Imágenes de páginas

782. How would you obtain lead, tin, bismuth, silver, and potassium in well-defined crystals ?

783. Arrange in order of (a) fusibility, (6) ductility, (c) tenacity, (d) specific gravity, (e) conductivity, the following list of metals—iron, gold, mercury, silver, potassium, zinc, lead, lithium, platinum, antimony, copper, tin, and bismuth.

784. What property do you regard as most characteristic of the metals ?

785. When the terminals from a galvanic battery are placed in an easily decomposed metallic chloride, at which pole should the metal appear? How are the metals and metalloids classified from their electrical relations?

786. Define the terms “specific heat” and “atomic heat." How would you ascertain the specific heat of mercury and of sodium ?

787. A kilogramme of mercury at 100° C. was mixed with one of water at JO° C. The temperature of the mixture fell to 12.998 C. Find the specific heat of the mercury.

788. Describe Bunsen's ice calorimeter. 789. How does the determination of the specific heat

of an element serve to control the determination of combining weight?

790. How may the atomic heat of an element be ascertained from the molecular heat of one of its compounds ?

791. What are alloys and amalgams? What is remarkable about the fusing point of alloys ?

792. Explain the terms “atomicity of the elements » and " quantivalence of the metals."

793. Arrange the elements in the order of their combining weights from hydrogen to bromine, and point out any coincidences which that arrangement suggests.

short account of Mendelejeff's researches on the connection between the atomic weights and the chemical and physical properties of the elements.

795. Point out how Mendelejeff's classification has aided chemical investigations.

796. Give a short history of the various researches on light which led to the introduction of spectrum analysis by Bunsen and Kirchhoff.

797. Hów has spectrum analysis advanced our know

794. Give


ledge (a) of the sun and stars, (6) of the metals, (c) of the distribution of the elements ? :

798. Describe the construction of a spectroscope, and explain how it is used for the detection of (a) metallic salts, (6) gases, (c) coloured liquids such as blood, solution of permanganates, &c. What are absorption spectra?



799. How does lithium occur in nature ? From what sources, and how, are the lithium compounds prepared ?

800. How is the metal obtained, and what are its properties ? Give reasons for classing it with the alkali metals.

801. How much lithium by bulk would weigh the same as I c.c. of platinum ?

802. By what reactions is lithium distinguished from potassium and sodium ? How could small quantities of lithium salts be detected in a mineral water?


803. Mention the chief natural sources of sodiuin compounds. How is the metal prepared on the large scale, and what is it chiefly used for ?

804. Give a full account of Leblanc's process for the preparation of soda from common salt, and illustrate the changes which occur by equations.

805. What improvements on the original process of Leblanc have been recently introduced ?

806. In practice 1,800 lbs. of salt (containing 2'4 per cent. of impurities) are treated with 1,800 lbs. of vitriol having a specific gravity of 1'42 (= 52.8 per cent. H,SO.) for the preparation of salt-cake. Find how much hydrochloric acid and sodium sulphate should theoretically be obtained from these quantities of material.

807. For the preparation of black ash, 224 lbs. each of salt-cake and limestone are fused with 140 lbs. coal. What quantities are theoretically required for this weight of salt-cake ?

808. What are the chief constituents of commercial salt-cake, black ash soda ash, and caustic soda?

« AnteriorContinuar »