

Research Assistant Wanted
Brother Gregory wants you to help him find answers to various questions
about energy and energy related subjects. In these investigations he
will ask you a series of questions and give you the tools to find the answers.
You then become his research assistant. You must first print out your personal investigation page, find out which questions you are required to answer, carry out the experiment, gather and record your data, analyze your results and write down your results on your personal investigation page.
(Hint: If you run into trouble, ask his mother for help!).
This is important
Bring your completed investigation page to the examination, if it is required. Consult the topic schedule.


Brother Gregory's Dinner, (and breakfast, lunch and snack).
Brother Gregory was concerned about his spreading waistline.
He felt that he was putting on too much weight.
So he wants you to answer four questions, (one from each group), about the number of calories in his diet.

Start Here:
Print out your
personal investigation page

Carefully enter your Seat Number or PCIN number
(e.g. MM34, or MA56, or WA41)
in the box below, click, and print out the page that appears.
Answer the four questions (one from each group), write your answers on the investigation page, and bring the completed assignment to the exam for grading purposes.


Personal Investigation Page

Blue Questions:
Group One

Question 1:
What is the calorific value of apple?
Question 2:
What is the calorific value of pork?
Question 3:
What is the calorific value of cheese?
Question 4:
What is the calorific value of olives?

Green Questions:
Group Two

Question 1:
What are the total number of kilocalories in this meal?
Breakfast: 116 grams of bacon; 174 grams of eggs; 50 grams of tea.
Question 2:
What are the total number of kilocalories in this meal?
Lunch: 203 grams of salmon; 145 grams of broccoli; 348 grams of milk.
Question 3:
What are the total number of kilocalories in this meal?
Dinner: 232 grams of beef; 290 grams of beans; 125 grams of olives.
Question 4:
What are the total number of kilocalories in this meal?
Snack: 248 grams of apple; 95 grams of almonds; 60 grams of cheese.

Red Questions:
Group Three

Question 1:
How many grams of beans contain the same number of calories as 15 grams of salmon?
Question 2:
How many grams of cheese contain the same number of calories as 12 grams of pork?
Question 3:
How many grams of broccoli contain the same number of calories as 18 grams of chicken?
Question 4:
How many grams of olives contain the same number of calories as 23 grams of beef?

Brown Questions:
Group Four

Question 1:
How many grams of apple would you have to burn in the calorimeter to raise the temperature of 300 grams of water by 14.5 degrees centigrade?
Question 2:
How many grams of egg would you have to burn in the calorimeter to raise the temperature of 300 grams of water by 50.2 degrees centigrade?
Question 3:
How many grams of bacon would you have to burn in the calorimeter to raise the temperature of 300 grams of water by 77.1 degrees centigrade?
Question 4:
How many grams of chicken would you have to burn in the calorimeter to raise the temperature of 300 grams of water by 8.5 degrees centigrade?


Tools of the Trade
In order to carry out this investigation you will need to learn how scientists determine the number of calories there are in a sample of a substance.
The piece of equipment they use is called a Calorimeter.


Using the Calorimeter
The Apparatus
The Calorimeter consists of a container inside a container.
The sample is placed inside the inner container, and sometimes
pure oxygen gas is also added. This container is then placed
inside the outer container. Water is also placed in the outer
container so that it surrounds the inner container.
A thermometer is placed into the water.



The Measurement
 A small amount of the sample under investigation is weighed,
the weight written down and the sample placed into the inner container.
 The inner container is sealed, placed in the water,
and the whole apparatus allowed to equilibrate.
 The initial starting temperature of the water in the outer container
is written down as the first data point.
 The sample is burnt in the air (or oxygen) and energy is released.
 The energy from burning the food moves into the water surrounding
the inner container and the temperature of the water goes up.
 The increase in temperature is written down.


Calculating the Results
The investigator now has four pieces of data:
T1 = The starting temperature of the water.
T2 = The final temperature of the water.
V = The volume of water in the apparatus.
S = The weight of sample (in grams).


Definition
A calorie is the amount of energy needed to raise the temperature of one gram of water from 14.5 to 15.5 degrees centigrade.
A kilocalorie = 1,000 calories


Calculation
The number of calories of energy in the sample can be calculated
from the following formula:
Number of calories = V x (T2T1)
Knowing the total number of calories of energy given off by
burning the sample, and knowing the number of grams of sample
that were burnt, the following formula gives the "calorific value" of the sample:
Calorific Value = Number of Calories / grams of sample
or a combined formula for the calorific value of the sample would be:
Calorific Value = (V x (T2T1)) / S
