Investigation into the effect of acid/alkali strength on the heat change when acids and alkalis are mixed
Investigation into the effect of acid/alkali strength on the heat change when acids and alkalis are mixed Planning The main aim of this experiment is to investigate the heat change when acids and alkalis are mixed. The temperature of the acid and alkali that are going to be mixed will be taken prior to mixing, and after they have been mixed in a polystyrene cup. The maximum temperature rise will be noted as this will be the biggest heat change that has occurred. The highest temperature after mixing and the temperature prior to mixing will be subtracted to give the heat change. To ensure that this is a valid test the volume of the acid and alkali will be kept constant at 40cm3. The volume will be kept constant because if there were a differing volume of acid to alkali this would have an influence on the temperature rise as there is not the same amount of solution. The only variable in this experiment will be the strength of the acid and alkali. This will allow us to examine the manner in which the heat evolved differs for differing strengths. Comparisons can then be undertaken to see how concentration affects the heat change in set volumes of acid and alkalis. When the acid and alkali of the same volume are mixed, this will cause the process of neutralisation to occur. Neutralisation is the reaction between an acid and a base. It is the formation of a bond between
To determine the amount of ammonia in a sample of household cleaning product, 'cloudy ammonia', in the form of NH4OH through the process of volumetric analysis.
Volumetric Analysis of Ammonia in Household Cleaning Product Aim: To determine the amount of ammonia in a sample of household cleaning product, 'cloudy ammonia', in the form of NH4OH through the process of volumetric analysis. Introduction: Neutralisation refers to the process whereby an acid reacts with a base in stoichiometric proportions to each other to form a salt and water. In this experiment, the neutralisation reaction can be summarized by the following equation: HCl (aq) + NH4OH (aq) NH4Cl (aq) + H2O (l) In this prac, the primary standard is Na2CO3. Primary standards are substances that possess certain properties (i.e. it is soluble), which enable it to be made up into a solution of a known concentration with distilled water to high degree of accuracy. A secondary standard on the other hand, is any solution that has an accurately known concentration. In this experiment, HCl acid is the secondary standard. The standardising of HCl can be summarized by the following equation: 2HCl (aq) + Na2CO3 (aq) 2NaCl(aq) + CO2 (g) + H2O (l) Since sodium carbonate is deliquescent, it is kept in a desiccator to prevent it from absorbing water vapour from the atmosphere. The equivalence point of a titration is the point where the reactants are present in stoichiometric proportions to each other. The end point of a titration is the stage at which the chosen
The Periodic Table - Revision Notes The numbers in italics are the page numbers of where more information can be found in the revision guide.
CD6 The Periodic Table Revision Notes The numbers in italics are the page numbers of where more information can be found in the revision guide. Elements and atom 6 Everything is made up of 100 different chemicals called elements . An element is a pure substance that is only made up of one type of particle called an atom. Each element has its own symbol on the periodic table. Eg Copper = Cu Oxygen=O An atom is made up of two parts. In the centre there is a small , heavy lump with a positive charge called the nucleus. On the outside small light ,negatively charged particles called electrons orbit around the nucleus. Nucleus (+ve) Electrons (-ve) An Atom Each element has two numbers on its symbol. The smaller number is the atomic number and tells you the number of protons in the nucleus of an atom of that element. The larger number is the atomic weight (Ar) . The atomic weight tells you the total number of neutrons and protons in the nucleus. Eg 23 Na The atomic number is 11 . The atomic weight (Ar ) is 23. 7 11 Isotopes are two different atoms of the same element that are only different because they have different
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
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
What an ester is, how it is made, examples of esters, animal testing issues and ethics.
Using esters in cosmetics Esters are used regularly and are in many of our everyday cosmetic products, drinks, foods etc. The most They provide an artificial smell or flavouring and provide a wide range of smells and tastes (depending on the type of carboxylic acid used). A lot of people would not have heard about esters, thus, they would also not know many important ingredients in the cosmetics they buy. Many products test on animals which many people would find unethical. We were investing at school esters and how to make an ester, also, we looked further into the unknown ingredients we may find in our products and how many people would but things and not know if it was animal tested or not . In this essay I will write about: what an ester is, how it is made (the experiment I carried out to make an ester), examples of esters, animal testing issues and ethics, a questionnaire I carried out to see what people knew about the cosmetics they own, what an emollient is and I will write about a fair test that I can carry out to see if the cosmetics are right about the information they give about their cosmetics- to the general public. (http://www.myhealthguardian.com/wp-content/uploads/2009/10/cosmetics-070126-1-full.jpg ) So what are cosmetics? The US Food and Drug Administration believe that cosmetics are "articles intended to be rubbed, poured, sprinkled, or sprayed on,
Marble Chips and Hydrochloric Acid.
Marble Chips and Hydrochloric Acid PLANNING AIM To find if changing the concentration of an acid will increase or decrease the rate of the reaction when marble is dissolved in hydrochloric acid. With the equation CaCO3 + 2HCl CaCl2 +H2O + CO2 HYPOTHESES A reaction occurs when particles collide. This process is based on random particle movement. So therefore, the more particles you have in a space, the more likely they are to collide. Therefore making the reaction accelerate. This theory can be proved if you compare the rates of reaction with marble in hydrochloric acid. 'If the acid is of a higher concentration, the reaction will be quicker.' Also if the particles have more energy, they will be travelling faster, making them collide more frequently. PREDICTION When the concentration of acid increases, more gas will be given off faster. I know this from my trial experiments. METHOD Since I will be working with strong acid, I will wear safety goggles while conducting the experiment. I will use Marble chips all of a small size. I can use a sieve to make sure they are all roughly similar size- about 7mm diameter. The amount of acid I have decided on is 10ml. And so the amount of marble must be in excess - 3g. I can measure the speed of the reaction by how much gas is given off. I can measure this in cm3 in a gas syringe. when the experiment takes place, I will take
My experiment will be conducted to find out at what concentration does sodium thiosulphate with hydrochloric acid have the most reaction and how the concentration generally affects the rate of reaction.
How does concentration affect rate of reaction? I am going to conduct an experiment on rate of reaction and how the concentration of sodium thiosulphate affects the rate of reaction. Several things such as temperature, ph and concentration can affect the rate of reaction. My experiment will be conducted to find out at what concentration does sodium thiosulphate with hydrochloric acid have the most reaction and how the concentration generally affects the rate of reaction. Particle size has a big impact on the speed of a reaction, if the particles are big then the reaction would be slow but if the particles are small the reaction will be fast. A catalyst often changes a reaction rate and they increase the speed of reaction always. The rate of reaction for this experiment will be measured by timing how long it takes for the sulphur from the sodium thiosulphate to cover an 'x' under a beaker. To test the rate of reaction and what affects it, we could have tested the effect of ph on rate of reaction, but that was not complicated enough. We used: * Sodium thiosulphate * Water * Hydrochloric acid Dilute sodium thiosulphate with water according to these measurements: Concentration HCL THIO H2O 00% 20ml 60ml 0ml 75% 20ml 45ml 5ml 50% 20ml 30ml 30ml 40% 20ml 24ml 36ml 25% 20ml 45ml 5ml How we carried out the investigation ) Prepare equipment 2)
