Anti-acids
Rates of Reaction in Antacids Aim I plan to investigate the effectiveness of indigestion tablet on HCl. I will take five different tablets containing a specific pH of alkali and discover how long it takes for the indigestion tablet to neutralise the acid. The test will tell me which is the fastest acting tablet is in the case of indigestion. Antacids Antacids are bases and most of them react on the excess build up of stomach acid and neutralises the acid. The most common of these bases are hydroxides, carbonates or bio carbonates. Neutralisation If you have a weak acid you can eliminate the acidic pH by combining it with a weak alkali. Neutralisation is a chemical reaction which is caused by combining both an acid and an alkali, this reaction causes both the solutions to cancel each other out, and this reaction leaves you with water and salt. Neutralisation is simply the combination of hydroxide ions OH and hydrogen ions H+ this process leaves you with the molecule H2O and forms salt. A Catalyst Catalyst are use to speed up a reaction without being used up. In some reaction like digestion catalyst are essentially needed to speed the process or digestion would take too long to gain nutrients. A catalyst breaks down a substance to provide a larger surface area to speed up the process. The Rate of Reaction The amount of time the reaction occurs. Magnesium +
Is Aluminium a Suitable Metal for Manufacturing Bicycles?
Is Aluminium a Suitable Metal for Manufacturing Bicyces? Extraction Process for Aluminium The ore of aluminium is Bauxite and it contains 52.9% aluminium and 47.1% oxygen. The extraction of aluminium takes three main stages: * The mining of bauxite * Refining of the ore to produce aluminium oxide * Electrolysis of aluminium oxide to produce aluminium Mining Bauxite is mined by removing the top layers of soil and then removing the ore from the area by use of explosives to break it into moveable pieces. The bauxite is then crushed on site, sometimes washed to remove soil and clay and then dried in a kiln or it may just be dried. It is then ready to be transported by railway or ships to refineries. Refining Bauxite is made of aluminium oxide-2-water (Al2O3.2H2O) and silicon (IV) oxide (SiO2) and iron (III) oxide (Fe2O3). The bauxite is refined to extract pure aluminium oxide: * The bauxite is ground * Then heated with concentrated NaOH (aq) * This forms a solution of sodium aluminate and sodium silicate, plus a residue of iron (III) oxide, which is removed. * CO2(g) is blown in and the sodium silicate remains in solution, but a precipitate if aluminium hydroxide is formed. * The mixture is then filtered, washed and heated to leave anhydrous aluminium oxide (alumina). * Al2O3 is left. Electrolysis This is how the aluminium and oxygen is separated, through
the chemistry of iron
Write an essay on the chemistry of iron Introduction Iron has an electronic configuration of . It is a d-block element. Also, iron is a transition metal. It has all the properties of a transition metal, including variable oxidation states, complex formation, coloured ions and catalytic properties. General properties of iron Like other metals, iron has a shiny surface. It conducts heat and electricity well. Iron is very tough, so it is always used as building materials. Moreover, iron is cheap when compared with other metals; therefore, it is widely used in all kinds of manufacturing. Variable oxidation states Since the successive ionization enthalpies of transition metals only increases gradually and in particular, the energy difference between 3d and 4s shells is very small, transition metals have variable oxidation states. Iron has two major oxidation states: +2 and +3. Fe2+: Fe3+: As Fe3+ has a half-filled 3d subshell, Fe3+ has extra stability over Fe2+. This can be reflected from the particularly low third ionization enthalpy. Fe2+ can readily be oxidized to Fe3+. Coloured ions and complex formation Complex is formed when ligands form dative covalent bonds with the central atom/ion. Transition metal ions like Fe2+ and Fe3+ can form complexes with ligands readily because they have large charge/radius ratio and low lying vacant d-orbitals available for
Effect of increasing charge on Mass of Copper Deposited.
