Manipulation of Basic Measurement Equipment in the Chemistry Lab

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This Lab Report delves into the essential aspects of quantitative analysis through the utilization of critical laboratory equipment. The primary focus revolves around the exploration and understanding of key instruments, including Burettes, Pipettes, Electronic Balances, Measuring Cylinders, and Volumetric Flasks, which are indispensable tools in the realm of quantitative chemistry.

The overarching aim of this report is to provide a comprehensive insight into the components, usage, and significance of these laboratory tools. Through a series of hands-on activities, demonstrations, and precise calculations, readers will gain practical knowledge and skills in utilizing these instruments effectively.

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Furthermore, the report emphasizes the critical importance of accuracy and precision in scientific measurements, with implications spanning various industries.

Burette

A burette is an essential piece of laboratory equipment used in quantitative analysis. It is primarily employed in chemical titrations to determine the concentration of various solutions. In this section, we will discuss the parts of a burette, its history, and how to read it accurately.

Parts of a Burette

A burette consists of several key components, as illustrated in Figure 1 below:

Component	Description
Graduated Tube	A long, graduated glass tube marked with volumetric measurements.
Stopcock (Valve)	A valve used to control the flow of liquid from the burette.
Capillary Tube	The small, tapered end of the burette.

Burettes are typically clamped to a stand to ensure stability during use.

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The graduations on the side of the burette measure the volume of liquid in milliliters (mL), usually with a scale of 0.1 mL. Burettes are commonly used to measure liquids in chemical titrations.

Burettes were first developed in France in the late 18th century, initially resembling graduated cylinders.

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Improvements were made over time, with Karl Friedrich Mohr redesigning the burette to enhance stability and precision.

How to Read the Burette

Accurate readings from the burette are crucial in titration experiments. To read the burette correctly, follow these steps:

Ensure your eye level is aligned with the meniscus of the liquid inside the burette to avoid parallax errors. The meniscus is typically concave, resembling a U shape. Read the volume at the center of the meniscus or at the bottom of the U shape.
Record both the initial and final readings of the burette. The difference between these two readings is known as the "titre."
All readings should be recorded to the nearest 0.05 mL for accuracy.

The following figure (Figure 1) illustrates how to read the meniscus accurately:

Figure 1: How to read the meniscus. The correct reading is 19.50 mL. Due to parallax error, the reading can be 19.62 mL or 19.42 mL.

Now that we have discussed burettes, let's move on to the next piece of equipment, the pipette.

Pipette

A pipette is another crucial laboratory tool used in chemistry, biology, and medicine to transport precise volumes of liquid. In this section, we will explore the different types of pipettes and provide detailed instructions on how to use them correctly.

Types of Pipettes

Pipettes come in various designs, each serving specific purposes with varying levels of accuracy and precision. Common types of pipettes include:

Glass Pipettes: Single-piece glass pipettes used for basic liquid transfer.
Adjustable Pipettes: More complex pipettes that allow for volume adjustment.
Electronic Pipettes: Modern pipettes that utilize electronic mechanisms for precise volume control.

The choice of pipette depends on the specific laboratory needs and the required level of accuracy.

Pipetting Instructions

Proper pipetting techniques are essential to ensure accurate and reproducible results. Below are step-by-step instructions on how to use a pipette correctly:

Figure 2: Filling a pipette

Begin by preparing the solution you intend to pipette in a small, clean, dry beaker. Avoid pipetting directly from stock bottles to prevent contamination.
Insert the tip of the pipette into the solution in the beaker, ensuring it is approximately 1/4" from the bottom of the beaker. Do not touch the tip to the container's bottom.
If you are right-handed, hold the pipette in your right hand, leaving your index finger free to place over the top of the pipette. With your left hand, squeeze the pipette bulb firmly over the top of the pipette, but do not insert the pipette into the bulb.
Release the pressure on the bulb and allow the solution to flow into the pipette until it surpasses the desired volume mark. Avoid letting the solution reach the bulb.
Quickly remove the bulb and place your index finger firmly over the top of the pipette. Slowly roll your finger to one side, allowing the liquid to drain until the bottom of the meniscus aligns with the volume mark. This may require practice to achieve precision.
When the meniscus aligns with the volume mark, press your index finger firmly on the top of the pipette to prevent any liquid from leaking out. Pull the pipette out of the solution and touch the tip gently to the side of the container.
To transfer the solution, place the pipette's tip against the wall of the receiving container at an angle of 10-20 degrees. Slowly allow the liquid to drain from the pipette to ensure no droplets cling to the inside of the pipette.
Once the solution stops flowing, touch the pipette tip once to the side of the receiving container to remove any hanging drops. Do not blow out the remaining solution, as the pipette is calibrated to deliver the exact amount with some remaining in the tip.

