Wednesday, July 29, 2009

Propylene Glycol

Most of us are not familiar with chemical terms such as propylene glycol.
However, it is used by all of us every single day.


This chemical is usually found in:

  • makeup
  • shampoo
  • deodorant
  • detangler
  • styling mousse
  • cleansing cream
  • mascara
  • soap
  • skin cream
  • bubble bath
  • baby powder
  • conditioner
  • toner
  • after shave
  • baby wipes





Seems non-harmful to us so far.
But what we do not know is that it is also contained in:
  • Antifreeze
  • Tyre sealant
  • Rubber cleaner
  • De-icer
  • Stain removers
  • Fabric softener
  • Degreaser
  • Paint
  • Adhesive
  • Wallpaper stripper



Sounds kinda harmful now doesn't it?

The product that we use everyday on our hair and skin has nearly the same contents as the ones in we use in the car engines, for the walls and fabrics!
It's like antifreeze with the shampoo and soap label on it.
Maybe you thought "Oh well, at least we don't eat it..". but sadly we actually do. Propylene glycol is present in food such as cake mixes, salad dressings, soft drinks, popcorn, food colorings, fat-free ice cream and sour cream. It is even used as a preservative!

cake mix

Propylene glycol may cause eye irritation, skin irritation and skin drying.

Isn't it ironic that it is in our soap and make up, which IS TO BE USED ON OUR SKIN!
This is one of the causes of premature aging of our skin.

Make a quick check on what products you are using. It may as well be.. brake fluid...

Propylene glycol is also known as propane-1,2-diol, is an organic compound. It is usually a faintly sweet colourless clear viscous liquid.
Ingestion of this chemical in high doses would of course bring some health issues.




propylene glycol, C3H8O2

This chemical is an alcohol and it is hygroscopic and miscible with water, acetone and chloroform.
Propylene glycol is prepared by hydrolysis of propylene oxide.


Although not a huge threat to humans through the daily products, one should not use much of the products containing this chemical for health benefits.
Check your products now! =)

Friday, July 24, 2009

Going green inside out

The world had always admired the Japanese for their ever youthful looking complexion and also their low cancer rates.
So what is the secret?
Sushi?

Perhaps.. but the most significant key to these statistics is in the tea they always drink.


Green tea.


Green tea or scientifically known as Camellia sinensis possesses numeral chemical composition which gives humans a lot of benefits. Green tea extracts are now infused with other products to enhance its chemical benefits. Green tea contains polyphenols and flavonoids (catechin, epicatechin, epicatechin gallate, epigallocatechin gallate, and proanthocyanidins). It also contains minor traces of caffeine, theanine , lignin , organic acids, protein and chlorophyll.

Epigallocatechin gallate (EGCG) is the most significant active compound in green teas.

EGCG is a polyphenol which have benzene rings with -OH attachments.

How does EGCG help us?

Firstly, EGCG are able to produce a healthy, youthful skin by triggering the old skin cells to reactivate and divide.


So instead of having lots of wrinkles and dull spots, we have a m
ore radiant, youthful look, thanks to the chemical properties of EGCG. There are even proven researches of using EGCG extracted from green teas to cure scars and skin diseases.

Besides that, it is proven that EGCG in green tea can even help in weight loss. EGCG in green teas increases the body's metabolism and also triggers a certain hormone so as to prevent digestion of certain carbohydrates which converts to fats later on. This would also mean that EGCG helps to burn certain fats in your body and reduce your body weight.
EGCG extracts are slowly becoming weight loss supplements in the market.


Last but not least, EGCG in green teas are proven to lower the risk of heart attacks and various cancer. EGCG shows antioxidant properties which helps in preventing atherosclerosis and supressing cancerous cells.

According to Japanese research, green tea reduces the levels of LDL or also known as 'bad' blood cholesterol, thereby reducing the risk of coronary heart disease.
European studies have found that regular consumption of tea protects against heart disease, with one study documenting that the risk was 36 per cent lower for tea drinkers. It is believed that the polyphenols in tea help prevent arthrosclerosis.

EGCG also blocks the formation of cancer-causing compounds such as nitrosamines, suppresses the activation of carcinogens, and detoxifies and traps cancer-causing agents.

The EGCG stops cancer cells from growing by binding with an enzyme, called dihydrofolate reductase, in the body.
It is a popular custom in Japan to drink green tea with meals. This is why cancer rates in Japan are lower compared to other countries.

