Lab Material Classification

• Lab materials are designed for specific uses and need proper handling.

Material Classification by Fabrication

• Metals: Typically iron or alloys like copper, nickel, platinum, silver, and lead, used for supports, clamps, rings, tripods, etc.
• Porcelain: Used to make capsules, crucibles, spatulas, mortars, funnels, triangles.
• Wood: Used for racks and stands for tubes and funnels.
• Cork: Used for stoppers and ball supports.
• Rubber: Used to make hoses and stoppers.
• Asbestos: Used for making meshes, gloves, and as thermal insulation.
• Teflon: Used for hoses, valves, burette keys, flask tops, containers, and more.
• Glass: A common lab material that resists acids and alkalis.
• Two categories of lab glassware:
• Common Glassware (non-volumetric): Includes beakers, Erlenmeyer flasks, flat-bottom flasks, round-bottom flasks, funnels, test tubes, condensers, ground glass stopper flasks, watch glasses, Thiele tubes.
• Volumetric Glassware (high-precision): Calibrated for accuracy and are for measuring the exact volume to "contain" or "deliver". Indication on the glassware specifies if it's for containing or delivering, along with the calibration temperature.

Material Classification by Specific Use

• Balances: Used for determining the mass of a substance.
• Two common types:
• Granular Balances: Used when less precision is needed for solid or liquid quantities. This balance is used for preparing approximate concentration solutions. Modern versions are digital with a single top plate for rapid weighing.
• Capacity ranges from 2 to 0.01 g with a precision up to 0.1 or 0.01 g; some measure up to 100 or 200 g with a precision up to 0.001 g.
• Analytical Balances: Instruments for weighing from one gram to a few kilograms with a precision of at least one part in 10^5 of their maximum capacity. Some surpass one part in 10^6.
• Types of analytical balances. - Macrobalances: a max capacity range of 160 to 200 g and a precision of 0.1 mg. - Semimicroanalytical Balances: max capacity of 10 to 30 g and a precision of 0.01 mg. - Microanalytical Balances: max capacity of 1 to 3 g and a precision of 0.001 mg.

Using Balances

• Important norms when using a balance include:
• Handle with care.
• Do not place chemical substances directly on the plate; use a weighing boat, a beaker, weighing paper, or another container.
• Do not spill liquids on the balance.
• Adjust the balance and ask for help if you need it.
• Weigh the object or substance at room temperature.
• Reset to zero after weighing.
• Clean up any residue on the balance or around it.

Measuring Volumes

• Accuracy is an important factor when measuring volumes in labs. Choosing the right apparatus, such as a graduated pipette, volumetric pipette, volumetric flask, burette or test tube, depends on the requirements.

Pipettes

• Pipettes are designed for transferring known volumes from one vessel to another.
• Common kinds: volumetric, graduated, and automatic.
• Volumetric or Aforadas Pipettes: Used to measure a single, precise volume, ranging from 0.5 to 200 mL.
• Graduated Pipettes: Calibrated in units to pour any volume less than their max capacity, usually between 0.1 and 25 mL.

Using pipettes

How to fill:

• Draw liquid slightly above the mark using a pipette and a pro-pipette.
• Wipe the outer tip with absorbent paper. Vaciado:
• While holding the pipette vertically, touch its tip to the internal wall of a tilted collection vessel and allow the contents to empty, and don't move it.
• Begin timing a 5 second wait as soon as the meniscus is still at the tip if using AS class pipettes.
• Move the pipette up the container wall approximately 10mm after waiting to release the drop.
• Note: A small volume remaining in the pipette tip is accounted for during calibration, so avoid blowing or shaking it out as it will affect the concentration of the solution in question. Don't trust pipettes with damage tips.

Pro-pipettes

Operating Pro-pipettes:

• 1. Attach the pipette.
• 2. Squeeze 'A' button compressing bulb and creating a vacuum
• 3. While pressing 'S,' draw liquid slightly above the desired mark on the pipette.
• 4. Press 'E' slowly releasing liquid until the meniscus aligns with mark.
• Note: Close a side vent when blowing viscous fluids using a small balloon. To prevent damage, avoid liquid in the pipette.

Volumetric Flasks

• Volumetric flasks are pear-shaped vessels that precisely contain a certain liquid volume at a set temperature and are for preparing solutions with defined concentrations or for weighing a pure solid to bring it to volume.
• Designed with long necks to ensure small volume changes lead to significant meniscus height differences, minimizing error.
• Ample distance from the mark to the stopper allows sufficient mixing when filled. Use lower meniscus edge as the volume level.

