NECT Gr 10 Heating and Cooling Curve of Water

Summary

In this educational video, hosts John McBride and Joyce Polka conduct an experiment to measure the temperature changes of water as it melts and boils, and as it cools down. They use a thermometer, ice, and a Bunsen burner to record temperatures at one-minute intervals. The experiment aims to plot heating and cooling curves of water, illustrating the phase changes and temperature fluctuations over time. The video guides viewers through setting up the apparatus, identifying variables, and recording data, concluding with a demonstration of how to plot the results.

Takeaways

• 🔬 The experiment involves measuring the temperature of water as ice melts and is heated to boiling, and as hot water cools down.
• 📈 The goal is to plot heating and cooling curves of water, which show temperature changes over time.
• ⏱️ Temperature is measured every minute during the experiment to record changes in the water's state.
• ❄️ The initial setup includes crushed ice, a thermometer, a heat source (Bunsen burner), and a beaker to contain the ice and water.
• 🌡️ An alcohol thermometer is used, and readings are taken from the bottom of the meniscus.
• 🔥 The Bunsen burner is used to heat the ice and water mixture, with a gozman to distribute heat evenly.
• 🕒 The independent variable is the time interval between temperature recordings, set at one minute.
• 💧 The dependent variables are the temperature of the water and its phase (solid, liquid, or both).
• 🔍 Control variables include maintaining a constant Bunsen burner flame and ensuring the mass of water remains constant throughout the experiment.
• 📊 Data collected will be used to plot graphs, with careful attention to accuracy and decimal places for consistency.

Q & A

What is the purpose of the experiment described in the script?

The purpose of the experiment is to measure the temperature of water as it melts and is heated to its boiling point, and also as it cools, to plot heating and cooling curves of water.

What are the two types of graphs that will be plotted based on the experiment?

The two types of graphs that will be plotted are the heating curve of water and the cooling curve of water.

What is the initial temperature of the crushed ice mentioned in the script?

The initial temperature of the crushed ice is zero degrees Celsius.

What is the role of the Bunsen burner in the experiment?

The Bunsen burner is used as a heat source to heat the ice and water, allowing the temperature to rise and the ice to melt.

Why is it important to pack ice around the thermometer?

Packing ice around the thermometer ensures that the temperature measured is that of the ice and not the surrounding air.

What is the significance of the time interval chosen for recording temperatures?

The time interval between temperature recordings is the independent variable in this experiment, and it affects the dependent variable, which is the temperature of the water.

What is the dependent variable in the context of this experiment?

The dependent variable is the temperature of the water, which changes based on the amount of heat supplied by the Bunsen burner and the time the water is heated.

Why is the phase of water also considered a dependent variable in this experiment?

The phase of water is considered a dependent variable because it changes when the ice is heated above zero degrees Celsius, indicating a transition from solid to liquid.

What are the control variables in this experiment, and why are they important?

The control variables include the constant rate of the Bunsen burner flame, the mass of water, and ensuring no additional water is added or lost during the experiment. These variables are important to ensure consistent and reliable results.

How does the experiment account for the water that evaporates during heating?

The experiment acknowledges the slight loss in mass due to evaporation but does not adjust the mass of the water manually; it is considered a natural part of the heating process.

What is the expected outcome when the ice is heated at a constant rate?

When ice is heated at a constant rate, the expected outcome is a graph showing a constant temperature until the ice melts, followed by a steady rise in temperature as water is heated towards its boiling point.

Outlines

00:00

🔬 Introduction to Water's Heating and Cooling Curves

This paragraph introduces an experiment led by John McBride and Joyce Polka, aiming to measure the temperature changes of water as it melts and boils, and as it cools down. They plan to plot heating and cooling curves of water, which theoretically should show a constant temperature during the phase change and a steady rise in temperature otherwise. The setup involves crushed ice, a thermometer, a Bunsen burner, and a beaker. The experiment will measure the temperature every minute, focusing on the phase changes of water. The paragraph also discusses the need to control variables such as the constant heat source and the mass of water.

