A Colorimetric Method for the Estimation of Glucose in Solution.
A Colorimetric Method for the Estimation of Glucose in Solution Method A clean pipette was used to transfer 10cm of 10% glucose into a boiling tube. The pipette was then used to transfer 9cm of 10% glucose into a different boiling tube. 1 cm of distilled water was added to give 10cm of 9% glucose. This was repeated to make 10cm of 8%, 7%, 6%, 5%, 4%, 3%, 2%, and 1% glucose solutions (use the table below to help): Concentration of glucose (%) Volume of 10% glucose to transfer (cm ) Volume of distilled water to transfer (cm ) Total volume of solution (cm ) 0 0 0 0 9 9 0 8 8 2 0 7 7 3 0 6 6 4 0 5 5 5 0 4 4 6 0 3 3 7 0 2 2 8 0 9 0 A clean pipette was used to transfer 5 cm of 1M sulphuric acid into each solution. A clean pipette and pipette filler was used to transfer 2cm of potassium permanganate solution into each boiling tube. A stopwatch was started the exact moment the potassium permanganate was added to the acidified glucose solutions. A time was recorded, in seconds for the complete decolourisation of the potassium permanganate solutions. Results Concentration of glucose (%) Start time (seconds) Finish time (seconds) Elapsed time (seconds) 0 90 562 472 9 80 578 498 8 70 590 520 7 60 605 545 6 50 614 564 5 40 629 589 4 30 635 605 3 20 963 943 2 0 787 777 0 2486 2486 Results of
Deducing the quantity of acid in a solution
Sofia Gaggiotti Chemistry coursework: Deducing the quantity of acid in a solution 20/03/2008 Index Aim and Background information 3 Hazards 3 Protection 4 Method 5 Previous calculations 5 Making the Solution 6 Equipment needed 6 Quantities of materials needed 8 Procedure 8 Making the Titration 9 Equipment needed 10 Procedure 13 References 15 Results and calculations 16 Evaluation 19 Chemistry coursework: Deducing the quantity of acid in a solution Aim and background information The aim of this experiment is to find how to develop and determine an accurate, precise and reliable concentration of an acid rain solution. 1 To do this, we are going to make first a solution of sodium carbonate with distilled water and then a titration in order to calculate the concentration of sulphuric acid in a solution. Solution: a solution is a homogeneous mixture composed of two or more substances. In this mixture, a solute is dissolved in a solvent. Solutions are characterized by interactions between the solvent phase and solute molecules or ions that result in a net decrease in free energy. 2 Titration: a titration is a laboratory technique by which we can determine the concentration of an unknown reagent using another reagent that chemically reacts with the unknown. At the equivalence point (or endpoint) the unknown reagent has been reacted with the known reagent.
Finding the number of Moles of Magnesium and Oxygen in Magnesium Oxide
Finding the number of Moles of Magnesium and Oxygen in Magnesium Oxide Table of Results: SUBSTANCE MASS/g Before After Crucible + lid 39.48 39.48 Crucible + lid + Magnesium 39.61 N/A Magnesium 0.13 N/A Crucible + lid + Magnesium Oxide N/A 39.63 Magnesium Oxide N/A 0.15 Oxygen N/A 0.02 Calculations for Empirical Formula: . Number of moles of Magnesium in Magnesium oxide: Moles/mol = Mass/g ____ Relative atomic mass/ g/mol Moles/mol = __ 0.13g__ = 0.00541 moles ( 3sf) 24g/mol 2. Number of moles of Oxygen in Magnesium oxide: Moles/mol = ____Mass/g______ Relative atomic mass/ g/mol Moles/mol = ___0.02g__ = 0.00125 moles ( 3sf) 16 g/mol 3. Put into ratio: Mg : O 0.00541 : 0.00125 0.00541 = 4.33 0.00125 4.33 : 1 12.99 : 3 13 : 3 Empirical Formula of Magnesium Oxide = Mg O Comparison between calculated empirical formula and literature empirical formula and Sources of Error: The literature empirical formula for Magnesium oxide is MgO meaning the ratio between Magnesium and Oxygen is 1:1. However the results from my experiment differed greatly. Our results ended up in a ratio of 13:3. This could be a result of numerous sources of error and the limitations of the method.
