only one question, 1.) Make a conclusion about the Common Laboratory Operations Title of the Experiment: Common Laboratory Operations I. Objectives:...
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only one question, 1.) Make a conclusion about the Common Laboratory Operations 

 

Title of the Experiment: Common Laboratory Operations 


I. Objectives:

 

1. To observe proper wearing of PPEs for performing common laboratory operations.

2. Conduct procedures involving heating and evaporating operations.

3. Provide a proper procedure for performing common laboratory operations.

 

II. Scenario

              Your activity for today is to perform Common Laboratory Operations as listed in your lab guide. Before doing any procedures, you must observe the proper wearing of PPEs. Can you give the different PPEs necessary to conduct any experiments or activities in the chemistry laboratory?

 

              The first procedure is to heat non-flammable and flammable liquids in a test tube, precipitation, separation of solids from liquids, measuring colorless and colored solution, weighing of solid substances, transferring of liquid and solid substances from one container to another container. Another procedure is to evaporate some liquids, separation of liquids with different densities, and detecting odors. How do you design a procedure appropriate for each laboratory operation mentioned above?

 


 

II. Hypothesis-Testing Method Design

This section is where you write the hypothesis-testing method you designed. This should have the following components:

 

  1. Problem:

For the Common Laboratory Operations, proper wearing of PPEs must be observed. The different PPEs necessary to conduct experiments or activities in the chemistry laboratory must be given. In this activity, the first procedure is heating non-flammable and flammable liquids in a test tube, precipitation, separation of solids from liquids, measuring colorless and colored solution, weighing of solid substances, transferring of liquid and solid substances from one container to another container. Another procedure is to evaporate some liquids, separation of liquids with different densities, and detecting odors. A design of the procedure appropriate for each laboratory operations mentioned above must be shown.

 

  1. Theory:

Importance of PPE in the Laboratory

Appropriate PPE is required when there is a potential for exposure to hazardous materials such as hazardous chemicals and biohazards. Proper PPE and laboratory attire help minimize the potential for skin exposure to hazardous chemicals, biological agents, and other hazardous materials. Make sure your legs are covered and that you wear closed shoes. Additional PPE such as face masks or respirators may be needed for specialized tasks.

 

Common Laboratory Operations

Heating Liquids

There are different methods used for heating material in the laboratory. Steam is often used for heating volatile, non-aqueous, flammable solvents in 100oC maximum temperature from steam is sufficient for most commonly used organic solvents including many mixed aqueous solvents. A steam bath is a relatively safe way to heat flammable organic liquids. They are designed to heat beakers, Erlenmeyer flasks, and round-bottomed flasks, and have a series of concentric rings that can be removed to adjust to the size of the flask.

Precipitation

Precipitation reactions occur when cations and anions in an aqueous solution combine to form an insoluble ionic solid called a precipitate. Whether or not such a reaction occurs can be determined by using the solubility rules for common ionic solids. Because not all aqueous reactions form precipitates, one must consult the solubility rules before determining the state of the products and writing a net ionic equation. The ability to predict these reactions allows scientists to determine which ions are present in a solution and allows industries to form chemicals by extracting components from these reactions.

Filtration

Filtration, the technique used to separate solids from liquids, is the act of pouring a mixture onto a membrane (filter paper) that allows the passage of liquid (the filtrate) and results in the collection of the solid. Two filtration techniques are generally used in chemical separations in general chemistry laboratory: "gravity" filtration and "vacuum" filtration. The filter paper should be folded properly to ensure efficient filtration.

Reading a Meniscus

Learning how to read a meniscus is a very important lab skill. A meniscus may be either concave or convex. A concave meniscus curves downward; if you are looking down from the top, it curves away from you, like the opening of a cave would. In contrast, a convex meniscus curves upward; if you are looking down into the container, the meniscus curves toward you. You have to be at eye level to read one and you always look for the bottom of the curvature. Sometimes it helps to put your finger behind it so that you can see the exact number better.

Centrifugation

Centrifugation is a technique used for the separation of particles from a solution according to their size, shape, density, viscosity of the medium, and rotor speed. The particles are suspended in a liquid medium and placed in a centrifuge tube. The tube is then placed in a rotor and spun at a defined speed.

Evaporation

Evaporation in a technical sense denotes the conversion of a. liquid into a vapor for the purpose of separating it from another. liquid of higher boiling point, or from a solid which is dissolved in it.

Extraction

Extraction is a method for moving a compound from one medium to another. It is a separation process consisting of the separation of a substance from a matrix. Common examples include liquid-liquid extraction and solid-phase extraction. The distribution of a solute between two phases is an equilibrium condition described by partition theory.

 

  1. Hypothesis:

The different PPEs necessary to conduct any experiments or activities in the laboratory has been given. The design of the procedures appropriate for each laboratory techniques mentioned has been provided.

