1655 results found

#### Rates of reactivity.

Introduction Rates of reactivity The rate of reaction is simply how fast it takes for a complete reaction to occur. In this coursework the following factors will be investigated to discover whether or not they affect the rate of reaction: * Surface area of reactants. * The temperature of reactants. * The concentration of reactants. * The involvement of a catalyst in a reaction. Collision Theory This states that reactions only commence when reacting particles collide with each other with a sufficient amount of energy, the minimum amount of energy. When the temperature of the reactants is increased particles absorb energy and move around a lot faster. This increases the chance of collisions. Increased concentration leads to more reactive particles and therefore more chance of collisions, increasing the rate of reactivity. Small pieces of reactants mean a large surface area. This allows more collision to take place resulting in a faster rate of reaction. Catalysts allow particles to react with a lower amount of energy. They also provide a surface for the particles to attach to; therefore the chances of collisions are higher. What is meant by rate of reaction? Magnesium + Hydrochloric Acid Magnesium Chloride + Hydrogen Mg (s) + 2HCl(aq) MgCl2 (aq) + H2 (g) In order for the magnesium and acid particles to react together, they must have the following bullet

• Word count: 8024
• Level: GCSE
• Subject: Science

#### Kinetic Theory of Matter Investigation

The Kinetic Theory of Matter The main points of the kinetic theory are: . All matter is made up of tiny, invisible, moving particles. 2. Particles of different substances have different sizes. 3. Smaller particles move faster than heavier ones at a given temperature. 4. As the temperature rises, the particles move faster because the particles have more kinetic energy. 5. In a solid, the particles are a very close together and they can only vibrate about fixed positions. 6. In a liquid, the particles are a little further apart. They have more energy and they can move around each other. 7. In a gas, the particles are far apart. They move rapidly and randomly in all the space they can find. This diagram shows the particles in the three states of matter: The Collision Theory of Chemical Reactions A chemical reaction cannot happen unless particles in the reacting substances collide with each other. There are three main conditions which must be presenting order for a reaction to occur: . The reactant particles must collide. 2. They must collide at the correct orientation (e.g. a head on collision is better than a glancing blow) 3. The must collide with a minimum amount of energy, (the activation energy) to allow the rearrangement of atoms; otherwise they simply bounce of each other. Changing the Rate of a Chemical Reaction The rate of reaction is only affected if

• Word count: 2546
• Level: GCSE
• Subject: Science

#### In my investigation, I intend to find out what effect changing the concentration of sodium thiosulphate has on the rate of reaction between hydrochloric acid and sodium thiosulphate.

Plan of Experimental Procedures Preliminary Experiment Our teacher demonstrated the experiment for us. She drew an X on a piece of filter paper and placed it under a flask with sodium thiosulphate in it. She added the hydrochloric acid to the sodium thiosulphate. As the reaction occurred, the solution gradually became cloudy. We saw that the experiment ›visible. Introduction In my investigation, I intend to find out what effect changing the concentration of sodium thiosulphate has on the rate of reaction between hydrochloric acid and sodium thiosulphate. Na2S2O3 + 2HCl › S + SO2 + 2NaCl + H20 Independent Variable to be Investigated In the experiment, the independent variable will be the concentration of sodium thiosulphate. This is so I can see the effect of changing the concentration of sodium thiosulphate on the rate of reaction between the sodium thiosulphate and hydrochloric acid. Theory I predict that the rate of reaction will be directly proportional to the concentration of sodium thiosulphate solution. When the concentration is low, then there will be less chance of successful collisions between the hydrogen ions and the thiosulphate ions and so, will take longer to react. However, if the concentration of sodium thiosulphate is increased, there will be more chances for the hydrogen ions and thiosulphate ions to collide. Also, if the concentration

