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Rates of reaction Plan Aim: In this experiment I will find the rate of reaction between Sodium thiosulphate NaS2o3 and Hydrochloric acid HCl. There are different variables I could use to see the change in the rate of reaction. These include temperature, concentration or catalysts. I will investigate how temperature affects the rate of reaction between Sodium thiosulphate and Hydrochloric acid. Prediction When sodium thiosulphate and hydrochloric acid react they produce a cloudy precipitate. The two chemicals are both clear solutions and will react together to form a yellow precipitate of sulphur, the equation for which is as follows: NaS2O3 aq+ HCll¨Sg+NaCls+ H2Ol+SO2s As the solution will turn cloudy, we can observe the rate of reaction by placing a black cross underneath the beaker and seeing how long it takes for it to disappear. There are factors that affect this experiment such as temperature, concentration and time. I do not think that surface area will affect the experiment, as both chemicals are liquids. For my experiment I will study temperature as this is easily observed and can be easily varied. I think that as the temperature of sodium thiosulphate increases, the amount of time taken for a reaction decreases. I know this because before two particles can react they must meet. The higher the temperature there is the more successful collisions between other particles is increased. When temperature increases the bonds in NaS2O3 break quicker because more energy is available greater than the activation energy of the reaction. As a result S2O3 2- ions are available so it takes less time to bond with H+ ions from HCL and new bonds are formed quicker and therefore sulphur precipitates quicker and the rate of reaction increases. S2o3 2- aq +2H+ aq S02aq+Sg+H2Ol When the temperature increases it causes an increase in kinetic energy so you have more chances of successful collisions between NaS2O3 particles and HCl particles so the rate of reaction increases. Also more activation energy is made available to overcome the activation energy of the reaction; the reactants have greater energy than the activation energy, so the reaction takes place quicker. I will keep the concentration of NaS2O3 constant to prevent more successful collisions as there would be more particles available if a higher concentration is fed which will increase successful collisions. I will also keep the concentration of HCl constant as an increase or decrease in concentration will affect the rate of reaction. I will change the temperature of NaS2O3 so I can see how the temperature affects the rate of reaction. I will keep the temperature of the HCl acid at room temperature as we are only concentrating on the NaS2O3 and if we heat the HCl it might affect the rate of reaction it would not be a fair test if we heat the HCl when we are observing how NaS2O3. I also predict that every time the temperature increases by 10oC the rate of reaction doubles. The preliminary results Time on heat sec Temperature of NaS2O3 0C Time taken for cross to disappear sec 0 24 60 10 34 52 Method For the preliminary experiment I heated the NaS2O3 to get it to the temperature I wanted but it was difficult to get the NaS2O3 to the right temperature so the results were not as accurate, but for my real experiment I will use a water bath to get accurate results instead of a Bunsen burner. For the preliminary experiment I only recorded the temperature of the NaS2O3 but for my real experiment I will record the temperature of the HCl as well to get more accurate results because if the NaS2O3 was high and the HCl could bring the temperature down quicker and also have to make sure all the temperature of the HCl is the same. I will also take the temperature of the mixture so I know the temperature at which the reaction took place. 1. I will set up my apparatus and put an X on a piece of paper and measure out 50ml of NaS2O3 and 10ml of HCl. 2. I will pour the NaS2O3 into a conical flask and measure the temperature and pour the HCl in to the same conical flask and time how long it will take for the cross on the paper to disappear. 3. I will do 4 different temperatures and I will do them three times each to get accurate results. 4. I will record the results in a table of results. Apparatus used Sodium thiosulphate NaS2O3-50ml Hydrochloric acid HCl-1M Conical flaskx2 Measuring cylinderx2 Thermometer Water bath at different temperatures Paper marked with X Stop watch Distilled water Analysis From graph 1 I can see that when temperature increases the time taken for reaction to take place decreased. In graph 2 I can see when temperature increases the rate of reaction increases. There was an anomalous result in graph 2, when the temperature was 480C and 1€time was 1.18. My results agree with my prediction because I predicted that the higher the temperature the lower the time taken for the reaction to take place and we can see this from the graphs. The graph shows this pattern taking place. For my experiment I studied temperature as this is easily observed and can be easily varied. The temperature of sodium thiosulphate increased, and the amount of time taken for a reaction decreased. When temperature increased the bonds in NaS2O3 broke quicker and more energy is available greater than the activation energy of the reaction and S2O3 2- ions are available so it takes less time to bond with H+ ions from HCl and new bonds were formed quicker