Heat Energy Experiment Aim: To measure the heat energy released in a burning fuel.
Heat Energy Experiment Aim: To measure the heat energy released in a burning fuel. Diagram: Method: * The apparatus was set as shown in the diagram. * 20ml of water were measured. * The initial temperature of the water was measured as well as the distance from the tile to the bottom of the test tube. * The mass of the watch glass with and without the fuel was measured. * The fuel was lighted with a lighted splint and left to burn until it ends. * The mass of the watch glass was then re-measured. * The final temperature of the water was recorded. For safety reasons a heat-proof tile was placed under the watch glass and goggles were used. The fuel was lighted with a splint and not the Bunsen burner, and the experiment area was completely clear for space. For accuracy, the maximum temperature of the water was measured. The fuel was not left for a long time as the water would evaporate and the bottom of the test tube was cleaned in order not to interfere with the heating process. To make it a fair test, the time taken of different fuels to burn could be measured. If this happened, the apparatus should be properly washed, everything re-weighed and re-measured, and the thermometer left to cool. Results: (Averages) Ethanol Fire Lighter Distance from test tube to tile (cm) 2.5 cm 2.5 cm Initial temperature (ºC) 4.5 ºC 7.5 ºC Final Temperature
An investigation into the factors which affect the currentflowing during electrolysis
An investigation into the factors which affect the current flowing during electrolysis Introduction Electric current is the flow of electrons. Sodium chloride in solution is able to conduct electricity because when dissolved sodium ions and chloride ions are produced. The chloride ions that are negatively charged due to their extra electron are attracted to the anode where they give up that extra electron and bond with other molecules to form the chlorine gas, Cl2. The extra electron then flows through the circuit to the cathode. H+ ions in the solution are attracted to the negative charge of the cathode and there they gain the extra electrons that originally belonged to the Cl- ions. Hydrogen gas is then formed and the circuit is complete. 2e + 2H+ --> H2 2Cl- - 2e --> Cl2 Variables Concentration of NaCl- The bigger the concentration the more ions will be in the solution. This will mean that more ions will get to the electrodes, which means more electrons will get into the wire. This will greater the current. Temperature- the ions will go quicker to the electrodes as the water will vibrate quicker when hotter. This will increase the current. Voltage- The current would be decreased because by ohm's law v=ir Surface area of the electrodes- if the surface area on the electrode increases there will be more space for the ions to go to and therefore the current will
Biodegradable Polymers
Biodegradable polymers are environmentally friendly. Write an article for your school magazine to promote more extensive use of biodegradable polymers in Hong Kong. As many of you would know, Hong Kong is heavily polluted and solid waste pollution remains a serious problem to be solved. In Hong Kong, an average of 23000 tonnes solid waste were produced per day, and this figure is obviously increasing. Among all the solid wastes that we dispose of daily, non-biodegradable plastics are one of the kinds that are the most difficult to handle and pose serious threats to our environment. But do you ever think of any solutions to this problem? In fact, everyone can play a part in protecting our Earth from plastics by using biodegradable polymers as substituents. Problem caused by non-biodegradable polymers We have been using non-biodegradable plastics for so many years that we simply ignore their harmful effects. Plastics produce various problems in different areas, including ecological, environment and economical fields. A. Ecological problems Plasticizers and polychlorinated hydrocarbons used in the manufacture of plastics pose a health hazard and they may incorporate into the food chain, eventually getting into human body. Plastic wastes in the sea directly affect fishes. Small fishes have been found dead with their digestive tracts clogged by fragments of plastic foam
Investigate the effect of huddling on heat loss.
