Salters AS Chemistry Assessed Practical - Enthalpy of Combustion
Salters AS Chemistry Assessed Practical Activity DF 1.3: Enthalpy of Combustion For my assessed practical I will be comparing the enthalpy changes of different alcohols. The enthalpy change of combustion of a fuel is the measure of energy transferred when one mole of fuel burns completely. To find this change I will be using the fuel to heat up some water and I know that to heat up 1g by 1ºC it takes 4.2 J of energy. Requirements * A small copper can or other metal container to act as a calorimeter (base approximately 10cm in diameter). * 0-110ºC thermometer * 100cm3 measuring cylinder * Spirit burners containing: -Methanol -CH3OH -Ethanol -CH3CH2OH -Propan-1-ol- CH3CH(OH)CH3 -Butan-1-ol -CH3CH2CH2CH2OH * A measuring balance * Bunsen burner * Draught shielding * Clamp Method . Set up the apparatus as shown in the diagram above; the calorimeter should be placed into the clamp and the draught shielding should be placed either side of this so that when the spirit burner is alight the flame isn't interfered with. Heatproof mats may be used as draught shielding. 2. Using the measuring cylinder, pour 200cm3 of cold water into the calorimeter and use the thermometer to record its temperature. 3. Place the spirit burner with the selected alcohol contained within underneath the calorimeter that is being held by the clamp. Make sure that the draught shield is
Chemistry Practical Plan
Chemistry Practical Plan. Aim: The aim of this experiment is to identify the chemicals below in the solutions A to F using suitable reactants, and also carry out a titration procedure to determine the concentration of aqueous nitric acid. *Aqueous calcium hydroxide *Ethanoic acid *Nitric acid *Aqueous Potassium Bromide *Aqueous Sodium Chloride Safety: Wear goggles to avoid chemicals getting into eyes. Immediately clean up spills that might occur. Use gloves if handling strong chemicals. Aqueous sodium hydroxide: Apparatus: Solutions A to E Calcium Carbonate Bunsen burner Stand and Clamp Test tube Conical Flask Stopper with tube. Diagram: Method: I will set up the apparatus as shown as above. When heating calcium carbonate carbon dioxide gas is released; this gas will go down the tube to the solutions. If the solution is calcium hydroxide, the carbon dioxide will react with it leaving a milky white precipitate. Equations: CaOH(aq) + CO(g)--> CaCO(aq) + H0(l) Word Count: 134 Ethanoic acid: Apparatus: Solutions A to E Ethanol Concentrated Sulphuric acid Bunsen Burner Stand Water supply Round bottom flask Condenser Tubes Diagram: Method: I will set up the apparatus as shown above. Warming ethanol with ethanoic acid, and a strong acid catalyst (concentrated sulphuric acid), it forms an ester. The O-H bond in ethanol is broken in the
Chemistry: Practical Investigation
Chemistry: Practical Investigation Aim To see how varying the concentration of hydrochloric acid affects its reaction time with calcium carbonate. CaCo3 + 2HCl CaCl2 + H2O + CO2 Apparatus In this experiment I will need: Hydrochloric acid, calcium carbonate, water, conical flask, a bung with hole for tube, burette, water basin, eye protection, stopwatch. Background science "A reaction rate is the speed at which reactants are converted into products in a chemical reaction. The reaction rate is given as the instantaneous rate of change for any reactant or product"1. Collision theory is the theory that atoms or molecules need to collide to react. Most, if not all, reactions also need activation energy for the reaction to occur, also orientation is needed. Factors affecting collision theory are surface area, catalysts, temperature and concentration. Surface area affects the rate of reaction because it increases the frequency of collisions as there is more to collide with, temperature affects the rate of reaction because it both increases the frequency of collisions and the energy in the collisions as it excites the atoms, while concentration affects the rate of reaction because it also increases the frequency of collisions as there are more atoms to collide into the calcium carbonate. Catalysts affect the rate of reaction by providing an alternate route with a
A-level Practical Chemistry experiment - Estimation of available chlorine in a commercial bleaching solution.
