Concentration Of Sodium Thiosulphate Biology Essay

Purpose: To look into how the rate of reaction between hydrochloric acid ( HCI ) and sodium thiosulphate ( Na2S2O3 ) is affected by the concentration of Na thiosulphate.

Prediction: I predict that as the concentration of Na thiosulphate doubles, the rate of reaction will duplicate. This is because if you double the figure of atoms you will besides duplicate the sum of successful hits.

Sodium thiosulphate + hydrochloric acid i‚® sulfur + Na chloride + sulfur dioxide + H2O

Na2S2O3 ( aq ) 2HCl ( aq ) S ( s ) 2NaCl ( aq ) SO2 ( g ) H2O ( cubic decimeter )

Theory: By increasing the concentration of Na2S2O3, you will besides increase the rate of reaction between HCI and Na2S2O3. This is because the more atoms there are the faster the reaction will take topographic point since there is a greater opportunity of a Na thiosulphate atom hitting a hydrochloric acid atom.

File: Molecular-collisions.jpg

Collision Theory: The hit theory describes how chemical reactions take topographic point and why rates of reaction alteration. The theory states that for a reaction to take topographic point the reactant particles must clash. It besides states merely a certain part of the entire hits cause chemical alteration ; these are called successful hits. The successful hits have adequate energy ( activation energy ) at the minute of impact to interrupt the bing bonds and organize new bonds, ensuing in the merchandises of the reaction. Increasing the concentration of the reactants and increasing the temperature causes more hits and hence more successful hits which increases the rate of reaction.

hypertext transfer protocol: //upload.wikimedia.org/wikipedia/commons/4/41/Molecular-collisions.jpg

Variables:

Volume of Na thiosulphate – usage a measurement cylinder or burette

Volume of distilled H2O – usage a measurement cylinder or burette

Volume of HCL- usage a measurement cylinder or burette

Concentration of Na thiosulphate -.by thining the sum of Na thiosulphate with the same sum of H2O each clip.

Temperature of room – this is because if the room is hot the faster the reaction will be and if the room is cold the reaction between HCl and Na2S2O3 will be slow.

Person watching – this is because both spouses oculus sight are non precisely the same so while one will see the cross, the other might non.

Height of oculus from conelike – this is because the closer your oculus is to the flask, the more opportunity you have of seeing the cross. Whereas if your oculus is farther off from the flask, the more opportunity of you non seeing the cross.

Type of mensurating equipment used – whether you choose to utilize a measurement cylinder for larger or smaller sums or possibly a burette for the sums in the experiment.

Concentration of HCl – by thining the sum of HCl with the same sum of H2O each clip.

Safety:

Wear goggles at all times to protect your eyes from any chemicals.

Wear baseball mitts to protect your custodies from any acerb spillage.

Wear an apron to protect your tegument and apparels.

Keep bags, coats and any other objects unrelated to the experiment out of site.

Do non eat or imbibe in the lab.

Before get downing work in lab, clean your work country.

Clean all equipment before usage.

Never look straight into a trial tubing when you have no goggles on.

Always use the equipments the manner your instructor taught you.

Never gustatory sensation any chemicals.

Always with the labels on chemical bottles before usage.

Return all lab stuffs and equipment to their proper topographic points after usage.

After the experiment ever wash and dry you equipment every bit good as your work country.

Sodium thiosulphate can be really harmful when swallowed and can besides annoy the eyes or lungs.

If there is a contact between HCl and the eyes or clamber it can do a serious lasting harm.

Concentrated solutions of hydrochloric acid are highly caustic ; really dilute solutions are mildly caustic.

Toxic by inspiration – the concentrated HCl solution releases unsafe measures of H chloride vapor.

Equipment/ Apparatus:

6 mensurating cylinders

( 3 ) 25cm3 mensurating cylinders ( + or – 0.5 cm3 )

( 3 ) 10cm3 mensurating cylinders ( + or – 0.2 cm3 )

3 50cm3 burette ( + or – 0.1 cm3 )

3 100cm3 beakers

2 100cm3 conelike flasks

2 laminated little squared documents with a midst cross

Hydrochloric acid ( 2 grinder ) – same concentration in each experiment

Sodium Thiosulphate ( 40g/L )

Distilled H2O

Stopwatch

Goggless

Baseball gloves

Apron

3 funnels

3 different coloured ( board ) pens

Apparatus ( burette base )

Method:

First, clean work surface and equipments e.g. conelike flask, mensurating cylinder e.t.c

Collect all equipments and put them on your work country.

Topographic point the measurement cylinders, burette, conelike flasks and beakers in three groups -distilled H2O, hydrochloric acid ( HCI ) and sodium thiosulphate ( Na2S2O3 ) .