and therefore sulphur precipitated quicker and the rate of reaction increased. This is why in graph 2, I had a strait line positive correlation graph. When the temperature increased it caused an increase in kinetic energy so we had more successful collisions between NaS2O3 particles and HCl particles and the rate of reaction increased. Also more activation energy was made available to overcome the activation energy of the reaction; the reactants had greater energy than the activation energy, so the reaction took place quicker. I think my results support my prediction because I predicted when temperature increases the rate at which the reaction takes place is faster. In graph 2, the theory that every time the temperature increases by 10oC, the rate of reaction will double did not work in my experiment and the results of that theory is given below: 10"¹C¨0.018 0.024€0.018=1.333 20"¹C¨0.024 0.052€0.024=2.167 30"¹C¨0.052 0.078€0.052=1.500 40"¹C¨0.078 0.086€0.078=1.103 50"¹C¨0.086 0.104€0.086=1.209 60"¹C¨0.104 0.120€0.104=1.154 70"¹C¨0.020 0.1380.120=1.1500 80"¹C¨0.138 Evaluation I think my method worked well as I repeated the experiments three times for five different temperatures and got three results which were similar. I think the experiment worked but when we used NaS2O3 with a high temperature, it was difficult for us to time the reaction as it was more rapid than we had expected. If I had the chance to repeat the experiment I would concentrate on the concentration of the NaS2O3 rather than the temperature as there are a lot of factors which could affect the temperature. I think my experiment was done reasonably well as l got similar results when I repeated them three times. There was one anomalous result in graph 2 and I think there was an anomalous result because the NaS2O3 was at a high temperature and the reactants reacted rapidly that the timing was wrong. I also think this was caused by the open window we worked next to which brought the temperature down quickly. I think my results are fairly reliable and it supports my analysis as I said, when temperature increased the time taken for the reaction to take place decreased. I could try the experiment with different methods and different reactants to get additional knowledge. I could use magnesium instead of Sodium thiosulphate and I could heat the hydrochloric acid instead of heating the NaS2O3 and to make more of a fair test I could make sure all the windows and doors are closed and no cold air comes in.
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Rates of reaction Plan Aim: In this experiment I will find the rate of reaction between Sodium thiosulphate NaS2o3 and Hydrochloric acid HCl. There are different variables I could use to see the change in the rate of reaction. These include temperature, concentration or catalysts. I will investigate how temperature affects the rate of reaction between Sodium thiosulphate and Hydrochloric acid. Prediction When sodium thiosulphate and hydrochloric acid react they produce a cloudy precipitate. The two chemicals are both clear solutions and will react together to form a yellow precipitate of sulphur, the equation for...
worked next to which brought the temperature down quickly. I think my results are fairly reliable and it supports my analysis as I said, when temperature increased the time taken for the reaction to take place decreased.

I could try the experiment with different methods and different reactants to get additional knowledge. I could use magnesium instead of Sodium thiosulphate and I could heat the hydrochloric acid instead of heating the NaS2O3 and to make more of a fair test I could make sure all the windows and doors are closed and no cold air comes in.

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Intro In this experiment I... Intro In this experiment I am going to investigate the reaction of sodium thiosulphate thio and hydrochloric acid. There are four main factors that affect the rate of reaction. Temperature-You would have to have the EXACT temperature. Surface Area particle size - It's hard to do this one as it is a liquid state. Catalysts-Increase the rate of a chemical reaction- Concentration- This is the best way as its fair and a better experiment to do rather than any of the other main factors that affect rate and reaction. I have done a variety of experiments on rates of reactions such as the marble chip and gas syringe experiment which tested the effect on surface area. I have decided that concentration is the best way to measure rates of reaction in this experiment. When sodium thiosulphate reacts with an acid it should go cloudy and I then have to measure how long this reaction takes. In this experiment I am going to investigate the reaction of sodium thiosulphate thio and hydrochloric acid. Hydrochloric Acid Sodium Thiosulphate Sodium Sulphate & Sulphur Na2S2O3 aq Na2 SO3 aq + S s I am going to change the concentration of these experiments, by adding water to the thio to see if this affects the reaction. The total volume of the liquid will stay the same; only the concentration of the thio will vary. Prediction I predict that if I add water to the thio, the reaction will decrease in speed, and this will make the solution less concentrated. It will take longer for the cross to disappear the less concentrated it is. If you half the concentration of thio I think this will double the time of reaction. 