Questions and answers on the essentials of medical chemistry / By Lawrence Wolff.

  • Wolff, Lawrence.
Date:
1888
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Licence: Public Domain Mark

Credit: Questions and answers on the essentials of medical chemistry / By Lawrence Wolff. Source: Wellcome Collection.

Provider: This material has been provided by the Harvey Cushing/John Hay Whitney Medical Library at Yale University, through the Medical Heritage Library. The original may be consulted at the Harvey Cushing/John Hay Whitney Medical Library at Yale University.

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    Metals of the Alkalies. Which are the metals belonging to this group and their common characteristics ? Potassium, sodium, lithium, rubidium, ccesium, and am- monium. This latter though a compound is generally grouped with them. They are all soft, fusible, and volatile, have great affinity for oxygen, decompose water, readily forming basic oxides which with water yield caustic hydrates ; they form sol- uble carbonates and only one chloride. Potassium. What is potassium ? A waxy, bluish-white metallic element K1, a. w. 39, sp. gr. 0.8(35, melting at 62.5° C, distilling at red heat. What are its chemical properties ? It has a great affinity for O, tarnishes in the air, and if thrown on water it decomposes it; K-f H,0=KOH-fH liberat- ing H which ignites and burns with a violet flame. It has to be kept immersed in a hydrocarbon on this account. Where and how is K formed ? Potassium exists in nature only in compounds, both in minerals as well as in plants, from the latter of which it is largely ob- tained by leaching out their ashes after combustion; it is then termed potash or pearlash, which consists principally of K2COa. How is K separated from K,C03? By reduction of the carbonate with charcoal and distilled over K2C03+2C=2K+3CO. When metallic potassium is thrown on water how is the water affected after the reaction, and why ? The water will become alkaline after reaction on account of the formation of potassium hydrate KOII.