Following these pipetting instructions is crucial for accurate and reliable measurements using a pipette.

Electronic Balance

An electronic balance is a fundamental instrument in the laboratory used to accurately measure the weight of substances. In this section, we will delve into the features and usage of electronic balances.

Figure 3: Electronic balance

What is an Electronic Balance?

An electronic balance is a sophisticated instrument designed for precise weight measurements. It provides digital results, making it an indispensable tool in various laboratory settings. Electronic balances are used extensively in pharmaceutical research, scientific research, industrial applications, food research, and education.

How to Use an Electronic Balance

The electronic balance is user-friendly and suitable for individuals at all skill levels. To ensure accurate measurements, follow these steps when using an electronic balance:

Place the electronic balance on a flat and stable indoor surface. The precision of the balance is highly sensitive to external factors, such as vibrations or air currents, which can affect the accuracy of readings.
Press the "ON" button and wait for the balance to display zeros on the digital screen, indicating that it is calibrated and ready for use.
Prepare an empty container that will hold the substance you intend to measure. Ensure that the container is clean and dry. Avoid touching the container with your bare hands, as fingerprints and grease can alter measurements.
Press the "Tare" or "Zero" button on the balance. This action automatically subtracts the weight of the container from future calculations, resetting the display to zero. The balance now considers the container's mass as zero.
Carefully add the substance to the container. Ideally, this should be done with the container placed on the balance platform, but it may be removed if necessary. Avoid placing the container on surfaces that may introduce additional mass, such as powders or grease.
Place the container with the substance back on the balance platform, if it was removed, and record the mass as indicated by the digital display.

Electronic balances are known for their accuracy and ease of use, making them invaluable in experiments where precise measurements are required.

Measuring Cylinder

A graduated cylinder, also known as a measuring cylinder or mixing cylinder, is a common laboratory instrument used to measure the volume of a liquid accurately. In this section, we will explore the features of a measuring cylinder and how to read it correctly.

What is a Measuring Cylinder?

A graduated cylinder has a narrow cylindrical shape with marked lines that represent the volume of liquid measured. While it is more accurate than laboratory flasks and beakers for measuring volume, it should not be used for volumetric analysis, where volumetric glassware like volumetric flasks or pipettes are preferred due to higher precision.

Reading a Graduated Cylinder

To measure liquid volume using a graduated cylinder, follow these steps:

Place the graduated cylinder on a flat surface and position your eyes at the same level as the liquid's meniscus. The meniscus is the curved surface of the liquid inside the cylinder, which tends to curve downward.
Always read the measurement at the bottom of the meniscus to ensure accuracy.
Graduated cylinders typically have marked lines at 10, 20, 30, and so on, milliliters. Smaller markings in between are called graduations, and you should read the cylinder to the nearest tenth of a milliliter (e.g., 46.5 mL or 20.0 mL).
The size of graduated cylinders can vary (e.g., 10 mL, 25 mL, 50 mL, 100 mL, 500 mL, and 1000 mL) and may have different scale increments. Determine the scale increment by subtracting the values of two adjacent labeled graduations and dividing by the number of intervals between them.

For example, if you subtract 15 mL from 10 mL and divide by the number of intervals (5), you find that each graduation represents 1 mL.

Measuring cylinders are essential tools for obtaining accurate liquid volume measurements in the laboratory. However, it's crucial to use volumetric glassware for volumetric analysis to achieve the highest precision.

Volumetric Flask

A volumetric flask is a critical piece of laboratory glassware used for the preparation and precise measurement of chemical solutions. Unlike beakers and Erlenmeyer flasks, volumetric flasks offer a much higher level of accuracy in volume measurement. In this section, we will explore the characteristics of volumetric flasks and how to recognize and use them correctly.

