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35 Cards in this Set
- Front
- Back
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Which branch of analytical chemistry deals with the determination of identity of an unknown chemical species in a sample?
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Qualitative analysis
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To weigh a chemical using an analytical balance, the reading is 0.2546g. The uncertainty of this reading of mass is?
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0.0001g
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In physio-chemical experiments (in which temperature as well as the volume of the system change), the most appropriate way of expressing concentration is through this unit
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Molality
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Avogadro's number represents the number of particles in this amount of substance
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1 mole
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The average of this type of error is zero
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Random Error
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This type of error cannot be eliminated
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Random Error
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A laboratory protocol requires a reaction to be carried out using methanol as the solvent. A careless technician performed this reaction using hexane as the solvent. In this instance, this type of error occured
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Gross error
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Statistical methods are applied to improve data containing only this type of error
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Random
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faulty calibration of an analytical instrument will cause this type of error
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Systematic Error
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The variance of a sample is represented by this symbol
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s^2
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A symmetrical bell-shaped curve represents this type of distribution
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gaussian
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The maximum of the gaussian distribution curve corresponds to this parameter of the sample presented on the x-axis
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mean
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in Gaussian distribution, 95% of data points are located within this span around the true value
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2 sigma
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in order for experimental data to be meaningful, it must be accompanied by this information
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error involved
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in replicate measurements, the closeness of the mean to the true value is represented by this term
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accuracy
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systematic error affects this in experimental measurements
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accuracy
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the true value of a population is estimated by this parameter
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confidence interval
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This parameter is not a measure of precision
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Mean
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In a data set, the number of data points that can be independently specified is known as this
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degrees of freedom
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The confidence interval shows a range of values that includes this parameter of the population with an ascribed degree of confidence
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Mean
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in order to compare two means, one should perform this type of significance test
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t-Test
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In a significance test, if the calculated value of the test parameter exceeds its critical value, then one should do this with the null hypothesis
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Reject
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When a null hypothesis is accepted, it signifies that the observed difference between the compared values is due to this
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random variation
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Which term describes the minimum detectable concentration of an analytical method
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detection limit
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What are the characteristics of Random error
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- it cannot be eliminated
- it fluctuates randomly around the mean value - the average of random errors is zero |
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What are the characteristics of Systematic error
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- unstable temperature in the lab
- incomplete reaction during the experiment - misreading of the scale |
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Random error affect this in experimental measurements
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Precision
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Confidence interval represents for a defined confidence level that
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the true value lies in a certain range around the mean
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In order to compare the precision of two methods, one should perform this type of significance test
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F-test
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In a significance test, if the calculated value of the test parameter is smaller than its critical value, the one should do this with the null hypothesis
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accept
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To determine the concentration of Ni 2+ in a sample, small aliquot of standard solution containing Ni 2+ was added to the sample for the measurements. what kind of calibration is it
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standard addition
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The standard addition method is used in analysis when
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the sample matrix is too complicated to duplicate
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The straight line with large R^2 indicated good fit
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represents linear square, y=mx+b
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The SI unit of electric current
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Ampere
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A macro-analytical balance commonly used in the laboratory has a capacity of 170 g. Its Tolerance is
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0.1 mg
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