Chemical Analysis-PAPER2 Flashcards
When something is described as pure, what does it usually mean?
That nothing has been added to it
What can you tell from a melting/ boiling point
how pure a substance is, if it is very different to the pure melting point it isn’t likely to be very pure.
How to calculate the ratio between the distance travelled by the dissolved substance and the distance travelled by the solvent?
Distance travelled by substance/distance travelled by solvent
How does paper Chromatography separate mixtures?
During paper chromatography the molecules of each chemical in the sample move between the stationary phase and the mobile phase. The mobile phase moves through the stationary phase over the course of the experiment, and anything that’s dissolved in it will move with it. The distance a compound moves through the stationary phase depends on how long it spends dissolved in the mobile phase compared to it. They will move different amounts through the stationary phase so will separate.
How do you test for hydrogen?
Squeaky pop
How to test for Carbon dioxide?
Bubbling CO2 through limewater causes the solution to turn cloudy.
How to test for oxygen?
Relight a glowing splint.
How to test for chlorine?
Chlorine bleaches damp litmus paper white.
How to test for halide ions (chlorine,bromine or iodine) ?
Add a couple of drops of dilute nitric acid, followed by a couple of drops of silver nitrate solution. They will give a distinguished colour precipitate.
What colour precipitate does each halide ion go?
Cl-white silver chloride
Br-Cream silver bromide
I-yellow silver iodide
How do you identify metal ions?
Flame tests, the flame will be a different colour depending on the ion.
How are the colours that the flame will turn depending on the metal?
Lithium-Red Sodium-Orange Potassium- Lilac Calcium-Orangey red Copper- green
How can you identify metal hydroxides?
After adding sodium Hydroxide (NaOH) they willl turn a characteristic colour.
Why might it be necessary to use flame emission spectroscopy instead of a flame test to identify metal ions?
Flame emission spectroscopy can be used to identify the metal ions in mixtures. Whereas flame test can only be used for substances containing a single metal ion.
