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Meaning Of Rate Of Reaction<br />MEASUREMENT OF RATES OF REACTION:<br /><ul><li>Plot graph of quantity of product / </li></ul>reactant against time<br /><ul><li>Calculate the average rate of reaction
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Calculate the rate of reaction at the specific time from the graph.</li></ul>EXPLANATION FOR THE RATE OF REACTION BASED ON COLLISION THEORY:<br /><ul><li>Particle Size
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Experiment On Effect Of Catalyst</li></ul>Is proven by<br />
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How KFC can cook Fried chicken in quickly?<br />
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Application of The Rate Of reaction In daily Activities<br />
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Observable changes in quantity that use to determine rate of reaction<br />Meaning rate of reaction<br />Unit for rate of reaction<br />Avarage rate of reaction<br />Measurement <br />Rate Of Reaction<br />Rate Of reaction at specific time<br />Factors that affect rate of reaction<br />Rate Of Reaction<br />
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Reaction Types<br />2<br />1<br />Chemical<br />Bonds are made / broken<br /> Change in oxidation states<br /> Plasma<br />Li<br />+1<br />P+1<br />P+1<br />
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Chemical properties/ changes/ reactions (i.e., reactivity, combustibility).<br /> development of a gas, formation of precipitate, and change in color).<br />Reactivity<br />Combustibility<br />Gas formation <br />Precipitate<br />Color change<br />
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The speeds of reactions are very varied<br /><ul><li>Rusting is a ‘slow’ reaction, you hardly see any change looking at it!
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The weathering of rocks is an extremely very slow reaction. </li></ul>weathering of rocks <br />
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The fermentation of sugar to alcohol is quite slow but you can see the carbon dioxide bubbles forming in the 'froth' in a laboratory experiment or beer making in industry! <br />Bubble gas<br />
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<ul><li>A faster reaction example is magnesium reacting with hydrochloric acid to form magnesium chloride and hydrogenor the even faster reaction between sodium and water to form sodium hydroxide.
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Combustion reactions e.g. when a fuel burns in air or oxygen, is a very fast reaction.</li></li></ul><li>Combustibility<br />The tendency to react with Oxygen, releasing heat.<br />O2 <br />BURNING<br />
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evidence of Chemical Change:<br />development of a gas<br /> formation of precipitate<br /> change in color<br />
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Meaning Of Rate Of Reactions<br />The rate of reaction is a measurement of the change in the quantity of reactant or product against time: <br />Rate Of Reaction= Change in quantity of reactant / product <br />Time taken<br />Student ans: Changes of reactant or product against time (0 Mark)<br />
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Meaning Of Rate Of Reaction<br />A rate of reaction is high if the reaction occurs fast within a short period of time..<br />A rate of reaction is low if the reaction occurs slowly within a long period of time..<br />A rate of reaction is inversely proportional to time: <br /> Rate of reaction α 1<br /> time taken<br />
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Meaning Of Rate Of Reactions<br />The Higher rate of reaction the shorter time taken to complete the reaction<br />The lower rate of reaction the longer time taken to complete reaction<br />granule<br />powder<br />5 minute <br />1 minute <br />Which is the higher rate of reaction?<br />
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CaCO3 (s) + 2HCl (aq) -> CaCl2 (aq) + H2O + CO2 (g)<br />
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CaCO3 (s) + 2HCl (aq) -> CaCl2 (aq) + H2O + CO2 (g)<br />
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Observable changes<br />The change in amount of reactant / product that can be measured :<br /><ul><li>Decrease in total quantity of mass / concentration of the reactant per unit of time.
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Increase in total amount of mass / concentration of the product of reaction per unit of time
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Formation of precipitate.</li></li></ul><li>Decrease in total quantity of mass / concentration of the reactant per unit of time.<br />
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Increase in total amount of mass / concentration of the product of reaction per unit of time <br />
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Total volume of the gas released.<br />CaCO3 (s) + 2HCl (aq) -> CaCl2 (aq) + H2O + CO2 (g)<br />Deliverytube<br />Conical flask<br />burette<br />water<br />Must shade!<br />
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Formation of precipitate.<br />Na2SO3+2HCl->NaCl+S+SO2+H20<br />PERCIPITATE<br />stopwatch<br />
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Precipitatethe formation of insoluble ionic compounds.<br />Does NOT dissolve in water.<br />
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Example:Study the reaction: Between calcium carbonate and excess 1 mol dm-3 hydrochloride acid.CaCO3 (s) + 2HCl (aq) -> CaCl2 (aq) + H2O + CO2 (g)<br />
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CaCO3 (s) + 2HCl (aq) -> CaCl2 (aq) + H2O + CO2 (g)<br />
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Observable changes<br />CaCO3 (s) + 2HCl (aq) -> CaCl2 (aq) + H2O + CO2 (g)<br />stopwatch<br />
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Observable changes<br />CaCO3 (s) + 2HCl (aq) -> CaCl2 (aq) + H2O + CO2 (g)<br />Hydrometer <br />
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Observable changes<br />CaCO3 (s) + 2HCl (aq) -> CaCl2 (aq) + H2O + CO2 (g)<br />Hydrometer <br />
