Experiments Flashcards
(21 cards)
What 2 phases does paper chromatography use
-mobile phase: where the molecules can move
-stationary phase: where the molecules can’t move
How does paper chromatography work
-the substances in the s… constantly move between the m… and stationary p…
—>and e… is formed between the 2 s…
-the m… phase moves through the … phase, and anything d… in the mobile stage m… with it
-how q… a chemical m… depends on how it’s d… between the 2 p…
-the c… that spend more t… in the m…. phase will move f…
-components in a m… spend d… amounts of t… in the m… phase
-the substances in the sample constantly move between the mobile and stationary phase
—>and equilibrium is formed between the 2 stages
-the mobile phase moves through the stationary phase, and anything dissolved in the mobile stage moves with it
-how quickly a chemical moves depends on how it’s distributed between the 2 phases
-the chemicals that spend more time in the mobile phase will move further
-components in a mixture spend different amounts of time in the mobile phase
How many spots will a pure substance form in paper chromatography
1
During paper chromatography what is the stationary phase and what is the mobile phaee
Stationary: the paper
Mobile: solvent
What does the amount of time the molecule spends in each phase depend on
-how soluble they are in the solvent
—>the higher the solubility the further they will travel
-how attracted they are to the paper
—>the less attracted the further they will travel
What is the result of chromatography analysis called
Chromatogram
What is the Rf value
The ratio between the distance travelled by the dissolved substance and the distance travelled by the solvent
Formula to calculate Rf
Rf= distance travelled by substance/
distance travelled by solvent
How can u test to see if a certain substance is present in a mixture using paper chromatography
-find the … value of the p… sample
-and run that a… the unknown m…, if the Rf v… match the s… may be p…
-find the Rf value of the pure sample
-and run that alongside the unknown mixture, if the Rf values match the substance may be present
What is the test for chlorine
-chlorine bleaches damp litmus paper, so if chlorine it present it will turn white
Test of oxygen
-if you out a glowing splint inside a test tube containing oxygen, then the splint will relight
Test for carbon dioxide
-bubbling CO2 through an aqueous solution of limewater, the solution will turn cloudy
Test for hydrogen
-if you hold a lit splint at the open end of a test tube containing hydrogen there will be a squeaky pop
How can u test for carbonates
-putting a s… of the unknown s… into a … tube, then add a couple of d… of dilute a… using a p…
-then c… the test tube to a … tube of l…
-if c… ions are present the l… will turn c…
-putting a sample of the unknown solution into a test tube, then add a couple of drops of dilute acid using a pipette
-then connect the test tube to a test tube of limewater
-if carbonate ions are present the limewater will turn cloudy
How to test for sulfates
-use a dropping p… to add a couple d… of dilute H… followed by a few drop of b… chloride solution
-if s… ions are present a w… precipitate of b… sulfate will f…
-use a dropping pipette to add a couple drops of dilute HCl followed by a few drop of barium chloride solution
-if sulfate ions are present a white precipitate of barium sulfate will form
How to test for halides
-to identify a halide i… add a couple drops of dilute n… acid followed by a couple drops of silver n… solution
-a c… forms a w… precipitate of silver c…
-a b… forms a c… precipitate of silver b…
-an i… forms a y… precipitate of silver i…
-to identify a halide ion add a couple drops of dilute nitric acid followed by a couple drops of silver nitrate solution
-a chloride forms a white precipitate of silver chloride
-a bromide forms a cream precipitate of silver bromide
-an iodide forms a yellow precipitate of silver iodide
How to identify metal ions
-c… of some m… burn with a c… colour
-lithium ions burn with a c… flame
-sodium ions burn with a y… flame
-potassium ions burn with a l… flame
-calcium ions burn with an o…-red flame
-copper ions burn with a g… flame
-dip a p… wire l… into the sample and put it into the f… and record the c…
-compounds of some metals burn with a characteristic colour
-lithium ions burn with a crimson flame
-sodium ions burn with a yellow flame
-potassium ions burn with a lilac flame
-calcium ions burn with an orange-red flame
-copper ions burn with a green flame
-dip a platinum wire loop into the sample and put it into the flame and record the colour
Identifying metals in a metal hydroxide
-some m… ions have a c… colour
-add a few drops of s… hydroxide solution to a solution of your c…
-calcium forms a w… precipitate
-copper forms a b… precipitate
-iron II forms a g… precipitate
-iron III forms a b… precipitate
-aluminium forms a w… precipitate at first, but r… to form a c… solution
-magnesium forms a w… precipitate
-some metal ions have a characteristic colour
-add a few drops of sodium hydroxide solution to a solution of your compound
-calcium forms a white precipitate
-copper forms a blue precipitate
-iron II forms a green precipitate
-iron III forms a brown precipitate
-aluminium forms a white precipitate at first, but redissolves to form a colourless solution
-magnesium forms a white precipitate
Why do different metal ions produce different colours of light
-during f… emission s… a sample is placed in a f…
-as the i… heat up their e… move more quickly, when the electrons drop back to their o… energy l… they transfer e… as l…
-the light passes through a s.., which can detect different w… of light to produce a light s…
-different i… emit different w… of light, so each ion produces a different p… of w… and has a different line s…
-during flame emission spectroscopy a sample is place in a flame
-as the ions heat up their electrons move more quickly, when the electrons drop back to their original energy levels they transfer energy as light
-the light passes through a spectroscope, which can detect different wavelengths of light to produce a light spectrum
-different ions emit different wavelengths of light, so each ion produces a different pattern of wavelengths and has a different line spectrum
On a line spectrum what does the intensity of the spectrum indicate
The concentration of that ion in the solution
Advantages of using instrumental analysis
-they are very s… so can detect s… substances
-they are very f… and tests can be a…
-they are very a…
-they are very sensitive so can detect small substances
-they are very fast and tests can be automated
-they are very accurate
