Wednesday, March 2, 2011

How to Find the Empirical Formula

By: fajar sadiq
As a student of chemistry , is it very importand to understand how to find the Empirical Formula. We know that Empirical Formula is the simplest ratio of the atoms present in a molecule.
One sample of problem about EF like this:
“Find the empirical formula for a compound consisting of 63% Mn and 37% O”
The steps for solving that problems are:
1.Assume you have 100 gr of the compound
2.Consider the amounts you are given as being in units of grams.
So, there would be:
Mn = 63% x 100 gr = 63 gr
O = 37% X 100 gr = 37 gr
3.Convert the grams to moles for each element.
Do this by dividing the mass of element by the Atomic Relative Mass of element
(Look up the Periodic Table)
Mn = 63 / 54,94 = 1,1 mol
O = 37 / 16 = 2,3 mol

4.Find the smallest whole number ratio of moles for each element.
This step can achieved by dividing the number of moles of each element by the
number of moles for the element present in the smallest molar amount. In this case
there is less Mn than O, so divide by the number of moles of Mn:
1,1 mol Mn/1,1 = 1 mol Mn
2,3 mol O/1,1 = 2,1 mol O
The best ratio is Mn:O of 1:2 and the formula is MnO2
The empirical formula is MnO2

Terjemah bebas:
Dimapa manciri i Rumus Empiris

Amun handak pintay jadi murid nang balajar kimia, panting bangat ya’ paham kayapa caranya urang mancari rumus impiris matan suatu sanyawa. Tahu ja kalo leh, rumus impiris tu kada lain adalah kita tanding akan banyaknya satiap atum dalam mulekul , tapi dalam parbandingan nang paling sadarhana.

Sabuah cuntuh sual rumus impiris nang kaya naya:
“Cari I pang rumus impiris dari sanyawa nang didalamnya baisi 65% Mn wan 37% O.

Nah, dimapa caranya, umpati haja langkah2 kaya ni nah:
1.Anggap ja ikam baisi senyawa tu 100 gram
2.Maka kawa di hitung gram tiap unsurnya
Mn = 63% x 100 gr = 63 gr
O = 37% X 100 gr = 37 gr

3.Lalu ubah gram tadi ka mol, caranya bagi haja gram unsur wan Ar nya(liati di Sistem
Periodik)
Mn = 63 / 54,94 = 1,1 mol
O = 37 / 16 = 2,3 mol


4.Carii parbandingan paling sadarhana. Bagi haja hasil hitungan mol tadi lawan mol
nang paling halus.
1,1 mol Mn/1,1 = 1 mol Mn
2,3 mol O/1,1 = 2,1 mol O
Hasilnya parbandingan Mn : O kita sadarhana akan, jadinya = 1 : 2
Akhirnya tatamu rumus empris sanyawa tadi adalah MnO2

5 comments:

  1. melalui penjelasan yang sangat gamblang, maka belajar kimia menjadi lebih gampang...

    ReplyDelete
  2. Bener Bli, jadi para guru harus terus mikir gimana caranya menyampaikan materi dengan penjelasan yg gambang itu. Thk's kunjungannnya.

    ReplyDelete
  3. Pembahasan yang gamblang, sangat bermanfaat bagi kita semua

    Salam sukses

    ReplyDelete
  4. Salam persohiblogan
    Baru update dan BW lagi nih daku

    Teruslah berbagi ilmu :)

    ReplyDelete
  5. @padamara: Salam sukses juga Pak, terima kasih kunjungannya

    @cucuharis: salam juga Mas, semoga makin manfaat. Thks

    ReplyDelete