Label the equipments

Sodium thiosulphate ( Na2S2O3 ( aq ) ) ( 40g/L )

Distilled H2O ( H2O )

Hydrochloric acid ( HCl ( aq ) ) 2 moldm-3

Wear your safety equipment at all times.

Experiment 1:

Measure 20 cm3 of hydrochloric acid and 20 cm3 of Na thiosulphate in 25 cm3 mensurating cylinders.

Pour the chemicals in the conelike flask at the same clip and allow your spouse get down the stop watch when the last bead of chemicals beads in the flask.

Stop the stop watch when you and your spouse are unable to see the cross underneath the conelike flask.

After you have stopped your stop watch and recorded the consequence, pour the mixture off and rinse the conelike flask. This is because the chemicals will solidify if it ‘s non washed/ thrown off. Wash the conelike flask so that the old chemical reaction does n’t impact your following experiment.

Repeat the experiment once more twice. You can reiterate your experiment once more if you think it ‘s necessary.

Experiment 2:

Repeat experiment 1 altering the followers:

15 cm3 of Na thiosulphate

5 cm3 of distilled H2O

10 cm3 mensurating cylinder for distilled H2O

Experiment 3:

Repeat experiment 1 altering the followers:

10 cm3 of Na thiosulphate

10 cm3 of distilled H2O

10 cm3 mensurating cylinder for Na2S2O3 and H2O

Experiment 4:

Repeat experiment 1 altering the followers:

5 cm3 of Na thiosulphate

15 cm3 of distilled H2O

10 cm3 mensurating cylinder for Na2S2O3

Experiment 5:

Repeat experiment 1 altering the followers:

3 cm3 of Na thiosulphate

17 cm3 of distilled H2O

Burette alternatively of mensurating cylinder for all solutions

Experiment 6:

Repeat experiment 1 altering the followers:

2 cm3 of Na thiosulphate

18 cm3 of distilled H2O

Burette alternatively of mensurating cylinder for all solutions

Experiment 7:

Repeat experiment 1 altering the followers:

1 cm3 of Na thiosulphate

19 cm3 of distilled H2O

Burette alternatively of mensurating cylinder for all solutions

Volume of Na thiosulphate ( Na2S2O3 ) ( cm3 )

Volume of distilled H2O ( H2O ) ( cm3 )

Concentration of Na thiosulphate

( Na2S203 ) ( g/L )

20

40

15

5

30

10

10

20

5

15

10

3

17

6

2

18

4

1

19

2

I

V Na2S2O3 = new

Vermont

Initial Concentration

Volume of Na2S2O3 = New Concentration

Entire Volume

1

Rate ( s-1 ) =

Average Time ( s )

Table of Consequences

Try

Concentration of Na2S2O2

( g/L )

Volume of Na thiosulphate ( Na2S2O3 ) ( cm3 )

Volume of Distilled H2O ( H2O ) ( cm3 )

Entire Time

( seconds )

Average clip

( seconds )

Ratess ( s-1 )

( 3 important figures )

Ratess in

standard signifier ( s-1 ) ( 10-3 )

1

1

40

20

None

46:25

34.05

0.0332

33.2 x 10-3

2

20

None

30:06

3

20

None

30:59

4

20

None

33:19

5

20

None

29:81

6

20

None

34:38

2

1

30

15

5

47:94

48:76

0.0205

20.5 x 10-3

2

15

5

48:84

3

15

5

49:50

3

1

20

10

10

76:07

74:69

0.0134

13.4 x 10-3

2

10

10

73:25

3

10

10

74:75

4

1

10

5

15

173:62

172:77

0.00579

5.79 x 10-3

2

5

15

170:56

3

5

15

174:13

5

1

6

3

17

453:53

451:26

0.0022

2.22 x 10-3

2

3

17

449:03

3

3

17

451:23

6

1

4

2

18

600:00+

2

2

18

600:00+

3

2

18

600:00+

7

1

2

1

19

1800:00+

2

1

19

1800:00+

3

1

19

1800:00+

Table of Results ( for graph )

Experiment

Try

Volume of hydrochloric acid ( HCl ) ( 2 moldm-3 )

Volume of Na thiosulphate ( Na2S2O3 ) ( 40 g/L )

Volume of distilled H2O ( H2O )

( cm3 )

Entire Time ( seconds )

Ratess ( s-1 )

( 3 important figures )

Ratess in

standard signifier ( s-1 ) ( 10-3 )

