Common Lab Techniques Video

Summary

This chemistry lab tutorial introduces essential laboratory techniques for an introductory chemistry course. It covers the proper use of an electronic balance for precise mass measurement, the importance of using weighing boats or paper, and the correct operation of a Bunsen burner for safety and temperature control. The video also demonstrates how to measure liquid volumes with a graduated cylinder, take accurate temperature readings with a thermometer, and perform filtration to separate mixtures. Each technique is explained with a focus on safety and accuracy, ensuring students are well-prepared for lab work.

Takeaways

• 🔬 Chemistry is the study of matter and its changes, and laboratory techniques are crucial for understanding these processes.
• 📏 Proper use of an electronic balance is essential, with sensitivity to one-hundredth of a gram and a maximum capacity of 400 grams.
• 🚫 Avoid placing substances directly on the balance pan to prevent contamination and ensure accurate measurements.
• ⚖️ Always zero the balance before use and use a weighing boat or paper to measure the mass of substances.
• 🌡️ Measuring specific volumes of liquids accurately requires the use of graduated cylinders, which are more precise than beakers or flasks.
• 💧 When measuring liquids, ensure the meniscus is at eye level for accurate readings and select the appropriate cylinder size for the volume needed.
• 🌡️ Accurate temperature measurements involve submerging the thermometer fully without touching the container walls and estimating to the nearest tenth of a degree.
• 🧪 Filtration is a technique used to separate mixtures, requiring a funnel, filter paper, and a beaker, with careful pouring to avoid spillage.
• 🔥 Safety is paramount when using a Bunsen burner, including removing combustibles, securing loose clothing, and using safety goggles and an apron.
• 🔥 Correctly lighting and adjusting a Bunsen burner involves opening the gas valve, making a spark, and adjusting the combustion column for a blue flame.

Q & A

What is the primary focus of chemistry as a science?

Chemistry is the science of the study of matter and the changes that matter undergoes.

Why are electronic balances sensitive instruments in a chemistry lab?

Electronic balances are sensitive because they are designed to measure mass to the nearest one-hundredth of a gram and have a capacity of only 400 grams.

What is the proper way to turn on an electronic balance?

You can turn on an electronic balance by holding the on button for several seconds or by pressing the on zero button quickly to rezero or tare it.

Why should you not place substances directly on the metal pan of a balance?

To prevent the substance from coming in contact with the pan, you should use a plastic weighing boat or dish or a piece of weighing paper.

How can you ensure the balance is correctly zero before measuring the mass of an object?

Before placing an object on the pan, ensure the balance is correctly zero by either turning it on or pressing the zero button to tare it.

What is the significance of the negative mass displayed by the balance when the weighing dish is removed?

A negative mass indicates that the balance is subtracting the weight of the plastic weighing dish, which means it has been successfully zeroed.

Why should you not touch chemical substances directly with your fingers in a lab?

Direct contact with chemical substances should be avoided to prevent contamination and ensure safety; use tools like a spoon or other apparatus designed for dispensing chemicals.

How can you accurately measure a specific volume of a liquid in a chemistry lab?

Use a graduated cylinder, ensuring it is the right size for the volume you need to measure, and check the meniscus at eye level for precise readings.

What is the purpose of swirling a mixture of water, salt, and sand in a beaker?

Swirling helps the salt dissolve and allows the sand to settle to the bottom of the beaker.

How should you handle a thermometer for accurate temperature readings in a chemistry lab?

Submerge the thermometer as far as possible into the material without touching the container walls, and use a stand with a clamp for longer measurements.

What is the importance of filtration in a chemistry lab and how is it set up?

Filtration is used to separate mixtures, such as transferring sand into filter paper while allowing salt water to flow through. It involves setting up a funnel with filter paper, supported by a triangle and a stand.

What safety precautions should be taken when lighting a Bunsen burner in a chemistry lab?

Ensure the area is clear of combustible materials, wear appropriate safety gear, and adjust the gas valve and combustion column correctly before lighting.

