Percobaan kimia sederhana : Mewarnai Telur (Dyes of the Eggs for Easter)

Simple experiment in home

In Easter, some people especially parents that want doing for their children tried to make colored eggs. For the best treatment, it is recommended to use natural dyes such as from fruits or vegetables.
How to make it :
first of all, I will give some materials that we need, (1) water, (2)dyes (natural), (3)vinegar, (4)hard boiled eggs. Some equipment you need are (1)pan, (2)spoon.(3)stove.
After all things are prepares, put the eggs in pan and add water until the eggs are covered. Then add 1 teaspoon of vinegar, and natural dyes (colored you want). Boil that approximately 15 minutes and look at the quality of color you want, if it is enough, take the eggs, or if you want deeper color let them some minutes.

Valentine, Chocolate and Science

taken from The Science of Chocolate
by Stephen T. Beckett
Royal Society of Chemistry: Cambridge, 2000. xiii + 175 pp.
ISBN 0-85404-600-3. reviewed by Jeffrey Kovac


Like most people, I am fond of chocolate. My favorites
are the dark bittersweet chocolates, but I enjoy eating it in
almost any form. However, until I read The Science of Chocolate,
I didn’t realize how interesting chocolate is as a material.
Consider: chocolate is a solid at room temperature, but
melts into a smooth viscous liquid at body temperature
(“melts in your mouth, … .”). What other food has this property?
I can’t think of any. When you break a chocolate bar, it
snaps, so there must be something crystalline in it to give
that rigidity. Most of us have put some chocolate away for
another day, forgotten about it, then returned months later
to find the glossy brown surface marred by a white “bloom”.
The candy is usually still edible, though it doesn’t taste quite
as good. I’ve always wondered why this happens and precisely
what the white stuff is.
The Science of Chocolate is a concise, readable survey of
the history, manufacture, biology, physics, and chemistry of
chocolate. The author, Stephen T. Beckett, works for Nestlé
and is well versed in his subject. While the book is probably
best suited to those studying food science and technology,
there is a lot of interesting chemistry in its pages. Chocolate
is an interesting example of many of the principles that are
taught somewhere in the chemistry curriculum.
One of the important issues in chocolate manufacture
is controlling the flow properties of liquid chocolate. Much
of the taste and sensual pleasure in eating chocolate comes
from its smooth flow in the mouth. Chocolate is a complex,
composite material containing cocoa particles, sugar particles,
and fat, mainly cocoa butter and milk fat. To get good flow
properties, the cocoa particles must be ground finely—otherwise
the chocolate is gritty—but also with a distribution of
particle sizes. The solid particles, however, must be coated
with fat to get them to flow, so there are important problems
in surface chemistry to consider. While the cocoa particles
are lipophilic, the sugar particles are not, so an emulsifier,
usually lecithin, is needed. The mixture is a Bingham
fluid requiring a nonzero shear stress to get it moving, but
also shear thinning, which means that the viscosity decreases
as the shear rate increases. Ketchup is another familiar example
of a Bingham fluid.
The familiar snap when a chocolate bar is broken occurs
because the fats are partly crystalline. Since cocoa butter is a
mixture of triglycerides, its phase behavior is complex. There
are at least six different crystal phases: the desirable form for
confections, called form V, has a melting point about 33 °C.
The molten chocolate must be “tempered” to produce seed
crystals so that the final product contains mainly this desirable
crystalline phase rather than the lower-melting forms. But
there is a more stable, and more dense, phase, form VI, which
can be produced in the final product in a slow solid–solid
transformation. If this occurs, some of the fat will be forced
to the surface, causing the white fat bloom that makes the
confection unattractive and less pleasant to eat.
This is fascinating science, all contained in the humble
chocolate bar. Once I started reading The Science of Chocolate,
I found myself carried along by the connections to things I
have learned and taught over the years. I will be able to use
chocolate as an example in several courses that I regularly
teach. This is a book that I will recommend to students to
show them how the basic science they are learning is used to
manufacture and improve one of their favorite foods. Chapter 10 contains 18 experiments for students to perform, so it could easily be a lab
course as well. Of course, our library should have a copy. Best
of all, it makes the eating of chocolate a richer experience.

