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GCSE: Patterns of Behaviour
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Type of nucleation observed Spherulites are recognized by their characteristic appearance in the polarizing microscope, where they are seen as circular birefringrent areas possessing a dark Maltese cross pattern. Spherulite thus appears to represent the crystalline portion of the sample, growing as the expense of the non-crystalline melt. The point of initiation of spherulite growth, its nucleus, was arises spontaneously in the melt that means nucleation is homogeneous nucleation. 4. Sample melted for 10 minutes before crystallization The melting of the perfectly crystalline substance is an equilibrium process characterized by a marked volume changed and well defined temperature.
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of it, the ratio of r:h remains fixed, so As we are only interested in the rate of change of the height we need to eliminate r so use r = 3h/10 for all levels So the new V = so to find h3 = and h = So making a table to find for t= 0 to 25 and hence work out roughly how long the cone takes to fill up, and the height value at each stage and also radius each time.
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My aim is to see how the concentration affects the rate of reaction by measuring the amount of gas produced when reacting with limestone [caco3] with hydrochloric acid [hcl] of differing concentrations.
Explanation I think this because in lower concentrations there are less acid molecules to attack the limestone, whereas in higher concentration the more chance there is of a collision which means the rate of reaction speeds up. Equipment In my experiment I will use the following equipment: Conical flask, Delivery tube, Gas syringe, Water basin, Goggles, Stopwatch, 15x of 5g caco3 chips, 3x 20ml of 20% hcl, 3x 20ml of acid.
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Aim: To find out how much the concentration affects the reaction below. Thiosulphate ions + Hydrogen ions Sulphur dioxide + water + Sulphur
Catalysts 3) Concentration 4) Surface Area I will need to measure the following items in my investigation. 1) The amount of sodium Thiosulphate 2) The amount of water 3) The amount of acid I believe this experiment will work because we have already done a preliminary experiment to check that this investigation will produce results for us to produce a table of results which we can analysis and form and evaluation from. In the preliminary investigation we added a small amount of sulphuric acid to a solution of Thiosulphate the reaction that occurred was that the solution changed from a colourless clear mixture to a cloudy yellow solution approximately five seconds after we added the acid this showed that the experiment works and you can get results from it.
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However, catalysts can become physically damaged, for example the surface of the catalyst can crumble. Only small amounts of catalysts are needed in a reaction, as they are being re-used. Catalysts only affect the rate of the reaction, not the amount of product formed. Catalysts usually speed up chemical reactions; however some catalysts slow down reactions and these are called inhibitors, or negative catalysts. Catalysts are usually specific for one type of reaction, as are biological catalysts (enzymes). Catalysts can be added to cars (catalytic converters)
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In this Investigation, I am going to investigate the effects of concentration on the rates of reaction between magnesium and hydrochloric acid.
If the temperature is decreased then the reaction will decelerate because less heat makes particles move slower therefore this leads to the average kinetic (movement) energy of the particles to decrease. As a result, the particles collide with each other less frequently and hit each other less hard, this causes fewer bonds to break and new ones to be formed at a slower rate. Concentration allows us to see how much of a particle is in a given volume, so an increase in concentration leads to an increase in the rate of reaction because there are more particles in a
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An investigation into the effect of diffusion on the size of a cellWhat I am going to do is place some agar phenolphthalein in a HCl solution and time until the cubes go clear.
The rate of diffusion is dependant on a number of factors- * Particles will diffuse quicker when there is a high concentration gradient. * A short distance fro particles to diffuse across. * If the substance is small molecules they will diffuse quicker. * Larger surface area increases rate of diffusion. For if there is larger surface area then it allows particles to diffuse faster as there is less resistance. The last one is the key one, as this one plus knowing the concentrations of the solutions allows you to work out the rate of diffusion by Ficks law.
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How does the concentration affect the rate of reaction between sodium thiosulphate and hydrochloric acid
* Record the results and repeat x5. Repeat for 0.5m and 1.0m. How to make up the different concentrations of hydrochloric acid. Apparatus Conical flask 6 beakers Clamp stand Burette Stop clocks Sodium Thiosulphate Different concentrations of HCI acid. Table 2 Concentration of acid (M) Volume of water (ml) Volume of HCI acid (ml) 1 0 100 0.8 20 80 0.6 40 60 0.4 60 40 0.2 80 20 What is a reaction? A reaction occurs when two reactants successfully react together to form a new product.
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Our assignment was to produce a piece of coursework investigating the rates of reaction, and the effect different changes have on them.
Aim: - To see the effects of a change in concentration on the rate of a reaction. Sodium Thiosulphate + Hydrochloric Acid = Sodium +water + sulphur dioxide Na( S( 0( + 2HCl = 2Nacl +H(O + So( We will be varying the concentration (while keeping everything else constant). Both the sodium Thiosulphate and the Hydrochloric acid are soluble in water, so the concentration of either can be changed. However I have chosen to vary the sodium Thiosulphate as it is available in larger amounts, and various concentrations are prepared.