• Word count: 1046
• Level: GCSE
• Subject: Science

#### Experiment To Investigate the Effect On the Rate of Reaction Caused By Changes In Temperature.

Experiment to investigate the effect on the rate of reaction caused by changes in temperature. Plan The Aim of this experiment is to investigate the effect on the rate of reaction caused by changes in temperature. Safety Safety in this case includes: * The use of a heatproof mat * Sensible setup of equipment so that the desk is clear and everything is stable * Setting the bunsen to a safety flame while it is not in use * Wearing goggles while using hydrochloric acid and sodium thiosulphate * Wearing an apron to protect clothes Fair Test To make any experiment a fair test, I must make sure that I wash and dry the apparatus after every test so that the substances do not get contaminated. Also, because the solutions are both clear it would help to use different sizes of measuring cylinder and beaker so that the two liquids can be distinguished Equipment Theory The rate of reaction is the amount of a substance that takes part in a chemical reaction in a given time. The main thing that can change the rate of reactions is a catalyst because they provide an easier path to overcoming the activation energy. Concentration also affects reaction rate. A higher concentration increases the amount of particles that can collide. If reacting substances are heated, the rate of the reaction usually rises because the particles that make up the substance already have more

• Word count: 1652
• Level: GCSE
• Subject: Science

#### To investigate the effect of the concentration of nitric acid on the rate of reaction between the nitric acid and magnesium granules.

FACTORS AFFECTING RATES OF REACTION AIM: To investigate the effect of the concentration of nitric acid on the rate of reaction between the nitric acid and magnesium granules BACKGROUND KNOWLEDGE: The equation for this reaction is: Word: Magnesium + Nitric acid Magnesium Nitrate + Hydrogen Gas Balanced Equation: The products of the reaction between nitric acid and magnesium are magnesium nitrate, water and hydrogen gas. In my main investigation, I will measure the rate of reaction by calculating the volume of hydrogen gas produced, using a gas syringe, over a certain time period. I will then plot a graph of gas produced against time for all of the different concentrations of nitric acid. Having plotted gas produced against time for each concentration, I will then take a tangent of the line produced by each concentration graph and calculate the rate of reaction for each concentration. The rate of reaction will be calculated as follows: Rate of reaction = volume of gas produced/time (cm³/second) Having done that, I will plot a graph of rate of the reaction for each concentration against concentration, and then state what type of relationship there is between the concentration of acid and the rate of reaction. I will then be able to conclude and state from my results what type of relationship my results show as explained on the following page. I will then analyse

• Word count: 5293
• Level: GCSE
• Subject: Science

#### Sodium Thiosulphate + Hydrochloric Acid Coursework

Sodium Thiosulphate + Hydrochloric Acid Coursework Plan Aim I must produce a piece of coursework investigating the rates of reaction when Sodium Thiosulphate + Hydrochloric Acid are mixed. The reaction that will be used is: Na S O + 2CHl 2Na Cl + S + SO + H O Sodium + Hydrochloric Sodium + Sulphur + Sulphur + Water Thioslphte Acid Chloride Dioxide Variables Other variables, which may affect the outcome of this experiment, if not kept constant, are as follows: o Temperature of liquids. I believe that the hotter the temperature, the faster the rate of reaction. This is because when a substance is heated up, each particle has more energy, resulting in more collisions between the free moving particles in a liquid, causing more particles to react, therefore increasing the overall rate of reaction. The second effect this has is that the particles collide with more force, increasing the chance of the particles reacting. I will keep this variable constant so that it does not affect the results by avoiding heating the sodium thiosulphate in any way, and so it will stay at room temperature. o Human Error/People. This experiment relays on people and their eye sight, because to determine how long

• Word count: 1661
• Level: GCSE
• Subject: Science

#### Investigate the effect of concentration on the reaction between Thiosulphate ions (S2O32-) and H+ ions.

(1) Skill area P: PLANNING Problem: Investigate the effect of concentration on the reaction between Thiosulphate ions (S2O32-) and H+ ions. Introduction: When sodium Thiosulphate solution reacts with acid, a precipitate of sulphur forms. The time taken for a certain amount of sulphur to form can be used to indicate the rate of reaction. In this experiment the effect of concentration of sodium thiosulphate on the rate of this reaction is investigated. Prediction: I predict that as the concentration of sodium thiosulphate, (Na2S2O3) in MoLdm-3 increases it will take a shorter time for the sulphur precipitate to form. Thus: * The higher the concentration, the faster the rate of reaction. This is also vice-versa, * The lower the concentration the slower the rate of reaction. Background Information: Collision theory: If solutions of reacting particles are made more concentrated there are more particles per unit volume. Collisions between reacting particles are therefore more likely to occur. Also, When the temperature is increased the particles will have more energy and thus move faster. Therefore they will collide more often and with more energy. Particles with more energy are more likely to overcome the activation energy barrier to reaction and thus react successfully. If solutions of reacting particles are made more concentrated there are