Huddle investigation PLANNING A Aim: to investigate the effect of huddling on heat loss Hypotheses: . That the larger the huddle, the smaller the amount of heat lost. That is, an organism (test tube) on its own will lose more heat than if it were huddled in a group. In an experiment using test tubes, this will be supported by data which shows that a test tube by itself will lose more heat in the same amount of time than if it were in a huddle. 2. The temperature loss should decrease proportionally as the size of the huddle grows. 3. Also, the organism (test tube) in the centre of the huddle will lose less heat than an organism or test tube on the outside of the huddle. The reasoning behind this hypothesis is that as the huddle group grows in size, the amount of exposed 'surface area' will be reduced per test tube. Although in practice not every test tube is exposed, theoretically, this is a way of comparing huddles. Also, in a huddle of many organisms, or test tubes, if there is a centre test tube which is not 'exposed', it will be warmer than those on the periphery of the huddle. This hypothesis can be supported by data collected in the experiment by measuring the temperature of the centre of the huddle and the periphery of the huddle. The centre will be warmer because it has no surface area exposed to the outside. Huddling is a behavioural adaptation
Biology Practical Investigation to find the lowest concentration of Copper Sulphate solution that will denature egg albumen.
Biology Practical Investigation to find the lowest concentration of Copper Sulphate solution that will denature egg albumen Introduction Proteins are organic compounds of large molecular mass. They are not truly soluble in water; instead they form colloidal suspensions. Proteins are made up of amino acids.. There are three main types of bonding. The first is a disulphide bond. This occurs between cysteine molecules in the same amino acid chain (intrachain) or between molecules in different chains (interchain). This is the strongest and last bond to break. The second bond is an ionic bond. At a suitable pH, an interaction may occur between ionised amino and carboxylic groups. This forms an ionic bond. These ionic bonds are weak and can be broken in an aqueous solution by changing the pH of the medium surrounding the polypeptide. The third bond is the hydrogen bond, which occurs between hydrogen and oxygen atoms within the polypeptide chain. Hydrogen bonds are not strong on their own, although a large number of them together makes them very strong. The primary structure is the linear sequence of amino acids stablised by peptide bonds. There are an endless number of different possible primary structure The secondary structure is the sequence of amino acids arranged as either an alpha helix of a beta pleated sheet stabilised by peptide s. bonds and hydrogen bonds. In an
An Investigation into the Effects that Different Light Intensities have on the Speed of Woodlice:
An Investigation into the Effects that Different Light Intensities have on the Speed of Woodlice: Introduction: Woodlice are one of the easiest terrestrial arthropods to obtain in large numbers throughout the year. Porcellio scaber, the most common species is not difficult to identify with the naked eye, and is large enough to be handled without employing special techniques. Their behaviour is relatively simple yet providing perfect examples of kinesis and taxis. i A species, which shows taxis, can orient the direction of their movement with respect to the source of an external stimulus whilst kinesis is a steady-state dependence of the movement velocity on the stimulus intensity.iii Thus it is clear that kinesis will be the important response in my investigation as I am not concerned with the stimulus direction. Woodlice lack a waxy cuticle on their exoskeleton and have a high surface area to volume ratio. This means that they are prone to desiccation. As a result, much of their behaviour is concerned with reducing water loss. Woodlice will therefore tend to congregate in more humid, cooler and darker regions where their water loss will be lower.ii Although light does not affect the physiological state of woodlice in the same way as humidity and temperature, it plays a very important part in woodlice behaviour. Woodlice have a negative photokinesis- they move faster as
Water is a molecule composed of two elements of hydrogen covalently bonded with one element of oxygen