Tang King Po School A-level Practical Chemistry Date: 13-11-2003 Class: 6A Class Number:11 Name: Kong Siu Wai Mark: ___________ Title Estimation of available chlorine in commercial bleaching solution. Aim Understand and handle iodometry. Learn to write a full report. Introduction For indirect determination of oxidizing agents, iodometry is widely applied. Here, standard solutions of sodium thiosulphate are required as the titrating agent. The procedure to determine an oxidizing agent is as follows: An oxidizing agent to be analyzed is added to an approximate concentration, excess of potassium iodide solution. The iodine liberated is then titrated with a standard solution of sodium thiosulphate until the end point is reached. In general, the reactions may be represented as follows: Oxidizing agent ( to be analyzed ) + I- (excess ) --> I2(aq) + other products I2(aq) + 2S2O32-(aq) --> 2I-(aq) +S4O62-(aq) In this case, iodide ion acts as a moderately effective reducing agent. The quantity of iodine formed is chemically equivalent to the amount of oxidizing agent and thus serves as the basis for the analysis. Similarly, for this experiment, the active ingredient is chlorate (I) ion in a bleach which will undergo redox reaction with excess of potassium iodine solution in the presence of acid, liberating iodine, which is then titrated against standard sodium
Chemistry Major Practical On Factors Affecting the Rate of Reaction
CHEMISTRY MAJOR PRACTICAL ON FACTORS AFFECTING THE RATE OF REACTION AIM: To examine the ways in which changing the concentration of the reactant affects the rate of the reaction. The two chemicals used as reactants are Sodium Thiosulfate (Na2S2O3 (aq)) and Hydrochloric acid (HCL (aq)). The equation of the reaction is Na2S2O3 (aq) + HCL (aq) 2NaCl(aq) + H2O (l) + SO2 (g) +S(g) HYPOTHESIS/PREDICTION As reactions between solids reactants is much slower than liquid reactants we normally use liquids. According to the Collision theory three conditions must be satisfied before a reaction between molecules can occur. These are: a) the molecules must collide with one another b) the molecules must be made in a way that the right bonds can be broken and made c) there should be enough energy to make sure that the reaction can occur The first of the above three conditions affect this reaction. This is because as you lower the concentration you will lower the number of molecules in 1 litre of the solution (Because concentration or molarity of a substance is the number of moles of the substance present in 1 litre of the solution). KEY VARIABLES They key variables in this experiment are concentration, temperature, the size of the reactants and whether a catalyst is used or not. Because I've chosen to find the affect of changing
PGCE Portfolio - Chemistry Lesson Observation.Year 7 Practical Burning Metals in Oxygen: Making a Sparkle
PGCE Portfolio – School Visits Year 7 Practical – Burning Metals in Oxygen: “Making a Sparkle” 4/11/08 The lesson I observed was part theory, part practical demonstration and had a qualified teacher, one PGCE Science student assisting and myself observing. The lesson began with a starter activity (DCFS 2008) where the teacher asked the students what they thought the aim of the lesson was going to be, what an investigation was and from drawing on knowledge they gained from their previous lessons on how elements react with water and how they thought the same elements would react with oxygen. The pupils were asked to discuss within their set groups of 2-3 pupils and come up with a few ideas while the PGCE student walked around the class asking the pupils what they had come up with. The importance of pupil-pupil interaction is stressed by Lemke (1990) as a way for pupils to share their own ideas and to gain a better understanding of those ideas. While the pupils were discussing the task, the teacher used the interactive white board to put up a number of key words; reactivity, risk assessment, element, hazard, safety, variable and constant which the pupils were again asked to brainstorm before the practical demonstration took place. Although I didn’t pick up on it at the time, this was to be scaffolding for a task set later in the lesson. The main part of the lesson
Chemistry Practical: Finding the water content of Na2 CO3 .xH2O by Titration
Chemistry Practical: Finding the water content of Na2 CO3 .xH2O by Titration Method Step 1: making up the solution Step 1. Weigh about 4g of sodium carbonate hydrate crystals into a dry weighing bottle. Place bottle, lid and powder onto the balance and weigh using an accurate balance to record weight to 3 d.p. Note: remember not to expose crystals to air for too long to avoid water loss from crystals. Step 2. Transfer the powder to a beaker (100 ml+ in size) Step 3. Reweigh the bottle and lid (and subsequently any powder left in the bottle that didn't fall out). Hence find the weight of sodium carbonate transferred to the beaker by subtracting it from the weight of the bottle, lid and powder. Step 4. Dissolve the powder in distilled water by stirring the solution. Step 5. Transfer the solution to a 250cm3 volumetric flask washing the beaker out with distilled water into the flask to ensure as much of the solution is washed into the flask as possible. Step 6. Add distilled water to the solution to make it up to 250cm3 ensure exactly the correct amount is in the flask and that the bottom of the meniscus rests on the calibration mark. Stage 2: titration Step 1. Wash out: i.) the pipette, with a little of the sodium carbonate solution ii.) the burette, with a little of the hydrochloric acid solution iii.) the conical flask, with a little distilled water. Step 2.
