{"id":957,"date":"2019-10-14T14:27:19","date_gmt":"2019-10-14T14:27:19","guid":{"rendered":"http:\/\/chemdictionary.org\/?p=957"},"modified":"2019-10-14T14:35:15","modified_gmt":"2019-10-14T14:35:15","slug":"flame-test","status":"publish","type":"post","link":"https:\/\/chemdictionary.org\/flame-test\/","title":{"rendered":"Flame Test"},"content":{"rendered":"\n

Introduction<\/strong><\/h2>\n\n\n\n

The\nflame test is one of the most commonly used analytical processes in chemistry.\nIt is widely used to detect and analyze the presence of certain elements in the\ngiven salt or compound. Primarily, the flame test detects the presence of metal\nions in a compound, and as ions of each element have a specific characteristic\nbased in their emission spectrum, the flame test for every element is different\nand distinctive. <\/p>\n\n\n\n

This\ndistinction is shown by the color of flames given out when the salt containing\ncertain metal ions is burnt. <\/p>\n\n\n\n

It\nis important to note here that the emission spectrum of each element that\ndetermines the flame color involves atoms instead of ions. The transition of electrons\nin the atoms tends to produce the visible color lines which are seen in the\nflame test.<\/p>\n\n\n\n

Chemistry\nBehind Flame Test<\/strong><\/h2>\n\n\n\n

The\nchemistry behind the flame test is simple. As we know that when an atom or ion\nis excited by heating to high temperatures, the electrons are promoted from\ntheir normal unexcited state into other orbitals, known as higher orbitals, as\nthey have higher energy as compared to the normal or ground state orbitals.<\/p>\n\n\n\n

When\nthese excited electron falls back down to lower levels which can happen\nsimultaneously or in several steps, the energy they have absorbed is released.\nThis energy is released in the form of light.<\/p>\n\n\n\n

Each\njump involves the release of a specific amount of energy in the form of light. And\neach transition from higher to lower orbital corresponds to a frequency or wavelength.<\/p>\n\n\n\n

All these\njumps or transitions result in the formation of a spectrum of lines. Some of these\nlines are part of the visible part of the spectrum. <\/p>\n\n\n\n

And\nthe final color we see is a combination of all these individual colors. This\ncolor is the distinctive color of the element we observe in the flame test.<\/p>\n\n\n\n

For\ninstance, in the case of potassium or sodium ions or many other metal ions, the\ntransition of electrons involves very high energies. This result in lines that\nfall in the UV part of the spectrum which is invisible to the naked eye. <\/p>\n\n\n\n

This\nexplains the role of atoms rather than ions to be the basis of flame test.<\/p>\n\n\n\n

And the\njumps we can see in flame tests are due to falling of electrons from a higher\nto a lower level in the metal atoms.<\/p>\n\n\n\n

When\nwe put sodium chloride, containing sodium ions, into a flame, the sodium atoms are\nformed as a result of certain sodium ions that regain their electrons and\nproduce neutral sodium atoms again.<\/p>\n\n\n\n

The\norbitals and their configuration are very important features in each element with\nrespect to a flame test.   <\/p>\n\n\n\n

The\nstructure of the unexcited state of sodium atom 1s2<\/sup>2s2<\/sup>2p6<\/sup>3s1<\/sup>\nand within the flame, there are different sorts of excited states of the\nelectrons.<\/p>\n\n\n\n

Sodium\ngives a bright orange-yellow flame color. This results from promoted electrons\nfalling back from the 3p1<\/sup> level to their normal 3s1<\/sup>\nlevel.<\/p>\n\n\n\n

The\nexact size of the potential energy jumps varies from one metal to another. <\/p>\n\n\n\n

This\nmeans that each metal will have a different pattern of spectral lines, and so have\na distinct flame color.<\/p>\n\n\n\n

The\nelements of the Group1 are the easiest metals that can be accurately identified\nusing the flame test.<\/p>\n\n\n\n

For\nother metals, flame test does not provide a definitive identification, however,\nit gives a general idea of the probable compound.<\/p>\n\n\n\n