Vitamin D lack with Pesticide

Pesticides could be suppressing people's vitamin D levels, leading to deficiency and disease, say scientists. The warning follows the discovery that adults with high serum concentrations of organochlorine pesticides such as DDT have lower vitamin D levels.

Exposure to lose doses of organochlorine pesticides has been previously linked to common diseases like type 2 diabetes, metabolic syndrome and cardiovascular disease. Vitamin D deficiency has similarly been associated with a rise in chronic diseases, but the two have been studied separately by researchers in different fields. 'The known associations between vitamin D deficiency and various diseases can be at least partly be explained by the common exposure to organochlorine pesticides,' says senior author Duk-Hee Lee of Kyungpook National University in Korea.

The US-Korean research team studied 1275 adults in the US aged 20 years or older and checked their blood for seven organochlorine pesticides. DDT and beta-hexachlorocyclohexane levels in study volunteers showed significant associations with lower serum concentrations of a vitamin D pre-hormone, 25-hydroxyvitamin D, which is the standard way to assess vitamin D levels in the body. The study sheds no light on how pesticides might influence vitamin D levels, though.

Organochlorine pesticides were banned in the US decades ago, but are still detectable in people because they resist biodegradation in the environment, are lipophilic and accumulate in fat tissues. The World Health Organization still recommends the use of DDT to control mosquitoes in malarial regions and, while there is a global moratorium on spraying it on crops, illegal use in some countries is suspected.

Levels of these chemicals are far lower than they were in the 1960s and 1970s, but Lee believes that they may still be significant because they act as endocrine disruptors. 'One characteristic of endocrine disruptors is that they show their possible harmful effects at levels lower than those which we currently think are safe,' Lee says. 'As chemicals like organochlorine pesticides travel a long distance through a variety of ways, humans can be exposed to these kinds of chemicals even though the country where they live does not use them anymore.'

'We have known for many years that DDT causes egg shell thinning,' says David Carpenter, director of the institute for health and environment at the University of Albany, New York. 'Since egg shell thickness is regulated by vitamin D, this study shows that the same suppression of vitamin D occurs in humans.' Carpenter says he is concerned about the push to bring DDT back into use as a potent pesticide against mosquitoes and other insects. 'It is very important to communicate how harmful DDT is to humans, not just mosquitoes.'

Eksperimen Kimia sederhana : The Blue-Bottle

Kimia mengajarkan kita untuk tahu apa yang ada di sekitar kita. Termasuk sebagai seorang pengajar, entah itu dosen ataupun guru akan sangat menyenangkan jika bisa menyampaikan materi kimia dengan menarik. Salah satunya adalalah dengan eksperimen kimia. Hari ini saya ikut mendampingi praktikum mata kuliah IPA di kelas calon guru SD di Muenster University, Jerman. Berikut kami sajikan satu dari beberapa percobaan kimia sederhana, contoh lain percobaan di berbagai negara juga ada di youtube:

Blue-Bottle Experiment : Reaksi kimia dalam botol berisi larutan tak berwarna, terdiri dari metilen blue, glukosa, dan larutan NaOH.
Reaksi ini adalah contoh dari reaksi redoks. Glukosa dalam larutan basa akan teroksidasi oleh oksigen yang berasal dari udara dalam botol dan secara perlahan membentuk asam glukonat. Metilen blue berfungsi sebagai oksidator untuk glukosa. Metilen Blue akan tereduksi menjadi leukometilen blue dan menghasilkan larutan tidak berwarna. setelah kita menggoyangkan botol kembali dengan tersedia oksigen dalam larutan maka leucometilen blue akan teroksidasi kembali dan menghasilkan larutan biru. Kembali didiamkan akan bening kembali dan seterusnya.

http://www.youtube.com/watch?v=61ek9u9TlfA

Source : Shakhashiri, B.Z. Chemical Demonstrations: A Handbook for Teachers of Chemistry

Big "Katastrophe"

This is the word I found after discussing with my supervisor. The theme is about Indonesian school system that started 2006. The government has decided some schools such as elementary, junior and senior high school included university to implement international standard class. There are some standards related to them especially in classroom learning.

