8) Pumice and obsidian are both forms of volcanic glass. What are one similarity and one difference in the
composition of these two rocks? (p.150)
pumice
• igneous extrusive rock
composed largely of silica;
light in color, light enough to
float on water
• commonly used in soaps
and cleansers, concrete and
plaster
obsidian
igneous extrusive rock
composed largely of silica:
dark due todark-colored
minerals distributed within
• commonly used to make
jewelry and surgical
instruments

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Nconcentration refers to the molar concentration of an ion in solution. it may be identical to, or greater or less than, the molar concentration of the compound containing the ion that was used to make the solution. for soluble salts, the molarity of a particular ion is equal to the molarity of that compound times the subscript for that ion. for example, 1 m of alcl3 is 1 m in al3+ and 3 m in cl−. 1 m of (nh4)2so4 is 2 m in nh4+ and 1 m in so42−. part a what is the concentration of k+ in 0.15 m of k2s? view available hint(s) nothing m m part b if cacl2 is dissolved in water, what can be said about the concentration of the ca2+ ion? view available hint(s) if is dissolved in water, what can be said about the concentration of the ion? it has the same concentration as the cl− ion. its concentration is half that of the cl− ion. its concentration is twice that of the cl− ion. its concentration is one-third that of the cl− ion. part c a scientist wants to make a solution of tribasic sodium phosphate, na3po4, for a laboratory experiment. how many grams of na3po4 will be needed to produce 550 ml of a solution that has a concentration of na+ ions of 0.700 m ? express your answer numerically in grams. view available hint(s) mass of na3po4 n a 3 p o 4 = nothing g provide feedback

Acontrol during an experiment. might change remains constant does not exist does change

Complete each row of the table below by filling in the missing prefix or missing exponent.