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70 Cards in this Set
 Front
 Back
Qualitative Analysis

identification


Quantitave Analysis

relative amounts


Calibration Equation

Ca = k X
Ca = concentration of analyte k = proportionality constant X = measurment 

Determinate Error
or Systematic Error 
errors with a definate value


Indeterminate Error
or Random Error 
errors which fluctuate in a random fashion


What are the sources of determinate error?

instrument, method, and personal


Accuracy

agreement of a measurment/result (Xi) with its true value (Xt)


What is accuracy dependent upon?

knowing the true value


Absolute Error Equation

Er = Xi  Xt
Xi= measurment Xt= true value 

Relative Error Equation

Er = (Xi  Xt)/Xt
Xi= measurment Xt= true value 

What methods can be used to detect error?

standard samples, independent analysis,blank detmination, and varying sample size


Stadard Samples

known concentration


Independent Analysis

perform analysis using two different methods (gravimetric, volumetric, and spectrographic)


Blank Determination

run analysis without sample


Proportional Error

proportional to sample size


What are some causes of indeterminate error?

position of a meter needle relative to a fixed scale, liquid level in volumetric ware, or electronic noise


Precision

agreement between two or more measurments/results obtained in an identical fashion


What is another name for a Gaussian Curve?

normal error curve


What detmines the width of the normal error curve?

sigma


Standard Deviation Equation

S=


Relative Standard Deviation Equation
(RSD) 
RSD=


Coefficient of Variation Equation (CV)

CV=


Spread or Range

numerical difference between the highest and lowest result


Confidence limits Equation from Population Standard Deviation

CL=


Confidence Limits Equation from Sample Standard Deviation

CL=


How do you detmine if a outlier should be removed from a set of data?

calculate Qexperimetal and compare to Qcritical. If Qexperimental is larger remove.


Coprecipitation

the precipitation of soluble impurities


Surface Absorbtion

surface contaminates (major problem with collidal precipitates)


Occlusion

rapid trapping of impurities


Mixed Crystal Formation

impurity becomes part of the crystalline lattice


Mechanical Entrapment

trapped impurities when several crystals grow together


What are three major problems with the purity of a crystalline precipitate?

occlusion, mixed crystal formation, and mechanical entrapment


What are some ways to remove impurities?

absorption, reprecipitation,and digestion


Absorbtion

remove by washing with a hot electrolyte solution (watch out for peptization)


Reprecipitation

redissolve and reform precipitate from a cleaner solution


Digestion

heating over a period of time.


Collidial Precipitate

large surface area to mass ratio


Coagulation of Colloidal Particles

attaching particles to each other to improve filtering


What are the benifits of digestion?

reduces surface charge and consequent double layer, increases particle size via bridging, and particle gain K.E. and overcome electric double layer


What are the types of gravimetric analysis?

precipitation, and gasification


Precipitation Gravimetric Analysis

the substance to be determined is isolated by formation of a known precipitate or a precipitate convertible to a known substance


Gasification Gravimetric Analysis
What are the two types of gasification gravimetric analysis? 
the analysis involves producing a gas related to a sample


Direct Gasification Gravimetric Analysis

the determination of the mass of a gas produced by a chemical reaction


Indirect Gasification Gravimetric Analysis

the determination of the mass lost by a sample as aresult of production of a gas


Gravimetric Analysis Mass % Equation

Mass%=


What are the desired properties of a precipitate?

readily filtered and washed of contaminants, low solubility, unreactive with atmospere, known composition


What are the physical properties of a colloid?

they are smaller and gennerally more impure than crystalline precipitates


What affects particle size?

the relative supersaturation of the system at the moment, of precipitation


Nuclei Formation

minimum nuber of ions or molecules forming a second phase


If Q is small the particles will be?

crystalline


If Q is large the particles will be?

colloidal


If s is small the particles will be?

colloidal


If s is large the particles will be?

crystalline


How can you lower the q value?

dilute solution, slow rate of mixture, vigorous stirring


What does solubility do with temperature increases?

generally increases with temerature


Mean

the average


Median

the middle value for an odd set of data if arranged numerically


Sample Varience

standard deviation squared


Peptization

a coagulated colloid returns to its disperesed state


Mixed Crystal Growth

a type of coprecipitation in which a contaminat ion replaces an ion in the lattice of a crystal


Nucleation

process in which a minimum number of atoms, ions, or molecules join together to give a stable solid


CounterIon Layer

a layer of solution surrounding a colloidal particle within which there exists a quantity of ions suffecient to balance the charge on the surface particle


Mother Liquor

the solution from which a precipitate was formed


Supersaturation

a condition in which a solution temporarily contails an amount of solute that exceeds its equilibrium solubility


Population Standard Deviation Equation

=


Standard Error of the Mean Equation

=


Q

=


wt/wt Equation

=


vol/vol Equation

=


wt/vol Equation

=