• Word count: 2645
• Level: GCSE
• Subject: Science

#### "An investigation to find out the optimum temperature for the activity of Lipase".

"AN INVESTIGATION TO FIND OUT THE OPTIMUM TEMPERATURE FOR THE ACTIVITY OF LIPASE" * AIM To investigate the effect of temperature has on enzyme activity and the hypothesis that there is an optimum temperature for the activity of the enzyme lipase. * INTRODUCTION Enzymes are catalysts made up are protein molecules, usually with a globular structure. They accelerate chemical reactions in organisms that would otherwise occur to slow. (Green, Stout, Taylor, 1991) Lipase is a digestive pancreatic enzyme which works to hydrolyses fats into glycerol and fatty acids. (Simpkins, Williams, 1987) These products will react with the Sodium Carbonate (put into the mixture to raise the pH) and in effect lower the pH level towards a more acidic content. This pH change can be observed by using the indicator Phenolphthalein, which changes from a pink colour to colourless at a pH below 8.3. * HYPOTHESIS Lipase is an enzyme found in the human body and from knowledge of human enzymes I expect the optimum temperature to be around 40°C. I also expect that at low or high temperatures the rate of reaction will be slowest. * METHOD MATERIALS USED: Electric Kettle, 100ml Beaker, 10 Boiling tubes, 2 Boiling tube racks, Milk, Sodium Carbonate, Phenolphthalein, Spirit Thermometer, 5% Lipase. PROCEDURE: STEP 1: We mixed 5cm³ of milk with 7cm³ of Sodium Carbonate and added 6 drops of

• Word count: 1094
• Level: GCSE
• Subject: Science

#### Rates of Reaction between hydrochloric acid and marble chips

GCSE Coursework Science Rates of Reaction Chantal du Thoit Candidate Number: 0002 01/08/2005 Table of Contents ) Planning 2 a) What I'm going to do. 2 b) Scientific factors and theorems that affect my plan. 3 c) Apparatus I'm going to use. 4 d) Preliminary Work 5 e) Graph to show figure 1 results 7 f) Prediction 8 2) Method 9 3) Results 10 4) Evaluation 12 5) Conclusion 13 ) Planning a) What I'm going to do. I am going to investigate the rate of reaction between hydrochloric acid and marble chips. I am going to measure 5g of different sized Marble Chips and six different concentrations of Hydrochloric Acid. I will then put the chips into each concentration. They will then react to produce carbon dioxide and water. It is at this point when I start timing how long it takes for the water in the 50cm3 cylinder to be replaced by a gas. b) Scientific factors and theorems that affect my plan. I read a book 'GCSE Chemistry' that states that reaction rates are explained perfectly by Collision Theory - the more collisions there are the higher the rate of reaction. I also read an Internet article that can be found at www.gcsescience.com. It stated that a chemical reaction could only occur between particles that collide (hit each other). Particles could be atoms, ions or molecules. In order for the particles to react with each other, they need to have a

• Word count: 2029
• Level: GCSE
• Subject: Science

#### sodium thiosulphate

Investigation: How does the concentration of the acid affect the rate of reaction? The aim of this investigation is to test how concentration affects the rate of reaction. My prediction for my investigation is that the higher the concentration, the faster the reaction will be. My reason behind my prediction is: * The higher the concentration, the more particles there are which will collide with enough energy to overcome activation energy, which is explained as the collision theory. Collision theory explains how chemical reactions occur and why rates of reaction differ. For a reaction to occur, particles must collide. If the collision causes a chemical change it is referred to as a fruitful collision. For a reaction to occur, the reactant particles must collide. Only a certain fraction of the total collisions cause chemical change; these are called successful collisions. The successful collisions have activation energy at the moment of impact to break existing bonds and form new bonds, resulting in the products of the reaction. Increasing the concentration of the reactants and raising the temperature bring about more collisions and therefore more successful collisions, increasing the rate of reaction. When a catalyst undergoes collision with the reactant molecules, less energy is required for the chemical change to take place, and hence more collisions have sufficient

• Word count: 1754
• Level: GCSE
• Subject: Science