SC25-26 Flashcards
What are flame tests used for?
To identify metal ions.
How do you carry out a flame test?
- First clean a nichrome wire loop by dipping it into hydrochloric acid and then rinsing it in distilled water.
- Then dip the wire loop into a sample of the metal compound and put the loop in the clear blue part of a Bunsen flame.
- Record the colour the flame goes.
What flame does- Lithium Sodium Potassium Calcium Copper - ion give off
Lithium - red Sodium - yellow potassium - lilac Calcium - orange/red Copper - blue/green
How can flame tests be inaccurate?
Different metal ions may give a similar colour, so hard to distinguish.
Machines are more accurate and sensitive. A flame photometer can measure light intensity.
How can you identify dissolved metal ions?
Precipitate reactions involving dilute sodium hydroxide (NaOH) solution.
How do you carry out a precipitate reaction?
- You just add a few drops of sodium hydroxide solution to a solution of your mystery compound.
- If a hydroxide precipitate forms, you can use its colour to tell which metal ion was in the compound.
What is the colour of precipitate for - Aluminium Calcium Copper Iron (ll) Iron (lll) - ions?
Aluminium - white Calcium - white Copper - blue Iron (ll) - green Iron (lll) - brown
How do you know if the ion is aluminium or calcium in a precipitate reaction?
Keep adding sodium hydroxide.
Aluminium will go colourless.
How do you test for carbonate ions?
- Add dilute HCL to the solid or solution and look for bubbles of carbon dioxide being produced.
- The gas can be identified as carbon dioxide by bubbling through limewater.
How do you test for sulfate ions?
- Add dilute HCL to remove any carbonate ions.
- Add barium chloride solution.
- The presence of sulfate ions is shown by a white precipitate of barium sulfate.
How do you test for negative ions/halide ions?
Chloride, bromide, iodide
- Add a few drops of dilute nitric acid to remove any carbonate ions.
- Add a few drops of sliver nitrate solution.
In the test for halide ions what colour does - Chloride Bromide Iodide - go?
Chloride - white
Bromide - cream
Iodide - yellow
What are nanoparticles?
Really small particles.
What are some features of nanoparticles?
Have huge SA:VR
Not visible to the eye.
They’re structure, 1-100 nanometers in size, that usually contain only a few hundred atoms.
100 times larger than atoms and simple molecules.
They’re smaller than cells.
What is an example of a nanoparticle?
Fullerenes.