Biology Issue Report on GM Foods
A Level Biology – Unit 3 Issue Report Food Shortage March 2012 Course Code: AN03 Biology A Level 2009 Unit 3 - 6BIO3 -------------------------- ________________ Problem – Producing Enough Food for the World’s Growing Population Food shortages are not a new problem but they have become more widespread in recent years. Food riots took place in Haiti in 2008 following demonstrations over the rising price of food and India suffered drought due to the failure of monsoons in 2009 (1). Famine is a very real issue right now in Africa with the Sahel region of West Africa facing a “worsening food crisis (2)”. In the Horn of Africa (see fig 1) in 2011 tens of thousands of people died (estimates range between 50,000 and 100,000) from famine following a drought said to be the worst in 60 years (3). Climate change is one of the reasons behind the drought that triggered East Africa’s 2011 famine. As climate change is unlikely to be reversed in the near future, reduced rainfalls are expected to continue and a solution is needed to combat the diminished growth of crops and yield in arid, populated areas. The world population is nearly 7 billion at the moment and the United Nations estimates it will reach 9.3 billion by the middle of the century (4). The majority of the increase is expected to be in developing countries. The UN also states that food production must
The Industrial Application of Enzymes.
The Industrial Application of Enzymes. Enzymes are naturally occurring biological molecules found in all living organisms, plant, animal and microorganisms such as bacteria. All enzymes are proteins and, as with all proteins, are made up of a chain or polymer of amino acids held together by peptide bonds. This chain coils to form a specific three-dimensional globular shape, which, typically, means an enzyme will only work with one specific substrate. The purpose of an enzyme is to lower the activation energy required for biochemical reactions to take place. As a result a reaction catalysed by an enzyme will be much more efficient at breaking down a substrate into its products and consequently are used in industry for just this purpose. To obtain these enzymes scientist look mostly to naturally occurring microorganisms, as they are the most productive producers, are easy to handle, can be grown in huge tanks without light, and have a very high growth rate. This may sound all very new and scientific but microorganisms have been used for brewing, baking and alcohol production long before anybody knew of the existence of enzymes. One of the earliest references can be found in Homer's Greek poems dating from about 800 BC where he mentions the use of enzymes in the production of cheese. The starch industry has been using enzymes too for many years in the production of
The Human Genome Project
Amira Nicola January, 2001 The Human Genome Project The Human Genome project is a scientific research effort to analyse the DNA of human beings and that of several other types of organism. The project began in the United States in 1990 under the sponsorship of the U.S. Department of Energy and the National Institutes of Health. It was scheduled to be completed in 15 years. The project's goal is to identify the location of every human gene and to determine each gene's precise chemical structure in order to understand its function in health and disease. In the nucleus of every cell in the human body, there are 23 pairs of chromosomes, each of which is composed of several genes. Genes are discrete stretches of nucleotides that carry the information the cell uses to make proteins. The most important component of a chromosome is the single continuous molecule of DNA. This double-stranded molecule, which is shaped as a double helix, is composed of linked chemical compounds known as nucleotides. Each nucleotide consists of three parts: a sugar known as deoxyribose, a phosphate compound, and any one of four bases-adenine, thymine, guanine, or cytosine. These parts are linked together so that the sugar and the phosphate form the two parallel sides of the DNA ladder. This double-helical structure of the DNA molecule was discovered Watson and Crick in 1953, for
The Effect Of Temperature on the Respiration Of Yeast.
