SBI4U1 - Paper Chromatography Lab

SBI4U1 -Paper Chromatography Lab

Discussion Questions

1. What is chromatography? Describe two uses in society. [3 Marks]

                Chromatography is a process whereby the components of a solution or mixture are separated into individually identifiable substances based upon their physical characteristics. These characteristics can include molecule size, hydrophobicity, and more. All forms of chromatography involve a stationary phase and a mobile phase. One use of chromatography in society is its use in the field of drug testing. By having a urine sample undergo chromatography the presence of illegal substances can be identified as they separate from the other components of the urine. This is useful in the fields of athletics and criminal justice. A second use of chromatography is the analysis of water. Through the use of chromatography pollutants and other additives to water sources can be isolated and identified. This process allows for municipal water to be quality controlled for the general populous.

2. List three chromatographic techniques (besides paper chromatography), and briefly state how they work. [3 Marks]

                One chromatographic technique is "Thin Layer Chromatography". Thin layer chromatography (TLC) uses a thin layer of silica gel spread on an inert piece of glass or metal as its stationary component. Once the sample is deposited on the gel a solvent is added and the different components of the sample migrate up the gel at different rates. The different components separate and can be analyzed based on their migration distance. A second chromatographic technique is gas chromatography. Gas chromatography uses a high boiling liquid as its stationary phase and an inert gas such as helium as its mobile phase. A vapourized sample is placed into a tube containing the gas and liquid. The gas forces the sample to interact with the liquid along the walls of the tube and separate. As the separated substances leave the tube they pass through a sensor which records the identity and quantity of each substance that composed the original sample. This information is represented on a graph. A third chromatographic technique is gel filtration chromatography. A bed of porous gel beads acts as the stationary phase while liquid solvents act as the mobile phase. Using different solvents the sample is passed through the bed of beads. Smaller molecules permeate the porous gel beads and move through the bed slower while the larger molecules pass through with less resistance. This separates the different substances based on molecular shape and size.

3. What is Rf? Show the calculation of the green fragment from your lab results. [2 Marks]

                Rf is a short form used to represent Retention Factor. Retention factor is the distance a substance will travel along the stationary phase when in the presence of a specific solvent. This value is constant for each substance given that all other factors remain constant.  

4. List and briefly explain two factors that would determine your chromatographic profile (theory of paper chromatography separation). [2 Marks]

                One factor that helps to determine the chromatographic profile of the sample is the polarity of the molecule. The solvent that was used in the lab was at a 9:1 polar to non-polar ratio. As the solvent was more polar the polar components of the sample were more readily dissolved. This resulted in an increased ability to migrate up the filter paper. Another factor that helps to determine the chromatographic profile of the sample is the variety of chromatography paper which is used. Different varieties of paper have different characteristics which affect a substance's ability to travel through it. Paper with more dense characteristics limit the movement of substances whereas less dense paper is conducive to the  migration of the various samples.

5. List three factors that would improve your chromatogram (sources of error). [3 Marks]

                One source of variability in the lab was the lack of a predetermined incubation period. As each group exposed the ethanol and spinach mixture to heat for different amounts of time a different amount of the green substance was extracted from the spinach. These varying concentrations in the initial sample could affect the accuracy of the final product between the different groups. Another source of variability within the lab was the number of samples deposited on the chromatography paper. The number of drops being placed on the paper from the capillary tube was not specified. As a result each group could have a different concentration of the sample being tested. This variability in concentration could affect the final results. A third factor which added to the variability found in the lab was the lack of a predetermined value for the amount of ethanol used to extract the chloroplast pigments from the spinach. Each group used a different amount of ethanol based on an approximation and as a result the concentration in each sample varied. All in all the slight variation between each group's interpretation of the vague instructions affected the accuracy of the final result. By changing the concentration of the substance being tested the rate of migration was affected and the possibility for difference in Rf values was increased. Note that Rf values are only constant when all other variables remain the same but due to the variation between groups a uniform Rf value may not be found.

6. List two proposals for future experiments. [2 Marks]

                A future experiment which could generate additional information pertaining to the chloroplast pigments in spinach leaves involves the use of gas chromatography. Through the use of gas chromatography the exact values of each component of the sample could be analyzed. By identifying exact molecules and the concentrations in which they are present more in depth analysis of chloroplast pigments in spinach could be undertaken. A second lab proposal would be the comparison of varying vegetables. By having a variety of different lettuces, and other green plants undergo chromatography comparisons could be drawn between samples. The possibility for identifying a component present in all or many of the samples arises and comparative studies could be done expanding on the results. By analysing the different pigments present in different samples information can be inferred about environmental effects on the presence of different pigments.

