You determine the acetic acid (HOAc) content of vinegar by titrating with a sodium hydroxide standard solution to a phenolphthalein (an indicator) end point. An approximately 5-mL sample of vinegar is weighed on an analytical balance in a weighing boat and this is found to be 5.0268 g. The standard deviation in making a single weighing is 0.2 mg. The sodium hydroxide must be accurately standardised (this means its concentration must be accurately determined) by titrating known mass of high-purity potassium hydrogen phthalate, and three such titrations give molar concentrations of

You determine the acetic acid (HOAc) content of vinegar by titrating with a sodium hydroxide standard solution to a phenolphthalein (an indicator) end point. An approximately 5-mL sample of vinegar is weighed on an analytical balance in a weighing boat and this is found to be 5.0268 g. The standard deviation in making a single weighing is 0.2 mg. The sodium hydroxide must be accurately standardised (this means its concentration must be accurately determined) by titrating known mass of high-purity potassium hydrogen phthalate, and three such titrations give molar concentrations of

Chemistry: The Molecular Science

5th Edition

ISBN:9781285199047

Author:John W. Moore, Conrad L. Stanitski

Publisher:John W. Moore, Conrad L. Stanitski

Chapter4: Energy And Chemical Reactions

Section: Chapter Questions

Problem 120QRT

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You are preparing a 100.0 mL standard solution needed for titration analysis. The NaOH (40 g/mol) pellets are measured to be 0.5341 g in a balance with acceptable uncertainty of +0.001 g. Mass of the pellets is recorded after taring the container. The pellets are put in a beaker and added with 50 ml distilled water measured by a graduated cylinder. The solution is then quantitatively transferred to a 100-mL volumetric flask with uncertainty of ±0.08 mL and diluted to a 100-mL mark. What is the concentration (M) of the solution and estimate its uncertainty by propagation? Assumption: There is no uncertainty in molar mass. Express your answer as C+/- u M.
The molarity of a solution is determined by four separate titrations or replicates, where the obtained data was 0.4120, 0.4920, 0.3920, and 0.4320 M. Calculate the standard error of the mean for the above data. O 0.00185 O 0.02160 O 0.43200 O 0.04320 O 0.01080
Is the concentration of the solution prepared in the question below only approximate because sodium hydroxide is not a primary standard? * Find the mass in grams of sodium hydroxide that will be required to prepare a solution with a concentration of 0.500 mol·dm⁻³ in a 250 cm³ volumetric flask. [Round the answer to three decimal places. Do not type in the unit. Use a decimal point.] *
Norepinephrine can be analyzed in human urine. A fixed amount of DHBA was added to each sample and standard in a fixed concentration. Please explain the analytical function of adding DHBA. To the 1 mL of urine sample, small amounts of 1 µg/mL norepinephrine standard is added and the following results were obtained. What is the concentration of the norepinephrine in the urine sample with uncertainty?
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