A' level Psychology - Practical Report and Article analysis
Source: Newspaper article from 'NME' Title: "Official: Radiohead makes kids think of death (and ice cream) - NME Date: September 2003 What are the underlying psychological assumptions in the source? The article focuses on childrens perceptions of music by Radiohead who are known for being a depressive band but others say 'creative geniuses.' If the media changes trends and perceptions then what effect can one bands' songs have on an individual. 'Those social stimuli that are the products of the behaviour of other people essentially constitute culture.' As stated by Segall, culture relates to perception and generalisation of this can depend on age, wealth and country. The children, aged ten years old from California, USA listened to Radiohead tracks and then drew their impression of the songs showing what perceptions were created from the stimuli. The children requested 'Sean Paul instead' but were told to listen to Radiohead so forced compliance (Festinger and Carlsmith) may have caused them to cognitively 'switch off' and draw anything which is why pictures such as 'Aliens, church organs and McDonalds fries' were created. The negativity of the situation by not being allowed their music may have caused dissonance as the children try to make sense of the consequences and the effect on their arousal level (Cooper and Fazio.) These children were used as they are "the
AS Chemistry: Chemistry of the Stratosphere
AS Chemistry Open book paper (March 1997) There are several techniques used to investigate the chemistry of the stratosphere. The first of these is monitoring which involves analysing the air using spectroscopy. Given that ozone absorbs in the infra-red and ultra-violet regions of the spectrum, the concentration on ozone in a sample can be calculated form the strength of its absorption (figure1). This has to be carried out at different times and in different conditions to ensure any decrease is not due to natural fluctuations. Figure 1 - Ozone Distribution in the Atmosphere Once the molecules present in the stratosphere are identified, laboratory measurements can be carried out to investigate the reactivity of the molecules concerned and how radiation affects them. Special techniques such as flash photolysis have to be used to work out how fast the reactions are occurring. This technique allowed scientists to work out that the reactions breaking down and making ozone are generally occurring at the same rate and consequently there is a steady concentration of ozone. The study of meteorology involves learning about the movements of air currents which circle around the lines of latitude and help gas to mix within a layer. Meteorology allows scientists to obtain a better idea of how the reactions occur in the stratosphere as opposed to the very different conditions under
AS Biology Practical - Planning Exercise
Biology Practical Examination 1 (Part A - Planning Exercise) Aim: To investigate the effect of the concentration of calcium ions on the coagulation of milk. Scientific Knowledge and Prediction[1][2][3][4][5] The major proteins in milk are the caseins; ?-caseins, ß-caseins and ?-caseins which a group of small phosphoproteins that are able to easily form aggregates (called sub-micelles (see Fig 1.1)). In the presence of calcium ions, these sub-micelles can together form a larger aggregate called the casein micelles (see Figs 1.2 and 1.3). The enzyme rennin binds with ?-casein, forming an enzyme-substrate complex [3], hydrolysing a peptide bond and thus splitting it into two fragments (see Fig 2). The fragment that does not remain part of the sub-micelle (the macropeptide) carries the carbohydrate units[1]; the loss of the carbohydrate 'coats' means that strong cross-links between micelles can be formed which is essentially the process of coagulation [1][4] (see Fig 3). Notice how all bonds between sub-micelles in a micelle contain calcium (Fig 1.2). Therefore without calcium ions, no bonds can be made between sub-micelles meaning that micelles can not be formed. Even if rennin did act on the ?-casein, no effect would take place due to the lack of micelles in the first place. Fig 1: Fig 2: Fig 3: Hypothesis: As long as there is plenty of substrate available, if the
