The alkali metals are so reactive that they are never found in nature in elemental form. Although some of their ores are abundant, isolating them from their ores is somewhat difficult. For these reasons, the group 1 elements were unknown until the early 19th century, when Sir Humphry Davy first prepared sodium (Na) and potassium (K) by passing an electric current through molten alkalis. (The ashes produced by the combustion of wood are largely composed of potassium and sodium carbonate.) Lithium (Li) was discovered 10 years later when the Swedish chemist Johan Arfwedson was studying the composition of a new Brazilian mineral. Cesium (Cs) and rubidium (Rb) were not discovered until the 1860s, when Robert Bunsen conducted a systematic search for new elements. Known to chemistry students as the inventor of the Bunsen burner, Bunsen’s spectroscopic studies of ores showed sky blue and deep red emission lines that he attributed to two new elements, Cs and Rb, respectively. Francium (Fr) is found in only trace amounts in nature, so our knowledge of its chemistry is limited. All the isotopes of Fr have very short half-lives, in contrast to the other elements in group 1.
<span>3 AgNO3 + FeCl3 = Fe(NO3)3 + 3 AgCl
moles AgNO3 = 18.0 g/ 169.87 g/mol=0.106
moles FeCl3 required = 0.106/3=0.0353
mass FeCl3 = 162.206 g/mol x 0.353 mol=5.73 g
mass FeCl3 in excess = 32.4 - 5.73 =26.7 g.
26.7 gram of excess reactant remain after the reaction is over</span>
532 mg of hemoglobin
Explanation:
The concentration of hemoglobin in the blood is 15.2 g/dL. It we transform the g in mg and the dL in mL we have the value for the concentration to be 15200 mg / 100 mL.
Knowing the concentration we devise the following reasoning:
if there are 15200 mg of hemoglobin in 100 mL of blood
then there are X mg of hemoglobin in 3.5 mL of blood
X = (15200 × 3.5) / 100 = 532 mg of hemoglobin
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mass per volume concentration
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