Lab 1B Applying the Scientific Method

Sample Lab Report

QUESTION

What type of cup will keep water the hottest for the longest period of time?

# INTRODUCTION

In doing this experiment, we will be applying the steps of the scientific method to a specific question.  From the question and our combined knowledge, we will develop hypothesis (what we think will happen), design an experiment to test the hypothesis.  We will collect data and analyze the data to see if the hypothesis is supported by the results of the experiment.  If the experimental results do not support the hypothesis, we will examine the experimental design for flaws.  If none are found that would explain the results, we will modify our hypothesis or experimental design.

The question we are asking and the hypothesis we will develop are both testable.  We are asking a very specific question that is measurable with a thermometer, a very subjective instrument.  However, in order to have good accurate results, we will need to make sure that only one variable changes between each test of the hypothesis.  In this case what will change is the type of cup.  All other variables will remain the same such as the type of thermometer used, the amount of hot liquid (coffee, water, tea) in the cup, the interval the temperature is taken and the air temperature.  If any of these vary between the tests, it could alter the data and we would not be sure which variable caused the results.  Because the starting temperature of the water in all cups might not be the same, we will compare the amount of heat lost from each cup over a period of time and not the actual temperatures of the liquid.

# HYPOTHESIS

IF an insulated (thermal) coffee cup is the best for keeping water the hottest for the longest period of time, THEN we will see less of a temperature drop in the water contained in the insulated (thermal) cup than in any other type of cup.

# For this experiment, we will need the following:

1 cup paper (cardboard) cup

1 Styrofoam cup

1 ceramic cup

1 thermal insulated cup

Four thermometers

Hot liquid (coffee, water or tea)

Clock with a second hand

# PROCEDURES

1.                   Heat at least 1000 ml of water in a coffee maker till serving temperature.

2.                 Assemble the four cups in a row on the counter.

3.                 Using the graduated cylinder, measure100mL water and pour into the paper cup.

4.                 Have one group member immediately measure the temperature of the water and record on the data sheet.

5.                 Continue to take the temperature of the liquid every 5 minutes for a total period of 30 minutes.

6.                 Using a different group member, repeat steps 3-5 for the Styrofoam cup, the ceramic cup and the thermal insulated cup.

7.                 Leave the thermometer in the liquid at all times.  Do not remove it between readings.

# RESULTS

Data Table

Change in Temperature in Degrees Celsius in Four Kinds of Cups Over 30 Minutes

 Type of Cup Initial Temp. Temp 5 min Temp 10 min Temp 15 min Temp 20 min Temp 25 min Temp 30 min Paper 58 50 45 42 38 36 34 Difference 0 8 13 16 20 22 24 Ceramic 54 53 44 41 38 37 35 Difference 0 1 10 13 16 17 19 Styrofoam 61 59 55 55 52 51 50 Difference 0 2 6 6 9 10 11 Thermal 55 53 50 49 47 45 44 Difference 0 2 5 6 8 10 11

I

# DISCUSSION

Our hypothesis was supported by the data collected during this experiment.  Our data clearly showed that, at the end of 30 minutes, the drop of the water temperature in the insulated cup was less than in the other cups except for the Styrofoam cup.  The results for the Styrofoam cup showed an equal amount of heat loss however, it appears to be a faster rate of loss even though the total heat loss was the same in the two cups.

Objectives from Unit 1 that were important and demonstrated in this lab were the Scientific Method, controlled and experimental variables, what can be tested and the metric system.

We had to use the steps of the Scientific Method to design an experiment that would test which type of cup would keep the coffee hottest for the longest period of time.  To do this the question that was originally asked had to be testable.  It had to be based on something that could be observed and measured and not something that was only based on belief or faith.  We are not trying to measure an opinion or value.  Our hypothesis was based on our collective knowledge and from the fact that we have each used these different kinds of cups so we have had personal experience to use to make our hypothesis.  Our hypothesis included a prediction of what we expected to see when we carried out the experiment.  We wrote this as an IF/THEN statement.  If the thermal cup kept the coffee hottest the longest, THEN (the prediction) we would expect to see less heat lost from that cup.

In order to be sure the change in temperature was due to the kind of cup and nothing else, we had to identify the controlled variables, that is, those factors that had to be kept the same in all four cup experiments.  The controlled variables included using the same room temperature and setting the cups on the same table top, using the same graduated cylinder to measure the liquid, having the same student measure the liquid at the meniscus, using the same volume of coffee in each cup, having all of the temperature measurements being taken in degrees Celsius every five minutes.  We also know that since the hot water in all the cups did not start at the same temperature we had to calculate the difference so we would know how much heat each cup lost.  With all these variables being the same or held constant, the only thing that changed was the type of cup.  So if the coffee in one cup stayed hotter than the others, the results must have been because of the type of cup and nothing else.  The type of cup is the experimental variable.  By having only one experimental variable our data can be shown to either support or refute the hypothesis.

There were some variables we could not control.  We could not control how accurate each group member was in taking the temperature.  We also noticed that the diameter of the cups was different.  This could not be controlled.  The thermal cup also had a lid available which we did not use, but whether a lid was used or not would have been another variable.

We wrote the procedures for this experiment with exact steps so that it could be repeated by anyone else doing the experiment.  The more times an experiment is done with consistent results the more likely that the results are correct.

The data we collected showed that the thermal cup and the Styrofoam cup each lost 11 degrees of temperature.  This supported our hypothesis.  We could modify our hypothesis to state that if the thermal cup AND the Styrofoam cup were the best a keeping hot water hottest the longest, then they would show about the same temperature loss.  If all the other groups in our class and other classes came up with the same data for these two types of cups, we could develop the Coffee Cup Heat Loss Theory.  As long as no data was collected to show our hypothesis was incorrect, this theory would stand.  If someone did an experiment that repeatedly showed a different cup kept hot water hotter longer, we could then change our theory.  This exercise helped me put the scientific method into perspective and to see it can be used with very basic kinds of questions that maybe we wouldn’t consider to be “science”.

The metric system and Centigrade/Celsius system came in handy, as we were using them to measure the volume of our hot water in milliliters and the water’s temperature in degrees Celsius.  As we measured the amount of hot water, we measured at the bottom of the meniscus where the water was sticking to the sides of the cylinder.  The experiment helped me to understand better the metric and Celsius systems of measuring.  Until now I could never quite grasp just how hot something was if I was given a temperature in Celsius.  Nor could I understand how much liquid there was if I was told in the metric system.  Now it is a bit easier.  I always thought 100mL was much more than that!

I would like to change the experimental design so that all the cups were the same size.  I think it would be good to compare our results to the other groups in the class.  It would be interesting to follow someone else’s directions like we did with the potato and hydrogen peroxide.

Additional questions that I have now are: Is there a difference in cooling if the coffee has cream and/or sugar added?  What about artificial sugar compared to real sugar?  What about coffee cups with lids?  I am interested in seeing if the lid makes any difference in the rate of cooling.  I would guess that it keeps the water from cooling as quickly.  I’m also wondering if the thermal cup would have won this contest if the thermal cup had the same diameter.  Since it was bigger I would think it would lose the heat faster so if it was the same diameter it should have lost less heat.  I think I could make a hypothesis about that now and test it.