Measuring Sugar Content of a Liquid with a Laser Pointer.

[Alaa1991]

Hello, I have already started on my research. But I want a little bit of help.
My topic is the following: Measuring Sugar Content of a Liquid with a Laser Pointer.

However, I wonder how can a hypothesis be formed out of this? , what excatly is supposed to be done here? I understand that in this project I am supposed to test several liquids, such as water, diet coke, coke, pepsi, apple juice, and etc.

Please do help me I need more information.
Thank you
please reply as soon as possible.

[JanelleSchlossberger]

Dear Alaa1991,

Sometimes the answers to your questions can be found right in you own backyard. It seems that the experiment you have chosen is one already on the Science Buddies website. I also found a similar description on another web site. Here are the links for both of these.


https://www.sciencebuddies.org/mentorin ... p028.shtml

http://jchemed.chem.wisc.edu/HS/Journal ... /p1479.pdf



Also, in the How To Do a Scence Fair Project section of Science Buddies, there's a page describing how to formulate a hypothesis for any experiment.

For your hypothesis, you basically want to state what it is you want to measure, and what thing you're going to allow to change (independent variable) during the experiment and then state what you predict will be the outcome of your measurement (dependent variable) as a result of allowing the change to occur.

You can read more about it on this web page:

https://www.sciencebuddies.org/mentorin ... bles.shtml

It sounds like it should be a fun experiment.

Good luck !
Janelle

[Alaa1991]

Well, I have decided to do something different, than the one in the website, I mean its quite similar but I added more to it.
For example I decieded to test also the salt, and not just suger.

Do you have any advice?

[Alaa1991]

I want to ask you what kind of liquids can I test?
I planning to test salt water, apple juice, and one more
do you have any ideas of what else I can test?

[deleted-2131]

You should also test distilled water, which can be bought at the grocery store, as a control since it has no sugar in it. Controls are important; they allow you to compare, in this case, the liquids with sugar in them to one that yuo think doesn't have any sugar. This will allow you to make a judgement of the accuracy of your method.

[deleted-71576]

Sports drinks come to mind, like Gatorade, or Powerade, etc. Most have a clear variety.

[Alaa1991]

Oh thank you that was very helpful

[Alaa1991]

As part of my introduction is to prove why this project is important, and how it can help people, what is the benefit in " real life"?

I have done many research, but couldn't find why it is important , and what is the partical value. I thought maybe it had to do something with fishing, and where you aim.

Thank you.
reply as soon as possible

[Alaa1991]

Should I limit my research to just suger, or study suger and salt. And infer to other soultion?

[deleted-2131]

The main application I can see of your project would be quality control in manufacturing processes. If your project does indeed suggest a new, accurate, and precise method for measuring the sugar content of liquids, then your protocol could be used in manufacturing processes where the sugar content of a particular liquid is important.

[Alaa1991]

Does this answer, why my project is important or whether I should test salt or suger?

Thank you

[Louise]

Does this answer, why my project is important or whether I should test salt or suger?

Thank you

Terik explained why this would be important. I believe this technique is already used in some industries. If you search for "using refractive index change to measure salt" or "... suagr" you will find many examples of people using this technique in the "real world". This method is popular because you don't have to use up any of your sample for the test.

I don't know why you are testing sugar and salt... Why did you make this choice? Sugar and salt can both be measured with this technique assuming you made the proper solutions as a standard, but you cannot tell the difference between the two with this method. Similarly, a hot and cold cup of water will also refract differently from each other.

You should probably re-read the links given to you earlier about this project.

Louise

[Alaa1991]

1) I have decided to stick to one additive, and try various concentrations like 5 g, 10 g, 15 g, etc. to a fixed amount of water. and then I will do different sweet liquid like pop, etc. I will use Diet pop to see if the laser can pick up the content of "fake sugar" as well.

2) But at the same time I thought maybe I should not limit my research to just sugar. And study maybe sugar and tea or coffee or salt and infer to other solutions. And that way the research would be more valuable to other people.

That is what I am asking. To help me decide what i should do, either part 1 or 2.
Thank you

[Louise]

1) I have decided to stick to one additive, and try various concentrations like 5 g, 10 g, 15 g, etc. to a fixed amount of water. and then I will do different sweet liquid like pop, etc. I will use Diet pop to see if the laser can pick up the content of "fake sugar" as well.