The Effect Of Temperature on the Respiration Of Yeast Introduction: - I am going to find out how temperature effects the respitory action of yeast. I am going to do this by using six different temperatures, 25oC, 30oC, 35oC, 40oC, 45oC and 50oC and a solution called TTC which is absorbed by the yeast cells turning them pink when hydrogen is removed from the metabolic pathway by the dehydrogenase enzyme. Background Information: - Yeast: - Yeast is unicellular fungus that buds profusely under favourable conditions. They are classified as sac-fungi (Ascomyctes) even though they are unicellular. Yeast is common in areas where there is sugar because of this they are given the name saccharomyces (Sugar fungi). They grow on the surface of fruits, in the nectar of flowers, in sap excluded from trees, in the soil and in fresh water. Yeasts are used in all sorts of arrears such as alcoholic fermentation (fermentation is the name given only to the anaerobic respiration of yeast) to baking bread. Yeasts are of a great economic importance and are yeast for biochemical research for example in respiration and enzymes. Yeast exists as Diploid or Haploid cells and divides by mitosis and meiosis. Yeasts are not plant or animal because they do not photosynthesise and they do not have any chloroplast. Yeast is a saprophyte. This is an organism, which obtains its nutrients from dead or
The Effect of Enzyme Concentration On Enzyme Activity
THE EFFECT OF ENZYME CONCENTRATION ON ENZYME ACTIVITY AIM: To investigate the effect of a reduction in enzyme concentration on the rate of reaction, in this case the breakdown of protein by protease enzyme. The protein substrate in this reaction will be trypsin milkprotein (casein). PREDICTION: I believe thath a higher enzyme concentration results in protein trypsin to be broken down faster/ a faster rate of reaction. The protein solution would turn clear quicker when enzymes are more concentrated. The site of the reaction occurs in an area on the surface of the protein (protease) called the active site. At low enzyme concentration there is great competition for the active sites and the rate of reaction is low. As the enzyme concentration increases, there are more active sites and the reaction can proceed at a faster rate. Therefore i believe as the protease concentration is reduced, the rate of reaction, as well as the trypsin mlk protein, is also reduced. FACTORS AFFECTING THE RATE OF REACTION: Temperature - enzmes work best at an optimum temperature. Below this, an increase in temperature provides more kinetic energy to the molecules involved. The numbers of collisions between enzyme and substrate will increase so the rate will too. Above the optimum temperature, the enzymes are denatured. Bonds holding the structure together will be broken and the active
The Effect Of Temperature On The Permeability Of The Cell Membrane
"The Effect Of Temperature On The Permeability Of The Cell Membrane" Aim: My aim of this experiment is to investigate whether changing the temperature (independent variable) of the water around a disk of a beetroot will affect the permeability of a beetroot, by measuring the release of pigment (dependant variable) into water using a digital colorimeter. The colorimeter will be used to measure the light absorbency of anthocyanin (the pigment found in the cell membrane of the beetroot) this can help us work out how much diffusion takes place at different temperatures such as 0,20,40, 60 and 80 degrees Celsius. Introduction I will be conducting an experiment to find out what effect different temperatures has on the permeability of the Beetroot's cell membrane; the temperatures that I will be testing on the beetroot is 0, 20, 40 and 60 degrees Celsius. Background Knowledge Most people think that Beetroot cells are colored red because they contain a red dye called anthocyanin, But in fact they are colored red caused by two distinct pigments, there is a yellow one known as a betaxanthin and a purple pigment known as betacyanin and are together they are referred to as betalins. In beetroot cells the red anthocyanin pigment occurs in the vacuoles. A membrane called the tonoplast surrounds each vacuole. The cytoplasm and vacuole is surrounded by the plasma membrane. The
The Biological Importance of Water
The Biological Importance of Water Water is by far one of the most important substances found on earth; it is vital for living organisms to survive and its structure plays a critical role in this. The most important factor in the structure of a water molecule is its polarity. This occurs because the oxygen atom is larger and therefore of a higher electronegativity (3.44) than hydrogen atoms (2.2). The electronegativity or tendency to pull electrons closer towards itself, determines the polarity of an atom or molecule. For example, a water molecule consists of one oxygen atom and two hydrogen atoms. The high electronegativity of the oxygen atom gives it a slight negative charge (shown by δ-) while the relatively low electronegativity and the consequent drawing away of electrons gives the hydrogen atoms a slight positive charge (shown by δ+). This means that each individual water molecule is dipolar, it has two separate and opposite charges within the same molecule. This is important because it allows a weak ‘hydrogen bond’ to be formed between water molecules, making it a generally cohesive substance. We can observe these electrostatic attractions when rainwater is beaded up on a leaf. It has formed droplets of many water molecules ‘stuck’ to each other through hydrogen bonding. If water did not have a dipole, then it would spread out over the leaf in a thin layer
