Lab #1

Introduction, Check-In;

Scientific Method and Basic Laboratory Techniques in Nutrition ScienceA. Laboratory Objectives:

Students will: Understand the course syllabus. Understand the laboratory rules.

Complete the laboratory safety contract.

Understand how to use the scientific method. Participate in hypothesis generation.

Review the metric units of mass, volume, density, and temperature and how these measurements relate to food science.

Be able to convert between measurements of the metric system and English system.

Laboratory Report due next class period:

Data Record and Discussion Questions B. Introduction to Lab SafetyThe laboratory setting is a potentially dangerous environment. It is a place where hazardous materials and substances are stored. It is also a place where chemicals are manipulated and combined, sometimes with unpredictable results. Accidents in the lab do happen. It is therefore important to keep in mind the following safety precautions at all times: Safety Rules:

1. Eyewear- safety goggles are recommended.

2. Tie back loose hair, remove dangling jewelry, and wear low-healed, closed-toed shoes.

3. Long sleeve shirts and/or lab coats must be worn at all times (Lab coats are highly recommended to protect clothing, etc. and are available in the FIU bookstore).

4. Gloves must be used when handling chemicals or heated glassware.

5. No eating, drinking, smoking, or gum chewing allowed (minor exception during hypothesis testing laboratory).

6. No pranks or horseplay.

7. No visitors allowed in lab.

8. You are responsible for knowing the location of the safety eyewash, fire extinguisher, telephone, and first aid kit.

9. Notify instructor immediately of any accident or spill.

10. Trash should be put in trash cans, NOT sinks, trays, desks, or cabinets.

11. Dispose of chemicals as directed by Laboratory Instructors.

12. Dispose broken glass in appropriate boxes, not in trash bags.

13. Broken or missing equipment should be reported to your instructor to obtain replacement. DO NOT take equipment from other stations.

14. Keep work area clean and organized.

15. Do not taste or sniff anything. Any food stuffs utilized in the laboratory are potential experiments and should NEVER be tasted or eaten.

16. Do not remove any chemical, food or supplies from the lab.

17. In dispensing reagents, swirl the bottle to assure mixtures are uniform. Measure only the amount called for. Do not return any reagents or chemicals to the stock bottle (to avoid contamination of the entire supply).

18. Add acid to water when carrying out dilutions, not the other way around.

19. Reduce clutter on laboratory benches by placing personal materials such as backpacks or purses inside drawers.

20. Wash all glassware and clean equipment after use.

21. Handle all reagents as if hazardous.

Replacement Policy for Glassware/Lab Equipment

Your lab fees cover the use of the equipment that has been assigned to you. However, it is your responsibility to maintain the equipment and glassware that you use.

Each lab group will be given a tray containing the small equipment and lab supplies required for the lab session.

It is your responsibility to make sure you have received all of the supplies and your equipment is in working order before you begin the experimentation.

The equipment should be cleaned after each use.

You will be excused to leave the lab only after all of your large equipment has been accounted for at your station and your small equipment has been returned to the instructor in the original tray.

Students Responsibilities:

It is the responsibility of each student to:

Read and understand all procedures before scheduled lab.

Maintain a clean work area and wash all glassware before leaving. Be present and complete ALL portions of each laboratory session. LAB COATS/LONG SLEEVE SHIRTS AND CLOSE-TOED SHOES MUST BE WORN DURING EACH LAB SESSION!C. Introduction to Basic TechniquesThe Scientific Method

The scientific method is a way to approach solving science-based problems. It is a 5-step process that begins with making observations and ends by drawing conclusions based on your experiment and analysis of the outcomes. The following is a brief explanation of each of the steps:

i. Observation using the 5 senses to gain information about the environment

ii. Hypothesis prediction of an outcome based on your observations

1. null hypothesis there is no difference between groups

2. alternate hypothesis there is a significant difference between groups

iii. Experiment manipulation of independent variable(s) to measure a change in the dependent variable

1. independent variable variable that is manipulated

2. dependent variable variable that is measured

3. control basis for comparison; receives no treatment during experimentation

iv. Analysis analyzing the data to look for trends or differences between groups

v. Conclusion indicates finding based on analysis of data

Significant Figures

When you are recording scientific data you will be reporting some measurements to the nearest 1 ml or 1 gram, and other things you may be measuring to the nearest 0.1 ml or the 0.01 g. In measurement, a significant figure is defined as a digit that we believe to be correct, or nearly so. The number of significant figures recorded conveys information about the precision of a test, that is, the ability of the test to detect small differences.For example, in this laboratory the balances will weigh to the 100th of a gram. The balance read out will provide 2 decimal places, i.e., 0.00. If you weigh 3 items and record the weights of each of those items to 2 decimal places, anyone looking at those values would know the precision of the measurement.