The minimum instruction can be conducted in bilingual. of course English and Bahasa Indonesia. I make underlined in chemistry classes. Chemistry is one of subjects that perceived by students as difficult one. Every teacher tries to make the students well understood about the lesson in Bahasa Indonesia. But some of the students don't really know what they are learning. Can you imagine what will happen if two languages applied? is that as a big Catastrophe?

Lab School Workshop 2010

Sebelas Maret University (Solo-UNS) as one member of the Consortium of Higher Education Indonesia - Pittsburgh (KPTIP) for five days, 19-23 April 2010 hosted the "International Workshop: Establishment and Management of Laboratory Schools". International Workshop on Establishing and Managing Laboratory Schools organized by FKIP UNS UNS and the International Office at Sahid Kusuma Hotel is one of the activities of 11 (eleven)KPTIP program strategic plans. According to Chairman Panita, Dra. Dewi Rochsantiningsih, M. Ed, PhD, this workshop presents 9 (nine) speakers, two of which are:

Prof. Wendell McConnaha, Lab Director Falk School, University of Pittsburgh
Prof. This Knight, Dean Clemmer College of Education, East Tennessee State University
Other speakers of information derived from:
Desentralised Basic Education (DBE-2) USAID
State University of Malang
UNS-Solo

Workshop participants is about 40 people who came from 15 universities in Indonesia KPTIP members, LPTK FKIP Forkom members throughout Indonesia, and Higher Education in Central Java.
The purpose of this workshop is held:
improve understanding of the concept and essence Labschool college-based;
improve the ability of the formation of needs assessment / renewal Labschool;
improve the skills of identifying needs and funding sources Labschool formation;
improve preparedness for managing Labschool associated with leadership;
improve the ability of networking with stakeholders;
improve the quality of learning and the quality of self through Action Research.

Additionally this workshop also targets the formation of associations Labschool throughout Indonesia.

Launching "Laskar Pelangi" as one of Indonesian edu film

Great news for us....
A great film that is adapted from best seller book in Indonesia will be launched soon.
In september 2008, Indonesian can enjoy and feel how education can wake us up. Based on Film Director Report, it has been finishing in Bangka Belitung as the origin settings, and will be completed in Thailand.

"laskar pelangi" will be launch not only in cinema but also in "Layar Tancap" for serving areas that do not support cinema/movie theater. "Nidji" will be primary soundtract artist. Song inspired by Laskar Pelangi will be added with Netral, Gita Gutawa, Sherina, Ipang, Garasi, Float, Gugun and Bluesbugs.

Viva Academica :)

http://belajarkimia.net/

(http://belajarkimia.net)It is one of online learning models based on web. Students can learn chemistry nice and enjoyable while they are using internet connection. it is completed with interesting performances. Teachers and Students can conduct interactive learning via this model.

plastics around us

perhatikan pada tempat minuman yang kamu jumpai di sekitarmu....
temukan kode label nomor yang ada di bawah botol plastik itu dan cocokkan apa kah kamu benar dalam memilih..

#1. PETE atau PET (polyethylene terephthalate) biasa dipakai untuk botol plastik yang jernih/transparan/tembus pandang seperti botol air mineral, botol jus, dan hampir semua botol minuman lainnya. Boto-botol dengan bahan #1 dan #2 direkomendasikan hanya untuk sekali pakai. Jangan pakai untuk air hangat apalagi panas. Buang botol yang sudah lama atau terlihat baret-baret.

#2. HDPE (high density polyethylene) biasa dipakai untuk botol susu yang berwarna putih susu. Sama seperti #1 PET, #2 juga direkomendasikan hanya untuk sekali pemakaian.