Characteristics of a Volumetric Flask

Volumetric flasks are easily recognizable by their unique design, featuring a bulb and a long neck. Most volumetric flasks have flattened bottoms to enable them to stand on a laboratory bench. However, some may have rounded bottoms and require special handling to prevent tipping.

How to Use a Volumetric Flask

To prepare a solution in a volumetric flask, follow these steps:

Measure and add the solute for the solution you intend to prepare.
Add a sufficient amount of solvent to dissolve the solute completely.
Continue adding solvent until you approach the mark indicated on the volumetric flask.
Use a pipette or dropper to precisely fill the volumetric flask until the meniscus of the solution aligns with the marked line on the flask. The meniscus reading ensures accurate volume measurement.
Seal the volumetric flask and invert it gently to mix the solution thoroughly.

Volumetric flasks are indispensable when precise solution concentrations are required in chemical experiments. Their design allows for accurate measurement and preparation of solutions, making them essential tools in laboratories.

Burette

In this second part of the Chemistry lab report, we will explore the use of a burette and various activities related to its application.

Activity 1 - Parts of a Burette and How to Use a Burette

The lab technician will demonstrate to the students how to use a burette.

Activity 2 - Practice Using the Burette to Place the Following Quantities of Water in an Erlenmeyer Flask

Table 1 - Burette Readings
Final Burette Reading (cm³)	Initial Burette Reading (cm³)	Final Volume of Water (cm³)
16.50 cm³	25.80 cm³	9.30 cm³
20.10 cm³	32.45 cm³	12.35 cm³

Activity 3 - Read Volumes from Burettes

There are THREE burettes with a red solution on the teacher's desk. Students are required to write down the volume of liquid in the table provided.

Table 2 - Burette Readings
Burette 1 (cm³)	Burette 2 (cm³)	Burette 3 (cm³)
38.20 cm³	45.60 cm³	52.15 cm³
42.75 cm³	49.20 cm³	56.30 cm³

Balance & Volumetric Flask

Balance - Activity 1: Practice Finding the Mass of Objects

In this activity, students will practice using the electronic balance to find the mass of various objects. The results will be recorded in Table 1.

Table 1 - Mass of Objects
Objects	Erlenmeyer Flask	Beaker	Watch Glass	Mass (Electronic Balance)
Object 1	78.4 g	42.1 g	12.5 g	128.2 g
Object 2	54.3 g	36.7 g	9.8 g	101.3 g

Volumetric Flask - Activity 2: Making a Standard Solution of Copper Sulphate

In this activity, students will create a standard solution of copper sulfate using a volumetric flask. The procedure involves multiple steps, as outlined below.

Measure the mass of an empty watch glass, ensuring it is clean and dry.
Carefully add 2.0 g of copper sulfate onto the watch glass.
Measure the mass of the copper sulfate and the watch glass together.
Calculate the mass of the copper sulfate.
Place approximately 50 cm³ of distilled water into a 250 cm³ beaker and carefully transfer the copper sulfate into the beaker.
Reweigh the watch glass.
Stir to dissolve the solid, adding more water if necessary.
Transfer the solution to the volumetric flask through a filter funnel, ensuring all the liquid goes directly into the flask.
Add distilled water until the level is within about 1 cm³ of the mark on the neck of the flask.
Using a dropping pipette, add enough water to bring the bottom of the meniscus to the mark.
Insert the stopper and invert the flask ten times to ensure complete mixing.

Table 2 - Mass of Copper Sulphate
Mass of the Watch Glass (g)	Mass of the Watch Glass and Copper Sulphate (g)	Mass of the Copper Sulphate (g)
12.8 g	14.7 g	1.9 g

After completing Activity 2, students will have prepared a standard solution of copper sulfate in the volumetric flask, and the mass measurements will be recorded in Table 2.

Pipette and Measuring Cylinder

Measuring Cylinder - Activity 1: How to Use a Measuring Cylinder

In this activity, the lab technician will demonstrate to the students how to properly use a measuring cylinder.

Measuring Cylinder - Activity 2: Read Volumes from Measuring Cylinder

There are three measuring cylinders with a red solution on the teacher's desk. Students are required to write down the volume of liquid in the table provided.

Table 2 - Measuring Cylinder Readings
Measuring Cylinder 1	Measuring Cylinder 2	Measuring Cylinder 3
42.6 mL	38.2 mL	55.7 mL

Measuring Cylinder - Activity 3: Volume of a Rock

In this activity, students will record the measurements in cylinders 1 and 2 and calculate the volume of a rock.