Chemistry Coursework Effect of increasing charge on Mass of Copper Deposited Diagram Method * I will fist weigh the cathode * I will then set up the apparatus as shown in the diagram * Then switch the power pack on * I will wait 10 minutes and then weigh the cathode, I will do this for 50 minutes every 10 minutes My Independent Variable is the Charge My Dependent Variable is the Mass of the cathode The controlled variables are the concentration of Copper sulphate and the temperature Prediction: I can predict that there will be a positive coloration between the increase of charge and the amount of copper produced at the cathode. Scientific Explanation: Current is the flow of electrons in a circuit - in the case of electrolysis the flow is towards the cathode and away from the anode. Within the solution, the current flows because of the presence of negative and positive ions. Copper sulphate is an ionic salt, which contains no free electrons. However, it does contain ions (which are charged particles) fixed in a crystalline structure. When copper sulphate is dissolved, the copper sulphate solution becomes an electrolyte because the ions become free to move and they can conduct electricity. At the cathode, the copper ions, being more reactive than the hydrogen ions are deposited whilst the hydrogen ions
Revision of Atomic Structure
Revision of Chemical Bonding Bonding occurs between elements in order that they can obtain stable 'full shell' (noble gas) electron configurations. Types of bonding: ionic, covalent, metallic Ionic Bonding Transfer of electrons to create charged particles called ions Ionic compounds contain positive and negative ions whose charges balance. Usually found in compounds that contain metals combined with non-metals - electrons are transferred from the metals (to leave positive metal ions) to the non-metals (to create negative ions). e.g. sodium chloride NaCl e.g. magnesium chloride MgCl2 (simplified diagram - only outer shells shown) The ions are held together by the strong electrostatic attraction between opposite charges. In the solid they form giant regular structures called lattices. Greater charges generally means stronger forces, so MgO (Mg2+ O2-) has a higher melting point than NaCl. Properties of ionic compounds: Usually solid at room temperature with high melting points and boiling points. Usually hard Usually soluble in water Do not conduct electricity when solid, but can when molten or in aqueous solution because the ions are free to move. Covalent Bonding Sharing of electrons between atoms. Usually between non-metal atoms. Atoms overlap outer shells to create stable full shells. e.g. hydrogen H2 Shared pair of electrons is known as a single covalent
equilibrium constant
Experiment 13 Aim: To determine the equilibrium constant for esterification from ethanoic acid and propan-1-ol. Procedure: . 0.25 mole (equals to 14.3 cm3) of glacial ethanoic acid (density = 1.05 g cm-3) and 0.25 mole (equals to 18.8 cm3) of propan-1-ol (density = 0.8 g cm-3) was put into a clean, dry pear-shaped flask. It was mixed thoroughly. 2. 1.0 cm3 of the mixture was transferred by pipette to a 250 cm3 conical flask containing about 25cm3 deionized water and 2 drops of phenolphthalein indicator. It was titrated to end point with 0.50 M sodium hydroxide solution. The titre (V1 cm3)was recorded. 3. 8 drops of concentrated sulphuric(VI) acid was added to the remainder of the acid-alcohol solutions while continuously swirling the flask. Another 1.0 cm3 sample was titrated immediately. The titre (V2 cm3)was recorded. The difference between V1 and V2 Represents the volume to be subtracted from subsequent titration to correct for the amount of sulphuric (VI) acid present. 4. A few anti-bumping granules were added to the flask, and it was attached to a water-cooled reflux condenser. It was refluxed for 1 hour. The flask and its contents in an ice bath was cooled. 1.0 cm3 sample was removed from the flask for titration with the 0.50 M sodium hydroxide solution as before. The titre needed was recorded (V3)and was corrected for the sulphuric(VI) acid. 5. Refluxing was
An experiment to investigate the rate of reaction between