#3. V atau PVC (polyvinyl chloride) adalah plastik yang paling sulit di daur ulang. Plastik ini bisa ditemukan pada plastik pembungkus (cling wrap), dan botol-botol. Kandungan dari PVC yaitu DEHA yang terdapat pada plastik pembungkus dapat bocor dan masuk ke makanan berminyak bila dipanaskan. PVC berpotensi berbahaya untuk ginjal, hati dan berat badan.

#4. LDPE (low density polyethylene) biasa dipakai untuk tempat makanan dan botol-botol yang lembek. Barang-barang dengan kode#4 dapat di daur ulang dan baik untuk barang-barang yang memerlukan fleksibilitas tetapi kuat. Barang dengan #4 bisa dibilang tidak dapat di hancurkan tetapi tetap baik untuk tempat makanan

#5. PP (polypropylene) adalah pilihan terbaik untuk bahan plastik terutama untuk yang berhubungan dengan makanan dan minuman seperti tempat menyimpan makanan, botol minum dan terpenting botol minum untuk bayi. Karakteristik adalah biasa botol transparan yang tidak jernih atau berawan. Cari simbol ini bila membeli barang berbahan plastik

#6. PS (polystyrene) biasa dipakai sebagai bahan tempat makan styrofoam, tempat minum sekali pakai, dll. Bahan Polystyrene bisa membocorkan bahan styrine ke dalam makanan ketika makanan tersebut bersentuhan. Bahan Styrine berbahaya untuk otak dan sistem syaraf. Selain tempat makanan, styrine juga bisa didapatkan dari asap rokok, asap kendaraan dan bahan konstruksi gedung. Bahan ini harus dihindari dan banyak negara bagian di Amerika sudah melarang pemakaian tempat makanan berbahan styrofoam termasuk negara China.

#7. Other (biasanya polycarbonate) bisa didapatkan di tempat makanan dan minuman seperti botol minum olahraga. Polycarbonate bisa mengeluarkan bahan utamanya yaitu Bisphenol-A ke dalam makanan dan minuman yang berpotensi merusak sistem hormon. Hindari bahan plastik Polycarbonate

yang paling aman botol yang berkode no #4 & #5
tapi kode #7 masi diperdebat kan karena di amrik bisphenol-A aman buat makanan

botol plastik air mineral sebaiknya jangan di pakai berulang2 karena botol kode #1 cuma layak di gunakan 1x

Atomic Structure

Matter has mass and takes up space. Atoms are basic building blocks of matter, and cannot be chemically subdivided by ordinary means.
The word atom is derived from the Greek word atom which means indivisible. The Greeks concluded that matter could be broken down into particles to small to be seen. These particles were called atoms
Atoms are composed of three type of particles: protons, neutrons, and electron. Protons and neutrons are responsible for most of the atomic mass e.g in a 150 person 149 lbs, 15 oz are protons and neutrons while only 1 oz. is electrons. The mass of an electron is very small (9.108 X 10-28 grams).
Both the protons and neutrons reside in the nucleus. Protons have a postive (+) charge, neutrons have no charge --they are neutral. Electrons reside in orbitals around the nucleus. They have a negative charge (-).
It is the number of protons that determines the atomic number, e.g., H = 1. The number of protons in an element is constant (e.g., H=1, Ur=92) but neutron number may vary, so mass number (protons + neutrons) may vary.
The same element may contain varying numbers of neutrons; these forms of an element are called isotopes. The chemical properties of isotopes are the same, although the physical properties of some isotopes may be different. Some isotopes are radioactive-meaning they "radiate" energy as they decay to a more stable form, perhaps another element half-life: time required for half of the atoms of an element to decay into stable form. Another example is oxygen, with atomic number of 8 can have 8, 9, or 10 neutrons.

International Standard School

This year, some secondary high schools implement learning with international based. Especially in school with higher quality from others. They give additional treatment learning to students. They are learning in english, references in english, and many more related to english learning standard. School management give higher fees for students in it. The Students' parents hope their children can get more qualified than others, but how does it work in reality?
We have to see school competences related to resources required, infrastructures, and how prepare school?