Basic chemistry lab skills

Summary

In this educational video, Lucy from the University of Glasgow demonstrates essential chemistry lab techniques. She guides viewers through the proper use of a pipette and burette, emphasizing safety with lab gear. Lucy also explains how to prepare a standard solution of sodium chloride, detailing each step from weighing to dissolution and final mixing in a standard flask, highlighting the importance of these skills for aspiring chemists.

Takeaways

• 🧪 Lucy introduces basic chemistry skills including the use of a burette and pipette.
• 👓 Safety first: Always wear lab glasses and gloves before starting experiments.
• 💧 Properly wash and fill a pipette by rinsing it with the solution before use.
• 📏 Read the meniscus at the bottom curve for accurate liquid measurement in the pipette.
• 🔄 Standard practice includes tying hair back and ensuring safety equipment is on.
• 🧴 Clean the burette by ensuring the tap is closed and rinsing it with the solution.
• 🔬 Fill the burette carefully, removing the funnel to prevent drips that alter volume.
• ⚖️ Tare the balance to zero before weighing chemicals for accurate measurements.
• 🌊 Dissolve sodium chloride completely in deionised water for a standard solution.
• 🔄 Mix the solution thoroughly by inverting the flask after adding the stopper.

Q & A

What is the purpose of the video presented by Lucy?

The purpose of the video is to demonstrate basic chemistry skills, including using a burette, pipette, and preparing a standard solution.

Why does Lucy wear lab glasses and gloves before starting the experiment?

Lucy wears lab glasses and gloves to ensure safety and prevent contamination during the experiment.

What is the capacity of the pipette that Lucy uses in the video?

Lucy uses a 20ml pipette in the video.

How does Lucy ensure the pipette is properly filled with the solution?

Lucy ensures the pipette is properly filled by drawing up the solution until it is half filled, rinsing it around the pipette, and then filling it up to the mark while reading from the bottom of the meniscus.

What safety measures does Lucy take before setting up the burette?

Before setting up the burette, Lucy ties her hair up, puts on safety specs, and gloves, which is standard practice for safety in the lab.

Why does Lucy pour sodium hydroxide solution into the burette only half full initially?

Lucy pours the sodium hydroxide solution into the burette half full initially to wash it out and ensure there are no bubbles left in the underside of the tap.

How does Lucy ensure the burette is ready for use after filling it?

Lucy ensures the burette is ready for use by removing the funnel, opening the tap to let the meniscus fall to the zero point, and then closing the tap.

What is the first step Lucy takes to prepare a standard solution of sodium chloride?

The first step Lucy takes to prepare a standard solution of sodium chloride is to put on her lab gloves and glasses and tare the balance to zero.

How does Lucy transfer the sodium chloride to the beaker after weighing it?

Lucy transfers the sodium chloride to the beaker by removing the weighing boat from the balance, adding the chemical, and then putting the boat back on the balance to check the correct mass.

What is the purpose of rinsing the beaker with a pipette during the preparation of the standard solution?

Rinsing the beaker with a pipette ensures that no chemical is left behind, which could affect the concentration of the standard solution.

How does Lucy ensure the standard solution is well mixed after transferring it to the flask?

Lucy ensures the standard solution is well mixed by inverting the flask several times after adding the stopper.

Outlines

00:00

🧪 Basic Chemistry Skills Demonstration

Lucy, a chemistry student at the University of Glasgow, introduces a video tutorial on basic chemistry lab techniques. She and her lab partner demonstrate how to use a pipette and burette, and how to prepare a standard solution. Lucy starts by putting on lab safety gear, including glasses and gloves. She shows the process of washing and filling a 20ml pipette, emphasizing the importance of reading the liquid level at the bottom of the meniscus. Following this, she sets up the burette, ensuring safety protocols are followed by tying her hair, wearing safety specs, and gloves. She demonstrates washing the burette with sodium hydroxide solution, removing air bubbles, and filling it up to the zero mark. Lucy then explains the process of preparing a standard solution of sodium chloride, detailing the steps of weighing, dissolving, transferring, and making up to the mark with deionised water. She concludes by emphasizing the importance of these skills in a chemistry degree and future career.

Keywords

💡Burette

A burette is a piece of laboratory equipment used to measure and dispense precise volumes of liquid. In the video, Lucy demonstrates how to wash and fill a burette with a sodium hydroxide solution, highlighting its importance in accurately measuring reagents for chemical reactions. The burette is crucial for experiments requiring precise titrations.

💡Pipette

A pipette is a laboratory tool used to transfer small, measured volumes of liquid. Lucy shows how to wash and fill a 20ml pipette, emphasizing the importance of proper technique to ensure accurate measurements. The pipette is used to draw up and dispense solutions, such as when preparing a standard solution in the video.

💡Standard Solution

A standard solution is a solution with a known and precise concentration of a solute. In the script, Lucy prepares a standard solution of sodium chloride by accurately weighing the solute and dissolving it in a known volume of solvent. This is essential for calibration and quality control in chemical analysis.

💡Meniscus

The meniscus refers to the curved surface of a liquid in a container, such as a pipette or burette. Lucy explains the importance of reading the volume from the bottom of the meniscus to ensure accurate measurements. This concept is crucial for precise volume readings in laboratory experiments.

💡Sodium Hydroxide

Sodium hydroxide is a strong base commonly used in various chemical experiments. In the video, Lucy uses sodium hydroxide solution to wash and fill the burette, demonstrating its role in preparing for titration experiments. Understanding the properties of sodium hydroxide is essential for conducting accurate chemical analyses.

