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THIS IS ALL ABOUT THE THESIS
TO STUDY THE EFFECT OF CONCERTRATION ON THE RATE OF REACTION BETWEEN SODIUM THIOSULPHATE AND HCL
Aim: To investigate how the rate of reaction between Sodium Sodi um Thiosulphate and Hydrochloric acid is affected by changing the concentration.
Background: THE REACTI!" when Sodium Thiosulphate reacts with hydrochloric acid sulphur is produced. The sulphur forms in very small particles and causes the solution to cloud over and turn a yellow colour. This causes the cross to fade and eventually disappear.
RE%ICTI!" As As the concentration of Sodium Thiosulphate increases the length of time for cross to disappear decreases
+inverse-. This is because the increase of concentration of Sodium Thiosulphate will increase the rate of reaction between Hydrochloric acid and sodium Thiosulphate particles.
SCIE!TI/IC REAS!S /R RE%ICTI!" the results from preliminary e&periments support the prediction made. /rom the results you can see that there is a directly proportional relationship between the concentration and the rate of reaction. If you increase the concentration then the rate of reaction will also increase. METHOD:
0. Set up apparatus as in preliminary e&periment. (. Record the temperature of the room. ). Add the first of the concentrations of sodium Thiosulphate to the flas1. As you add 02cm) of HC* and start the stopwatch 3. 'atch the solution as it clouds over. nce the cross has disappeared stop the cloc1. 4. Record the time in a results table 5. Repeat the above steps for the other concentration of sodium Thiosulphate. Repeat the e&periment ) times for each of the concentrations. 6. Record all results in a table and wor1 out the rate by dividing 0 by the average time for each. This e&tract was ta1en from the lin1 below"
7The Rate of Reaction 8etween Sodium Thiosulphate and Hydrochloric Acid.7 This e&periment is testing how the rate of reaction is affected when concentration is changed. The theory is said that increasing the concentration can increase the rate of reaction by
increasing
the
rate
of
molecular
collisions.
The
phenomenon behind all of this is the collision theory and how it plays a big role in this investigation. The higher the concentration the less time9faster it will ta1e for the system to turn into e,uilibrium: and if concentration id decreased: time ta1en for the solution to go cloudy increases. Hypothesis: The higher the concentration the faster the rate of reaction will be and the time ta1en to reach e,uilibrium will decrease. A more diluted concentration will have a longer rate of reaction and a longer time to reach e,uilibrium. Method: ;athered all the apparatus needed for the e&periment. of water. 'e mi&ed the solution until all the crystals were dissolved. Then you pour 42 cm>: 32 cm>: )2 cm>: (2 cm>: and 02 cm> of the solution into five identical conical flas1s. Then you add water to the other conical flas1s so that the total volume in each flas1 in 42 cm>. ?a1e sure to label the flas1s so you 1now which one has so much concentration.
nce that@s done: you must now ta1e a bea1er and add )4 cm> of concentrated Hydrochloric acid to 54 cm> of water to ma1e a diluted solution. !ow ta1e a piece of paper and draw a blac1 cross on it: and then place one of the flas1s on the paper +do one flas1 at a time-. of the hydrochloric solution: and add this to the flas1. Immediately stir the flas1 and start the stop watch. ne person should do this part. As soon as you can@t see the cross anymore stop the stopwatch: and record the results in a table. Repeat this with all the flas1s. Results: Concentration (cm³)
Time (s)
Rate of reaction (s)
50
24.9
0.04
40 + water
32
0.0313
30 + water
42.2
0.0237
20 + water
74.07
0.0135
10 + water
202.8
0.0049
The rate of reaction is measured by dividing 0 by the time ta1en for the reaction to ta1e place. !umber of moles of sulphur used" n m9? n =9)( 2.(4 mols
Discussion: Bou can see from the graph that as concentration increases: the time ta1en for the solution to go cloudy decreases. So the stronger the concentration the faster the rate of reaction is. As the concentration of sodium Thiosulphate decrease the time ta1en for the cross to disappear increases: this is an inverse relationship.'hen e,uilibrium was reached the solutions turned a yellow color: the stronger the concentration was the higher the turbidity was. 'hen e,uilibrium was reached S( gas and water were released. The more concentrated solution has more molecules: which more collision will occur. So therefore the rate of reaction should depend on how fre,uently the molecules collide: so more molecules have greater collisions and the reaction happens faster as more products are made in a shorter time. All related to the collision theory. 'hat we saw what happened was e&actly what we e&pected from the e&periment. ur predictions were accurate. Evaluation: The method we used was fairly accurate: our results weren@t perfect but they were good enough for us to see what happens during the e&periment. So overall the results proved the hypothesis and I was able to draw graphs with a line of best fit. In our e&periment we 1eep the HC* a constant: and also
1eeping the volume of the solution was important to get more accurate results. The results were fairly reliable under our conditions. They could be a bit off from bad measuring: unclean e,uipment and the timing. Conclusion: 'hen the concentration of Sodium thiosulphate was increased the rate of reaction increased and the time ta1en to reach e,uilibrium decreased: so therefore the rate of reaction is directly proportional to the concentration. Bibliography:
"The Rate of Reaction Between Sodium Thiou!hate and #$droch!oric %cid."