1

1

20 cm3

20 cm3

None

30:06

0.0332

33.2 x 10-3

2

20 cm3

20 cm3

None

30:59

3

20 cm3

20 cm3

None

29:81

Average clip

30:15

2

1

20 cm3

15 cm3

5

47:94

0.0205

20.5 x 10-3

2

20 cm3

15 cm3

5

48:84

3

20 cm3

15 cm3

5

49:50

Average clip

48:76

3

1

20 cm3

10 cm3

10

76:07

0.0134

13.4 x 10-3

2

20 cm3

10 cm3

10

73:25

3

20 cm3

10 cm3

10

74:75

Average clip

74:69

4

1

20 cm3

5 cm3

15

173:62

0.00579

5.79 x 10-3

2

20 cm3

5 cm3

15

170:56

3

20 cm3

5 cm3

15

174:13

Average clip

172:77

5

1

20 cm3

3 cm3

17

453:53

0.0022

2.22 x 10-3

2

20 cm3

3 cm3

17

449:03

3

20 cm3

3 cm3

17

451:23

Average clip

451:26

6

1

20 cm3

2 cm3

18

600:00+

2

20 cm3

2 cm3

18

600:00+

3

20 cm3

2 cm3

18

600:00+

Average clip

600:00+

7

1

20 cm3

1 cm3

19

1800:00+

2

20 cm3

1 cm3

19

1800:00+

3

20 cm3

1 cm3

19

1800:00+

Average clip

1800:00+

Experiment 5,6 and 7 are near together because I started with 1cm3 Na thiosulphate and 19cm3 distilled but the reaction was really long so I did 2cm3 Na thiosulphate and 18cm3 distilled H2O which besides took really long to respond. I so tried 3cm3 Na thiosulphate with 17cm3 distilled H2O, which went absolutely good and I decided to utilize low sums of Na thiosulphate because I wanted to cognize how long it took the lowest to respond with HCl besides I wanted to cognize the highest and lowest that I could utilize for my tabular array of consequences.

Average Time Graph

As the concentration of Na2S2O3 additions, the clip decreases.

Ratess Graph

As the concentration of Na2S2O3 increases the rates besides increases.

Decision

The form in my consequences shows that as the concentration of Na thiosulphate increases the reaction clip is diminishing which means that the rate of reaction additions due to the fact that, it takes less clip for a/the reaction to take topographic point. Using the graphs, I can do a decision from my experiment. I can see that with the clip graph as the concentration increased the clip taken for the reaction to take topographic point decreased. There is one variable that has affected the consequences and that is the temperature which may hold changed somewhat, giving an wrong consequence. This is because when the temperature is increased the atoms will hold more energy and so do the atoms move faster. Therefore they will clash more frequently and with more energy. Atoms with more energy are more likely to respond successfully and hits between responding atoms are accordingly more likely to take topographic point, as stated in the hit theory. As the concentration of Na thiosulphate additions, the sum of clip lessenings because the reaction is acquiring faster. This is because the higher the concentration, the more atoms there are, so there is a bigger opportunity of successful hits go oning between Na thiosulphate and hydrochloric acid. When the concentration of the hydrochloric acid was lower the reaction took longer, this is because there were fewer atoms, so there was a smaller opportunity of successful hits go oning.

Evaluation

I believe that all my consequences are dependable because I repeated the experiment with consequences I think did n’t suit and my tabular array of consequences have merely 3 anomalousnesss which were rather close to the concluding consequences. In my experiment 1, consequences 1, 4 and 6 are outliers because their readings did n’t lie within the scope of the other three consequences, there may hold been a mistake in the stop watch or the room temperature changed during the experiment. In experiments 6 and 7, the chemical reaction took rather a long clip even though the solution went cloudy it was n’t opaque so, I decided to increase the volume of Na thiosulphate and diminish the volume of distilled H2O. From my consequences I noticed that as the concentration of sodium thiosulphate increased, the rate of reaction besides increased. This is because the more atoms there are in the volume of Na thiosulphate the faster the reaction will take topographic point, since there is a greater opportunity of a Na thiosulphate atom hitting a hydrochloric acid atom. This confirms my theory which states that increasing the concentration of the reactants and increasing the temperature causes more hits and hence more successful hits which increases the rate of reaction. To better the truth of my consequences, if I was to make the experiment once more, I would utilize a burette to mensurate the right volumes of Na thiosulphate solution and hydrochloric acid. I realised that I may non hold been precise plenty when utilizing the measurement cylinder. If I did the experiment once more, alternatively of visually look intoing when the cross has disappeared, I would utilize a light metre to mensurate the sum of light left in the reaction. When the reaction turns cloudy, the light metre would observe it. This would give more just and precise consequences. I would besides utilize a H2O bath to maintain the mixture the same temperature. The room temperature may hold been different on the yearss I did the experiment so this could do anomalousnesss.

The equipment I used for my experiments were precise because for greater sums of HCL, Na2S2O3 and distilled H2O I used a measuring cylinder but for smaller sums of HCl, Na2S2O3 and distilled H2O I used a burette to be more precise. I am confident humor my consequences because

We measured everything carefully excessively, to guarantee better consequences and we besides found that the higher the concentration of Na thiosulphate the faster the reaction. Overall I think my experiment was a success.