Practical\nProcess Detail<\/strong><\/p>\n\n\n\n

The procedure\nof this test is simple as it involves introducing sample of the compound or\nelement to a non-luminous, hot flame, and examining the color of the resulting flame.\n<\/p>\n\n\n\n

The flame\ntest is an easy experiment to set up and is often conducted in science classes.<\/p>\n\n\n\n

The principle\nof the test is that the atoms of the sample evaporate and as they are hot, they\ngive off light when present in the flame. <\/p>\n\n\n\n

A mixture\nof samples of a large amount of sample can also emit light. But such light is\nnot good for identification analysis. <\/p>\n\n\n\n

As\ndescribed earlier, the individual atoms of a sample that are present in the\nflame emit light due to the transitions of electron between different atomic\nenergy levels. Such transitions emit light that has very specific frequencies, and\nwhich is the characteristic of the chemical element.<\/p>\n\n\n\n

Hence, the\nflame gets the color. And it is determined by the characteristics and properties\nof the chemical element of the material that is introduced into the flame. <\/p>\n\n\n\n

There are\ncertain points that need to be followed to obtain precise results in a flame\ntest.<\/p>\n\n\n\n

For\ninstance, the samples are carried on a platinum wire, which is repeatedly cleaned\nwith hydrochloric acid (HCl) to remove traces of any elements.<\/p>\n\n\n\n

The\ncompound to be assessed is usually made into a paste with concentrated\nhydrochloric acid, as it is volatile, and give good quality results. <\/p>\n\n\n\n

It is also\nrecommended to use different flames to avoid errors in the results due to contaminated\nflames, and to confirm the precision of the color. <\/p>\n\n\n\n

The\npresence of sodium is considered as a common component in many compounds. And\nits spectrum is likely to dominate the light spectrum of other elements. To\navoid this, the test flame is often viewed using a cobalt blue glass that\nfilters out the yellow of sodium and allows the accurate presentation of color\nof other metal. <\/p>\n\n\n\n

Flame\nTest Results of Common Elements<\/strong><\/h2>\n\n\n\n

Here\nis the list of most common elements that are detected through the flame test.\nThey have a distinct emission spectrum that allows them to show specific\ncolored flame in a flame test. However, the colors given in the table are only\na guide as colors are perceived differently by different people. <\/p>\n\n\n\n
\n Sr #\n <\/td>\n Element\n <\/td>\n Symbol\n <\/td>\n Color\n <\/td><\/tr>
\n 1\n <\/td>\n Sodium\n <\/td>\n Na\n <\/td>\n Intense Yellow\n <\/td><\/tr>
\n 2\n <\/td>\n Potassium\n <\/td>\n K\n <\/td>\n Intense Yellow Orange\n <\/td><\/tr>
\n 3\n <\/td>\n Calcium\n <\/td>\n Ca\n <\/td>\n Orange Red\n <\/td><\/tr>
\n 4\n <\/td>\n Lithium\n <\/td>\n Li\n <\/td>\n Red\n <\/td><\/tr>
\n 5\n <\/td>\n Strontium\n <\/td>\n Sr\n <\/td>\n Red\n <\/td><\/tr>
\n 6\n <\/td>\n Barium\n <\/td>\n Ba\n <\/td>\n Pale green\n <\/td><\/tr>
\n 7\n <\/td>\n Copper\n <\/td>\n Cu\n <\/td>\n Blue-green\n <\/td><\/tr>
\n 8\n <\/td>\n Cesium\n <\/td>\n Cs\n <\/td>\n Blue\n <\/td><\/tr>
\n 9\n <\/td>\n Iron\n <\/td>\n Fe (II)\n <\/td>\n Gold\n <\/td><\/tr>
\n 10\n <\/td>\n Germanium\n <\/td>\n Ge\n <\/td>\n Pale blue\n <\/td><\/tr>
\n 11\n <\/td>\n Mercury\n <\/td>\n Hg\n <\/td>\n Red\n <\/td><\/tr>
\n 12\n <\/td>\n Nickel\n <\/td>\n Ni\n <\/td>\n Silver-white\n <\/td><\/tr>
\n 13\n <\/td>\n Hafnium\n <\/td>\n Hf\n <\/td>\n White\n <\/td><\/tr>
\n 14\n <\/td>\n Phosphorus\n <\/td>\n P\n <\/td>\n Pale bluish green\n <\/td><\/tr>
\n 15\n <\/td>\n Molybdenum\n <\/td>\n Mo\n <\/td>\n Yellowish Green\n <\/td><\/tr>
\n 16\n <\/td>\n Manganese\n <\/td>\n Mn\n <\/td>\n White\n <\/td><\/tr>
\n 17\n <\/td>\n Tin\n <\/td>\n Sn\n <\/td>\n Blue-white\n <\/td><\/tr>
\n 18\n <\/td>\n Zinc\n <\/td>\n Zn\n <\/td>\n Colorless or bluish-green\n <\/td><\/tr>
\n 19\n <\/td>\n Lead\n <\/td>\n Pb\n <\/td>\n Bluish white\n <\/td><\/tr>
\n 20\n <\/td>\n Zirconium\n <\/td>\n Zr\n <\/td>\n Light red\n <\/td><\/tr>
\n 21\n <\/td>\n Radium\n <\/td>\n Ra\n <\/td>\n Crimson\n <\/td><\/tr>
\n 22\n <\/td>\n Chromium\n <\/td>\n Ch\n <\/td>\n Silver-white\n <\/td><\/tr>
\n 23\n <\/td>\n Cadmium\n <\/td>\n Cd\n <\/td>\n Brick red\n <\/td><\/tr>
\n 24\n <\/td>\n Arsenic\n <\/td>\n As\n <\/td>\n Blue\n <\/td><\/tr><\/tbody><\/table>\n\n\n\n

