How to Grow a Big Alum Crystal

7/27/2019 How to Grow a Big Alum Crystal

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How to grow a big alum crystal

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by Ernest Capraro

Created on: September 03, 2007

Alum - potassium aluminum sulfate - KAl(SO4)2 is one of the more popular crystals to grow. This

may be because it makes a nice octahedral crystal that is visually appealling, or because it isn't

terribly toxic. It probably also has a lot to do with its very convenient solubility curve. The biggest

drawback, in my opinion, is that the crystal will be colorless.

Here are solubilities for anhydrous alum at a few temperatures:

Temperature (Celsius) Solubility (grams alum per 100 grams water)

20 12.0

50 36.8

70 94.4

80 195.0

If you are working with a hydrated alum sample (indicated on the label), multiply each solubility by

(N*18.02 + 258.2)/258.2 where N is the number of water molecules in the formula. (258.2 is themolar mass of alum, 18.02 of water)

To grow your crystal, you need to make a supersaturated solution of alum. This is done by making a

near-saturated solution of alum at a high temperature and allowing it to cool. If you want to grow a

single suspended crystal, hang a small "seed" crystal from a thread. It should be near the center of

the container to avoid merging with any smaller crystals that may form at the surfaces.

If you need detailed steps, try this:

1. Choose your container (probably a beaker) and fill it 2/3 - 3/4 full.

2. Measure the volume of the water and calculate its mass (1 mL ~ 1 g), or if you were clever, you

weighed the beaker before filling it, and you can weigh it again to see how much the water added.

3. Multiply the grams of water by the solubility at 80 degrees C (or the solubility at a lower

temperature if you don't want to use as hot a temperature) and measure out about that amount of

alum. (It's okay to use less, but don't go over.)
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4. Heat your beaker of water to 80 degrees C (use a thermometer) carefully. You don't want it to boil.

5. Stir in your alum while the water is hot, keep stirring until it is all dissolved. Remove the solution

from the heat.

6. Tie your seed crystal to a thread (sometimes you can get by with just rolling the thread in small

alum crystals/powder).

7. Tie the other end of the thread to a pencil, glass rod, or something else that can reach across the

top of the beaker. Make the string long enough that the crystal will hang halfway between the top of

the water and the bottom of the beaker.

8. Suspend the seed crystal in the hot solution.

9. Cover the beaker and let it sit for days/weeks. Keep an eye on it, but don't disturb it until you're

ready to take the crystal out.

10. When you're happy with the crystal you've made, or wish to begin again, just lift out the crystal

using your string.

Hint - Grow an even bigger crystal by repeating the procedure, but using your current crystal as the

seed crystal.

Hint - Crystal growing takes a lot of patience. You can't rush it when striving for a big crystal. On the

plus side, these crystals will last. My father helped me grow one when I was 8 (23 years ago) and I

still keep it hanging in my room. You can also help protect it from moisture by spraying it lightly with

hairspray


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PT LIKU TELAGAAnggota Gratis

PT LIKU TELAGA

[email protected]

Katalog Produk: Ammonium Alum ( Tawas Bening ) [17 Aug. 2010,11:37:13]

Negara Asal: Indonesia

Harga: Nego

Cara Pembayaran: Tunai

Kemas &Pengiriman:

50 Kg

Keterangan: Ammonium alum banyak digunakan dalam industri kosmetik,sebagai bahan bantu produk pangan dan lain sebagainya

Kenalkan ke teman Anda

Korespondensi Perusahaan

Nama: Tn. Danang Wiryanto [Pemasaran]

E-mail: [email protected]

Pesan Instan

Nomer HP: 0813 2847 3066

Nomer Telpon: 081328473066

Nomer Faks: 031-3951669

Alamat: KM 24 Desa Sukomulyo, Manyar Gresik, Jawa TimurIndonesia
mailto:[email protected]://likutelaga.indonetwork.co.id/prodhttp://indonetwork.co.id/recomm.html?prod+2092044mailto:[email protected]:[email protected]:[email protected]://likutelaga.indonetwork.co.id/prodhttp://indonetwork.co.id/recomm.html?prod+2092044mailto:[email protected]:[email protected]


4/5

(Gambar)

[email protected]

Aluminium Sulphate / tawas

Ammonium sulfat commonly digunakan untuk produk cosmetic, industri makanan dan kegunaanlainnya

Harga: Nego

Cara Pembayaran: Transfer Bank (T/T)

Kemas &Pengiriman:

zak



Nama: Tn. Santoso Akhmad [Direktur/CEO/Manajer Umum]


Pesan Instan

[email protected] HP: +623216114233/082139818849

Nomer Telpon: +62-321-396551

Nomer Faks: +62-321-396551

Alamat: Jl. Raya Gayaman no. 57Mojokerto, Jawa TimurIndonesia
mailto:[email protected]://indonetwork.co.id/recomm.html?prod+2502660mailto:[email protected]:[email protected]://www.google.com/talkmailto:[email protected]://indonetwork.co.id/recomm.html?prod+2502660mailto:[email protected]:[email protected]


5/5

(Gambar)

[email protected]

Katalog Produk: Aluminium Sulphate

Harga: 2700/Kg

Cara Pembayaran: Tunai

Kemas &Pengiriman:

Sack

Keterangan: Aluminium Sulphate / Tawas merupakan salah satu dari bahan

kimia yang sangat berguna dalam kehidupan kita, dimanaaluminium sulphate / tawas sering digunakan untuk menjernikanair, kosmetik dll



Nama: Tn. muhamad nur nur jannah [Penjualan]


Nomer HP: 085697208633

Nomer Telpon: 021. 96349552

Nomer Faks: 021.59371730

Alamat: jl. Albarokah III Rt/Rw 014/01 No.24 duri kosambi cengkarengjakarta barat 11750, JakartaIndonesia
mailto:[email protected]://al-kimia.indonetwork.co.id/prodhttp://indonetwork.co.id/recomm.html?prod+1317704mailto:[email protected]:[email protected]:[email protected]://al-kimia.indonetwork.co.id/prodhttp://indonetwork.co.id/recomm.html?prod+1317704mailto:[email protected]:[email protected]

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How to Grow a Big Alum Crystal