Test-exam 2

078mgca 1mmolca 1molca l 22 when preparing the 100 ml

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Unformatted text preview: t is the expected minimum volume in milliliters required to dissolve the CaCO3(s) with 6M HCl? a. 100 b. 25.2 c. 10.1 d. 0.84* e. Impossible to pre-determine this except through experimentation. Ans. The reaction is CaCO3 ( s ) 2 HCl (aq) CaCl2 (aq) H 2O CO2 ( g ) The number of mL needed is therefore, 0.2512 gCaCO3 100.087 gCaCO3 / molCaCO3 2molHCl 1L 1000mL 0.84mL 1molCaCO3 6molHCl 1L 14 23 In the Buffers & Indicators (B&I) experiment, the following equations are introduced and used in solving a postlab problem, A bc AT 1 bc1 2bc2 (1) (2) In the Atomic Absorption Spectrometry – Calcium (AA) experiment, one of the key equations used in analyzing the experimental data is Csam AsamCstdVstd ( Asam std Asam )Vsam (3) where Cstd and Csam are measured in µg/mL and Vstd and Vsam, in mL. A is the absorbance which is defined as A 2 log %T , T log( I / I o ) Asam k and I represents intensity of the signal. Equation (3) is shown to be derived from Asam VsamCsam (4) Vtotal VC VC k sam sam k std std Vtotal Vtotal (5) Given the above information, which of the following statements is INCORRECT? a. Equations (2) and (5) are the result of applying...
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This note was uploaded on 03/03/2011 for the course CHEM 100A taught by Professor Dai during the Spring '06 term at UCSD.

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