Accuracy, precision, calibration, acid-base and complexometric titrations, buffers, solubility and statistics of measurement.
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- What is the difference between accuracy and precision?
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Accuracy is how close a measurement is to the true value; precision is how consistent repeated measurements are with each other.- State the significant figures rule for addition and subtraction.
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The answer has no more decimal places than the measurement with the fewest decimal places.- What is absolute error?
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The difference between a measured value and the true (accepted) value, expressed in the same units as the measurement.- Write the formula for relative error (percent error).
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Relative error = (Absolute error / True value) times 100 percent.- What does standard deviation measure?
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Standard deviation measures how far, on average, individual measurements deviate from the mean of a data set.- What is a 95 percent confidence interval?
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A range around the mean within which the true value is expected to lie 95 percent of the time, based on the sample standard deviation and sample size.- What is the Q-test used for?
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The Q-test determines whether a questionable data point (an outlier) should be rejected from a data set using a statistical criterion.- Define the equivalence point of a titration.
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The point at which the amount of titrant added is exactly enough to completely react with all the analyte, based on stoichiometry.- What is the endpoint of a titration?
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The point where the indicator changes color, signaling that the titration should stop.- What does it mean to standardize a titrant solution?
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To determine its exact concentration by titrating it against a known primary standard.- What is a back titration and when is it used?
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A titration in which a known excess of reagent is added to the analyte, and the excess is titrated with a second titrant to find the analyte indirectly. It is used when the analyte cannot be titrated directly.- List three essential properties of a primary standard.
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High purity, stability in air, large molar mass (to minimize weighing errors), does not absorb water, and reproducibly available in high purity.- Define the titrant in a titration.
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The solution of known concentration that is added to the analyte during titration.- What is a blank (or control) titration?
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A titration performed using only the solvent and indicator, without analyte, to account for any volume of titrant consumed by impurities or reaction with the solvent.- What is the typical uncertainty in reading a burette?
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Plus or minus 0.05 mL, which is half of the smallest division on a typical 0.1 mL-graduated burette.
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