QC1 GRAVIMETRIC ANALYSIS

Gravimetric Analysis is the determination of an analyte based on the _____ of a solid (ppt)

mass

_______ is simple, but most accurate in chemical analysis

Gravimetric Analysis

Gravimetric Analysis involves precipitation reaction at ______ condition to selectively precipitate species.

controlled

is used to find the percentage of one particular component in a mixture

Gravimetric Analysis

Gravimetric Analysis involves forming a suitable ________ with the ion in the sample

precipitate

What are the steps in gravimetric analysis? wspdfdwd

Weighing of sample
Sample dissolution

Precipitation

Digestion

Filtration and washing
Drying

Weighing

Data calculation

A good precipitate should have (high/low) solubility

low

A good precipitate should be easy to recover by __________

filtration

A good precipitate should be _________ to air, water

unreactive

A good precipitate should be something where our analyte is a (big/small) proportion of the ppt

small

A good precipitate should have a (known/unknown) formula

known

A good precipitate should be ___________ when heated

stable

A good precipitate (should/should not) form precipitates with other ions that are likely to be present

should not

What do you call the substance left in the filter paper?

residue (precipitate)

What do you call the substance in the conical flash after passing through the filter paper? (located in flask)

filtrate

two types of suspension:

Colloidal and Crystalline

Type of suspension w/ size range of 10-6 – 10-4 mm

Colloidal

Type of suspension w/ size range of 10-1 – 10 mm

Crystalline

What is the tendency of colloidal suspensions to settle

none at all

What is the tendency of crystalline suspensions to settle

Will settle spontaneously

Are colloidal suspensions pure?

They are not pure

Are crystalline suspensions pure?

higher purity than colloids

What are the factors that govern the particle size of a precipitate ptrr

Precipitate solubility

Temperature
Reactant concentration

Rate at which reactants are mixed

The net effect of the factors that govern particle size of precipitate can be accounted for, at least qualitatively, by assuming that the particle size is related to a single property of the system called its __________________ (RSS)

Relative supersaturation

Rss can be calculated by?

(Q-S)/S

Where q is the concentration of solute at any time

and s is the equilibrium solubility of the solute

_______ can be used to estimate/control the type of precipitate that is formed

RSS

If RSS is large, we tend to form _________

colloids

If RSS is small, we tend to form _________

crystalline ppts

drug that undergoes gravimetric analysis in which it acts as a surfactant and an emulsifying agent

Assay of Sodium Lauryl sulfate for Sodium sulfate content

drug that undergoes gravimetric analysis in which it is used for tx of congestive heart failure

Assay of Mercaptomerin Sodium

Drug that undergoes gravimetric analysis in which it is used

as a laxative to cleanse colons before colonoscopy

as a stabilizer

for tx of hypophosphatemia

Assay of Sodium phosphate solution

2 types of gravimetric methods:

Precipitation methods

Volatilization methods

Method of gravimetry in which it is based on isolation of an insoluble precipitate of known composition,

Precipitation methods

Method of gravimetry in which the analyte is volatilized, weighed and the concentration is determined.

Volatilization

Calculations associated with gravimetric analysis are based on ____________

stoichiometry

A ________________ gives the ratios, in moles of

materials produced or consumed in a reaction.

balanced formula

How much Pb(NO3)2 is need to convert 5.0 grams of NaI to PbI?

FW Pb(NO3)2 - 331.2 g/mol, NaI – 149.9 g/mol

5.52 g