05:00

🌡️ Setting Up the Experiment and Control Variables

The paragraph details the setup for the experiment, including the use of a Bunsen burner set at a constant rate, the importance of maintaining a constant mass of water, and the control of other variables to ensure accurate results. The experiment begins with measuring the temperature of crushed ice at zero degrees Celsius. The video script instructs learners to record the temperature and phase of water at one-minute intervals as the ice melts and the water heats up. The paragraph emphasizes the importance of recording data accurately and consistently.

10:03

📈 Recording Temperature Data for the Heating Curve

This paragraph continues the experiment by recording the temperature of the water at one-minute intervals as it heats up. The script provides a series of temperature readings, indicating the phase of water as it transitions from solid to liquid. The video demonstrates the process of recording these observations and emphasizes the importance of accuracy and consistency in data recording. The paragraph also mentions the use of a timer and the observation of the ice melting to ensure that the data is recorded at the correct time intervals.

15:04

❄️ Cooling Curve of Hot Water and Data Analysis

The final paragraph shifts focus to the cooling curve of hot water. It describes the process of cooling hot water in a trough of crushed ice to accelerate the cooling rate. The paragraph outlines the procedure for taking temperature readings at one-minute intervals as the hot water cools down. The video script encourages learners to work independently to complete the graphs and answer related questions, seeking teacher support if needed. The paragraph concludes by emphasizing the importance of individual work and guidance from teachers for a successful practical investigation.

Keywords

💡Thermometer

A thermometer is an instrument used for measuring temperature. In the context of the video, it is essential for recording the temperature of water as it undergoes phase changes from ice to boiling water. The script mentions using a thermometer to measure the temperature of ice, water, and steam, highlighting its critical role in scientific investigation.

💡Heating Curve

A heating curve is a graphical representation of the temperature of a substance as it is heated over time. The video script describes the process of plotting a heating curve for water, which involves recording the temperature at regular intervals as heat is applied. This curve helps to visualize the phase changes and temperature gradients of water from ice to boiling point.

💡Cooling Curve

A cooling curve is similar to a heating curve but represents the temperature of a substance as it cools down over time. The script discusses the experiment of creating a cooling curve for hot water, which involves measuring the temperature at set intervals as it cools in a trough of crushed ice. This curve is used to understand the cooling process and the rate at which water loses heat.

💡Phase Change

Phase change refers to the transformation of a substance from one state of matter to another, such as from solid to liquid or liquid to gas. The video script describes the phase change of water as it melts from ice to liquid and then boils to form steam, which is a critical aspect of understanding the behavior of water under different temperatures.

💡Bunsen Burner

A Bunsen burner is a type of gas burner used for heating in scientific experiments. In the video, a Bunsen burner is used as a heat source to melt ice and heat water, demonstrating its utility in providing a controlled heat source for scientific investigations.

💡Time Interval

The time interval is the duration between two points in time, which is crucial in experiments where changes are observed over a period. The script specifies measuring the temperature of water at one-minute intervals, emphasizing the importance of consistent timing in collecting reliable data.

💡Dependent Variable

In scientific experiments, the dependent variable is the one that changes in response to the independent variable. The video explains that the temperature of water and its phase are dependent variables, as they change based on the time the water is heated or cooled.

💡Independent Variable

The independent variable is the one that is changed or controlled in an experiment to observe its effect on the dependent variable. In the video, the time interval between temperature recordings is the independent variable, as it is controlled by the experimenters to study its effect on the temperature of water.

💡Control Variable

A control variable is a factor that is held constant in an experiment to ensure that changes in the dependent variable are due only to the independent variable. The script mentions controlling the Bunsen burner flame and the mass of water as control variables to ensure the accuracy of the experiment.

💡Data Recording

Data recording is the process of noting down observations and measurements during an experiment. The video script describes the importance of recording the temperature of water at specific time intervals, which is a fundamental part of data collection in scientific experiments.

💡Graph

A graph is a visual representation of data, often used to analyze trends and relationships. The video script discusses plotting heating and cooling curves, which are graphs that depict how the temperature of water changes over time, helping to visualize and understand the experimental data.

