Flame test sodium

Sodium flame test A test of HEPA filter efficiency using small particles generated from NaCl. 

BS 3928 Method for Sodium Flame Test for Air Filters. British Standards Institution, London, 1969. 

However, for the case of the effective nuclear charge Zeff for the excited outer electron in the sodium flame test, we found a noninteger value due to incomplete screening of the nuclear charge by the shell of electrons between the (n = 3, n = 4) shells of the atom and what we can call the Neon-core of the inner part of the Na atom. In the case of the L energy, the transition is from the (n = 3) —> (n = 2) level, so the K shell is between the L shell and the bare nucleus for sure. Further, the L shell may still be mostly occupied with perhaps one vacancy so the Ne core may be mostly intact. 

A technique that is somewhat easier to use is the sodium flame test, which produces an aerosol of sodium chloride particles, as with methylene blue, but assesses the dust content of the air upstream and downstream of the filter by the intensity of the yellow colour produced by the salt dust in a hydrogen flame (BS 3928). The size distribution of the salt dust is shown in Table 1.7, with a mean size around 0.6 pm, and no particle larger than 1.7 am. The colour of the flame is observed by a photosensitive cell connected to a meter, which can be calibrated to read the salt concentration directly. 

If an appreciable amount of residue remains, note its colour. Add a few drops of water and test the solution (or suspension) with htmus or with Universal indicator paper. Then add a httle dilute hydrochloric acid and observe whether efiervesceiice occurs and the residue dissolves. Apply a flame test with a platinum wire on the hydrochloric acid solution to determine the metal present. (In rare cases, it may be necessary to subject a solution of the residue to the methods of qualitative inorganic analysis to identify the metal or metals present.) If the flame test indicates sodium, repeat the ignition of the substance on platinum foil. 

The scheme that is shown in Figure 9.9 is very simple. More complex qualitative analyses involve many more steps of isolation and identification, including some steps that are not precipitation reactions. For example, some ions, such as sodium, Na", and potassium, K, cannot he precipitated out of an aqueous solution, because the ionic compounds that contain them are always soluble. Instead, chemists identify these ions using a flame test. In the following ThoughtLab, you will simulate a qualitative analysis that includes a flame test. 

Because its outet valence electrons ate at a gteatet distance from its nuclei, potassium is more reactive than sodium or lithium. Even so, potassium and sodium are very similar in their chemical reactions. Due to potassiums high reactivity, it combines with many elements, particularly nonmetals. Like the other alkali metals in group 1, potassium is highly alkaline (caustic) with a relatively high pH value. When given the flame test, it produces a violet color. 

Potassium and its salts can he identified hy flame test. It imparts hlac color to the flame. Potassium ion in aqueous solution can be identified by reaction with sodium tetraphenylborate, NaB(C6H5)4. In weakly acid solution, a white precipitate of the potassium salt KB(C6H5)4 is obtained. The precipitate is filtered, dried, and weighed to measure potassium. The test is quantitative. 

Marggraf independently recognizes the distinction between magnesia and lime, and uses flame tests to distinguish between the nitrates of sodium and potassium. 

Lithium Sodium Potassium Flame tests of alkali metals... 

Emission spectroscopy utilizes the characteristic line emission from atoms as their electrons drop from the excited to the ground state. The earliest version of emission spectroscopy as applied to chemistry was the flame test, where samples of elements placed in a Bunsen burner will change the flame to different colors (sodium turns the flame yellow calcium turns it red, copper turns it green). The modem version of emission spectroscopy for the chemistry laboratory is ICP-AES. In this technique rocks are dissolved in acid or vaporized with a laser, and the sample liquid or gas is mixed with argon gas and turned into a plasma (ionized gas) by a radio frequency generator. The excited atoms in the plasma emit characteristic energies that are measured either sequentially with a monochromator and photomultiplier tube, or simultaneously with a polychrometer. The technique can analyze 60 elements in minutes. 

