C8 Flashcards
What is a pure substance
A substance made up of only one tyoe of element or compound and no thing else
How do we test to see if a substance is pure or not
By seeing if the substance melts or boils at the exact melting or boiling point a pure substance should do
How do u calculate Rf value
Rf = distance travelled by substance ÷ distance travelled by solvent
Chromotagraphy practice method
What is the test for chlorine
Bleach damp litmus paper.
Posititve result: turn paper white
What is the test for oxygen
Glowing split inside test tube of oxygen
Posititve result: glowing splint relights
What is the test for carbon dioxide
Lime water turns cloudy
What is the test for hydrogen
Hold lit splint at open end of test tube. Posititve result: hear a squeaky pop
What can help to detect carbonates
Dilute acid - put sample of what ur testing in a test tube and add couple drops of dilute acid using pipette. Connect test tube to a test tube of lime water. If carbonate ion present, CO² will be released turning limewater cloudy
What is the test for sulfate ions
Add drops of HCL and barium chloride. White precipitate of barium sulfate will form
How do u test for hallides
Put drops of nitric acid and silver nitrate
What is the positive result if chloride is present
White precipitate forms of silver chloride
What is the positive result if bromide is present
Cream precipitate of silver bromide
What is the positive result if iodide is present
Yellow precipitate forms of silver iodide
How can metal ions be idnentified
Using the flame test
What is the positive test for lithium ions
Crimson flame
What is the positive test for sodium ions
Yellow flame
What is the positive test for pottasium ions
Lilac flame
What is the positive test for calcium ions
Burn with orange red flame
What do some metal ions form with NaOH
Coloured precipitates
What is the positive test for calcium Ca²
White precipitate
What is the positive test for copper (ll) Cu²
Blue precipitate
What is the positive test for iron (ll)
Greem precipitate
What is the positive test for iron (lll)
Brown precipitate
What is the positive test for aluminium
First white precipitate, then turn colourless
What is the positive test for magnisium
White precipitate
What is the positive about flame emission spectroscopy
It works for mixtures so more than one metal ion can e identified
What are the advantages of using machines to analyse unknown substances
. Very senesetive - can detect the tiniest amounts of substances
. Very fast and tests can be automated
. Very accurate
What are some examples of greenhouse gasses
Carbon dioxide, methane and water vapour
What is the greenhouse gas effect. How does it work
All particles absorb certain frequencies of radiation. Greenhouse gasses absorb long wave radiation that gets reflected back of the earth. They reradiate It in all directions. Including back towards the earth. The longwave radiition is thermal radiation, so the surface of the earth is warmed
How does desforestion effect amount of greenhouses gases in the atmosphere
Fewer trees mean less CO² is removed from atmosphere via photosynthesis
How does burning fossil feuls effect amount of greenhouses gases in the atmosphere
Carbon that was locked up in these fuels are released as CO²
How does agriculture effect amount of greenhouses gases in the atmosphere
More farm animals produce methane through thier digestive processes
How does createing waste effect amount of greenhouses gases in the atmosphere
More landfill sites and more waste from agriculture means more CO² and methane released by decomposition of waste
What, are potential consequences of climate change
. Increase in temps lead to ice caps melting, increase sea levels and flooding risk and coastal erosion
. Chang ein rainfall patterns - cause some regions to get too much or too little rain affect ability to produce food
. More frequent and severe storms