Highlights

Introduction to measuring the temperature of water as it melts and heats to boiling point.

Explanation of plotting heating and cooling curves of water.

Theoretical expectation of temperature against time graph for ice heated at a constant rate.

Description of the apparatus needed for the investigation, including ice, thermometer, and heat source.

Instructions on how to pack ice around the thermometer to ensure accurate temperature readings.

Demonstration of setting up the Bunsen burner and securing the thermometer in the beaker.

Clarification of the independent variable, which is the time interval between temperature recordings.

Identification of the dependent variable, which is the temperature of water affected by heating time.

Discussion on control variables, such as maintaining a constant Bunsen burner flame and water mass.

Emphasis on not adjusting the Bunsen burner flame during the investigation to control the heating rate.

Procedure for starting the heating process and recording the initial temperature of crushed ice.

Observation of ice melting and the corresponding temperature readings at one-minute intervals.

Guidance on recording the phase of water (solid/liquid) along with temperature readings.

Instructions on how to plot the heating curve of water using the recorded data.

Transition to the cooling curve experiment, where hot water is cooled in a trough of crushed ice.

Final instructions for learners to complete graphs and answer questions independently with teacher support.

Transcripts

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[Music]

our great Qin's I'm John McBride's and

I'm Joyce polka today we'll measure the

temperature of water as it melts and is

heated to its boiling point

we'll also measure the temperature of

water as it cools using this data we

will plot graphs of temperature against

time first for ice heated until the

water boils and secondly for hot water

cooling these graphs are called the

heating and cooling curves of water in

theory if we heat ice at a constant rate

we should get a graph of temperature

against time that looks like this one

the temperature of ice remains constant

for the time it takes for the ice to

melt the temperature of boiling water

remains constant while the water boils

to form steam and the temperature of

water rises steadily from ice point to

boiling point so you can see that we

need to measure temperature time enter a

cod phase of water while we carry out

this investigation we'll measure the

temperature every minute and record the

face of water when we do this so let's

take a look at the apparatus that we

need for this investigation okay we need

ice and a thermometer to start with here

is the container of ice we want to pack

ice around the thermometer so that we

measure the temperature of ice and not

that of the air that surrounds the ice

the thermometer fits snuggly in the ice

it's surrounded by the little chunks of

I just as we want it to be remember that

when we read the temperature using an

alcohol thermometer like this one we

must read from the bottom of the

meniscus the temperature of the crushed

ice is zero degrees Celsius so we have a

thermometer and some ice but we also

need a heat source and something to

recall the time between the recording

temperatures yes we will use a Bunsen

burner which we put underneath a tripod

stand we put a gozman on top of the

tripod so that it spreads the heat

evenly over the surface and we place a

beaker of crushed ice on top of the

cause met we need to secure the

thermometer in the beaker

the thermometer stays in the ice and

water so that it constantly measures the

temperature of the water we don't need

to take the thermometer out of the water

at any stage of this investigation so

we're going to clamp it into position so

here's that Richard stand and attempt to

support the thermometer in the beaker

push the thermometer through and one

hold or rubber stopper support the

stopper in the retort and clamp an

immersive thermometer in the beaker of

crushed ice do make sure that the

thermometer is a couple of centimeters

above the bottom of the beaker it must

measure the temperature of water rather

than the temperature of the flame here

is a diagram of the apparatus you'll

find the same diagram in your worksheet

[Music]

