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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 國中

請問whether 子句當主詞,主詞補語或介系詞的受詞時為什麼不可以用if代替?還是可以給個例句嗎?謝謝!

(2) → 主要子句是疑問句,用問號 2. whether / if引導的名詞子句的用法 whether 和 if 都可引導 Yes No 問句形成的名詞子句,也都可以接 例 We have no idea whether / if Gail will come to the party (or not). (我們不知道 Gail 是否會來參加派對。) (1) whether 引導的名詞子句 使用時機 當主詞或主詞補 語 當受詞 (2)if引導的名詞子句 使用時機 當主詞或主詞補語 當受詞 句型變化及例句 2. or not 或省略。 | whether... or not 引導的名詞子句可以當「主詞」或「主詞補語」 15 Whether you can get the job (or not) is not important to me. (你是否能得到那份工作對我來說不重要。) whether... or not 引導的名詞子句可以當動詞或介系詞的「受詞」 例① Mark doesn't remember whether he paid for the meal (or not). (Mark 不記得他是否付過那頓飯的錢。)→ 當動詞的受詞 ② I'm worried about whether Jane can pass the test (or not). 當介系詞的受調 ( 我擔心 Jane 是否可以通過那個考試。 ) 句型變化及例句 → whether 子句當「主詞」或主詞補語時,不可以用if 代替。 ① whether 子句當介系詞的「受詞」時,不可以用 if 代替。 ② whether 子句當動詞的「受詞」時,可以用if 代替。 o Let me know whether you will stay. (讓我知道你是否會留下來。 = Let me know if you will stay. 進防

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