Outlines

00:00

🔬 Introduction to Chemistry Lab Techniques

This paragraph introduces the viewer to common laboratory techniques used in an introductory chemistry course. It emphasizes the importance of understanding chemistry as the study of matter and its changes. The script discusses the correct use of an electronic balance for measuring the mass of substances with precision up to one-hundredth of a gram. The balance's sensitivity and cost are highlighted, cautioning against misuse. Instructions are provided on how to turn on the balance, zero it, and use it with a plastic weighing boat or paper to prevent direct contact with the pan. The process of measuring the mass of substances, subtracting the weight of the container, and adding chemicals using appropriate tools without direct contact are explained. The paragraph concludes with a practical exercise to measure specific masses of NaCl and sand, emphasizing cleanliness and preparation for the next user.

05:00

📏 Measuring Volumes and Temperatures in the Lab

The second paragraph focuses on measuring specific volumes of liquids using graduated cylinders, emphasizing the importance of selecting the right tool for the job. It provides a step-by-step guide on how to accurately measure 95.0 milliliters of water, including tips on using a squirt bottle and reading the meniscus correctly. The paragraph also covers the technique of mixing substances, such as salt and sand with water, to create a beach-like mixture. Additionally, it discusses the use of thermometers for measuring the temperature of substances, detailing how to obtain accurate readings and safety considerations, such as not leaving thermometers unsupported. The importance of estimating to the nearest tenth of a degree is mentioned, with an example of a 20.0 degrees Celsius reading. The viewer is instructed to measure the temperature of their mixture and record it before proceeding.

10:02

🧪 Filtration and Bunsen Burner Safety

The final paragraph covers the process of filtration to separate mixtures, such as sand from saltwater, using a funnel, filter paper, and a glass rod. It describes how to set up the filtration equipment, including the use of a triangle and a ring stand, and the importance of folding the filter paper correctly to create a cone shape that fits into the funnel. The technique of decanting is introduced, where the glass rod is used to direct the flow of liquid into the funnel. The paragraph concludes with a discussion on safely lighting and adjusting a Bunsen burner, including safety precautions, such as removing combustible materials and securing loose clothing. It provides a detailed guide on connecting the burner to the gas jet, lighting it with a striker, and adjusting the combustion column to control the flame's temperature and color. The viewer is encouraged to demonstrate their proficiency with the Bunsen burner and, if time permits,蒸发 the water from a previously filtered saltwater mixture to separate the salt.

Keywords

💡Chemistry

Chemistry is the scientific study of the composition, structure, properties, and reactions of matter. In the context of the video, chemistry is the overarching theme as it discusses laboratory techniques used in an introductory chemistry course. The script mentions that chemistry is the science of studying matter and its changes, which is central to the experiments and techniques being taught.

💡Laboratory Techniques

Laboratory techniques refer to the methods and procedures used in a laboratory setting to conduct scientific experiments and analyses. The video script introduces various common techniques such as using an electronic balance, graduated cylinders, thermometers, and Bunsen burners, which are essential for performing experiments in chemistry.

💡Electronic Balance

An electronic balance is a sensitive instrument used to measure the mass of substances with precision. The script emphasizes the importance of using an electronic balance correctly, such as not overloading it or placing substances directly on its pan, to ensure accurate measurements. It is a critical tool for weighing chemicals in the lab.

💡Graduated Cylinder

A graduated cylinder is a piece of laboratory glassware used for measuring the volume of liquids. The script explains the correct use of a graduated cylinder to measure a specific volume of liquid, such as water, with precision. It is highlighted as a better tool for volume measurement compared to beakers or flasks.

💡Thermometer

A thermometer is an instrument used to measure temperature. In the video, the proper use of a thermometer to obtain accurate temperature readings of substances is discussed. It is crucial for experiments where temperature control or measurement is a factor.

💡Filtration

Filtration is a laboratory technique used to separate solids from liquids or to separate particles based on size. The script describes the process of filtration, including the setup of equipment like a funnel, filter paper, and beaker, to separate sand from a saltwater solution.