Abstract The purpose of this lab is to identify the un1nown salts using the change in temperature to calculate heat realeased. 'ith the given ,D values for all three identiies of the un1nowns: one can compare the calculated heat of the reaction to the given value to identify the salt. The un1nowns chosen were un1nown CD for trials 0 and (: and un1nwon AD for trials ) and 3. The initial temperature was ta1en before the salt was added: and after the salt had dissolved for 02 minutes in )2 second intervals.
Calculations To calculate the heat released by reaction"
Conclusion
In conclusion: this e&periment was a success in showing the different amounts of heat released based on the type of salt added to the water. As the salt crystals dissolved in the water: it released energy from the bonds brea1ing: which contributed to the temperature raising based on what type of salt was added. Table salt only changed the temperature of the water slightly: while the *iCl caused the temperature of the water to Jump: then slowly decrease. The overal temperature change was 6.F degrees: versus a cooldown of .3 degrees for the !aCl. As far as errors are concerned: the measurements may have been ta1en before the salt was completely disolved: casuing the temperature to change. To combat this error: one might need to employ a different method of stirring to ma1e sure everything is disolved.
Preparation of soya ean !i"#
Aim" reparation of soya bean mil1 and its comparison with the natural
mil1
with
respect
to
curd
formation: effect
of
temperature and taste.
Theory: !atural mil1 is an opa,ue white fluid secreted by the mammary glands of female mammal . The
main constituents
of natural
mil1 are
proteins:
carbohydrates: minerals: vitamins: fats and water and are a complete balanced diet. &resh milk is s,eetish in taste However: when it is 1ept for a long time at a temperature of )4 K 42C it becomes sour because of bacteria present in air. These bacteria convert lactose of mil1 starts separating out as a precipitate. 'hen the acidity in mil1 is sufficient and temperature is around )52C: it forms semiGsolid mass: called curd. Soya bean mil1 is made from soya beans. !t resembles natural milkThe main constituents of soya bean mil1 are proteins: carbohydrates: fats: minerals and vitamins. It is prepared by 1eeping soya beans dipped in water for sometime.
The swollen soya beans are then crushed to a paste which is then mi&ed with water. The solution is filtered and filtrate is soya bean mil1 - Materials re.uired: 8ea1ers: pestle and mortar: measuring cylinder: glassGrod: tripodGstand: thermometer: muslin cloth: burner . Soya beans: buffalo mil1: fresh curd: distilled water - #rocedure: Soa1 about 022 g of soya beans in sufficient amount of water for (3 hours. Ta1e out swollen soya beans and grind them to a very fine paste with a pestleGmortar. Add about (42 ml of water to this paste and filter it through a muslin cloth. Clear white filtrate is soya bean mil1. Compare its taste with buffalo mil1. Ta1e 42 ml of buffalo mil1 in three bea1ers and heat the bea1ers to )22: 322 and 422 C respectively . Add spoonful curd to each of the bea1ers and leave the bea1ers undisturbed for = hours and curd is ready. Similarly: ta1e 42 ml of soya bean mil1 in three other bea1ers
and heat the bea1ers to )22:322 and 422 C respectively. Add 0 spoonful curd to each of these bea1ers 3 undisturbed for = hours and curd is formed.