SBI4U1 - Calculation and Analysis of VO2 Max Lab

SBI4U1 -Calculation and Analysis of VO2 Max

Introduction

                The basis of this lab is formulated around the calculation and analysis of VO₂ max in one individual using the Rockport Fitness Walking Test. Maximum oxygen consumption, or VO₂ max is a measure of the maximum volume of oxygen, in millilitres, that the cells of the body can remove from the bloodstream in one minute per kilogram of body mass while the body experiences maximal exertion. An individual's overall fitness can be accessed through a variety of different tests and criteria including aerobic fitness, muscular strength, muscular endurance, flexibility and body composition. Aerobic fitness is a measure of the ability of the heart, lungs, and bloodstream to supply oxygen to the cells of the body during physical activity. As a result, the VO₂ max value can be used to assess a portion of an individual's overall physical health.

                Although VO₂ max may be used to measure a portion of an individual's overall health it is not the defining factor in one's athletic ability. Athletic performance is affected by a myriad of factors including the efficiency of motion and the lactate threshold of the individual. At certain points in exercise lactic acid is produced in large values and leads to the burning sensation felt in the muscles. Based on genetics VO₂ max and the lactate threshold varies between individuals. Although both can be increased with exercise and a healthy lifestyle some individuals are simply not capable of overcoming certain barriers based on their physical formulation.

                In this lab a true VO₂ max measurement was not completed; instead, an estimation of VO₂ max was calculated from a collection of data. The Rockport Fitness Walking Test consists of a 1.6km walk and a collection of different data points which are placed into an equation to derive an estimation of VO₂ max. The age, weight, gender, walk time, and heart rate of an individual is all taken into consideration when making the final calculation. By including many of the factors that affect VO₂ max a fairly accurate estimation can be developed.

Methodology

                The calculation of the VO₂ max required the collection of various data points. To record the data points a table was made which included space for mass in kilograms, age in years, time of the walk in minutes, heart rate in beats per minute, and gender where a value of either one or zero was selected for male and female respectively. Height in centimetres and the overall average of last semester in percent were also recorded for further analysis. Using a bathroom scale the weight in kilograms was measured and recorded accurate to one decimal place. Height was then measured using a measuring tape and recorded in the chart. Exact age in years was calculated by comparing the birthday of the subject to the exact day at which the trial was completed. The average mark of last semester was also recorded in the table. The subject then prepared to walk 1.6km. The subject walked 1.6km while timing the walk using a stopwatch. Upon the completion of the walk the time which the walk took was recorded along with the heart rate of the subject. All of the recorded values were placed in an equation and a VO₂ max estimation for the subject was generated.

Results

Raw Data Collection Chart

Mass (kg)	Age (Years)	Gender (1-Male/0-Female)	Time (Minutes)	Heart Rate (Beats/Minute)	Height (cm)	Average Mark (Percentage)
63.5	18.16	1	13.34	78	153	95

Discussion

                When compared with the values found in the "VO2 Max Values For Males" table the VO2 Max calculated in this experiment is considered "superior".  This value is a result of the lifestyle which I have adopted and the genetics which formed the basis for my development. My father demonstrated an affinity for athletics when he was younger and as a result proved that a high level of physical fitness is part of the genetic make-up of my family. The other aspect of my life which led to the high VO2 Max value is the activities which I involve myself in. By swimming, running, and playing a wind instrument I have stressed my body in ways which forced it to adapt. By placing that stress on my body I have conditioned it and developed a  VO2 Max which is above the average male for my age group. The estimated value which was found is a culmination of my genetics and lifestyle.