2 1 In box number 1. There are fewer particles of acid therefore leading to a less reactive experiment, and in box number 2. There are many more acidic particles more concentration of acid leading to a much more reactive experiment. Collision theory For a reaction to take place, the particles of the substances that are reacting have to collide. If they collide, with enough energy then they will react. The minimum amount of kinetic movement energy that two particles need if they are going to react when they collide is called the activation energy. There are therefore two main ways of increasing the rate of a reaction: Increase the number of collisions The Higher the concentration the more collisions there are the lower the concentration the less collisions there are leading to a less reactive experiment. Increase the amount of movement kinetic energy so that more collisions lead to more reactions. Dilution of Sodium thiosulphate The smallest amount of time shows how fast the reaction took place The Longest amount of time shows how slow the reaction took place * Diagram of Apparatus Safety Issues These are the safety precautions that I have taken during this experiment: To wear Goggles during the pouring of the acids and solutions, as the there's always a risk of getting harmful solutions in your eyes or face. ALWAYS stand and not sit while in contact with acid. Concentrate!!!! When you don't concentrate things go wrong, so put all of your effort into the experiment. Chairs should be tucked in, out the way. All belonging such as bags and books should be cleared away of the experiment. Analysis I've drawn line graphs to show the results of the experiment, it shows that as the concentration is decreased it will take longer for the cross to disappear; this tells me that my prediction was correct. The Graphs Iv drawn are Lines of Best fit graphs as this way is the best way in order to show the results correctly. In my prediction I said that if I add water to the thio, the reaction will decrease in speed, and this will make the solution less concentrated. I said that it will take longer for the cross to disappear the less concentrated it is, I explained that if you half the concentration of thio it will double the time of the reaction. As the more particles there is the more reactive experiment, the fewer particles the less reactive experiment. The more concentrated the quicker the reaction the less concentrated the slower the reaction. When I examine my graphs I can see the same trend and pattern, as each line is best fit. My graphs show a line of best fit, this goes through many of the points of results. The shape is a curve with the largest concentration being 50cm3 and the smallest concentration being 10cm3. In my results the fastest time being"¦"¦"¦"¦"¦"¦"¦ seconds and the slowest time being"¦"¦"¦"¦"¦"¦"¦ seconds on the 1st set. In my quantitative 2nd prediction I said that if I half the concentration the time will double, looking at my results in the 1st experiment I looked at 20cm3 thio & 40cm3 and the times were"¦"¦"¦"¦"¦"¦"¦"¦"¦"¦"¦"¦"¦"¦"¦"¦"¦"¦"¦"¦"¦"¦"¦"¦"¦"¦"¦"¦"¦"¦"¦"¦"¦"¦"¦"¦. Evaluation On my line graph that I drew it shows that some results are odd compared to the other results which I have circled, this may be because of issues with the decontaminated equipment or the wrong measurement of acid and thiosulphate was not the same. Many things went wrong during the experiments and one was; getting the correct amount of solution therefore making it a fair test. Also another thing is that trying to press the STOP button on the stopwatch as sometimes you would press it a few seconds late, and we had to do the experiments again repeatedly to make sure we made the experiments as fair as possible. If I was do to the experiment again I would change a few things, such as I and the few other pupils concentration as we weren't concentrating enough a few times which would ruin the experiment and we would have to do it time and time again. Another point that could also have made the experiment 'unfair' was that the temperature varied which also made a big difference to the experiment as some days it would be colder or hotter than others. There are "¦"¦"¦"¦"¦"¦"¦"¦ anomalous results on my graphs. They are circled on the graphs If there were no odd results present this would either be because; I carried out the experiment VERY carefully and accurately making sure that I got all the measuring accurate. The possible reason for my results could have been because I didn't measure out the concentration accurate enough, or because I was not concentrating enough on what I was actually doing. What I found very difficult Judging whether or not the cross disappeared, because I had a different person judging each time and their opinion would be different to each others opinion. Making sure the stop watch was turned on and off at the right moment in time, because each second is very important and valuable. Measuring out the liquids because it had to be very accurate. What I need to improve Check the temperature does not change too much as this could change the results. If it's hotter the reactions would be faster and we are not measuring temperature we are measuring concentration. Keeping the same measuring cylinder.   

Intro In this experiment I am going to investigate the reaction of sodium thiosulphate thio and hydrochloric acid. There are four main factors that affect the rate of reaction. Temperature-You would have to have the EXACT temperature. Surface Area particle size - It's hard to do this one as...

