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自然科學 大學

為什麼[A(org)]=n[An(org)]成立 (第三張圖equation 7.9) 感謝

Experiment 7 Experiment 7 The partition of Organic acid between Water and Organic solvent Objectives Understand the partition of a solute between two immiscible solvents. Introduction A chemical analysis that is performed primarily with the aid of volumetric glassware (e.g., pipets, burets, volumetric flasks) is called a volumetric analysis. For a volumetric analysis procedure, a known quantity or a carefully measured amount of one substance reacts with a to-be-determined amount of another substance with the reaction occurring in aqueous solution. The volumes of all solutions are carefully measured with volumetric glassware. The known amount of the substance for an analysis is generally measured and available in two ways: 1. As a primary standard: An accurate mass (and thus, moles) of a solid substance is measured on a balance, dissolved in water, and then reacted with the substance being analyzed. 2. As a standard solution: A measured number of moles of substance is present in a measured volume of solution - a solution of known concentration, generally expressed as the molar concentration (or molarity) of the substance. A measured volume of the standard solution then reacts with the substance being analyzed. The reaction of the known substance with the substance to be analyzed, occurring in aqueous solution, is generally conducted by a titration procedure. The titration procedure required a buret to dispense a liquid, called the titrant, into a flask containing the analyte. A reaction is complete when stoichiometric amounts of the reacting substances are combined. In a titration this is the stoichiometric point. In this experiment the stoichiometric point for the acid-base titration is detected using a phenolphthalein indicator. Phenolphthalein is colorless in an acidic solution but pink in a basic solution. The point in the titration at which the phenolphthalein changes color is called the endpoint of the indicator. Indicators are selected so that the stoichiometric point in the titration coincides (at approximately the same pH) with the endpoint of the indicator.

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英文 高中

請問第16、17要怎麼作答

It's widely known that bees are important for our ecosystem and that they are facing increasing threats from modern agricultural practices involving pesticides. What many of us don't know, 16. (is that some industries should shoulder a bigger share of blame than they're given.) The almond industry, for instance, has quite an adverse impact on bee colonies. One potential harm to bee colonies is the stress caused by transporting them over long distances to almond orchards for the task of pollination. This transportation can be stressful for the bees, hence 17. them more vulnerable to diseases and pests. Moreover, since they're 18. having limited food sources aside from almond flowers further weakens bee colonies. Still another problem is the of honeybees to pesticides and other chemicals used in almond production. 19. 20. and One sustainable solution is to make habitats and species within almond orchards more stable. By creating various ecosystems and introducing other insects among almond trees, at least we can ensure enough food supply for bees and even lower the use of pesticides for almond trees in the long run. A 16. (A) therefore (B) however C17. (A) make A (B) made 18. (A) faced with a great increase in demand (C) looked after by beekeepers carefully (B) delivery 19. (A) cultivation 2 (C) in addition (D) for a start (C) making (D) to make (B) raised in their natural environment (D) physically removed from their habitat (C) exposure (D) restriction asant (D) particular

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