ORAL RECITATION Flashcards
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What is the purpose of Methods of Least Squares?
It used to draw the best straight line through experimental data points that have some scatter and do not lie perfectly on a straight line.
Explain what is linear regression.
The process of determining the best equation for the calibration curve is called linear regression.
TRUE OR FALSE
The errors in the y values are substantially greater than the errors in the x values.
TRUE
What is the equation of the line? Explain each variable.
y = mx + b
m: slope
b: y-intercept
y: the ordinate of the straight line where x=xi
What is the goal of linear regression?
The goal of a linear regression analysis is to determine the best estimates for b and m.
Why do we assume that the indeterminate errors are the same for all standards?
So that each standard contributes equally in our estimate of the slope and the y-intercept.
Why do we consider a result as considered an unweighted linear regression?
Because we assume that the indeterminate errors are the same for all standards So that each standard contributes equally in our estimate of the slope and the y-intercept.
What is a secondary reagent?
A reagent whose purity must be established relative to a primary reagent.
What is reagent grade?
Reagents conforming to standards set by the American Chemical Society.
How can a relative error be improved?
The relative error can be improved if the glassware is first calibrated
What is a single point standardization?
Any standardization using a single standard containing a known amount of analyte.
What is multiple-point standardization?
Any standardization using two or more standards containing known amounts of analyte.
What is an external standard?
A standard solution containing a known amount of analyte, prepared separately from samples containing the analyte.
What is a normal calibration curve?
A calibration curve prepared using several external standards.
What is matrix matching?
Adjusting the matrix of an external standard so that it is the same as the matrix of the samples to be analyzed.
When matrix problems are expected, an effort is made to match the matrix of the standards to that of the sample.
What does Medthods of Standard Additions mean?
A standardization in which aliquots of a standard solution are added to the sample.
What is an aliquot?
A portion of a solution.
What is an internal standard?
A standard, whose identity is different from the analyte’s, that is added to all samples and standards containing the analyte.
What is standard deviation about regression?
The uncertainty in a regression analysis due to indeterminate error.
What is a total Youden blank?
A blank that corrects the signal for analyte–matrix interactions.
Give an example of a primary standard.
Potassium hydrogen phthalate (KHP) KHC8H4O4
is a common primary standard used to standardize basic solutions.
Give an example of a secondary standard?
Sodium hydroxide (NaOH)
What is a reference standard?
A reference standard is a highly purified compound or material with a well-established identity & purity.
What is the purpose of a reference standard?
It is used to calibrate instruments, validate analytical methods, and ensure the quality and traceability of measurements.