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Observable changes<br />CaCO3 (s) + 2HCl (aq) -> CaCl2(aq) + H2O + CO2 (g)<br />Displacement Of water<br />
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Remember !!!<br />CaCO3 (s) + 2HCl (aq) -> CaCl2 (aq) + H2O + CO2 (g)<br /><ul><li>Quantities of reactant will decreases against time
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Quantities of product will increases against time</li></li></ul><li>Measurement Rate Of Reaction <br />Two ways to measure rate of reaction.<br />Average Rate Of Reaction. : <br />It is determined by calculating the total amount of reactant used or the total amount of product formed in a specific time.<br />Rate Of Reaction at a specific time :<br />It is determined by calculating the gradient of the graph at the time.<br />
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Introduction to the Rate of Reaction<br />A reaction between small pieces of excess calcium carbonate with 80 cm3 hydrochloric acid 0.05M is conducted a laboratory to study the rate of reaction at interval time. The volume of gas released is recorded in the table below.<br />
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(e)<br />A reaction between small pieces of excess calcium carbonate with 80 cm3hydrochloric acid 0.05M is conducted a laboratory to study the rate of reaction at interval time.<br />Number of mole in the solution will use :<br />MV<br />Mol, n <br />=<br />1000<br />0.05(80)<br />=<br />1000<br />=<br />0.004 mol<br />
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(f)<br />CaCO3 + 2HCl -> CaCl2 + H2O + CO2<br />From the chemical equation :<br />Mole Ratios:<br />2 mol HCl : 1 mol CO2<br />0.004 mol HCl<br />:<br />0.004 mol HCl<br />×<br />1 mol CO2<br />2 mol HCl<br />=<br />0.002 mol CO2<br />Volume of gas Co2 at room condition<br />=<br />0.002×24 <br />0.048 dm3<br />=<br />
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(g)<br />Because some of carbon dioxide gas can escape to surrounding during the experiment.<br />
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Volume of CO2, cm3<br />Connect the point without using ruler!<br />Not all the point is connected<br />Time , s<br />
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Volume of CO2 cm3<br />Cannot like this graph<br />Straight line<br />It’s must be smooth graph<br />Time s<br />
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(i)<br />Average Rate Of reaction<br />The average rate of reaction in the first 90 seconds.<br />= The total volume of gas released in the first 90 seconds<br /> Time taken<br />33.5÷90=0.372 cm3s-1<br />unit<br />= <br />Not cm3 per second<br />
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i(ii)<br />The average rate of reaction in the whole experiment.<br />= The total volume of gas released in the whole experiment<br /> Time taken<br />47.5÷180= 0.264cm3s-1<br />=<br />
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(h)<br />Volume of gas against time<br />y<br />x<br />α<br />How to fit your scale in graph?<br />For y: use ratio 5: 10 <br />Check it’s enough by 5÷10=0.5<br />Maximum volume 47.5÷0.5=95 small boxes <br />How about x:?<br />30÷10=3<br />Maximum 240÷3=80small boxes<br />
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Analysis of Data<br />Rate of reaction at t second = gradient AB<br /> = p/q cm3 s-1<br />Total volume of Hydrogen gas/cm3<br />Tangent is a line that touch just 1 point of graph in order to calculate gradient<br />B<br />Tangent <br />p<br />A<br />q<br />Cannot take directly at x<br />t<br />Time (second)<br />
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Tangent <br />Cannot touch more than 2 point because each of point have different gradient<br />Only touch 1 point of curve<br />
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Analysis of data<br />Total Volume of CO2(cm3)<br />F<br />D<br />E<br />Rate of reaction at t1 = gradient AB<br />B<br />Rate of reaction at t2 = gradient CD<br />C<br />Rate of reaction at t3 = gradient EF<br />Each of point have different gradient!<br />A<br />t1<br />t3<br />t2<br />Time (second)<br />
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Two method to calculate tangent:<br />Total volume of Hydrogen gas/cm3<br />number of small boxes ×value of <br />1 small unit box<br />B<br />Tangent <br />Y<br />A<br />X<br />Time (second)<br />
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First Method<br />Gradient of graph:<br />Total volume of Hydrogen gas/cm3<br />m = ΔY<br />ΔX<br />B<br />m = Y2-y1<br />y2<br />X2-x1<br />Tangent <br />A<br />y1<br />Time (second)<br />x1<br />x2<br />
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Analysis of Data<br />Rate of reaction at t second = gradient AB<br /> = p/q cm3 s-1<br />Total volume of Hydrogen gas/cm3<br />B<br />Tangent <br />p<br />A<br />q<br />t<br />Time (second)<br />
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Analysis of data<br />Total Volume of CO2(cm3)<br />F<br />D<br />E<br />Rate of reaction at t1 = gradient AB<br />B<br />Rate of reaction at t2 = gradient CD<br />C<br />Rate of reaction at t3 = gradient EF<br />A<br />t1<br />t3<br />t2<br />Time (second)<br />
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From the answer of question (i) (iii) and (i) (iv), <br />make a conclusion from the <br />calculation of this experiment.<br />(j)<br />Ans : Rate of reaction will decreases<br />
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(k)<br />Explain why does there is a difference of the rate <br />of reaction at 30 second and 120 second. <br />Ans: Rate of reaction at 30 second is higher because number of particles of reactant is higher than 120 second<br />
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(l)<br />In your opinion, what will happen to the rate of reaction if, <br /><ul><li>The concentration of acid is increased.
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A calcium carbonate powder is used in this </li></ul>experiment.<br /><ul><li>The volume of acid is increased.
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