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HYPOTHESIS We can recognize four... HYPOTHESIS We can recognize four types of substances due to their structure: ionic, metallic, covalent, and molecular. If a given substance has a metallic luster, is malleable and ductile, is a good conductor of heat and electricity, and has high melting and boiling points, than it is supposed to be a giant metallic structure. If a given substance has low melting and boiling points and does not conduct electricity, it surely is a molecular structure. If a given substance is soluble in water and in other polar solvents, if it conducts electricity after being melted or dissolved, and if it has high melting and boiling points, we can predict that it is a giant ionic structure. So we will have to check which of these properties does a given substance have. APARATUS spatula stirring rod open electric circuit batteries, light bulb, electric wire with two dismantled endings two metal plates the first made of copper, the second made of zinc plastic wash bottle test tubes in amount of 4 watch glasses in amount of 5 Bunsen burner test-tube rack porcelain crucible crucible tongs triangle tripod I decided to use separate watch glass for each substance to avoid possible laboratory errors resulting from contamination with the previous one. CHEMICALS substance A "“ white, granulated powder substance E "“ silver nodules, apparent metallic luster substance C "“ tiny, white crystals substance D "“ a bit larger white crystals substance B "“ black powder distilled water SAFETY RULES Be careful while burning substances in a flame! Don't put your hand into water when the electric current flows "“ you can have your skin seriously damaged! Do not touch hot crucible with bare hand, use crucible tongs! PROCEDURE I put a few grams of each substance except for substance E, which I put into a watch glass using a spatula into separate test tubes, placed in a test tube rack. I put a hint of each substance into separate watch glass. I use open electric circuit in order to investigate electric conductivity of each substance in solid state. I pour a few droplets of water into each watch glass using plastic wash bottle. Then I mix each substance with a stirring rod in order to make process of dissolving faster and more effective. I put two metal plates into each watch glass, so they are partly sunk in the water or solution, if it was formed in the manner one ending of the electric wire sticks to the first plate, and the second ending sticks to the second plate, and it is important that plates do not touch each other. Then I observe whether the light bulb is shining. I take a hint of each substance one by one, using a spatula. I put each substance into a porcelain crucible. I put crucible on a triangle placed on a tripod above the Bunsen burner. Then I turn the burner on and wait up to a minute in order to check whether the melting point is low or high. To handle the crucible I use crucible tongs. Note: I carefully clean spatula before using it again and again, I do the same with the stirring rod and porcelain crucible. DATA COLLECTION A B C D E Conductivity in solid state - + - - + Conductivity after being dissolved - - + - - Solubility in water + - + - - Melting point low high high high high CONCLUSION Substance A is soft and granulated. This substance has low melting point, what indicates that the intermolecular forces are weak. It does not conduct electricity, because molecules are not charged. So substance A has undoubtedly molecular covalent structure. However, on contrary to other substances with molecular covalent structure, it is quite soluble in water, what means that its' molecules can form hydrogen bonds to the water to compensate for the water-water hydrogen bonds broken. Example of such molecules are sugar molecules, so this substance is probably sucrose. In the case of the substance E there is an apparent metallic luster, so it has the giant metallic structure. This metal has high melting point, because it takes a lot of energy to break up a lattice of ions in a sea of electrons with strong forces of attraction, called metallic bonds, between them. Metals are good conductors of electricity because the delocalized, free electrons can move through the lattice carrying charge, when a voltage is applied across the metal structure. The substance C is the only substance aqua solution of which conducts electricity, so it has to have giant ionic structure. It's because the water molecules, which are dipoles, can attract the ions away from the lattice. The ions move freely, surrounded by water molecules. Dissolved or melted ionic compound conducts electricity, because the lattice breaks up and the ions are free to move as charged particles. It can be assumed that substance D is a giant covalent structure, because it is insoluble, it is very hard, but brittle, it forms crystal lattice, and it has high melting point. In addition, this substance does not conduct electricity at all. Substance B is soft and brittle in touch - the sheets can slide over each other easily. It may indicate that this substance has a molecular structure, like the first one. But it has much higher melting point than molecular substances. Besides that, it conducts electricity in solid state, and it does not dissolve in water. This set of properties is very specific "“ it is a combination of single properties of different types of structures. The fact that this substance could well be used as a lubricant layers are easily rubbed off could indicate that this substance can be graphite. EVALUATION After an experiment was finished, our chemistry teacher wrote the names of substances that we were to determine structures of, on the blackboard, so we could verify if our findings were correct and propose improvements to the method in case they were not. And so: substance A appeared to be glucose, substance B "“ graphite, substance C "“ sodium chloride, substance D "“ silicon dioxide, and substance E "“ chromium metal. My predictions according to substance A appeared to be correct. In case of substance E, which is chromium metal, I also obtained correct results. I think that this substance, like it is in case of all metallic substances, has a structure very easy to determine experimentally, even, to say, with bare eye, because we know that metals are the only type of substances that perform a property called metallic luster. Other properties I observed also form a set of properties typical for metal, which is chromium in this case. I was right in case of substance C, which, as it appeared later, is sodium chloride, and sodium chloride is the most characteristic representative of ionic substances. My assumptions relating to substance D are also proved to be correct, since I know now that this substance was silicon dioxide, commonly occurring as quartz, being a good exemplification of properties connected with a giant covalent structure. In case of substance B, I was again right, due to the fact that this substance appeared to be graphite, as I have predicted. Graphite is another example of giant covalent structure, but, on contrary to silicon dioxide, it conducts electricity "“ this property is specific only for this particular substance.   

HYPOTHESIS We can recognize four types of substances due to their structure: ionic, metallic, covalent, and molecular. If a given substance has a metallic luster, is malleable and ductile, is a good conductor of heat and electricity, and has high melting and boiling points, than it is supposed to...

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