AP Biology Essay 1 Water is a molecule composed of two elements of hydrogen covalently bonded with one element of oxygen. Because of the polarity created from the covalent bond these molecules of water are all connected with a hydrogen bond. A hydrogen bond is formed when two molecules are attracted to oppositely charged components of another molecule. A hydrogen bond has about 5% the strength of a covalent bond and is responsible for some of the unique qualities found in water. It takes a large amount of energy to break down the hydrogen bonds in water allowing it to have a high specific heat, giving water its high boiling point and allowing it to maintain a liquid form over a wide range of temperatures. The hydrogen bonds also allow water to have high surface tension. This happens because, although one hydrogen bond is relatively weak, when many of these bonds are formed between two molecules it causes the bonds to be sufficiently strong and quite stable. Hydrogen bonding also influences cohesion, the clinging of a water molecule to itself or adhesion, the clinging of a molecule to another molecule. Water is known as the "solvent for life" or the "universal solvent". Water is a good natural solvent because it exits in the liquid state in its natural habitat. Another one of water's reasons for being such a good solvent is credited to its feature of having polar
Stem Cell Therapy
Stem Cell Therapy Stem cells are those cells in our multi-cellular organisms which have retained their power to divide into different specialized cell types, therefore it is unspecialized. Having this unique property, the new and healthy cells made from stem cells can be used to replace damaged cells in adult organisms. Stem cells are very important to living organisms, as it is the stem cells in the blastocyst which develop different specialized cells that build up our heart, muscles, lungs, skin and other tissues. Stem cells are also present in the blood in the umbilical cord and in some adult tissues, like the bone marrow, muscle and brain. Even though there are no mainstream embryonic stem cell (stem cells from blastocyst) therapies today, there are therapies which use adult stem cells. The best known of all these therapies is the bone marrow transplant, which is used to treat patients with blood or immune system disorders such as leukaemia. Leukaemia is when leukocytes start to grow abnormally, becoming cancer. As bone marrow is the place where new blood cells are made, the marrow contains hematopoietic stem cells. This type of stem cell is responsible for creating all kinds of blood cells. Therefore, a bone marrow transplant can replace the damaged stem cells and white blood cells (leukocytes) after chemotherapy and radiation has killed all the abnormal stem cells
Biology Coursework - Osmosis
Contents Pg. 3 - Plan: Introduction & Aims Pg. 4 - Plan: Osmosis Research Pg. 6 - Plan: Potato Cell Research Pg. 8 - Plan: Variables & Non-Variables Pg. 9 - Plan: Proposed Method Pg. 10 - Plan: Hypothesis Pg. 11 - Preliminary: Introduction and Aim Pg. 12 - Preliminary: Variable and Controlled Variables Pg. 13 - Preliminary: Method Pg. 15 - Preliminary: Results Pg. 17 - Preliminary: Graphs Pg. 18 - Preliminary: Conclusion & Evaluation Pg. 19 - Experiment: Equipment Pg. 20 - Experiment: Safety Pg. 21 - Experiment: Method Pg. 22 - Results: Table Plan: Introduction & Aims In this coursework, I will be studying the process of Osmosis. To do so I will carry out an experiment, this will look at the effects of Osmosis on chips of potato in a sucrose solution. The experiment will involve placing identical potato chips into different sucrose solutions with varying concentrations, after 45 minutes, I will take the potato chips out of the solutions and weigh them, changes in mass would indicate Osmotic activity. My aim is as follows: "To investigate the effect of varying concentrations of sucrose solution on the amount of osmotic activity between the solution and a potato chips, identical in size" I hope that by the end of the investigation, I will have a better understanding of osmosis and a conclusion that demonstrates that knowledge. Plan: Osmosis Research To
Genetically modified crops - Do we know all the answers?
Genetically Modified Crops. Do we know all the answers? Genetic Modification is the method of obtaining individual genes, which are then copied and repositioned into another living organism to modify its genetic code and incorporating or removing particular characteristics into or from an organism.1 There are many viewpoints on the issue genetic modification, some scientifically based on environmental factors and potential economic growth, others concerning ethical, moral and social perspectives. Ever since the breakthrough of genetic modification, deliberation has surrounded all issues involving this controversial topic. Many organizations have published books, videos, and leaflets arguing their side of this debate. Advances in GM biotechnology, such as the incorporation of the gene which stops the Arctic Flounder from freezing, has been placed into the genetic sequence of strawberries to stop them shrivelling in the cold British weather2, these 'modifications' have led to many intrinsic and extrinsic moral issues arising from this "new" technology. Dr Robert Farley of the Monsanto Institute, USA3 believes that genetic modification of crops for human consumption is a much more efficient and effective way of creating more resilient wheat crops than traditional cross-pollination. This is because genetic modification is more specific in changing a particular gene,