it's time now to clearly identify the

dependent and independent variables and

the control variables in this

investigation firstly what is an

independent variable is the variable

that we choose to change the variable

that we are just before we take a

measurement in this investigation the

independent variable is the time

interval that we choose between

recording the temperature of the water

we are choosing a time of one minute

between recording temperature and phases

of water we will use a cell phone to

take the time I will warn Joyce to get

ready just before the minute so that she

has time to focus on the thermometer

let's move on to the dependent variable

the dependent variable is their variable

that changes its values depending on the

changes made to the independent variable

the temperature of water depends on the

amount of heat supplied by the Bunsen

burner and the amount of heat supplied

by the burner increases with time so the

temperature of water depends on the

amount of time the water is heated but

phase of water is also a dependent

variable when ice is heated above zero

degrees Celsius

it melts so the phase of water depends

on the temperature and therefore in this

case on the time for which the water has

been heated but for all of this to be

true we need to control a few other

variables yes the Bunsen burner flame

must be adjusted to burn at a constant

rate we must set the Bunsen burner to

burn and to leave it that setting for

the entire investigation we mustn't

readjust the Bunsen burner flame at any

stage during the investigation the rate

of heating is controlled the mass of

water must remain constant we start off

with a certain amount of ice in the

beaker and we shouldn't add or lose any

of the water during the investigation

that makes sense

but what about the water that evaporates

from the surface of the liquid as we're

heating it up in this investigation

there will be a slight loss in mass of

as we heated up but we will not change

the mass of the water ourselves while

the investigation takes place so the

mass of water is a control variable

right are you ready to start the

investigation learners you will need a

couple of minutes to read through the

worksheet you will need a pencil a pen a

ruler and maybe an eraser pause the

video while you read the worksheet and

organize yourself

you

this part of the investigation can take

up to 40 minutes to complete we're going

to show you how it starts off and then

we will fast forward the results for you

let's begin the apparatus is set up and

ready we start by measuring the

temperature of the crushed ice before we

begin hitting it the temperature of the

crushed ice is zero degrees Celsius this

result is at time equals zero minutes

and the phase of water is solid fill

these results into the table of your

worksheet we will help you with a first

set of readings but hereafter you need

to pay attention to what we're doing and

to record the result by yourself now we

begin hitting the water we set the

Bunsen burner flame place the burner

under the tripod at the same time we

start the timer on the cell phone now we

wait for the minute to pass but we keep

observing what is happening to the ice

and we keep an eye on the timer so that

we are ready for the next reading we can

see that the ice is beginning to melt

the temperature is zero degrees at one

minute the ice is melting there are

still big chunks of ice present just a

little bit of it has melted already so

what should we write down for the phase

of water perhaps is best to write solid

stroke liquid now we wait for the rest

of the minute

the temperature is zero degrees at two

minutes most of the ice has melted the

face is still liquid stroke solid the

temperature is 1.5 degrees Celsius at 3

minutes the water is still solid stroke

liquid now we're going to speed up the

video and just show you the temperature

readings each time if it goes too fast

you can always rewind the video or you

can pause between each of the set of

readings are you guys ready at 4 - the

temperature is 2.5 degrees Celsius the

water is still solid stroke liquid this

is the thermometer reading at 5 minutes

write it down for yourself learners this

is what the beaker looks like at 5

minutes this is the thermometer reading

at 6 minutes write it down for yourself

learners

visit the thermometer reading at 7

minutes

write it down yourself this is what the

beaker look like at 7 minutes this is a

thermometer reading at 8 minutes

write it down yourself this is what the

beaker look like at 8 minutes

[Music]

visit the thermometer reading at 9

minutes

write it down yourself this is what the

beaker look like at 9 minutes this is a

thermometer reading at 10 minutes

write it down yourself this is what the

beacon look like at 10 minutes this is a

thermometer reading at 11 minutes

write it down yourself this is what the

beaker looked like at 11 minutes this is

a thermometer reading at tough minutes

write it down yourself this is what the

beaker looked like at 12 minutes this is

a thermometer reading at 13 minutes to

write it down yourself this is what the

beaker looked like at 13 minutes this is

a thermometer reading at 14 minutes

write it down yourselves this is what

the beaker look like at 14 minutes this

is a thermometer reading at 15 minutes

ratted on yourself this is what the

beaker looked like at 15 minutes this is

a thermometer reading at 16 minutes

write it down yourself this is what the

beaker looked like at 16 minutes

[Music]

this is a thermometer reading at 17

minutes write it on yourself this is

what the beaker looked like at 17

minutes

this is a thermometer reading at 18

minutes write it down yourself this is

what the beaker look like at 18 minutes

[Music]