The benefits of green tea does not stop here.


There are many researches done in order to fully utilize the benefits of the various chemical compounds in green tea, especially EGCG.
What are you waiting for? Start the practice of drinking green tea for your health benefits. Grab a cuppa =)


Be it hot or cold. Traditional or modern.


Or even in food products.
The world has acknowledged the chemical benefits of green tea =)

Monday, July 20, 2009

Ripen up

Fruits.


Great source of vitamins, minerals and fibers.
Some like them sour, some like them sweet.
Most are sour during the pre-ripening stage while to enjoy the natural sweetness of the fruit, one has to wait till the fruit ripens.
Well, if you are the one who would rather enjoy the sweetness of the fruit, you don't have to wait for long the fruit to ripen.
We can easily accelerate the ripening process using the knowledge of chemistry =)

So what accelerates the ripening process of fruits?

Ethylene gas.


Ethylene molecule = 2 carbon and 4 hydrogen atoms

Ethylene gas (C2H4) is an colourless, odourless gas that exists in nature and is also created by man-made sources. In nature, the largest producers are plant and plant products which produce ethylene within their tissues and releases it into the surrounding atmosphere.

This discovery was discovered by an accident. Long ago, lemon growers would store newly harvested green lemons in sheds kept warm by kerosene heaters until they turned yellow and ripened enough to be sold in the markets. However, when new modern heating systems were tried, the lemons no longer turned yellow on time. Research soon found out that the key factor in the ripening process was small amounts of ethylene gas given off by the burning kerosene in the heaters.

The main purpose of the ripening process is to:
  • Produce more sugars. Fructose is a sugar found in many fruits and plants, and is the substance that causes fruits to taste sweet. The chemical process involved in ripening breaks down substances found in an unripe fruit and transforms them to sugars, including fructose.
  • Increase enzymes. A gas called ethylene occurs naturally during the ripening process, and increases the amount of enzymes that help soften the fruit and break down substances in an unripe fruit to make sugars.

Ethylene is a plant hormone. Like all hormones do, ethylene triggers and accelerates the production of certain enzymes in the fruit.
These enzymes includes
  • amylase, which is in charge of breaking down starch into simple sugars.

fructose, sugar in fruits

  • pectinase, which breaks down pectin, the substance which makes the fruit hard.
peptin, a polymer chain of sugars

Most of the fruits you see in the market are not fully ripe because fully ripened fruits don't make well money as it spoils quicker by over ripening.

However, if you wish to accelerate the ripening process of the fruit, the common solution is by placing a slightly over ripped tomato, avocado or banana in a paper bag for the action of ethylene to produce. Increased levels of ethylene contained within the bag, released by the fruit itself, serves as a stimulant after reabsorption to initiate the production of more ethylene. The overall effect hastens ripening, aging and eventually spoilage.

So, you have to remember to take out the fruit on time so that you don't get a rotten fruit instead of a fully ripened sweet and juicy fruit.

ripening of banana

Contrary to popular belief, refrigerators are actually not an ideal storage environment for fresh produce. Not only is it difficult to ensure adequate humidity levels for your products, but the enclosed space and limited airflow of your refrigerator creates an ethylene trap that allows ethylene gas to build up. Whilst this build up of ethylene is not harmful to people, it is deadly to your fresh fruits and vegetables. Well, this does not apply to those who have refrigerators which expels ethylene gas with the new technology we have now.

So now you know what to do to hasten or slow down the ripening process of fruits and vegetables. =)

Friday, July 10, 2009

Charge me to life

Imagine if there is no such thing as a rechargeable battery.
You'll have to always buy new batteries for your cellphone, laptop, camera and many other electrical items (which do need batteries to run).
It'll be a huge waste of money, time and energy having to buy packets and packets of batteries again and again just to power up electrical appliances without wires.
Well fortunately for us, the existence of rechargeable batteries solved our problems pretty much.


All we need to do is to just charge the battery after it has been completely used.
Rechargeable batteries are also known as secondary cells.
The commonly used secondary cells are lead acid, nickel cadmium lead acid, nickel cadmium (NiCd), nickel metal hydride(NiMH), lithium ion (Li-ion), and lithium ion polymer(Li-ion polymer).
The main concept behind secondary cells is the redox reaction.
During charging, the positive active material is oxidized, producing electrons, and the negative material is reduced, consuming electrons. In other words, one half reaction of oxidation and another half reaction of reductions makes a complete redox reaction.