💡Bunsen Burner

A Bunsen burner is a common piece of laboratory equipment that provides a flame for heating substances. The script covers the safety considerations and the correct procedure for lighting and adjusting a Bunsen burner, which is essential for experiments involving heat.

💡Weighing Boat

A weighing boat, or dish, is used to hold substances during weighing on an electronic balance. The script mentions the use of a plastic weighing boat to prevent direct contact between the substance and the balance pan, ensuring cleanliness and accuracy in measurements.

💡Meniscus

The meniscus is the curved surface of a liquid in response to its container or to gravity. When measuring liquid volume with a graduated cylinder, the script instructs to read the volume at the bottom of the meniscus to ensure an accurate measurement.

💡Decanting

Decanting is the process of transferring a liquid from one container to another, often to separate it from a solid. The script describes using a glass rod to direct the flow of saltwater into a funnel during the filtration process, which is a form of decanting.

💡Safety Precautions

Safety precautions are essential measures taken to prevent accidents in a laboratory setting. The script highlights several safety considerations, such as removing combustible materials and wearing safety goggles when using a Bunsen burner, to ensure a safe laboratory environment.

Highlights

Introduction to common laboratory techniques in chemistry.

Importance of proper use and care of an electronic balance for accurate mass measurements.

Avoiding damage to sensitive electronic balances by not applying excessive force.

Instructions on turning on and zeroing an electronic balance.

Using plastic weighing boats or paper to prevent direct contact with the balance pan.

Technique of taring the balance to subtract the weight of the container.

Proper handling of chemical substances to avoid direct contact with hands.

Measuring specific volumes of liquids using graduated cylinders.

Selecting the appropriate size of graduated cylinder for accurate volume measurements.

Correct technique for reading volumes at eye level and from the bottom of the meniscus.

Combining measured substances to create a mixture and observing the dissolution and settling process.

Measuring the temperature of substances using a thermometer and ensuring accurate readings.

Safety precautions when handling thermometers to prevent accidents in the lab.

Estimating readings to the nearest decimal place smaller than the scale's increment.

Filtration technique for separating mixtures using a funnel, filter paper, and support stand.

Proper folding and placement of filter paper in the funnel for effective filtration.

Decanting technique to transfer liquid through the filter paper without spilling.

Completing the filtration process and separating sand from salt water.

Safety measures and proper lighting of a Bunsen burner in the chemistry lab.

Adjusting the Bunsen burner for optimal flame temperature and color.

Conclusion of the laboratory techniques practice with a focus on safety and accuracy.

