A student prepared a NaCl solution to measure the diffusion coefficient through
ID: 836823 • Letter: A
Question
A student prepared a NaCl solution to measure the diffusion coefficient through a dialysis membrane. She weighed 4.5685 g of the dried reagent (FW = 58.4425) by difference into a 500.0 mL volumetric flask and diluted it to the mark with very pure deionized water. Calculate the molar concentration of the solution and the 95% confidence limits. Assume that the balance has a tolerence of sigma = 0.0006 g per reading, and that the volumetric flask has a tolerence of sigma = 0.20 mL. The formula weight may be assumed to have negligible uncertainty. If the prepared solution has a density of (1.005 plusminus 0.003) g -mL-1 (at a 95% confidence limit), calculate the wt % NaCl of the solution and the corresponding 95% confidence limits. Normal (or isotonic) saline is an aqueous solution of 0.905 wt % NaCl. The student claims that she has made a normal saline solution. Build and evaluate a hypothesis test to confirm or deny this at the 95% confidence level.Explanation / Answer
a.) 1.7x10^-13
b.) 3.2x10^-11
c.) 5.7x10^-9
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