C3 - Further Analysis and Quantative Chemistry Flashcards
How can chemicals be flame tested?
Flame tests are where you dip the wire loop in concentrated hydrochloric acid to remove any other substances then dip it in the solid and place it in the flame
L ithium S odium P otassium C alcium B arium
C rimson Y ellow L ilac R ed G reen
How can chemicals with positive charges be tested?
Adding sodium hydroxide.
Put 3ml of the salt solution into a clean test tube and then add sodium solution drop by drop. Note any colour change. If the precipitate is white add excess sodium hydroxide
A liminium C alcium M agnesium C opper I ron 2+ I ron 3+
W hite W hite W hite B lue G reen B rown
How can chemicals with negative charges be tested?
Testing chloride, bromide and iodide : add dilute nitric acid and silver nitrate solution.
Testing sulfate - add barium chloride and a few drops of hydrochloric acid
Testing carbonates - add hydrochloric acid
C hloride B romide I odide S ulfide C arbonate
W hite C ream Y ellow W hite W hite precipitate with limewater (CO2 given off)
Explain a titration.
Titrations can be done to find a solution’s concentration.
Fill the burette with the solution which WE KNOW THE CONCENTRATION OF. Do this on the floor using a funnel so the solution doesn’t splash everywhere.
Record the initial volume reading on the burette then stand it on the desk.
Using a pipette add 25cm3 of the solution of unknown concentration into a conical flask.
Add in a few drops of indicator and stand the conical flask on a white tile so that you can easily see the colour change.
Slowly add the known solution in, drop by drop while you swirl the flask around to mix the reactants together.
Stop adding the solution of known concentration as the solution just changes colour. Record the new burette reading.
Repeat the experiment three times so an average can be calculated.
How do you do a titration calculation?
n = c x v
n - number of moles
c - concentration (in mol/dm3)
v - volume (in dm3)