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An investigation to determine the effect of concentration of protease, trypsin has on the rate of digestion of protein.
It is also because the particles collide more often, so there is a bigger chance of collision. However, I am aware that enzyme can be denatured if temperature is too high. Enzymes work best at their optimum temperature, for human enzymes, this is around 37�C. I do not want the temperature to be so low that the reaction would be very slow, nor do I want the temperature to be so high that trypsin I used would be de-natured. Therefore I decide to set the temperature at 35�C. Temperature will be kept constant by the water in the beaker(temperature of water needs to be maintained at 35�C).
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Beaker * Safety goggles Safety Follow all the rules on safety while performing an experiment in the laboratory for example: * Wear safety goggles at all times * Put all stools away * Never sit down during an experiment Method 1. Measure out 3cm3 of hydrochloric acid. 2. Cut a piece of magnesium to 1cm in length. 3. Measure the temperature of the hydrochloric acid at the start. 4. Pour hydrochloric acid into test tube and add magnesium. 5. Record time taken for magnesium to fully dissolve.
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EXPERIMENT TO INVESTIGATE INTO THE EFFECT OF SURFACE AREA OF A SOLID REACTANT ON THE RATE OF REACTION
At the same time stop clock was started. * The mass was recorded with three particle size samples. APPARATUS/MATERIALS Items/chemicals Quantity Calcium carbonate 2.0g x 3 Hydrochloric acid 20cm� Beaker 3 Measuring cylinder 1 Measuring balance 1 RESULTS Large sample Medium sample Small sample Time in seconds (S) Total mass lost (g) Total mass lost (g) Total mass lost (g) 0 0 0 0 15 0.006 0.033 0.038 30 0.008 0.034 0.039 45 0.013 0.037 0.047 60 0.023 0.041 0.062 90 0.032 0.05 0.093 120 (2 mins) 0.079 0.063 0.123 240 (4 mins) 0.127 0.099 0.212 360 (6 mins)
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Also I use two so that the chemicals do not mix before I conduct the first experiment) * Thermometer (to check the temperature in the beaker) * Timer (to see how long it takes for the rate of reaction to happen) * Tripod (to hold the beaker above the Bunsen burner) * Gauze (to place on top of the tripod to hold the beaker) * I will also use a piece of paper with a cross on it, so I can tell when the reaction has taken place. Methods Firstly I will tuck my tie in so that it doesn't catch anything such as the Bunsen burner flame.
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How the surface area/particle size affects the rate of reaction by measuring the amount of gas produced and weight loss in a reaction between small, medium and large pieces of Marble Chips (Calcium Carbonate) and Hydrochloric
Apparatus that will be used: * Conical flask * Cotton wool * Scales * Measuring cylinder (50ml) * Stopwatch Method * Take one large piece of Calcium Carbonate and record its weight. * Measure 100cm� of hydrochloric acid (using measuring cylinder). * Place the flask on the scales. * Add the marble chip and hydrochloric acid to the conical flask at the same time. * Start the stopwatch. * Record the weight loss (gas given off) every 30 seconds for the 3 minutes of the reaction, then every 1 minute for 2 minute, then every 2 minutes until the reaction stops.
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The aim of this experiment is to determine the rate of reaction of hydrolysis on halogenalkanes. Explanation In this experiment, you compare the rate of hydrolysis of chlorine, bromine and iodine
This is due to the decrease in bond enthalpy as the halogen atom radius increases the bond gets longer and weaker and chlorine is the most electronegative and iodine the least electronegative. Electronegativity is the ability of an atom to inductively pull electrons towards it. The more electronegative an atom, the tighter it pulls the electrons, the higher the electronegativity, the more strongly an atom attracts, and Note electronegativity is the characteristic of an atom to take up electrons from another atom in an attempt to fill its outer shell.
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2HCl(aq) + Na2S2O3(aq) 2NaCl(aq) + SO2(g) + S(s) + H2O(l) Equipment used: Hydrochloric acid Sodium thiosulphate 10cm3 cylinder 100cm3 cylinder 250ml conical flask Stopwatch Thermometer Piece of paper with cross on Goggles Method 1. Mark a cross, (with a fine pen), on a piece of paper. Place on the table. 2. Place a 250ml conical flask on to the cross, (see the cross through the glass). 3. Measure out 50cm3 of sodium thiosulphate in to a 100cm3 cylinder, and pour into the flask. 4. Measure out 5cm3 of hydrochloric acid in a 10cm3 cylinder.