Certain precious metals,\nincluding platinum, titanium, palladium, gold, and silver do not produce a distinctive flame\ncolor. However, some can produce sparks when exposed to hot flame.<\/p>\n\n\n\n

Safety Notes<\/strong><\/p>\n\n\n\n

The flame test can be dangerous if proper protocol and safety measures\nare not taken. It is advised to use good safety techniques.  We should wear a chemical apron and good\nquality chemical splash resistant goggles. It is also important that we practice\nthe flame test under the supervision of a teacher.   <\/p>\n\n\n\n

References<\/strong><\/p>\n\n\n\n

https:\/\/www.soinc.org\/sites\/default\/files\/uploaded_files\/flametest.pdf<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

Introduction The flame test is one of the most commonly used analytical processes in chemistry. It is widely used to detect and analyze the presence of certain elements in the given salt or compound. Primarily, the flame test detects the presence of metal ions in a compound, and as ions of each element have a … Read more<\/a><\/p>\n","protected":false},"author":6,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"rating_form_position":"","rating_results_position":"","mr_structured_data_type":""},"categories":[4],"tags":[],"multi-rating":{"mr_rating_results":[{"adjusted_star_result":4.25,"star_result":4.25,"total_max_option_value":5,"adjusted_score_result":4.25,"score_result":4.25,"percentage_result":85,"adjusted_percentage_result":85,"count":12,"post_id":957}]},"_links":{"self":[{"href":"https:\/\/chemdictionary.org\/wp-json\/wp\/v2\/posts\/957"}],"collection":[{"href":"https:\/\/chemdictionary.org\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/chemdictionary.org\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/chemdictionary.org\/wp-json\/wp\/v2\/users\/6"}],"replies":[{"embeddable":true,"href":"https:\/\/chemdictionary.org\/wp-json\/wp\/v2\/comments?post=957"}],"version-history":[{"count":2,"href":"https:\/\/chemdictionary.org\/wp-json\/wp\/v2\/posts\/957\/revisions"}],"predecessor-version":[{"id":985,"href":"https:\/\/chemdictionary.org\/wp-json\/wp\/v2\/posts\/957\/revisions\/985"}],"wp:attachment":[{"href":"https:\/\/chemdictionary.org\/wp-json\/wp\/v2\/media?parent=957"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/chemdictionary.org\/wp-json\/wp\/v2\/categories?post=957"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/chemdictionary.org\/wp-json\/wp\/v2\/tags?post=957"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}