                Although this activity is designed to provide a VO2 Max value the value which is recorded is only an estimation. True VO2 Max must be measured through the use of an apparatus which analyzes respired air from a subject who is at their point of maximal physical exertion. The method used in this lab relies on predetermined constants and recorded data points to provide a simple estimation. The flaw present in the lab is that the subject is not forced to fully exert themselves. By simply walking around a track maximal exertion is not reached and the true definition of VO2 Max is lost. To remedy this an equation must be developed which requires full exertion by the subject or a simple measurement must be done by a special apparatus. One source of error is the precision of the apparatus being used in the lab. By having instruments which provide more precise data a number which is closer to the true value could be found. This includes a precise heart rate monitor, a stopwatch accurate to a thousandth of a second and a bathroom scale with an easy to read display. Another source of error present in the lab is the instruction which states "Walk a measured 1.6-km distance as fast as you can". The concept of walking as fast as you can is completely subjective. On any given day an individual's ability and drive to walk at peak speed is different. This speed also varies between individuals. To perform a true test in which reliable data is recorded a treadmill is required. By increasing the speed on the treadmill until the subject cannot keep up the true maximum walking speed can be attained. In a true test the subject would not be walking but rather running until their peak speed is reached. A third source of error is the equation used in the calculation of VO2 Max. By using predetermined values which are only accurate to a certain number of decimal places the accuracy of the final answer is reduced. The inherent problem with equations is the precision of the final answer. To remedy this situation and provide a "true" value or a value which is as close to the measured one as possible the inherent error of the equation must be included. An error calculation must be included using a true value or other standard to create an equation which provides accurate results. Another option is to develop an equation comprised of constants derived from an average value of an extremely large sample group. Either method would allow for a more accurate equation.

                One component in the equation is the gender factor. Males have approximately six units added to their final answer simply because of their gender. This is due to the difference in physiology between males and females. Males have this value added because in general,  the composition of males contains more lean muscle mass. Females tend to have more fat in their body composition then males due to the requirements of child birth. Muscle cells require more energy and as a result they possess a higher mitochondria content. Mitochondria is responsible for processing oxygen and providing the muscles with the energy needed for them to contract. As males have a higher muscle content than females there are more mitochondria processing the oxygen uptaken by the body.

SBI4U1 - Basic Chemical Concepts Assignment

SBI4U1 - Basic Chemical Concepts

Isotopes

                Isotopes are atoms of the same element with differing numbers of neutrons. This results in atoms of the same element having different molecular masses Therefore, isotopes are atoms of an element which possess the same atomic number but varying mass. As such, the recorded molecular mass of each element on the periodic table is simply a derived value based on the abundance of the varying isotopes. An example of a set of isotopes can be found when analyzing carbon atoms. There are Carbon-12 ( , Carbon-13 ( , and Carbon-14  atoms present in varying abundances in the world. Carbon-14 has been identified as a radioisotope because of its tendency to spontaneously decay into a smaller atom. In this case, Carbon-14 decays into Nitrogen-14. Carbon is a major component of living things in all of its isotopic forms. When organisms are living, they intake Carbon in its varying isotopic forms; however, upon death they stop the intake of Carbon. As Carbon-14 is present in trace amounts in the body and it decays at a defined rate the age of the dead organism can be determined. The time at which the amount of Carbon-14 is valued at half of its original amount is known as the half-life. By using the concept of the half-life, age can be determined. This process is known as Carbon dating and is used in a variety of different fields such as forensics and archeology. There are a myriad of different isotopes and consequently a myriad of radioisotopes. These radioisotopes are used in a variety of different medical roles including diagnostics and drug testing. Isotopes are present in daily life and they are now being used to improve the quality of life the human populous experiences.

Electronegativity

                Electronegativity is a measure of an atom's ability to attract a shared electron when participating in covalent bonding. When one atom's electronegativity is greater than another atoms the electrons will be more attracted to the first atom. That same atom will adopt a slightly negative charge(ɗ-). The atom with the lower electronegativity will adopt a slightly positive charge(ɗ+). The bonds formed are known as "polar covalent" however if the difference in electronegativity between the atoms is greater than 1.7 the bond is then classified as "ionic". If the difference between charges is zero then the bond is simply "covalent". An example of a non-polar covalent bond is carbon tetrachloride (CCl₄). Fluorine possesses the greatest electronegativity value at 4.1 however the second highest value is connected to oxygen at 3.5. Oxygen's high electronegativity allows for it to form a multitude of different molecules which are used for many biological processes. The high electronegativity that oxygen possesses also means that the bonds it forms tend to be polar in nature. Water is a polar molecule because the oxygen adopts a slightly negative charge whereas hydrogen adopts a slightly positive charge. Electronegativity decides the polarity of molecules and the characteristics that the molecule exhibits are extensions of its polarity. Therefore, electronegativity ultimately decides the role and characteristics that molecules will possess and how they will interact with other molecules. Polar molecules will dissolve polar molecules whereas non-polar molecules will dissolve non-polar molecules. This relationship is present in many different biological processes and allows for the human body to function.