2) But at the same time I thought maybe I should not limit my research to just sugar. And study maybe sugar and tea or coffee or salt and infer to other solutions. And that way the research would be more valuable to other people.

That is what I am asking. To help me decide what i should do, either part 1 or 2.
Thank you

All you are doing is measuring the refractive index change of the liquid. This test cannot tell the difference between salt, sugar, hot water, cold water, oil, etc. So, you should not measure across different types of compounds.

This test does not measure "sweetness", so your sugar calibration will not be valid for diet soda. It cannot "pick up" fake sugar. It can only "pick up" if the additives (salt, sugar, flavors, etc) change the refractive index. You should read the links included in the experiment- the Journal of Chemical Education article talks about testing soda. Remember, cold soda and warm soda will give different results. Also, carbonation is an issue, so I think you need to use flat soda.

You cannot test one type of compound and extrapolate to other compounds. If you calibrate to sugar, you cannot test the amount of salt.

As I said, this method is used commericially. But it is only used to test one thing. Suppose the company makes apple juice and they want to measure the sugar content from batch to batch. They would calibrate to a sugar solution (or even better to apple juice with different amounts of sugar) and use it for this one test. There testing guidelines would be very strict- this much juice, at this temperature, in this container, using this laser. Every time one of those variables changes, the calibration is no longer valid. You see? So your calibration data won't be used by any one other than you.

Louise

[Alaa1991]

Oh that was a very helpful information

So I follow do I follow what's in
https://www.sciencebuddies.org/mentorin ... ?from=Home

Like the expriemental Procedure part.

Once again Thank you for the information

[Louise]

Oh that was a very helpful information

So I follow do I follow what's in
https://www.sciencebuddies.org/mentorin ... ?from=Home

Like the expriemental Procedure part.

Once again Thank you for the information

I found the information under bibliography-
Information on making the hollow prism for this project came from:
Edmiston, M.D., 2001. "A Liquid Prism for Refractive Index Studies," Journal of Chemical Education 78(11):1479–1480

to be very helpful. What science classes have you had? I feel like maybe what I am saying is too advanced for you... do you understand about the "refractive index"

Louise

[Alaa1991]

Well I have taken Biology and now I am studying chemistry

I have borrowed a physics book from a physics teacher, for my research.

Yeah I am really having a hard time understanding my topic a little, but I understood what you explained to me before, it would be nice if you could give me a little bit of information in details about index of refraction, so far I know that refraction is the bending that occurs as light passes from one medium to another.

and that When a light ray passes from glass to air, the rays are refracted away from normal. and etc.

Do you think that there is something else that I have to know and include in my research.
I can put what I have written for the introduction if you would like here, and maybe you can see if there is something else missing that I should include.
Thank you

[Alaa1991]

[b]Research [/b]

