, causing them to swell and eventually rupture. On the other hand, when cells are surrounded by a hypertonic solution, they lose water and shrink. Red blood cells in a hypertonic solution appear to shrink, arrows indicate water leaving the blood cells as shown in image 2 above. The red blood cells in an isotonic solution have a normal shape, the arrows show the water entering and leaving the blood cells at the same rate. Red blood cells in a hypotonic solution swell to a larger-than-normal size, and arrows indicate water entering the blood cells. One of his blood cells burst.
5 ways to make laboratory safety procedure a more approachable topic
With those facts fully explained, here are five things to be incorporated into introductory laboratory classes to make them more fascinating, enjoyable, and delightful for you and your students.
1. Show the people behind the science
The earliest known laboratory is the home laboratory of Pythagoras of Samos, a famous Greek philosopher, and scientist. This laboratory was set up when Pythagoras conducted experiments on the pitch and vibration of strings.
In Louis Pasteur's 1885 painting by Albert Edelfelt, Louis Pasteur corresponded a note in his left hand to a bottle filled with solids in his right hand and without personal protective equipment.
2. Relate to the real world
Image 3: Sourced from Labster's theory page, where your students can participate fully and learn about the different laboratory guidelines.
There are four categories of biological hazards: the lowest ( Level 1) corresponds to the minimum risk and the highest ( Level 4) corresponds to the maximum risk. With minimal risk, it is enough to work with gloves and a face shield. In contrast, Level 4 requires special precautions such as wearing a split-air hyperbaric personal suit, multiple showers, use of vacuum chambers, and ultraviolet light chambers as shown in image 3.
3. Seeing is believing
Image 4: Sourced from Labster's theory page, where your students can participate fully and learn about the different laboratory guidelines.
Determining a person's blood type is important, for example in the case of blood transfusions or to test for possible Rh-incompatibility during pregnancy. A common method for quickly determining a person's blood type is based on agglutination. The patient's blood is mixed with antibodies that have previously been applied to a special test card called the Eldon card (Image 4) and this card contains antibodies specific to Antigen A (anti-A) and B (anti-B) antigens and the Rhesus factor (Rh) antigen D (anti-D). There is a fourth area on each card that is left blank and serves as a checkmark to ensure the experimental set is functioning properly. Image 4 of a blood group test card has been used for a patient diagnosis. Three circular boxes appear at the top of the map, labeled from left to right: Anti-A, Anti-B, and Anti-D. Blood coagulation occurs in the anti-A and anti-D fields, while no coagulation occurs in the anti-B plane thus the patient result is blood group "A" Rhesus "D" positive. Below the circle, the card is filled with information about the patient, such as a name and date of birth. The principle behind this test is that if the blood being tested contains the appropriate antigen of the specific antibody in the cycle, a blood clot will form.
4. Make it stick with word-play
Visualization can be very beneficial to one's understanding, but when learning all the chemical names and their sequences for a test, there are few options other than memorization. An example is the rate of diffusion can be affected by "MuST" factors where the alphabet "u" is not a part of the memory aid, then
M - Mass of the particle
S - Size of the particle and
T - Temperature.
5. Use virtual laboratory simulation
A unique way to teach introductory labs is through virtual introductory lab simulation. At Labster, we are dedicated to providing a fully interactive course that uses gamified elements such as storytelling and scoring systems in an immersive, 3D world. Explore Labster's educating simulations, which allow students to examine the introductory lab through inquiry-based active learning.
Learn More about introductory lab simulations here, or contact us to find out how you can commence virtual labs with your learners.