در سال ۱۸۹۷ جوزف جان تامسون فیزیکدان انگلیسی به دنبال مطالعه پدیده های مربوط به تخلیه الکتریکی در گاز ها اولین بار نسبت e/m را برای الکترون اندازه گیری کرد. روش ما در این آزمایش مشابه روش تامسون است که از میدان های الکتریکی و مغناطیسی عمود بر هم استفاده کرد.
هدف این آزمایش نیز اندازهگیری e/m است.
Concentrating Sulfuric Acid (H2SO4)
Sulfuric acid is an incredibly useful chemical and is readily available in the form of ‘Battery Acid’ used in Lead-Acid batteries (such as those found in automobiles). One can purchase Sulfuric / Battery acid at a very reasonable price at local automotive stores; this acid will usually have a concentration of about 30% to 35% H2SO4 by weight, the remainder being water.
For many applications, 30% H2SO4 will be more than concentrated enough to meet one’s needs, however on occasion one might require a substantially higher concentration of Sulfuric acid. But purchasing concentrated Sulfuric acid can be much more costly and a greater hassle than buying battery acid, so a process which would enable one to concentrate Sulfuric acid oneself can sometimes be a desirable alternative.
Fortunately, such a process exists and is relatively simple to perform.
One can concentrate Sulfuric acid by heating the liquid and boiling off water from the solution, leaving concentrated H2SO4 behind. By following this procedure, Sulfuric acid solutions may be concentrated to upwards of 98% H2SO4 by weight.
A flame test is a procedure used to test qualitatively for the presence of certain metals in chemical compounds. When the compound to be studied is excited by heating it in a flame, the metal ions will begin to emit light. Based on the emission spectrum of the element, the compound will turn the flame a characteristic color. This technique of using certain chemical compounds to color flames is widely used in pyrotechnics to produce the range of colors seen in a firework display.
To perform a flame test, prepare a solution of the compound to be tested by dissolving it in deionized water. Next, clean an inert wire loop by submerging it in a dilute Hydrochloric acid solution then rinsing with deionized water. Repeat this process until no distinct color is seen after placing the loop into a flame. When the wire loop is clean, dip it into the solution to be tested and place the loop into the hottest part of a non-luminous flame. Observe and record the color change to the flame.