 

  1. Procedure:

Heating non-flammable liquids in a test tube

1.     Place a lit Bunsen burner on top of a tripod with wire gauze to secure the heating apparatus.

2.     Liquid to be heated should occupy no more than 1/3 of the test tube.

3.     Then hold the test tube securely using a test tube holder.

4.     Ensure that the mouth of the test tube is pointing away from anybody.

5.     Move the test trip over the flame back and forth to ensure uniform heating.

 

Heating flammable liquids

1.     Place a lit Bunsen burner on top of a tripod with wire gauze to secure the heating apparatus.

2.     When heating volatile liquid, do not heat it directly over the flame. Use a steam bath.

3.     Place a steam bath half-filled with water over the flame and then place the beaker containing the volatile liquid on top of the steam bath. The heat of the steam will heat the liquid inside the beaker.

 

              Precipitation

1.     In this activity, will be utilizing AgNO3 and BaCl2. Mix 1 mL of AgNO3 and 1 mL of BaCl2 in a clean dry test tube.

2.     Observe the color changes or the possible formations of a solid substance if there is any.

              Separation of Solids from Liquids

1.     First, fold the filter paper crosswise to form a triangle

2.     Fold it again crosswise to form an even smaller triangle

3.     Lastly, open the base of the triangle to form a cone prior to mounting it to the funnel.

4.     Wet the tip of the filter paper with distilled water. This would ensure that it will stick properly on the funnel.

5.     Attach the wet filter paper into the funnel. Press it gently to ensure that it will stick properly.

6.     Pour the solution containing the precipitate on the filter paper. Observe the color of the solution that comes out in the funnel indicates that the solid was properly separated.

7.     Wash the texture with a few ml of distilled water to make sure that all the precipitates are being transferred. Wait until all of the liquids have been filtered off.

8.     Remove the filter paper gently from the funnel.

9.     Place the filter paper with the precipitate on a watch glass. The filtrate retained for this will be used for the other procedures.

              

              Measuring colorless and colored solutions

1.     To measure the volume of a colorless solution, take the lower meniscus into consideration to get an accurate measurement.

2.     To measure the volume of a colorless liquid, we will take the lower meniscus into consideration to get an accurate measurement.

 

Weighing of solid substances

1.     To weigh a solid substance, make sure that the balance is zeroed.

2.     Use a watch glass for the solid substance. Never place chemicals directly into the balance pans.

 

              Transferring of liquids and solid substances from one container to another container.

              For solid substances.

1.     Spoon out the solid reagents from the bottle by using a clean and dry spatula.

2.     When the container has a narrow mouth, use a piece of paper to transfer the solid. To make this, fold a piece of paper lengthwise. The width of the folded paper must equal to the diameter of the test tube so it will fit perfectly.

                             For liquids

1.     Transfer of chemical is usually done using a beaker because it has an indentation that facilitates the transfer when transferring liquid into a wide mouth container.

2.     Simply touch the indentation of the beaker into the mouth of the receiving container. This would prevent spillage or splashing of the chemical that is being transferred.

3.     When the container has a narrow mouth, you will be using a steering rod. This will be used to guide the liquid so that it will flow into the bottom of the test tube without spillage.

 

Evaporation

1.     Pour the filtrate into the evaporating dish and or the casserole.

2.     Boil the filtrates in the containers.

3.     Continue boiling until the liquid in the container starts to fully evaporate.

4.     When evaporation is finally done the solids dissolve in the filtrate will remain as residue in the evaporating dish or in the casserole.

 

              Separation of liquids with different densities

Centrifugation requires a centrifuge. It is a device that has the capacity to spin the solution at high speed. Thereby separating components based on different sets in their densities.

1.     Get another test tube containing water that has the same volume as the solution to be separated. This will ensure balance inside the device.

2.     Once it starts spinning, place the two test tubes across each other inside the centrifuge and then cover the lid of the texture before turning it on.

3.     After doing the precautionary measure, you can now turn on the centrifuge.

4.     Adjust it according to the desired speed. You may also set a timer for that once you turn it on. It will then start spinning. Wait until your timer is over.

5.     Once the centrifuge stops spinning, remove the test tubes from its compartment. Notice that the precipitate has already settled at the bottom. The liquid is now known as a supernatant liquid.

 

Detecting odors

When it is necessary to smell chemicals in the lab, the proper technique is to:

1.     Cup your hand above the container.

2.     Waft the air toward your face.

 

  1. Results and Discussion:

Required Laboratory Apparel in the Laboratory according to CDC guidelines in a school setting.

●      Always wear appropriate eye protection (i.e., chemical splash goggles) in the laboratory.

●      Wear Disposable Gloves, as provided in the laboratory, when handling hazardous materials. Remove the gloves before exiting the laboratory.

●      Wear a full-length, long-sleeved laboratory coat or chemical-resistant apron. Avoid wearing a shirt exposing the torso, shorts, or short skirts; long pants that completely cover the legs are preferable.

●      Wear shoes that adequately cover the whole foot; low-heeled shoes with non-slip soles are preferable. Do not wear sandals, open-toed shoes, open-backed shoes, or high-heeled shoes in the laboratory.

 

 

 

  1. Conclusion: 

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