When a scientist is calculating the average of replicates, the calculator (or computer) will often give a value with many digits. It is an important principal of science that the final value that you report cannot have more significant figures than the original measure. The scientist must know when it is necessary to round off the number so that it has no greater significant figures than the original measurements. The following rules will be helpful:Rule 1: In addition or subtraction, the value with the fewest decimal places will determine how far the significant figures should be reported in the answer.

204.754

(3 decimal places)

0.4324

(4 decimal places)

+10.41

(2 decimal places)

215.59

(2 decimal places)

Rule 2: In multiplication and division, the number of significant figures in the answer is the same as that in the number (quantity) with the fewest significant figures.

3.0 X 5.43 = 16.3

(Since there is only 1 decimal place in 3.0, the answer can only be recorded with one decimal place)The Metric System

The metric system of measurement is used in most countries of the world. It uses decimals rather than fractions and allows conversions to be made in units of 10. The metric system has long been the measurement system of science. Although in the United States the English system is used most often in areas other than science, it has become more common in recent years. For example, in the US the contents of most canned goods and beverages are given in both the metric and English units.

An international agreement was reached in 1960 specifying the use metric units in scientific measurements. These preferred units are referred to as SI units. Some commonly used units of measurement and the base units are described below.

Review of Common Units of MeasureMass the amount of matter in a substance.

The base unit is the gram.

Mass is most often measured using a scale

or balance.

Volume a derived unit of measure indicating

Volume - the amount of space a substance takes up.

The base unit is the liter. There are many

ways to measure volume. Solids of definite

shape can be measured and volume determined

from equations. Irregular solids often have

their volume measured using the water

displacement method. The volume of a

liquid can be measured using a graduated

cylinder or beaker. Similarly, volume of firm

food products often use a technique called

seed displacement. The volume of seeds

(most often rape seeds) that are displaced

is a valid estimate of volume of such foods.

Density is the mass per unit volume of a

substance. More simply put, density can be

obtained by dividing the mass of a

substance by its volume. The unit is

grams per milliliter.

Temperature is the amount of heat in a substance. Temperature is measured in degrees Celsius (oC). Celsius and Fahrenheit can be interconverted using the formula:

o C = 5/9 (oF 32o)

Or equivalently,

o F = 9/5 oC + 32oMetric Prefixes

A prefix can be added to the base unit to indicate fractions or multiples of various units. Some of the prefixes are listed below:PrefixAbbreviationMeaningExample

Kilo-k10001 kg = 1000g

Deci-d0.1 or one tenth10dL = 1L

Centi-c0.01 or one hundredth100cg = 1 g

Milli-m0.001 or one thousandth1000 mg = 1g

Micro-(0.000001 or one millionth1000000(L = 1L

Conversions:

Remember the metric system is a base 10 system. Therefore, converting between units of the same measurement requires movement of the decimal point.

Example: Begin with the units given. Multiply by the conversion factor putting the starting unit on the bottom. This will cancel out the starting unit and leave the unit that you are looking for.

15 mg = ____ g

15 mg X 1g___ = 0.015 g

1000 mgConcepts of Accuracy and Precision

The precision of a test or an instrument is its ability to detect small differences. A more precise instrument will give measurements in smaller (more precise) units. For example, some balances can measure mass more precisely than others, e.g. mg (0.001 g) instead of grams (1 g). Also, a 10 ml graduated cylinder measures more precisely than a 100 ml graduated cylinder.

The accuracy of a test is its ability to measure as it really is; to give a true value.