Transcripts

during your study of chemistry you will

be working in a laboratory setting to

perform various experiments the purpose

of this information is to introduce some

of the most common techniques that will

be used throughout the year and give you

a chance to practice them chances are

that your teacher has already discussed

with you that chemistry is the science

of the study of matter and the changes

that matter undergoes during this lab we

will look at various techniques that

will be used throughout the year and we

will examine two questions specifically

first what are the most common

laboratory tools and techniques used in

an introductory chemistry course and

second how are these tools and

techniques used and performed

effectively one of the most common

techniques in any laboratory is the

ability to measure the mass of a

substance using an electronic balance in

this section we will look at the proper

use and operation of an electronic

balance before we talk about how to use

the balance let's first talk about what

not to do with the balance the balances

that you will be using in chemistry lab

are sensitive instruments most of them

are designed to measure mass to the

nearest one one hundredth of a gram and

most of them have a capacity of only 400

grams which is less than a pound so

please resist the urge to test your

superhuman strength by pushing down on

the pan of the balance to see how high

the numbers will go they won't go very

high and you'll break the balance these

balances cost about three to four

hundred dollars a piece so they're

fairly expensive to replace step one in

using the electronic balance involves

turning the balance on or tearing or re0

in the balance both of these processes

can be done by either holding the on

button for several seconds if you want

to turn the balance on or off or simply

pressing quickly the on zero button if

you want the balance to rezero or tear

it

before placing anything on the pan of

the balance to determine its mass you

should make sure that the balance is

correctly zero one rule when using any

balance is to never place a substance

directly on the metal pan of the balance

instead we should use a plastic weighing

boat or dish or a folded piece of

weighing paper to prevent the substance

from coming in contact with the pan when

that weighing boat or paper is placed on

the balance the balance does what it's

designed to do it determines the mass of

any object placed on the pan so notice

now the balance is telling us the mass

of that plastic weigh boat

at this point if we simply press the

zero button the balance will

automatically Reiser o itself and

subtract the weight of the plastic

weighing dish most people find this to

be easier than recording the mass of the

dish and then subtracting it from the

mass of the dish and the compound notice

if we remove the dish the balance shows

a negative mass which is telling us that

the balance is subtracting the weight of

that plastic weighing dish which is two

point zero two grams at this point we

can place the plastic weighing dish back

on the balance and start adding to it

whatever substance we wish to measure

the mass of keep in mind that these are

chemical substances and we should never

touch them directly with our fingers we

should always use a spoon or some other

apparatus specifically designed for

dispensing chemicals to add the

substance to the plastic weighing dish

once you have obtained the desired mass

of a particular substance you're ready

to remove the plastic dish from the

balance and take it back to your lab

table area to carry on the rest of the

procedure if you spilled any substance

around the balance now would be the time

to clean up that substance so that the

balance area is ready for the next

person who needs to use it at this point

you're ready to try part number one of

the practicing laboratory techniques

procedure that can be found in your lab

manual notice the procedure asked you to

measure two separate substances with a

specific mass 0.5 zero grams of NaCl

which is common table salt and point

five zero grams of sand use the

techniques we just discussed and show

your teacher when you have completed

this step another common technique used

in the chemistry laboratory is being

able to measure a specific volume of a

liquid using a graduated cylinder an

important part of doing any job

correctly is selecting the right tool

for the job that you want to complete

lots of different glassware in the

laboratory can be used to measure volume

but remember graduated cylinders do that

job much better than beakers and flasks

since our goal is to measure exactly

ninety 5.0 milliliters of water we want

to be sure to select the appropriate

size graduated cylinder we're choosing

to use one that can measure a maximum

volume of 100 milliliters you may find

it easier to take the cap off the

deionized water squirt bottle and pour

the volume of water to about ninety

milliliters then you can fill up the

remaining volume using the fine tip of

the squirt bottle to level the volume at

95 milliliters remember to carefully

breathe the volume on the graduated

cylinder at eye level and remember to

measure from the bottom of the meniscus

formed by the surface of the water not

the top

at this point you should have measured

point five zero grams of salt and point

five zero grams of sand and they should

be in a 250 milliliter beaker you just

finished measuring ninety five point

zero milliliters of water and at this

point you're ready to combine those

substances by combining the water with

the salt and sand you've created a

mixture swirling will allow the salt to

dissolve and the sand will settle to the

bottom of the beaker you've just created

a day at the beach a third technique

that is often employed in a chemistry

laboratory is measuring the temperature

of a substance or material using a

thermometer in order to obtain the most

accurate temperature reading possible

the thermometer must be submerged as far

as possible

into the material without touching the

walls of the container for this

particular experiment and anytime you

need to take a quick measurement you can

simply hold the thermometer by hand but

for longer periods of time you may be