Refraction occurs as the light passes from one medium to another, in other words refraction is changing the direction of a light wave, and consequently, the light enters the object in a different direction than it leaves the object.
At the boundary, the wave’s phase velocity (rate at which the phase of the wave proliferates in space) distorted, it changes direction, and its wavelength increases or decreases but its frequency remains constant. For instance, a light ray will refract as it enters and leaves glass. Air has a refractive index of about 1.0003 and water has a refractive index of about 1.33. A refractive index is also known as index of refraction, is the ratio of the speed of light in a vacuum to the speed of light in a material.
By the time the light wave reaches the end of the medium, there is some reflection off the boundary, and transmission into the new medium. The transmitted wave endures refraction or bending if it reaches the boundary at an angle.
When light wave is traveling through air and reaches the boundary with a glass surface, from a denser medium into a less dense medium, the speed and the wavelength both increase. When passing from air into glass, both the speed and the wavelength decrease.
When waterfront is bent along the boundary, and passes across the boundary it travels in a straight line, a boundary behavior is observed, for that reason it is called refraction.
The denser the material is, the slower the speed light, in other words, as the speed of light is reduced in the slower medium, the wavelength becomes shorter, and the frequency is unchanged.
When a light ray passes from glass to air, the rays are refracted away from normal. The angle of refraction (the angle that the refracted ray makes with the normal to the surface) is larger than the angle of incidence. However, when light strikes a surface along the perpendicular, the angle of incidence is zero, and the angle will also be zero.
As light travels through a given medium, it travels in a straight line, but when light passes from one medium into a second medium, refraction occurs. Refraction only takes place at the boundary, and once it crosses the boundary it travels in a straight line, then the direction of that line becomes different than it was.
For instance, if a person looks at a straight object, such as a pencil, or straw which is submerged in the water, the object appears to bend at the water’s surface. This is because of the bending of light rays as they move from the water to the air. As the rays reach the eye, the eye traces them back as straight lines; this is called lines of sight. Moreover, this causes the pencil to appear high, and the water is shallower, then it is. When dept of water is viewed from the above it is known as apparent dept.
The shallower the water is, the waves travel more slowly, and so the wavelength decreases and the wave bends at the boundary. Any direction the waves travel in deep water, they always refract towards the normal as they enter the shallower water.
Rainbow is caused by refraction, where the splitting of white color light into rainbow-spectrum occurs, as it passes through a glass prism.
Glass and air have different frequencies of light travel at different speeds (dispersion) where glass has higher refractive index than air, and causes them to be refracted at different angles.
As light passes from one medium to another, it may be refracted or reflected. The degree which it is bent depends on the angle of incidence, and the properties of the medium.
A Dutch scientist Willebroad Snell discovered how angle depends on the angle of incidence. Snell’s law also known as Descartes’ Law or law or refraction is used to calculate the relationship between the angle of incidence and refraction, when referring to light or other waves, that pass through a boundary between two different isotropic ( same in all directions) such as air and glass. The law states that the ratio of the two sine of the angles of incidence and of refraction is a constant that depends on the media (materials through which electromagnetic wave promulgate). For light going to another medium, the constant, n, is called index of refraction. Snell’s law is written as


Where is the angle of refraction, n the index of refraction, and is the angle of incidence. In most cases the same equation can be written . Here n1 is the index of refraction of the medium in which the incident ray travels, the first medium, and n2 is the index of refraction of the medium in which the refracted ray moves, the second medium. is always used for the angle the incident ray makes with the surface, regardless of the medium.
Index of refraction can be calculated using the angle that light bends when traveling from one material to another material. Index of refraction changes based on the amount of solutes in a solution.
Light waves of different wavelengths have slightly different refractive indices. Thus, they are refracted at different angles.
There are many effects that are caused by the refraction of light, Mirages, and daylight that stays behind after the sun is below the horizon.

2.3 Experimental Purpose

Doing this project will help investigate whether it is possible to determine the concentration of a solution with a laser. There is an unusual fish known as the Archer fish its prey lives outside the water. An insect, butterfly, spider, or similar creature is the target of the Archer fish's powerful spray of water. Archer fish's trick is when light from the target to its eye endures refraction at the air to water boundary. This refraction causes visual distortion, making its prey appearing in a location where it isn't. The Archer Fish lines up its sight with the prey from a position directly underneath the prey. From this vantage point, light from the prey travels directly to the fish's eye without enduring a change in direction. Since the light is traveling along the normal to the surface, it does not refract; the light passes straight through the water to the fish's eyes.

[Alaa1991]

This is what I wrote for introduction in my report.

Do you have any advice?

Thank you

[Louise]

This is what I wrote for introduction in my report.

Do you have any advice?

Thank you

I will read this carefully tonight.


Louise

[Louise]

This is what I wrote for introduction in my report.

Do you have any advice?

Thank you

I will read this carefully tonight.


Louise

I think your background is generally very good. I don't know if you have footnotes in your real paper, but if you do not, you should add them. Citing the sources you use is very important.
See :
http://www.sciencebuddies.com/mentoring ... _lit.shtml

for additional information.

It might be good to have someone edit your paper for style. The science is good, but the writing could be a little clearer in some places. I'd probably puts snell's law earlier, since it is the exact decription of the light through different materials.

I think this technique is important because you can test a sample with out destroying it. Suppose you had glass bottles of a liquid going by on an assembly line. Suppose you had to have a salt concentration of 15%. You could pause each bottle in front of the laser and test them with out even opening the bottles. (well, assuming you have prismatic bottled. ) Even if you have to take a sample out, you don't destroy it. You could measure the salt content by drying the water, and then weighing the salt left, but then your sample is gone. This is not a good method because the sample is gone. The refractive method is also nice, because it is simple, and you don't need a lot of equipment to do it.