D. Materials Needed

Part D1: Hypothesis Testing Activity

Balance (Scale)

Mortar and pestleWeigh boats

Stopwatch

Beakers (2-150ml)

Water

Gum (at least two different brands/types)

Part D2: Basic Laboratory Techniques

Balance

Thermometer

Weighing paper/Weigh Boats (3)

Beans

Plastic transfer pipette

Water

10ml graduated cylinder

150 ml beakers (2)

100ml graduated cylinderE. Procedure

E1) Hypothesis Testing Activity

In order to become familiar with using the scientific method, laboratory groups will be asked to formulate a hypothesis related to how the mass of gum is affected by the amount of time it is chewed and the information provided below. Lab groups must formulate a hypothesis based on this information and the materials provided, develop methods to test their hypothesis, collect data (using replicates), analyze their data, present their results in a table format, and interpret their results by answering the discussion questions in section E).

Typically, over 60% of the mass of a piece of bubble gum is made up of sugar. Sugar is dissolved in the mouth and swallowed during chewing. If gum is chewed precisely until it loses its flavor, most if not all of the sugar content of the gum should be gone. How would this affect the mass of the gum? How will the mass of gum be affected by chewing time? How does the chewing time necessary to lose significant mass compare between different brands/types of gum? How large a role does saliva play in the processing of gum in the mouth?

***Note: To measure the gums mass and keep it sanitary to chew, please weigh all initial gum samples in their wrappers. Record the mass of the bubble gum in its wrapper. Then, the chewing volunteer from your lab group can place the gum in their mouths and chew it while holding on to the wrapper. After chewing, volunteers should carefully place chewed gum in original wrappers and re-weigh chewed gum and wrapper. How did the mass of the gum change under your experimental conditions? Is this what you predicted in your hypothesis?

E2) Basic Laboratory Techniques in Nutrition Science

Set Up:

1. Label 3 weigh boats A, B, and C.

2. Randomly select 5 beans for each of the boats.

3. Make an ice bath (crushed ice and water) in a 150 ml beaker by filling the beaker with approx. 75 ml tap water and crushed ice (use in Part II below)

4. Set up a hot bath by filling a 150 ml beaker with approx. 75 ml tap water and set it on a hot plate at setting 2 or 3 (use in Part II below).

Part I: Mass, volume and densityi.) Mass of beans1. Make sure the electronic balance reads zero.

2. Place a weighing paper on the balance and tare.

3. Place the beans from sample A on the balance.

4. Record the mass to the nearest 0.10 gram.

5. Repeat the steps 1-4 with samples B and C.

6. Calculate the average mass of 5 beans and of a single bean

ii.) Volume of beans7. Fill a 10 ml graduated cylinder with exactly 5 ml of tap water from the beaker. Use the disposable pipette to add the exact amount of water to the graduated cylinder.

8. Gently drop the 5 beans from sample A into the graduated cylinder.

9. Record the change in the volume to the nearest ml. (You have determined volume using the water displacement method).

10. Pour out the water and retrieve the beans.

11. Return the beans to cup A.

12. Repeat the procedure with samples B and C.

iii.) Density

1. Calculate the density for each of the three samples of beans (Remember the unit for density is g/ml.) Record them in data Table 1.

2. Calculate the average density of beans. Measurement of various liquids1. Record the mass of an empty 100 ml graduated cylinder to the nearest 0.01 gram.

2. Remove the cylinder from the balance.

3. Fill the cylinder with exactly 100 ml of tap water using the transfer pipette if necessary.

4. Determine the mass of the cylinder containing the water to the nearest 0.01 gram.

5. Calculate the mass of the water alone and record it in data Table 2.

6. Calculate the density of the water and record it in data Table 2.

Part II. Temperature

1. Using the thermometer, record the temperature of a sample of tap water.

2. Using the thermometer, record the temperature of the ice water bath and the boiling water bath.3. Make the necessary conversions and complete Table 3 in data record.Laboratory Report for Hypothesis Testing (Section E Below)

Student Name: ____________________________Date: ______________TA Name: _________________________________

________________________________________________________________F. Data Record and Discussion Questions (50 points)1.) What was the hypothesis of your lab group? (5 pts)

________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 2.) Provide a detailed description of the methods and materials used by your lab group to test your hypothesis? Include the number of participants, gum samples, time allotted, etc. in your answer. (10 pts)

________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

________________________________________________________________4) Please summarize the data collected and the results of your experiment in a table and/or graph below. Please make sure you show the work for any calculations you did to arrive at your results. (10 pts)

Independent variable = ____________________________________________Dependent variable = ______________________________________________Number of replicates = ____Data Table:

Show Work:

5.) Discuss below what conclusions can be drawn from the results of your experiment about gum chewing? How accurate and precise was the data you obtained?

