Please enable JavaScript.
Coggle requires JavaScript to display documents.
purity and formulations &testing for gases& chromatography…
purity and formulations &testing for gases& chromatography
purity is defined differently in chemistry to everyday
usually when referring to a substance as being pure it means that nothing has been added to it so its in its natural state
in chemistry a pure substance is something that only contains one compound or element throughout
boiling and melting points
3)the closer you measured the value to its actual boiling point the purer it is
4) impurities in your sample will lower the melting point and increasing the boiling point
2) you can test it by measuring its boiling point and melting point and comparing it to the melting and boiling point of a pure substance
5) impurities in your sample will also increase the boiling point and may result in your sample boiling over a range of temprichures
1)chemically pure substance will melt and boil at a specific temperature
formulations are mixtures with exact amount of compounds
2)formulations are really important in the pharmaceutical industry for example altering the formulation of a pill
3)in everyday life they can be found in cleaning products fuels cosmetics and many others
1) they are useful mixtures with a precise purpose that are made by using a formula
4) packaging tells you a products formulation lets you choose the right one for your use
tests for gases
oxygen
if you put a glowing splint inside a test tube containing oxygen the oxygen will relight the glowing splint
carbon dioxde
bubbling carbon dioxide through an aqueous solution of calcium hydroxide the solution will turn cloudy
chlorine
chlorine bleaches damp litmus paper turning it white if you use blue limus paper it may turn red for a moment
hydrogen
if you hold a burning splint at the open end of a test tube containing hydrogen you'll get a squeaky pop
chromatography
how quickly a chemical moves depends on how its distributed between the two phases whether its spends more time in the mobile phase or the stationary
the chemical that spends more time in the mobile phase than the stationary phase will move further through the stationary phase
he mobile phase moves through the stationary phase and anything dissolved in the mobile phase move with it
the separates components from spots the number of spots formed may change in different solvents as the distribution of the chemical will change depending on the solvent
during a chromatography experiment the substance in the sample constantly move between the mobile and the stationary phrase
a pure substance will only ever from one spot in any solvent since there is only one substance in the same
paper chromatography
in paper chromatography the stationary phase is the chromatography paper and the mobile phase is the solvent
the amount of time the molecules spend in each phase depends on two things
how soluble theyare in the solvent
how attacked they are to the paper
molecules with a higher solubility in the solvent and which are less attracted to the paper will spend more time in the mobile phase and they will be carried further up the paper
calculating the r value for each chemical
the further through the stationary phases a substance moves the larger r value
often carried out to see is a certain substance is present in a mixture
use this formula r= distance travelled by substance/distance travelled by solvent
an r value is the ratio between the distance travelled by the dissolved substances and the distance travelled by the solvent
the result of the chromatography analysis is called a chromatogram
how it effects the solvent
if the r value of the reference matches the rf value of one of the sots in the mixture
if you test both the mixtures and the reference in a number of different solvents
the r value of a substance is dependant on the solvent you use if you change the solvent the r value of the substance will change
if the spots in the mixture and spots in the reference only have the same rf value in some of the solvent then the compound isn't resent in the mixture