Louise

[Alaa1991]

Oh thank you so much for your advice

So you would recommend that i fill bottles like one bottle with 5g of suger or salt, and one 10g and one 15 g and etc. and have the laser placed in its postion and all I have to do is just move a bottle and put a different one, without opening the cap and adding. Is that basically what you mean. That is a really good idea thanks.

But I am kind of confused a little in the expriement part. Setting up the expriement is so hard that I don't understand what is extacly supposed to be done. Like in the following :

[i]Measuring the Index of Refraction of a Liquid[/i]http://www.sciencebuddies.com/mentoring ... ?from=Home

Where is starts off at

"The laser pointer should be set up so that its beam is perpendicular to a nearby wall. You should attach a big piece of paper to the wall for marking and measuring where the beam hits. The height of the laser pointer should be adjusted so that it hits about half-way up the side of the prism. The laser pointer should be fixed in place. Check periodically to make sure that the beam is still hitting its original spot. "


So am I going to put a piece of paper on a wall, and have the laser point to it and put a line where the laser hits. The part that I don't get is step 4 to 13, well isn't the same procedure done again but in details as in 1-3 under Measuring the Index of Refraction of a Liquid.

[Louise]

Oh thank you so much for your advice

So you would recommend that i fill bottles like one bottle with 5g of suger or salt, and one 10g and one 15 g and etc. and have the laser placed in its postion and all I have to do is just move a bottle and put a different one, without opening the cap and adding. Is that basically what you mean. That is a really good idea thanks.

But I am kind of confused a little in the expriement part. Setting up the expriement is so hard that I don't understand what is extacly supposed to be done. Like in the following :

Measuring the Index of Refraction of a Liquidhttp://www.sciencebuddies.com/mentoring ... ?from=Home

Where is starts off at

"The laser pointer should be set up so that its beam is perpendicular to a nearby wall. You should attach a big piece of paper to the wall for marking and measuring where the beam hits. The height of the laser pointer should be adjusted so that it hits about half-way up the side of the prism. The laser pointer should be fixed in place. Check periodically to make sure that the beam is still hitting its original spot. "


So am I going to put a piece of paper on a wall, and have the laser point to it and put a line where the laser hits. The part that I don't get is step 4 to 13, well isn't the same procedure done again but in details as in 1-3 under Measuring the Index of Refraction of a Liquid.

No, you cannot measure it in a bottle- that was a joke. You need the prism to work, or much more complicated math to correct for hitting a bottle instead of a prism. That is what the "if your bottle was a prism" part of my post meant. I was just trying to explain why this might be useful in the real world.

As for the instructions... you set up your laser with nothing in th way, and mark how the beam goes. Then you put in the prism, and measure where the beam goes. The path will change as you go through the liquid prism. The instructions have you measure roughly at the begining, and then more carefully as you get set up. Try it step by step and you will see it works.

Louise

[Alaa1991]

THANK YOU

[Alaa1991]

Hello, I really never started my exp. because I have bought my materials yet, do you know where I can buy the following materials from :

several 1" × 3" glass microscope slides,
diamond scribe or glass cutter
electrical tape,
epoxy glue (either 5-minute or 30-minute epoxy),
laser pointer
gram scale

I have searched online different stores such as walmart, home depot, target and etc. but couldn't find them there
Thank you

[Louise]

Hello, I really never started my exp. because I have bought my materials yet, do you know where I can buy the following materials from :

several 1" × 3" glass microscope slides,
diamond scribe or glass cutter
electrical tape,
epoxy glue (either 5-minute or 30-minute epoxy),
laser pointer
gram scale

I have searched online different stores such as walmart, home depot, target and etc. but couldn't find them there
Thank you

I found 5/7 of the materials at the stores you said you looked at in 30 seconds online

Louise

[Alaa1991]

Oh really I probably didn't look good, I wonder what are the two other materials that you did not find?
THANKS

[Alaa1991]

Where can you get the micrscope slides?

[Louise]

Where can you get the micrscope slides?

i would ask your teacher- also use the scale in the science class since they are costly (and look for 'kitchen scale' and you want g resolution)

This was the second thing I couldn't find- I didn't even look for slides
First was the cutter- art teacher could have one too you could use

Louise

[Alaa1991]

Oh thanks so much

do you think a physic teacher might have a prism, instead of me building it, and buying bunch of things to make it.

Is it possible to buy one from any stores?

Thanks for your advice