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Flashcards in Chemical analysis Deck (26):

What is purity?

Something that contains only one compound or element throughout


How do impurities effect the mp and bp in a substance?

They lower the melting point and increase the boiling point


What are formulations?

Useful mixtures with a precise purpose that are made by following a formula


What are the uses of formulations?

Pharmaceutical industry in pills, cleaning products, fuels, cosmetics, fertilisers and metal alloys


What are the two phases in chromatography?

A mobile phase and a stationary phase


What is a mobile phase?

Where the molecules can move


What is a stationary phase?

Where the molecules can't move


What affects the amount of time the molecules spend in each phase?

How soluble they are in the solvent and how attracted they are to the paper


What is a chromatogram?

The result of chromatography analysis


What is an Rr value?

The ratio between the distance travelled by the dissolved substance and the distance travelled by the solute


How do you find the Rr value?

Distance travelled by substance / distance travelled by solvent


How can you use the Rr value?

You can find it for a reference compound, then compare the two; if they are the same, then the reference compound is present in the mixture


How do you test for chlorine?

Chlorine turns damp litmus paper white


How do you test for oxygen?

If you put a glowing splint inside a test tube containing oxygen, it will relight


How do you test for carbon dioxide?

Bubbling CO2 through an aqueous solution of calcium hydroxide causes solution to turn cloudy


How do you test for hydrogen?

If you hold a lit splint at the end of a test tube containing hydrogen, a squeaky pop will be made


How do you test for carbonates?

By adding a sample with a test time with dilute acid and then connecting to a tube of limewater, you should be able to tell if carbonates are present by if the lime water goes cloudy


How do you test for sulfates?

Add dilute hydrochloric acid and barium chloride solution to the substance. If sulfate ions are present, a white ppt will form


How do you test for halides?

Add dilute nitric acid and sliver nitrate solution to the substance


How do you tell which halide is present in a halide test?

Chloride gives a white ppt, bromide gives a cream ppt and iodide gives you a yellow ppt


How do you test for metal ions using a flame test?

Clean a platinum loop wire by dipping it HCL and then holding over flame until no colour, then dip in sample and put back into flame


What are the distinctive colour flames for each metal ion in the flame test?

Lithium is crimson, sodium is yellow, potassium is lilac, calcium is orange and copper is green


How do you test for metal hydroxides using ppt?

Add sodium hydroxide to solution and observe colour


What are the ppt colours for the sodium hydroxide test?

Calcium is white, copper is blue, Iron (II) is green, iron (III) is brown, aluminium is white then clear and magnesium is white


How does flame emission spectroscopy work?

Sample placed in flame, energy transferred from electrons as light, light passes through spectroscope, wavelengths are detected to produce line spectrum


What are the advantages of using a machine for flame emission spectroscopy?

Very sensitive, very fast and very accurate