(5 pts)

________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________Part I Mass, Volume, and Density (5 pts)i) Mass of 5 beans

Sample A) _______g

Sample B) _______g

Sample C) _______g

5 bean Average_______g1-bean Average_______gii) Volume of 5 beans

Sample A) _______mL

Sample B) _______mL

Sample C) _______mL

5 bean Average_______mL1-bean Average_______mLData Table 1:

Irregular SolidDensity Sample ADensity Sample BDensity Sample CAverage of A-C

5 beans

Show work.

Measurements of various liquids

i) Mass of 100 mL graduated cylinder _______ g

ii) Mass of 100 mL water

_______ g

Data Table 2:

LiquidMass (g)Volume (mL)Density (g/mL)

Water

Part II (5 pts)

Data Table 3:

Substanceo Co F

Tap water

Ice water

Boiling water

Conversions (5 pts) A) Between Units of Metric System:

Ave. Volume of 5 beans =

_________ mL = _________ (LAve. Mass of 1 bean =

_________ g = _________ (g

B) Intersystem Conversions (5 pts):

Convert your body weight from pounds (lbs) to g (1 kg = 2.2 lb):

Weight _______lbs = ________kg = _________g

Convert your height from inches to meters (1 inch = 2.54 cm):

Height ___ ft ___in = _________in = _________cm = _________m

Convert these temperature readings:

Unless you are ill, your body temperature in Fahrenheit should be about 98.6 F. In C, what would it be in Celsius?

98.6 F = ______C

Altitude affects the temperature at which water boils. At the bottom of the Grand Canyon, ~ 2000 ft above sea level, water boils at 97.8C. At the top of the Grand Canyon, water boils at 92.2C. What would these temperatures be on the Fahrenheit scale?

97.8C = _____F

92.2C = _____F

STUDENT NUTRITION SCIENCE

LABORATORY SAFETY CONTRACT

I agree to:

Act in a responsible manner at all times in the laboratory

Follow all laboratory safety rules and instructions given by the instructor

Use good housekeeping practices in the lab

Wear eye protection, gloves, and lab coat when instructed to do so

Know the location of the emergency equipment

Know how to get help in an emergency

Tie back loose hair, remove dangling jewelry, and wear proper shoes in the laboratory

Never work unsupervised in the laboratory or carry out unauthorized experiments

Never take chemicals, supplies or equipment out of the laboratory without the knowledge and consent of the instructor

Never eat, drink, or smoke in the laboratory

Be actively engaged in all aspects of each laboratory session

I, ______________________ have read and understand the laboratory safety

(Print name)

rules. I agree to abide by the safety regulations and any additional instructions, written or verbal, provided by the instructor. I am aware that failure to abide by the safety regulations could result in dismissal form the laboratory. Furthermore, I understand that it is my responsibility to treat all equipment with the utmost care.

_____________________

__________

Student signature

Date

In case of emergency contact:

_____________________________

Name

relationship

(___)_______________

Phone number

How to Use a Scientific Balance.

Before the balance can measure accurately, it must be zeroed or tared.

Make sure the balance is level

Press the zero button until says 0.00

Place weighing paper on balance

Press zero again (i.e. tare the paper)

Place the sample on the weighing paper

Care of a Scientific Balance:

Balances are sensitive scientific instruments.

NEVER store anything on top of the balance or place anything there unless it is being weighed.

NEVER place anything on the balance greater than 1500 g (~3 lbs)

ALWAYS clean the balance before and after use, but be sure to take off the pan before wiping.

Using a graduated cylinder.

Always leave the cylinder on a flat surface when reading (Do not hold in hand).

Bring eye to level of liquid.

Read at the bottom of the meniscus

Definition:

Because of the properties of water, in a glass graduated cylinder, water sticks to the sides and causes a curve, rather than a straight line at the top. This curve is referred to as a meniscus.

D = m/V Density = grams/ml

Pure water has a density of 1. An mL is the volume of 1 gram of water.

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