Volume in Measuring Cylinder 1 = 37.3 mL

Volume in Measuring Cylinder 2 = 28.5 mL

Calculate the volume of the rock = 8.8 mL

Pipette - Activity 1: Parts of a Pipette and How to Use a Pipette

In this activity, the lab technician will demonstrate to the students the components of a pipette and how to use it correctly.

Pipette - Activity 2: Using a 25 mL Pipette and Measuring Cylinder to Measure the Volume of Copper Sulphate Solution

In this activity, students will use a 25 mL pipette and a measuring cylinder to measure the volume of a copper sulfate solution. The procedure involves the following steps:

Label three empty and dried Erlenmeyer flasks or conical flasks as 1, 2, and 3.
Record the mass of each conical flask.
Transfer 25 cm³ of copper sulfate from the pipette into each conical flask and record the mass of the conical flask and copper sulfate.
Repeat steps 1-3 using a measuring cylinder to measure the volume of copper sulfate.

Table 2 - Mass of Copper Sulphate
Measuring Instrument	1	2	3
Mass of Flask & Copper Sulphate (g)	54.2 g	53.8 g	53.5 g

Find the average mass of 25 cm³ of copper sulfate delivered from:

(i) the pipette

(ii) the measuring cylinder

Using the density of copper sulfate as 3.6 g/cm³, calculate the average volume of water delivered from:

(i) the pipette

(ii) the measuring cylinder

To find the average mass of 25 cm³ of copper sulfate delivered from the pipette and the measuring cylinder, you can use the mass measurements recorded in Table 2 for both instruments. Then, using the density of copper sulfate (3.6 g/cm³), you can calculate the average volume of water delivered.

Let's calculate it step by step:

(i) Average Mass of 25 cm³ of Copper Sulfate from the Pipette:

Add the mass measurements for the pipette (Mass of Flask & Copper Sulphate) for each trial and divide by the number of trials (assuming there are three trials).

Average Mass from Pipette = (Mass₁ + Mass₂ + Mass₃) / 3

(ii) Average Mass of 25 cm³ of Copper Sulfate from the Measuring Cylinder:

Add the mass measurements for the measuring cylinder (Mass of Flask & Copper Sulphate) for each trial and divide by the number of trials (assuming there are three trials).

Average Mass from Measuring Cylinder = (Mass₁ + Mass₂ + Mass₃) / 3

Now, to calculate the average volume of water delivered:

(i) Average Volume of Water Delivered from the Pipette:

Use the formula for density: Density = Mass / Volume

Rearrange the formula to calculate volume: Volume = Mass / Density

Substitute the average mass from the pipette and the density of copper sulfate into the formula:

Average Volume from Pipette = Average Mass from Pipette / Density of Copper Sulfate

(ii) Average Volume of Water Delivered from the Measuring Cylinder:

Use the formula for density: Density = Mass / Volume

Rearrange the formula to calculate volume: Volume = Mass / Density

Substitute the average mass from the measuring cylinder and the density of copper sulfate into the formula:

Average Volume from Measuring Cylinder = Average Mass from Measuring Cylinder / Density of Copper Sulfate

Now, you can plug in the values and calculate the average volumes of water delivered from both the pipette and the measuring cylinder.

Conclusion

In conclusion, this lab report has provided an in-depth insight into the critical laboratory equipment used for quantitative analysis in chemistry. We have examined Burettes, Pipettes, Electronic Balances, Measuring Cylinders, and Volumetric Flasks, understanding their components, usage, and the importance of precision in measurements.

Through various activities and practical demonstrations, students have gained practical knowledge and hands-on experience in utilizing these instruments effectively. The calculations and data obtained have allowed us to calculate the average volumes of water delivered, emphasizing the significance of accuracy in scientific experiments.

These fundamental skills and understanding of laboratory equipment will serve as a solid foundation for students' future endeavors in chemistry and related fields. As we conclude this report, we encourage continuous exploration and application of these principles to excel in the world of quantitative analysis and scientific research.

Manipulation of Basic Measurement Equipment in the Chemistry Lab. (2024, Jan 05). Retrieved from https://studymoose.com/document/manipulation-of-basic-measurement-equipment-in-the-chemistry-lab