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So this means if the concentration of any reaction in a solution is increased, the rate of reaction is increased too. 3 Surface area- If a solid or a solid catalyst is broken down into smaller pieces the rate of reaction increases. Therefore, there is more chance that a reactant particle will hit the solid surface and react. The increase in speed happens due to the smaller pieces of the same mass of solid have a greater surface area when compared to larger piece of a solid.
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Potato sample that was cut to size was placed into test tube and clamped to retort stand. 4. 10ml of hydrogen peroxide was poured carefully into test tube with potato sample
Control experiment was conducted for comparison of results. Results Size Surface Area (cm ) Volume (cm) Amount of oxygen produced (test1) in ml Amount of oxygen produced (test 2) in ml Control 0 0 0 0 1 cm (whole) 1x1x1=6 1x1x1=6 6 7 1/2 cm (halved) (1x 1/2)x4=6 1x1x2=2 2+6=8 1cm 8 9 1/4 cm (quarters) (1/2x1/2) x2= 1 2.5x4=1 =10 1cm 10 11 Size of cube Group1 (test1) Group 1 (test2) Group 2 Group 3 Group 4 Average Control 0 0 0 0 0 0 1cm (whole)
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In this lab, six different metals were tested for their reactivity in water. From less reactive to most reactive, the metals were as follows: Aluminum, Magnesium, Calcium, Lithium, Sodium, and Potassium
reaction * Pink flames * Loud "crack" before it finished reacting * Sparked * Left oily layer on surface * Pink/purple * Floated on surface Discussion In this lab, six different metals were tested for their reactivity in water. From less reactive to most reactive, the metals were as follows: Aluminum, Magnesium, Calcium, Lithium, Sodium, and Potassium. A pattern found in the periodic table explaining the reactivity of metals is the further down in a family, and the further left in a period, the more reactive the metal will be.
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The number of electrons in outer shell is the same as the number of the group (e.g. lithium 2�1). The blocks of elements between groups II and III are called transition metals. These are similar in many ways; they produce coloured compounds, have variable valency and are often used as catalysts. Elements 58 to 71 are known as rare earth elements. These elements are found on earth in only very small amounts. Elements 90 to 103 are known as the actinide elements. They include most of the will known elements, which are found in nuclear reactions. The elements with larger atomic numbers than 92 do not occur naturally.
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How does changing the concentration of hydrochloric acid alter the rate of its reaction with marble chips
The rate of reaction is increased by three factors . * Higher temperatures Temperature alters the rate of a reaction by supplying the reactant particles with more energy, the more energy the reactants have the faster they move around increasing they're are chance of bumping into one another and having a successful collision * The greater the surface area of the reactants the more particles are available for a successful collision. * Concentration effects the rate of a reaction because the higher the concentration of particles the greater the chance of a successful collision.
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Aim:The main point of this experiment is to find out how the concentration of sodium thiosulphate affects the rate of reaction.
It will also give the most accurate results. Step by Step plan: 1. Mix together 10ml of HCl and a preset amount of sodium thiosulphate solution in a flask and place the piece of paper with a cross on underneath. 2. Time how long it takes for the cross to 'disappear'. Record the results.
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In this experimet, a known starting mass of magnesium and the measured collection of hydrogen gas will be used to determine the reaction stoichiometry. This experiment determines the stoichiometry of a reaction of magnesium and HCl. The relationship between moles of magnesium reacted and moles of hydrogen produced are plotted. Magnesium Ribbon is a strip of Magnesium that is solid at room temperature. When mixed with hydrochloric acid it produces Magnesium Chloride, which is a liquid and Hydrogen gas. The below is the equation that occurs: Mg + XHCl --> MgClx + H2 The known amount of the magnesium is reacted with large excess of HCl , and the volume of H2 is measured.
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To investigate how enzyme concentration can affect the rate of reaction, in this case the breakdown of milk protein by trypsin, a protease enzyme.
Prepare trypsin solutions of different concentrations by mixing trypsin and distilled water together. 2 syringes are used to measure and transfer different volumes of trypsin and distilled water seperately. Label the test tubes: Test tube A - 2cm3 distilled water Test tube B - 0.5cm3 trypsin + 1.5 cm3 distilled water Test tube C - 1cm3 trypsin + 1cm3 distilled water Test tube D - 1.5cm3 trypsin + 0.5cm3 distilled water Test tube E - 2cm3 trypsin 2. Tap the bases of the test tubes to mix the enzyme-water solutions.
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Investigate how the change in concentration affects the rate of reaction between sodium thiosulphate and hydrochloric acid
+ ( aq ) ( aq ) + ( g ) + ( s ) + ( l ) Before I start the investigation, by having preliminary tests I can find a volume of each solution that I can use where I am able to complete the investigation in a reasonable period of time. When I am undergoing my experiment I will be making one variable. By changing the concentration of sodium thiosulphate, this is done by adding water to the solution. As I change the amount of water I put into the solution the concentration of it is changing.
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