Isomer

                Isomers are molecules that have the same atomic mass but different atomic arrangements. The components are the same in isomers however the three dimensional shape that they adopt varies. The molecular formula for isomers is also the same. The different arrangements that the isomers adopt change the function that they perform and how they interact with their surroundings. An example of some isomers are glucose and galactose. Although they are made up of the same basic components their arrangement changes how the human body deals with them and uses them. Glucose in the body is converted to galactose by changing the arrangement of the components. From this galactose can be more easily used in processes such as  breast feeding. Galactose can also be converted to glucose for use in the body as a basic energy source through conversion to ATP. The different shapes that isomers adopt allow for their form to suit their function. By specializing molecules in the body the functions that need to be accomplished for life are made more efficient. 

Radioisotopes

                Radioisotopes are atoms which spontaneously decay into smaller atoms while releasing subatomic particles and energy. As they decompose the energy that is released is radioactive in nature. This radioactivity can be traced, detected and used for a variety of different purposes. The most commonly used radioisotope in medicine is technetium-99. It has a half-life of only six hours which means it will be nearly non-detectable in the body within a day of  initial contact. Technetium-99 is used to view different areas of the brain such as the skeleton, brain, thyroid, lunges, and many more. As the radiation that the isotope releases is traceable the movement of the radioisotope can be used to image various body parts. Technetium is very versatile however some radioisotopes are much more specialized. Iodine-131 is mainly used to identify problems with the thyroid gland including enlargement and cancer presence. Radioisotopes are also used in medical research and drug development. By including radioisotopes in new drugs their movement and area of effect can be traced. If a drug is designed to treat a problem in the heart a radioisotope can be tracked to ensure that the drug moves towards the heart. Amazingly, radioisotopes are used for more than just medical diagnostics. They are also used in biological research. Melvin Calvin was a researcher who used Carbon-14 to trace the sequence of reactions present in photosynthesis. With a wide variety of uses radioisotopes and radioactive tracers enable humans to better visualize the world around them and gain a greater understanding of complex reactions in the world they inhabit.

Polymer

                Polymers are collections of mostly repeating molecules bonded together to form long complex chains. By bonding many simple molecules together more complex compounds can be developed. As the compounds become more complex their functions also become more complex. Again polymers demonstrate that form is simply reflective of the function that is being performed. Polymers in the body include lipids and proteins. Proteins are polymers which are composed of a variety of amino acids and bound by peptide bonds. The defining characteristic of proteins is the presence of nitrogen in the bonds. Proteins are used to develop many of the characteristics of human beings. Proteins are a result of the genes that code for the characteristics of individual organisms. These genes form amino acids which then bond to form proteins. These proteins are specialized polymers whose structure defines their function. An example of a polymer is albumin. It is a protein in the blood which acts as a transport for fatty-acids. Without the complexity that polymers provide the diversity of life present on the Earth would not be possible.

Oxidation-Reduction Reactions

                Oxidation-reduction reactions or redox reactions are chemical reactions which result in a change in the oxidation number of an atom. The reactions work in tandem to explain the final outcome of a chemical reaction. The oxidation reaction separates the initial atom or molecule into its ion and the electrons it has lost. The reduction reaction uses the lost electrons from the oxidation reaction in tandem with the other atom or molecule to create the second ion. From there the final equation can be derived and the new compound can be defined. In the human body these reactions are used to convert the fuel and oxygen present in our bodies into water and waste. Cellular respiration uses glucose and oxygen to provide energy while releasing carbon dioxide and water as a result. The final formula appears as C₆H₁₂O₆(aq) + 6 O₂(g) 6 CO₂(g) + 6 H₂O(l). Cellular respiration using the sugars in our body and the fats stored are one example of redox reactions however photosynthesis is another example. It is simply cellular respiration in reverse and provides sugar and oxygen. Redox reactions are the basis of life. They define the processes which form the defining characteristics of flora and fauna. Cellular respiration and photosynthesis are the most important functions in the natural world. These reactions allow for life and therefore redox reactions are the most important chemical reactions in the world.

Acids

                Acids are substances that increase the concentration of the hydronium ions present in water. They are sour in taste, support conductivity of electricity, and turn blue litmus paper red. There are a variety of different acids which possess these characteristics however some are more acidic than others. Hydrochloric acid is a strong or complete acid. All of the hydrogen atoms present in the acid will dissociate into the solution. This will make the solution extremely acidic. Acetic acid is a weak or partial acid. Only five percent of the hydrogen present in acetic acid will dissociate. The resultant solution will be acidic but not as drastically acidic as a hydrochloric acid solution. Acids are also classified as proton donors. Acids are responsible for changing the pH of a variety of different areas in the body and the genetic coding of individuals. The inside of the stomach is extremely acidic as the qualities associated with acids are able to kill many of the bacteria that are ingested during the digestion process. The introduction of acids are also present as a result of physical activity. Lactic acids are a by-product of physical exertion in the body. As such, the body needs to take action to eliminate the acidic environment being created. Amino acids are also an important part of biology. These acids allow for biological processes to occur. The proteins they form work to make-up the defining characteristics of different organisms and the amino acids procured from outside the body allow for healthy human development. All in all acids are a part of biology that can be both positive and negative. Their ability to change the pH of solutions can be dangerous but it can also have a positive outcome. If the blood in an individual becomes too basic the addition of carbonic acid can return the blood to a state of balance.