An experiment to investigate the rate of reaction between marble chips and hydrochloric acid The aim of this experiment is to find the factors that affect the rate of reaction between calcium carbonate and hydrochloric acid. The equation for this reaction is shown below. Calcium Carbonate + Hydrochloric Acid --> Calcium Chloride + Water + Carbon Dioxide The variables that I believe are most likely to have an effect in my experiment are: . Temperature 2. Concentration (of hydrochloric acid) 3. Surface area (of marble chips) 4. A catalyst However instead of investigating all four variables, I have chosen to investigate how different concentrations of hydrochloric acid affect the rate of reaction between marble chips and hydrochloric acid. My prediction for this experiment is that as the concentration of hydrochloric acid increases, the rate of reaction will also increase in direct proportion. My reasons behind the above prediction are that so a reaction can take place, the particles of the substances reacting have to collide. If they collide with enough energy then they will have enough energy in order for them to react. If the concentration of hydrochloric acid is increased it will, in turn, increase the number of particles in a given volume, in contact with the marble chips. This will lead to more collision, so the rate of reaction will increase also. Doubling the
To determine the concentration of limewater
To determine the concentration of limewater The aim of my experiment is to find the concentration of limewater solution provided. To do this I am provided with the following chemicals. Limewater: 250cm (1g dm ) Hydrochloric acid at concentration of 2 mol dm As you can see the hydrochloric acid is too concentrated for titration (i.e. one drop could change the colour of the solution.) therefore this acid will need to be diluted. Background knowledge: Limewater can be made by dissolved slacked lime in water to get a solution of calcium hydroxide (Ca (OH) 2 ) Quicklime + water --------> slaked lime CaO (s) + H2O (l) --------> CaCl2 (aq) + 2H2O (l) In this reaction it shows the calcium oxide reacts with water to produce calcium hydroxide. After adding more water to calcium hydroxide, it produces the saturated aqueous solution known as limewater. My experiment will be based on this neutralisation reaction between the limewater and hydrochloric acid. Ca(OH) 2 (aq) + HCl (aq) --------> CaCl2 (aq) + 2H2O (l) (back ground knowledge of limewater provided by AS chemistry 1 page...) Diluting hydrochloric acid: My first task for this experiment is to dilute the hydrochloric acid. To do this I first needed to work out how many moles I wanted for hydrochloric acid. For this part of my calculation I choose to use text book Calculations for chemistry to help me.
Reaction of Alcohol Lab
Name: Teacher: Date: October 16, 2010 Purpose: To test the theories of how the molecular structure of an organic molecule affects its properties and determine the different isomers of butanol through comparison of their reactions with distilled water, Lucas Reagent and Potassium Permanganate. Materials: - Unknown butanol isomers A, B, C, D - Pipettes - Distilled water - Lucas Reagent (conc. HCl + ZnCl2) - Potassium Permanganate (KMnO4) - pH probe/ pH paper - Test tubes (4) - Test tube rack - Rubber stoppers (4) - Goggles - 10-mL measuring cylinder - 25-mL measuring cylinder Flowchart: Prediction: Distilled Water Lucas Reagent Distilled Water & KMnO4 n-butanol Lowest solubility; mixture should be heterogeneous Takes much longer than 5min to turn cloudy Colour changes; pH should turn acidic, since it becomes an aldehyde and then a carboxylic acid i-butanol 2nd lowest solubility; mixture should be heterogeneous Takes much longer than 5min to turn cloudy Colour changes; pH should turn acidic; since it becomes an aldehyde and then a carboxylic acid s-butanol 2nd highest solubility; mixture should be heterogeneous Turns cloudy after ~5min Colour changes; pH should remain neutral, since it becomes a ketone t-butanol Highest solubility; mixture should be homogeneous Forms precipitate and turns cloudy immediately No colour change, since it
Study on food colourings
Food colourings - Should they be used? Contents: Why use food colourings? 2 The two main types of food colourings 2 Health risks of artificial food colourings 3 Case Studies . Cancerous Colouring in Sausages 3 2. No more blue Smarties 4 3. Colourful curries 5 Hyperactivity in children 6 Should food colourings be used at all? 7 Conclusion 8 Bibliography 9 Why use food colourings? As there is doubt over what food colourings do to your health wouldn't you think people would just leave them out of food? Manufacturers still have many reasons to still put them in such as: * Offsetting colour loss due to light, air, extremes of temperature, moisture, and storage conditions. * Masking natural variations in colour. * Enhancing naturally occurring colours. * Providing identity to foods. * Protecting flavours and vitamins from damage by light. * Decorating purposes such as cake icing * Food that looks good will sell more The two main kinds of food colourings As well as artificial colourings you can get natural colourings which also work, these are things such as Caramel colouring which is used is cola products, which is found in caramelised sugar and Annatto which is made from the seed in a tropical tree and used to create a reddish orange dye for food. Also natural food colourings can be made from many plants other plants.