better off using a stand with a clamp

attached specifically designed to hold a

thermometer one lab safety issue to be

aware of is never to allow a thermometer

to rest in a beaker or other container

unsupported if you bump into it it will

easily tip over

so if using a thermometer and holding it

by hand be sure to set it down flat on

the countertop when you are finished

remember when breeding any instrument

with a printed scale we are always

allowed to estimate one decimal place

smaller than the scale that is printed

so in this particular case the scale is

in one degree Celsius increments so we

can estimate to the nearest tenth of one

degree in this particular case our

reading would be twenty point zero

degrees Celsius so right now you should

measure the temperature of your water

salt and sand mixture and record this

value have your teacher check this value

before moving on another common

technique to master in

the lab is the separation of a mixture

using filtration the process of

filtration will involve a more

complicated equipment setup compared to

what we've used up into this point

notice in the picture a funnel is being

supported by a triangle which in turn is

supported by a rink Lant to a stand

which rests on the lab table underneath

the funnel is a clean empty beaker that

we're going to use to catch the salt

water that runs through the filter paper

by itself the funnel is not a good tool

to use to separate sand from salt where

in order to do this process more

effectively we will need to use a piece

of filter paper in order to get the

filter paper which is flat to fit into

the funnel which is not we have to do a

little paper folding first fold the

paper in half then fold the paper in

half again

finally notice if you look at the curved

end of your folded filter paper you

should see four distinct layers by

grabbing three of those four layers and

pulling them to one side you will create

a three-dimensional cone out of the

one's flat piece of filter paper that

cone-shaped

piece of filter paper will now fit very

nicely into the funnel and you're ready

to begin the process of filtration two

more carefully pour the salt water into

the funnel containing the filter paper

we're going to use a technique that's

called decanting notice that I'm holding

a glass rod against the top of the

beaker the rod will serve as a conduit

for the flow of water so I can aim that

flow of water directly where I want it

as I tip the beaker and the glass rod

over the funnel with the filter paper

the salt water will flow down the

surface of the glass rod and end up in

the middle of the filter paper this will

keep me from spilling salt water on the

lab table

our goal is to eventually transfer all

of the sand into the filter paper in

order to complete this task you may need

to rinse the beaker several times with

small volumes of water from the

deionized water squirt bottle another

successful filtration procedure

completed notice that all of the sand

has been transferred from the beaker

into the filter paper and all of the

salt water has flowed through the filter

paper and is now in the beaker resting

on the surface of the lab table be sure

to show your teacher the completion of

this technique before moving on the

final technique that we will talk about

today is properly lighting and adjusting

a Bunsen burner of all the pieces of

equipment in a chemistry laboratory

perhaps nothing is more symbolic than

the Bunsen burner in itself one of the

biggest considerations when using a

Bunsen burner in a laboratory is safety

so at this point you should prepare your

lab table area by removing any

combustible materials any long sleeves

or loose clothing should be rolled up or

secured and dangling jewelry should be

removed before attempting to light the

Bunsen burner you should also put on an

apron and safety goggles on the bottom

of the Bunsen burner itself there is a

gas shutoff valve before hooking the

Bunsen burner up to the gas jet at your

table please be sure to turn this valve

off by turning it in the clockwise

direction until it's tight in addition

to closing the gas valve on the bottom

of the Bunsen burner you should also

adjust the combustion column downward by

turning it in a clockwise direction this

will prevent there from being too much

oxygen mixing with the gas when you

first light the burner once those two

adjustments have been made on the Bunsen

burner itself you may hook up the tube

from the Bunsen burner to the gas jet at

your table please be sure that they

connect

you know the rubber to to the outlet of

the gas jet is tight at this point

you're ready to turn on the gas at the

table

notice that the valve has been moved

from a perpendicular position to a

position that's parallel and pointing in

the same direction as the outlet of the

gas jet at this point no gas is coming

through the Bunsen burner because the

valve on the bottom of the Bunsen burner

is shut off before attempting to light

the Bunsen burner you should be sure

that you can make a spark consistently

with the striker that's provided when

you can do this open up the valve on the

bottom of the Bunsen burner to allow gas

to move up through the combustion

chamber make a spark with a striker and

the Bunsen burner should light notice at

this point that the flame of the Bunsen

burner is a yellow color because not

much oxygen is mixing with the gas to

increase the amount of oxygen and the

temperature of the flame simply turn the

combustion column in a counterclockwise

direction moving it upward away from the

base this will increase the amount of

oxygen that mixes with the gas and

caused the flame to turn a bright blue

color

notice that the flame has a brighter

blue inner cone the tip of that inner

cone is the hottest most part of the

Bunsen burner flame be sure to show your

teacher that you can properly light and

adjust the Bunsen burner and ask them if

time allows if you can evaporate the

water from the salt water mixture that

we filtered previously which would

separate the salt from the water itself

if time doesn't allow simply clean up

your equipment and put it away at this

time congratulations you have

successfully completed the practicing

laboratory techniques lab