lab report osmosis final

7/30/2019 Lab Report Osmosis Final

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Title of practice: Osmosis between sucrose and water

Introduction

For the cell to work efficiently, it must be kept stable, this is known as

homeostasis. To maintain this balance there exists mechanisms for selective

transport of materials called membranes which are selectively permeable,

allowing the passage of some substances or particles (molecules, atoms, or ions),

and preventing the passage of others. This selectivity is due to the double layer

of membrane phospholipids. The manner in which the molecules pass through

the membrane depends in part on the polarity in each one. Hydrophobic

molecules, or non-polar, relatively free pass through the layer of lipid moleculeswhile hydrophilic or polar, including water, and larger molecules pass through

channels formed by carrier proteins. The regulation of the transport of molecules,

or the moving direction depends on its concentration gradient (the difference in

concentration between the two locations).

The molecules move constantly due to their kinetic energy and spread evenly

into the available space. This movement, called Brownian motion, is the driving

force of diffusion.

Diffusion is defined as the natural movement of the particles from an area of

higher concentration to an area of lower concentration to achieve a dynamic

balance in which the particle motion is zero net. There exist two kinds of

diffusions: passive and active transport, but the experiment only consisted on

passive transport. Passive transport is a transport mechanisms by which the

substances move across the cell passing through the plasma membrane and does

not requires energy. Osmosis is a passive transport and it is defined as a passive


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movement, or diffusion of water molecules across a partially membrane, from a

region of lower solute concentration to a region of higher solute concentration.

The objective of the following practice is to study how osmosis occurs, in two

plastics that worked as membranes, adhere certain amount of sucrose to the

plastics and weight them, then immersion the plastics in distilled water and after

certain time take the plastics out and weight the semi permeable membranes

again.


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Problem/Research question

What changed the experiment was the concentration of sucrose that was added in

the plastic bag (0.5 M, 1.5 M and 2M) they were submerged by 15 minutes in a

15mil solution of distilled water.

The research question is: What would happen if a membrane with concentration

solution sucrose of 0.5 M, 1.5 M and 2M is submerged in a 15 ml solution of

distilled water during 15 minutes?

The hypothesis is: If the concentration solution of sucrose in the membrane is

changed, after 15 minutes of been submerged in a 15ml solution of water, the

weight of them will change because osmosis will occur.


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Variables

There are 3 main factors that can prove the osmosis activity and they are:

sucrose, distilled water, and semi-permeable membranes; these three factors will

be controlled during all the experiment as can be seen in the following table:

Table 1 Variables involved

Type of variable Variable Units Control Method

Independent

Variable

Distilled

water

ml Distilled water will be the solute

that will be in contact with the

membrane (sucrose substance)

inside a beaker with 50 ml of

distilled water.

Dependent

Variable

Weight of the

membrane

Grams The weight of the membrane will

be monitored during all the

experiment with a balance.

Controlled

Variable

Sucrose M The amount of M will be controlled

when doing the semi-permeable

membrane with sucrose. Sucrose

will be used with a concentration of

2 M. The quantity of sucrose of the

semi-permeable membrane will be

controlled, to control the amount of

the initial solute inside the

membrane.

Temperature Celsius Room temperature


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Hypotonic

environment

--------- The membrane is hypotonic to the

amount of distilled water

Materials

2 Semi-permeable membranes (dialysis bag and string or rubber bandslaboratory)

Blotting paper1 Test tube rack1 Test tubeBeaker (distilled water 50 ml)Beaker (distilled water 50 ml)Beaker (sucrose 2 M, 50 ml)Laboratory balance

Reactants

Sucrose 2 M, 50 mlDistilled water 100 ml


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Picture or diagram of lab setup

Blotting paper to Semi-permeable membrane

dry the membrane with 15 ml of sucrose Balance

Sucrose 50 ml Sucrose 15 ml Distilled water 50 ml

Setup


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Methodology/Procedure

Based on the reaction of osmosis, the method was designed to measure weight,

the change of the membrane, to measure the quantity of distilled water that has

passed through the membrane. The following is the procedure that was used forthe experiment:

1. First the semi-permeable membrane was dried (dialysis bag) with ablotting paper.

2. Then the knots in one of their corners were made.3. 15 ml of the sucrose solution were measured from the beaker (50 ml of

sucrose) using the test tube.

4. The solution from the test tube was added to the semi-permeablemembrane.

5. Then the other side of the membrane was closed carefully, leaving no airinside it.

6. Then it was dried and measured, and with the balance the initial weightwas recorded in the chart.

7. Afterwards, the membrane was introduced inside a beaker with 50ml ofdistilled water.

8. After a time of 10 minutes, the membrane was taken out of the sucroseand was dried with perfection, and afterwards recorded in the chart.

9.Next, the membrane with sucrose is located inside the beaker, withdistilled water again.

10.The entire list of steps was repeated with the second membrane.


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Raw data

In the following tables the raw data collected from the experiments will be

represented. The tables contain the weight of the membranes that was taken in

the initial time (without dipping the membranes in distilled water) and after 15

minutes (submerged in distilled water). In the table it will be also the quantity

and molarity of Sucrose in each membrane and in some cases the distilled water,

the others didnt collect it. The weight was recorded with a balance uncertainty

of 0.5 g.

Tables

Shows the data recorded by the membrane in the initial time, and after 15 minutes submerged in distilled water.