FIGURE 16.18 Flame tests for (a) sodium (persistent yellow) and (b) potassium (fleeting violet). 

General Rules of Solubility as listed in Chapter 8 0.1 M solutions of the following compounds (these are the unknown solutions) Ag(N03) (silver nitrate), Ca(N03)2 (calcium nitrate), Cu(N03)2 (copper nitrate), NaOH (sodium hydroxide), KC1 (potassium chloride), Na2SC>4 (sodium sulfate), Nal (sodium iodide), and Na3PC>4 (sodium phosphate) eight small test tubes eight small disposable pipets pH paper one flame test wire in a cork glass plates a Bunsen burner and 3M HC1 (hydrochloric acid). 

Test 2. A 1 in 20 solution responds to the oxalate test for calcium, and to the flame test of sodium. 

Identification A sample responds to the flame test for Sodium, Appendix IIIA, and gives positive tests for Aluminum and for Sulfate, Appendix IIIA. 

Identification A 1 10 solution in 1 2 hydrochloric acid gives positive tests for Aluminum and for Phosphate, Appendix IIIA, and it responds to the flame test for Sodium, Appendix IIIA. Assay Not less than 9.5% and not more than 12.5% of AI2O3, calculated on the ignited basis. 

A table showing the colours imparted to the flame by salts of different metals is given in Section V.2(3). Carry out flame tests with the chlorides of sodium, potassium, calcium, strontium, and barium and record the colours you observe. Repeat the test with a mixture of sodium and potassium chlorides. The yellow colouration due to the sodium masks that of the potassium. View the flame through two thicknesses of cobalt glass the yellow sodium colour is absorbed and the potassium flame appears crimson. 

The most satisfactory precipitation for sodium ions is that with uranyl magnesium or zinc acetate (Section III.37, reactions 1 and 3). The flame test, in which an intense persistent yellow colouration is produced, is characteristic. Traces of sodium may be introduced from the reagents during the analysis, and hence it is important to look for a strong persistent yellow colouration a feeble yellow colouration may be ignored. 

Separation. In order to separate lithium from the other alkali metals, they are all converted into the chlorides (by evaporation with concentrated hydrochloric acid, if necessary), evaporated to dryness, and the residue extracted with absolute alcohol which dissolves the lithium chloride only. Better solvents are dry dioxan (diethylene dioxide, C4H802) and dry acetone. Upon evaporation of the extract, the residue of lithium chloride is (a) subjected to the flame test, and (b) precipitated as the phosphate after dissolution in water and adding sodium hydroxide solution. 

When electrolytic iron foil is immersed in concentrated solutions of jodium or potassium hydroxide for several weeks, and, after thorough cleaning, allowed to corrode in distilled water, the latter gradually becomes contaminated with traces of sodium or potassium salts, the bresence of which can be detected by the spectroscope or by the usual Bunsen flame test.6 Similar results have been obtained with lithium lydroxide, barium hydroxide, and with ammonia.7 It appears probable hat the alkali penetrates in minute quantities into the metal between he ferrite crystals, possibly in consequence of a certain amount of borosity in the intercrystalline cement. This theory is supported by he fact that iron which has been soaked in alkali invariably pits ... 

Clear liquid. Filter, if this liquid is not free from particles. Apply the flame test for sodium to this liquid. 

Experiment 143. — Recall (or determine again) the flame test, solubility in water, and color of the most common sodium compounds. Draw legitimate conclusions. 

The flame of an alcohol lamp looks almost colourless. Vhen a length of platinum v/ire which is dipped into a metal salt solutioh is put into the flame, the flame is coloured in the upper part by the wire. The colour is peculiar to the kind of the metal strontium colours the flame red, sodium yellow, barium pale green and copper blue. This is applied to the qualitative analysis of metal ions as the colour flame test. The emission of the coloured light is caused by atomic metal gas or a gas consisting of molecules of metal compound, and the process may be set out as follows ... 

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