Bases

                Bases are substances that increase the concentration of the hydroxide ions present in water. They are bitten in taste, slippery to the touch, support conductivity of electricity, and turn red litmus paper blue. Like acids there are strong bases and weak bases which will dissociate in the solution at different rates. Sodium hydroxide is considered a strong base because it ionizes completely in water whereas ammonium is considered a weak base. Ammonium ionizes only partially in water. Bases are also known as proton acceptors because they accept the protons that are released by acids. This relationship allows for bases to neutralize acids. Bases are extremely important in the development of flora however they are also present in human development. Ammonia is an important base that is used as a form of nutrients for many plants. This basic compound is broken down inside the plant and is used to develop many of its physical components. Bases are also used to counteract acidic conditions in the body. When the stomach becomes too acidic bases are added to neutralize some of the acid and return the pH in the stomach to its normal range. This concept is also true when considering the pH of the blood. When extended physical exertion is present the pH of the blood can become acidic. Carbonic acid, an acid, can be converted into a bicarbonate ion and vice versa. Some amino acids that make up the proteins in the body also occupy basic roles. They have the characteristics of bases and can sometimes act as buffers in certain circumstances. This transference between an acid and a base allows for the body to maintain the pH of the blood.

pH - Power of Hydrogen

                pH is the measure of how acidic or basic a substance is. More specifically, it is the negative logarithm of the hydronium ion concentration in a solution. This relationship is demonstrated through the equation pH =-log₁₀(10^-7 mol/L) =7. On the pH scale the value of seven is neutral as the presence of hydronium and hydroxide ions are equal. Any value less than seven is considered acidic as the amount of hydronium ions is greater than the number of hydroxide ions. Similarly any number above seven is considered basic as the amount of hydroxide ions is greater than the number of hydronium ions. In the body pH plays a vital role in the functions of many different components. The pH of gastric acid in the stomach is extremely low with a range from 1.5 to 3.5. This intense acidity is used to kill bacteria and other unwelcome guests of the digestion process. When the acidity of the stomach acid becomes too strong a base is added to neutralize the acid. Neutralization reactions occur between an acid and a base and leave water and a salt as the resultants. By controlling the pH of the stomach the quality of life experienced by people can be increased. pH can also be changed in the muscles of the body. An acidic environment is created during times of physical exertion. This acid hurts the effectiveness of the muscles and creates the burning sensation associated with muscle fatigue. Through the body's ability to return the pH to a neutral state it removes the acid and consequently the pain associated with exercising. The pH of blood is also important as it is constantly fluctuating.  Through the use of a buffer system the pH of the blood can be controlled through the constant transformation of components in the blood. During cellular respiration water and carbon dioxide are produced. These two components then synthesize to form carbonic acid. This acid releases hydrogen ions and bicarbonate ions which make the blood more acidic. To return the blood to a more basic state the two ions are returned to carbonic acid and eventually carbon dioxide and water. This process keeps the pH of blood consistently neutral allowing it to be efficient in its other processes. pH is important in the body because it allows for different bodily functions to occur effectively.

Buffer

                Buffers are chemical systems used by living organisms to resist significant changes in pH. They contain substances which can donate hydrogen ions when they are required and contain other substances which can remove hydrogen ions when there are too many present. One of the most common buffer-systems present in the human body is the carbonic acid/bicarbonate buffer. When the bloodstream becomes acidic due to environmental effects such as an acidic meal or physical exertion there is a surplus of hydrogen ions. The buffer system in place takes these excess ions and uses them to create carbonic acid. This balances the pH of the blood and keeps the organism healthy. This process can also work in reverse as carbonic acid can decompose into hydrogen ions and bicarbonate ions. This buffer allows for the pH of blood to be controlled. Proteins can also be used as buffers. Hemoglobin, a protein found in blood can remove excess hydronium or hydroxide ions as the amino acids which formulate their composition can be both acidic and basic in nature.