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Part 3. invisible ink

Invisible ink has been used to conceal secret messages for a long time. Many different liquids can be used as invisible inks such as lemon juice, milk, vinegar or a solution of phenolphthalein.

Part 4. breathalyzer

To determine whether a driver is driving under the influence of alcohol, law enforcement officers perform a Breathalyzer test to measure the blood alcohol content of the bloodstream. In the breath analyzer test, a breath sample is passed through a solution containing acidified potassium dichromate ( K 2 Cr 2 O 7 ) size 12{ \( K rSub { size 8{2} } ital "Cr" rSub { size 8{2} } O rSub { size 8{7} } \) } {} , which is bright yellow. Potassium dichromate, a strong oxidizing agent, oxidizes ethyl alcohol to acetic acid (vinegar). The chromium is consequently reduced from the VI to the III oxidation state, which is green. The unbalanced equation for this reaction is

Cr 2 O 7 2 + H + + C 2 H 5 OH Cr 3 + + CH 3 CO 2 H + H 2 O size 12{ ital "Cr" rSub { size 8{2} } O rSub { size 8{7} } rSup { size 8{2 - {}} } +H rSup { size 8{+{}} } +C rSub { size 8{2} } H rSub { size 8{5} } ital "OH" rightarrow ital "Cr" rSup { size 8{3+{}} } + ital "CH" rSub { size 8{3} } ital "CO" rSub { size 8{2} } H+H rSub { size 8{2} } O} {}


The amount of alcohol in a breath analyzer sample is therefore proportional to the amount of potassium dichromate that is used up and also therefore to the loss of yellow color.

The Blood Alcohol Concentration (BAC) may then be calculated from the equation

BAC = 0.8 A/WR

Where W is a body weight of the individual being tested, A is the amount of alcohol in the body (in mL) and R is a“Widmark R Factor”, approximately 0.68 for men and 0.55 for women.In most states, a BAC of 0.1 percent is sufficient to be convicted for driving under the influence of alcohol; in some states the threshold BAC is even lower.

Part 5: Blood Stain Analysis Using Chemiluminescence

Investigators often find bloodstains during their examination of a crime scene. They also find stains that could be similar substance, something other then blood, such as red paint. How would you test a stain to see if it is blood? Human blood contains a pigment called hemoglobin, which is used to transport oxygen through our body. This pigment is used by number of tests to identify the presence of blood. One most common test used by investigators that reveals the presence of blood is the Luminol Test. In this test the bloodstain can be made to glow with a blue light due to chemiluminescent reaction of the luminol reagent with the iron (Fe) in the hemoglobin. Chemiluminescence is the reversed case of photoreaction: by a chemical reaction, an excited particle is formed, which looses its energy by producing a light quantum of light. The most important characteristic is that the light is emitted in cold. In other words, chemiluminescence happens when a molecule capable of fluorescing is raised to an excited level during a chemical reaction. Upon its return to the ground state, energy in the form of light is emitted. Luminol is one of the most outstanding molecules that emit appreciable amounts of light.

Experimental Procedure

Part 1a: Latent Fingerprint Development using Iodine vapors

Caution! Iodine vapors are poisonous and should not be inhaled. Keep the jar with iodine in the fume hood at all times.

1. Press you finger onto a piece of filter paper.

2. Using tweezers, place the filter paper into a jar with iodine and recap it.

Questions & Answers

Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
yes that's correct
I think
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
how nano science is used for hydrophobicity
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
what is differents between GO and RGO?
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
analytical skills graphene is prepared to kill any type viruses .
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Honors chemistry spring. OpenStax CNX. Mar 10, 2008 Download for free at http://cnx.org/content/col10512/1.9
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