this is a thermometer reading at 19

minutes

write it down yourself this is what the

beaker look like at 19 minutes this is

the thermometer reading at 20 minutes

write it down yourself this is what the

beaker look like at 20 minutes this is a

thermometer reading at 21 minutes

write it down yourself this is what the

beaker look like at 21 minutes this is a

thermometer reading at 22 minutes I

write it down yourself this is what the

beaker looked like at 22 minutes this is

a thermometer reading at 23 minutes

write it down yourself this is what the

beaker look like at 23 minutes this is a

thermometer reading at 24 minutes

writing down yourself this is what the

beaker looked like at 24 minutes there's

a thermometer reading at 25 minutes I

ratted on yourself this is what the

beaker looked like at 25 minutes this is

a thermometer reading at 26 minutes

write it on yourself this is what the

beaker look like at 26 minutes this is a

thermometer reading at 27 minutes I

write down yourself this is what the

beaker look like at 27 minutes

[Music]

this is a thermometer reading at 28

minutes write it down yourself this is

what the beaker look like at 28 minutes

there's a thermometer reading at 29

minutes

write it down yourself this is what the

beaker look like at 29 minutes this is a

thermometer reading at 30 minutes

write it down yourself this is what the

beaker look like at 30 minutes

there's a thermometer reading at 31

minutes

write it down yourself this is what the

beaker look like at 31 minutes

[Music]

this is a thermometer reading at 32

minutes

write it down yourself this is what the

beacon looked like at 32 minutes this is

a thermometer reading at 33 minutes

write it down yourself

[Music]

this is what the beaker look like at 33

minutes

this is a thermometer reading at 34

minutes write it down yourself this is

what the beaker look like at 34 minutes

[Music]

these are thermometer reading at 35

minutes write it down yourself this is

what the beaker look like at 35 minutes

that's fantastic we have enough

information to plot a graph of the

heating curve of water learners before

you leave this table of results have you

given your table of results an

appropriate heading don't forget to do

that also check through your table of

results and make sure that all your

readings have the same number of decimal

values if one reading is 0 comma 5 or 7

comma 5 and all the other readings have

no decimal values then you need to write

them all to the accuracy of the same

decimal place finally the SI units are

shown in the column headings don't write

the SI units in every row as well this

is the correct way to record your result

in a table it's nice neat and clear it

makes it easier to work with the

information when you analyze it some of

you may have made a few mistakes in your

table and perhaps you want to correct

them nice and neatly we have printed

another table exactly for this purpose

you can transfer your results later and

make a clean start now we are moving on

to the cooling curve of hot water though

hot water has to cool down it can cool

down in the air but the rate of cooling

will be fairly slow we have decided to

cool the hot water in a trough of

crushed ice so that it cools at a faster

rate so let's pick up the beaker of hot

water and we're going to push it into

the ice

there we go and we must then be careful

that we don't lose any of the the

crushed ice either all the hot water

now the next thing is we're going to put

the thermometer into the hot water so

that we can see what happens we're

supporting it with the clamp and the

retort stand to make sure we are

measuring the temperature of the hot

water take a reading on the thermometer

and start the timer to measure one

minute intervals the temperature is

forty five point five degrees Sasha's at

zero minutes we don't have to worry

about a phase change during the

investigation as the water will never be

cold enough to form us unless we use a

fridge or a deep freeze two coolers get

ready for the readings at one minute at

one minute the temperature is 35 degrees

Sasha's right I ready for the

fast-forward readings here we go two

minutes three minutes four minutes five

minutes

six minutes all done if you missed a

couple of values you can ask for the

video to be replayed and you can pass it

at the individual values however don't

take too long doing that

there's plenty more work for you before

you complete this practical

investigation it's time now for you to

work individually and to complete the

graphs and answer the questions that

follow where necessary ask your teacher

for support don't ask your neighbor or

other learners in the class this is an

assignment which you need to complete by

yourself with expert guidance from your

teacher if necessary

[Music]

you