Preparing standard solutions in volumetric flasks:

• Transfer the weighted amount or a liquid concentrate to the flask.
• Fill halfway with distilled water to dissolve material.
• Add distilled water almost to the aforo.
• Using a pipette or wash bottle carefully fill up to the mark, reading at eye level. And don't wet the glass above.
• Mix the flask content thoroughly.

Test Tubes

• Test tubes are standard laboratory vessels. Though they aren't precise, they estimate volumes. How to operate:
• Add the liquid to the test tube.
• Match meniscus to desired volume and read carefully.
• Ensure no liquid remains on the glass above the line
• Correctly read the liquid.

Burettes

• Burettes used to accurately release variable, known volumes, mainly in titrations.
• Each has principal marks labeled with numbers to point to mililitres or subdivisions equivalent to 0.1 mL.
• A tap regulates liquid-flow. Position the burette on the universal stand and handle the key with nondominant hand and move the container below with dominant hand. How to do it:
• Rinse burette with the standard. Then align the burette making sure the tube is vertical and solutions lack turbidity, flocculation, or deposits.
• Overfill the burette past zero, then remove bubbles.
• Fill with titrant solution up beyond 5 mm from zero and avoid wetting.
• Set the zero point precisely by reading it horizontally
• Remove droplets.
• Add titrant slowly to the analytical solution while mixing and keeping the burette tip off the glass/side. A white base can optimize view.
• Read when reaction is complete
• Let the drop slide off inside by touching inside the container.
• Restart measuring at zero.

Temperature Measurement

• Thermometer: Measures system temperature quantitatively.

• Typically the substance has a regular property variation so that heat rises to display on scale, or vice-versa.

• Celsius is the most common temperature scale. Named after Anders Celsius who developed it in 1742, not centigrade.

• Types of common thermometers:

• Glass thermometers: sealed tube that displays changes in grade as liquid level is affected by fluctuating temperatures.

• Resistance thermometers: platinum wire changes resistance as heat varies.

• Thermocouple: composed of two wires of different content to measure a electric potential difference based on temperature.

• Thermometers calibrated via greater devices and certified.

Heating

• Systems of heating include electrical plates or blankets, stoves, muffles and burners. Selection based on experiment.
• Electric stoves can sterilize.
• Temperatures on the device can reach 250 to 300° C.
• Furnaces are lined with strong refractory material and can withstand temperatures from 400 - 1200°C and are for calcinating materials.
• Heating sleeve are resistant and are designed around beakers for safe distribution of warmth.
• Plates consist of metallic substance over an open source which heat objects directly, in some cases with the assist of agitators.
• Burners designed to produce maximal warmth, they work through a combination of combustibles and air. Combustion occurs at the top.
• Mix five parts air to one part gas for a blue flame, or lessen air for a yellow variant. Good measure of air to fuel provides cones.
• Inner cones compose of uncombusted gas. The outer contains it fully combusted in surrounding air.
• Commonly used burners include Bunsen created by Robert Wilhem Bunsen, Tirrill which regulates air, and Meker which produces hotter effect.

Support Material

• Beakers are for standard volumes and forming precipitates.

• Come at a wide range of volumes and have a shape to keep rods still.

• Erlenmeyer are conic recipients with a wide base and small mouth, useful in volumetry. The design assists mixture formation.

• Kitasato Flask are dense walled flask connected a tube.

• These can filter pastelike matter.

• Crystallizers used to speedy solid formations.

• Embudo have a conic form, designed to smooth actions.

• Decantation funnels are similar to a pear but utilize a key and are designed to separate immiscible materials.

• Desiccators prevent atmosphere contact in a container through vacuum. Materials include:

• One layer containing materials.

• Bottom layer containing dry agent.

• The lid must only slide sideways when removing it and needs greasing to ensure it slides well.

• Wash bottles emit solutions and are for washing things.

• Mortals assist the crushing of materials.

Support Utensils

• Universal adaptors connect parts.
• Ferrum rings keep items upright.
• Gradillas stand tubes up.
• Hoftman clamps stop latex.
• The last are designed to fix items and double designs keep bureta steady.
• Others still include: Mohr and Capsule Clamps, Asbestos Rejillas, tripod and triangle.