Table 2 Molarity 0.5

Sample 1 Sample 2Time

(minutes)

Sucrose

(molarity)

Membranes

weight(grams)

Membranes

weight(grams)

Distilled

water(mL)

Sucrose

(molarity)

Membranes

weight(grams)

Membranes

weight(grams)

Distilled

water(mL)

0 0.5 15.82 16.2 17.8 0.5 15.4 14.5 15.5

15 0.5 16.5 16.8 17.9 0.5 15.7 14.9 15.7

Table 3 Molarity 1.5

Sample 3 Sample 4

Time(minutes)

Sucrose(molarity)

Membranesweight

(grams)

Membranesweight

(grams)

Distilledwater

(mL)

Sucrose(molarity)

Membranesweight

(grams)

Membranesweight

(grams)

Distilledwater

(mL)

0 1.5 16.5 19.4 1.5 16.9 17.5

15 1.5 19.2 22.1 1.5 19.1 18.5

Table 4 Molarity 2

Sample 5

Time(minutes)

Sucrose(molarity)

Membranesweight

(grams)

Membranesweight

(grams)

Distilledwater

(mL)

0 2 19.3 18.3

15 2 23.5 21.8


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Processed data presentation

With the data obtained we are able to calculate the difference in grams. The

following table shows the initial and final mass of each membrane and in some

cases the mass of the distilled water. The mass released obtained during the 15

minutes and the mass before the 15 minutes show the difference of the mass

during the process, obtained with the formula Difference= (mass after 15

minutes)-(mass 0 minutes) For example; using the first data in the table 2

Molarity 0.5 of the experiment with the data collected, substitute the data in the

formula: () () you obtain 0.68 grams of difference between the

initial membrane and the final membrane, because a quantity of distilled waterwas adhering to the membrane during the 15 minutes . The same calculus was

done with the data obtained from all the trials.

Tables

Show the difference in the initial and final mass of each of the membranes of the experiment

showing every trial

Table 5 Molarity 0.5 (Difference)

Sample 1 Sample 2

Time

(minutes)

Sucrose

(molarity)

Membranes

weight(grams)

Membranes

weight(grams)

Distilled

water(mL)

Sucrose

(molarity)

Membranes

weight(grams)

Membranes

weight(grams)

Distilled

water(mL)

0 0.5 15.82 16.2 17.8 0.5 15.4 14.5 15.5

15 0.5 16.5 16.8 17.9 0.5 15.7 14.9 15.7

Difference 0.68 0.6 0.1 Difference 0.3 0.4 0.2

Table 6 Molarity 1.5 (Difference)

Sample 3 Sample 4

Time(minutes)

Sucrose(molarity)

Membranesweight

(grams)

Membranesweight

(grams)

Distilledwater

(mL)

Sucrose(molarity)

Membranesweight

(grams)

Membranesweight

(grams)

Distilledwater

(mL)

0 1.5 16.5 19.4 1.5 16.9 17.5

15 1.5 19.2 22.1 1.5 19.1 18.5

Difference 2.7 2.7 Difference 2.2 1


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Table 7 Molarity 2 (Difference)

Sample 5

Time(minutes)

Sucrose(molarity)

Membranesweight

(grams)

Membranesweight

(grams)

Distilledwater

(mL)

0 2 19.3 18.3

15 2 23.5 21.8

Difference 4.2 3.5

Graph 1 Molarity 0.5 Show the mass during the 0 minutes and 15 minutes

Graph 2 Molarity 1.5 Show the mass during the 0 minutes and 15 minutes

0

2

4

6

8

10

12

14

16

18

0.5 M0.5 M

Distilled

water0.5 M

0.5 MDistilled

water

0 minutes

15 minutes

0

5

10

15

20

25

1.5 M 1.5 M 1.5 M 1.5 M

0 minutes

15 minutes


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Graph 3 Molarity 2 Show the mass during the 0 minutes and 15 minutes

As it can be seen from the graphs the difference between the 0 minutes and 15

minutes changed because of molarity. The molarity of sucrose acts in a regular

way, more molarity more difference of membranes mass, less molarity less

difference of membranes mass. The mass change because of the hypertonic

environment, the membrane with sucrose was hypertonic to the distilled water.Then osmosis occur diffusion of water molecules (distilled water) across a

partially membrane (dialysis bag or rubber bags laboratory), from a region of

lower solute concentration (distilled water) to a region of higher solute

concentration (15 mL of sucrose inside the membrane).

Conclusion and evaluation

It is clear that an empirical lab practice with a good methodology will always be

successful, and that is in fact something this experiment had, in its planning and

0

5

10

15

20

25

2 M 2 M

O minutes

15 minutes


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in its materials, it was almost perfect, except for a few details that could be

improved for further lab practices.

First of all, the lack of knowledge of how to use the lab equipment, this is not a

fault of the teacher or the biology academy, but still, not taking in consideration

that some students lack the knowledge is something plain absurd.

This experimental practice was, even though the team lack of experience and

knowledge in the lab, a success, due to the results obtained throughout the

investigation and research and the correction of mistakes.

The hypothesis was support with the data obtained: a bag containing a certain

quantity of sucrose, when put inside a beaker with water, will deploy osmosis,

and thus distilled water will enter the membrane. This is verified by taking

measures on the weight of the bag, before and after putting it into water; the

difference between the data will (and actually did) prove that the process known

as osmosis happened within the laboratory parameters.

References

Peeters, Minka., Talbot, Christopher, and Mayhofer Antony. BiologyInternational Baccalaureate. Australia: IBID Press, 2007. Print

lab report osmosis final

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