1.6 Uncertainty, Precision, Accuracy and Significant Figures

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Equilibrium : CalcKp (2 Variations)
In one experiment chemists studied the formation of phosgene, COCl_{2}, by mixing {y} atm of carbon monoxide and {z} atm of Cl_{2} in a reaction vessel at 700K. After the system reached equilibrium, the total pressure was {x} atm. Calculate Kp for the reaction.

Hint: Remember that the total pressure is the sum of all the partial pressures.

Note:
Do Not use scientific notation
DO NOT use spaces
DO NOT write in the units.
Be sure to write your answer with only one decimal place even if this is not the correct number of significant figures.

Equilibrium |

Chemometrics

Equilibrium : CalcKc (4 Variations)
A container initially has {y} M ammonia at a certain temperature. When the system reaches equilibrium the concentration of ammonia is {x} M. Calculate K_{c} for the following reaction as written.

Note:
Answers must be written using scientific notation with "e"
DO NOT use spaces
DO NOT write in the units.
Be sure to use three significant figures.
eg: 2.44e-5

The Penny Experiment Revisited: An Illustration of Significant Figures, Accuracy, Precision, and Data AnalysisJoseph Bularzik In this general chemistry laboratory the densities of pennies are measured by weighing them and using two different methods to measure their volumes. The average and standard deviation calculated for the resulting densities demonstrate that one measurement method is more accurate while the other is more precise. Bularzik, Joseph. J. Chem. Educ.2007, 84, 1456.

Chemometrics |

Nomenclature / Units / Symbols |

Nonmajor Courses |

Physical Properties

Using a Graphing Calculator To Determine a First-Order Rate Constant: Author ReplyJosé E. Cortés-Figueroa When technology is used to help with mathematical calculations, the emphasis must be on the concepts being learned rather than simply the procedures. In our approach we are attempting to help students learn more about the concept and also to attain data analysis skills they will need in the future. Cortés-Figueroa, José E. J. Chem. Educ.2004, 81, 485.

Kinetics |

Chemometrics

Using a Graphing Calculator To Determine a First-Order Rate ConstantTodd P. Silverstein The authors use the graphing calculator to estimate the infinity reading from linearized kinetics data, and then they use linearized semi-log data to determine the first-order rate constant. Silverstein, Todd P. J. Chem. Educ.2004, 81, 485.

Visualizing Numerical Methods (2)William F. Coleman These movies are designed to help students visualize various numerical approaches to evaluating functions or solving equations. The methods themselves may be familiar to students from their mathematics courses, but they may have forgotten the material or never made the connection between a statement such as "the derivative of a curve at a given point is the slope of the line tangent to the curve at that point" and the way that one might evaluate such a derivative. All of the movies have VCR-style controls that enable the student to step through them one frame at a time and to move backwards as well as forwards.

Chemometrics

A Method of Visual Interactive RegressionMichelle S. Kim, Maureen Burkart, Myung-Hoon Kim Over the past decade many colleges and universities have placed increased emphasis on having students develop statistical and data analysis skills in a range of disciplines. Some institutions now require that all students complete at least one course with a strong component of data analysis, whether the data are from chemical experiments, the census, or some other source. As chemists, one of our concerns should be to ensure that students view data analysis as an integral part of any quantitative experiment, and, as far as possible, do not treat this process as a black box. The authors of A Method of Visual Interactive Regression, a spreadsheet application, have developed a visual approach to linear least-squares curve fitting that drives home the idea of minimizing the sum of the squares of the deviations in order to find the best fit to a set of data that are being described by a linear relationship. For many students these visualizations are likely to persist a great deal longer than the mathematical derivations of the equation for the slope and the intercept. The visualizations will provide a useful connection between a set of equations and the buttons on a calculator or the insertion of a trendline in a spreadsheet.