I shall focus on the 3 most commonly used secondary cells in this post.

  • Nickel-cadmium (NiCd)

Nickel-cadmium batteries has cadmium anode and nickel(III) oxyhydroxide cathode.
Anode is the positive electrode which undergoes oxidation while cathode is the negative electrode which undergoes reduction.
The electrolyte used in this reaction is potassium hydroxide (KOH).

The chemical reaction in nickel-cadmium battery during discharge is:
\mathrm{Cd + 2OH^- \rightarrow Cd(OH)_2 + 2e^-}

at the cadmium electrode, and

\mathrm{2NiO(OH) + 2H_2O + 2e^- \rightarrow 2Ni(OH)_2 + 2OH^-}

at the nickel electrode.

Therefore the net reaction during discharge is

\mathrm{2NiO(OH) + Cd +2 H_2O \rightarrow 2Ni(OH)_2 + Cd(OH)_2.}
When the battery is recharged, the reaction is reversed.
The flow of electrons from anode the cathode creates the electrical flow able to power up an electrical item.
  • Nickel-metal-hydride

The anode of the NiMH battery is nickel hydroxide. The active material for the negative electrode in the NiMH battery is actually hydrogen, the same as it is in a nickel hydrogen battery, except that the hydrogen ions (protons) are stored in the metal hydride structure which also serves as the cathode.
The electrolyte used here is also potassium hydroxide (KOH).
During discharge, the chemical reaction is as follows:

Anode:

\mathrm{Ni(OH)_2 + OH^- \leftrightharpoons NiO(OH) + H_2O + e^-.}

Cathode:

\mathrm{H_2O + M + e^- \leftrightharpoons OH^- + MH}.

The "metal" M in the negative electrode of a NiMH cell is actually an intermetallic compound. Many different compounds have been developed for this application, but those in current use fall into classes as shown in the table below.

AxBy Class

(Basis)

Components

Storage Capability (mA/g)

Comments

AB5

(LaNi5)

A: Mischmetal, La, Ce, Ti

B: Ni, Co, Mn, Al

300

Most commonly used alloy group for NiMH battery applications

AB2

(TiNi2)

A: V, Ti

B: Zr, Ni (+Cr, Co, Fe, Mn)

400

Basis of ‘multi-component alloys’ used in some NiMH battery systems

AB

(ZrNi)

A: Zr, Ti

B: Ni, Fe, Cr, V


Used in early development of hydrogen storage

A2B

(Ti2Ni)

A: Mg, Ti

B: Ni


Credits to http://www.cobasys.com/pdf/tutorial/InsideNimhBattery/inside_nimh_battery_technology.html.
  • Lithium-ion battery

The electrodes of this secondary cell may differ. However the most commonly used positive electrode is graphite (c) and the cathode is generally one of three materials: a layered oxide, one based on a poly anion, or a spinel.
Electrolytes used in Li-ion batteries consist of lithium salts in an organic solvent.
Li-ion battery mainly works by having the Li ions move from anode to cathode and then from cathode to anode. When a cell is discharging, the lithium is extracted from the anode and inserted into the cathode. When the cell is charging, the reverse process occurs: lithium is extracted from the cathode and inserted into the anode.
The reaction would be:

\mathrm{LiCoO_2} \leftrightarrows \mathrm{Li}_{1-x}\mathrm{CoO_2} + x\mathrm{Li^+} + x\mathrm{e^-}

With x as a variable coefficient based on moles.

Rechargeable batteries may cost more that normal batteries but the number of times we can recharge a battery back to life has already made every sen worth =)
Not forgetting also it does better for the environment compared to the disposable batteries.

About This Exothermic Blog

I'm exothermic. Face it.
I'm hot, and I shine through the crowd.

Alright that's not the truth. 'Exothermic' here would mean giving out information, not heat.
So I'm giving out information here!
What information you say?
My posts will be chemistry related. Chemistry in our daily life.
So you guys better be endothermic!
Endothermic??
Yes, as in taking in the information that I give in this very blog.
(chemistry lame joke I know)
So yah, enjoy your stay here.
Happy endothermic-ing!

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