💡Safety Precautions

Safety precautions are measures taken to prevent accidents and injuries in the laboratory. Lucy puts on lab glasses, gloves, and safety specs, illustrating the importance of personal protective equipment. These precautions are critical in a lab setting to protect against chemical exposure and other hazards.

💡Weighing Boat

A weighing boat is a small container used to hold chemicals during weighing on a balance. Lucy uses a weighing boat to accurately measure the mass of sodium chloride, emphasizing the importance of precise weighing for preparing solutions. This tool is essential for ensuring the correct concentration of solutions in chemical experiments.

💡Deionised Water

Deionised water is water that has had most or all of its mineral ions removed, making it ideal for laboratory use. Lucy uses deionised water to rinse the weighing boat and dissolve sodium chloride, highlighting its role in ensuring the purity of solutions and the accuracy of experimental results.

💡Glass Rod

A glass rod is a laboratory tool used for stirring solutions to ensure even mixing. In the script, Lucy stirs the sodium chloride solution with a glass rod to ensure complete dissolution. This tool is essential for achieving homogeneity in solutions, which is critical for accurate experimental results.

💡Standard Flask

A standard flask is a type of volumetric flask used to prepare solutions of precise volume and concentration. Lucy transfers the prepared sodium chloride solution into a standard flask, demonstrating how it is used to make a standard solution. This flask is crucial for volumetric analysis and ensuring the reproducibility of experiments.

💡Titration

Titration is a laboratory method of determining the concentration of an unknown solution by reacting it with a solution of known concentration. Although not explicitly mentioned in the script, the preparation of standard solutions and the use of a burette imply titration as a potential application of the demonstrated techniques.

Highlights

Introduction to basic chemistry skills at the University of Glasgow

Demonstration of using a pipette and burette

Safety measures including wearing lab glasses and gloves

Procedure for washing and filling a 20ml pipette

Explanation of the meniscus and its importance in pipette reading

Setting up a burette with safety precautions

Washing the burette with sodium hydroxide solution

Technique for filling the burette and avoiding bubbles

Preparation of a standard solution using sodium chloride

Use of a balance and weighing boat for accurate measurements

Transfer of sodium chloride to a beaker and dissolution process

Rinsing the weighing boat and transferring the solution to a standard flask

Technique for making up to volume and adjusting the meniscus in a standard flask

Mixing the standard solution by inverting the flask

Importance of these skills in a chemistry degree and future career

Transcripts

Hi, I'm Lucy and I study chemistry here at the University of Glasgow.

Today, my lab partner and I are going to show you some

basic chemistry skills, including using a burette,

pipette and preparing a standard solution.

I will now show you how to wash and fill a pipette.

First, I'm going to put my lab glasses and my lab gloves on.

We're going to be using a 20ml pipette, I'll attach the pipette

filler to the pipette, making sure to hold it at the very top.

Draw up the solution so that the pipette is half filled.

I'll take off the pipette filler and close the top with my thumb.

I'll now rinse the solution around the pipette,

spinning it and then drain it into the waste beaker.

And I reattach the filler and fill the pipette up to the mark,

making sure to read from the bottom of the meniscus. The meniscus

is the bottom of the curve of the liquid when in the pipette.

Now, I'm going to set up the burette. Before I start,

I'm first going to tie my hair up, put my safety specs on and put

on my gloves, which is standard practice before any experiment.

First, I'm going to pour out the sodium hydroxide

solution into a small beaker. Now we are going to wash the burette.

I'm going to make sure that the tap is definitely closed.

Now, I put the funnel into the burette. I pour in some sodium

hydroxide solution to make sure that the burette is only half full.

I open the tap to make sure that the sodium hydroxide moves

through and there are no bubbles left in the underside of the tap.

The remaining solution, I will wash out the top into the waste bucket.

Now to fill the burette, I make sure that the tap is again closed.

Add the funnel back to the top of the burette and pour in

more solution than is needed to fill.

I remove the funnel from the top of the burette

before I start the reaction. This is because it could

drip in and change the volume that is in the burette.

I now open the tap and watch the meniscus fall till it reaches the zero point and close the tap.

Now I will show you how to prepare a standard solution:

first I will put on my lab gloves and glasses.

Now I'll turn on the balance and tare it to zero.

A balance is a technical name for scales in chemistry.

I put the weighing boat on the balance and tare it again.

I remove the weighing boat and add the sodium chloride.

Taking the boat off the balance ensures there is no spillage of the chemical onto the balance.

I put the weighing boat back on the balance to check I've

got the right math and if not, I can adjust it accordingly.

I then note down the mass of the sodium chloride.

I pour the sodium chloride into the beaker.

Next, I rinse off the weighing boat with deionised water.

I add more deionised water and stir it with a glass rod until

it is fully dissolved. If your chemical doesn't fully dissolve,

you may need to add some more water.

Make sure to rinse off any excess chemical from the glass rod.

Next, I will put the funnel into the

standard flask and add the solution from the

beaker.

Rinse

the

beaker using a pipette to make sure there's no chemical left.

Top-up with extra water until you are near the graduation mark,

then use a plastic pipette to filter the meniscus.

The meniscus is the bottom of the curve of the solution in

the standard flask. Remove the funnel and add the stopper.

Invert the flask several times to make sure everything is mixed

thoroughly. I've now made a standard solution of sodium chloride.

This is a really useful technique throughout chemistry.

These are really useful skills that you would use throughout your degree

here at the University of Glasgow and in your future as a chemist.