Flashcards in C3 - Analysis & Synthesis Deck (45)
What are the two main methods for testing for positive ions?
-Reaction with sodium hydroxide.
How is a flame test carried out?
-The compound is put on a cleaned wire loop
-The loop is then held in a Bunsen burner.
-The colour of the flame can be used to identify a positive ion.
What colour flame does lithium produce?
What colour flame does sodium produce?
What colour flame does potassium produce?
What colour flame does calcium produce?
What colour flame does barium produce?
What possible elements are present if a white precipitate forms in sodium hydroxide?
Al3+, Ca2+, Mg2+
How is it possible to distinguish between Al, Ca and Mg ions?
-Adding more NaOH causes aluminium ions to dissolve.
-Calcium can be identified with a flame test.
Which ions produce a blue precipitate with NaOH?
Which ions produce a green precipitate with NaOH?
Which ions produce a brown precipitate with NaOH?
How can negative carbonate ions be identified?
-Adding dilute acid produces CO2 gas.
-Limewater is then turned cloudy.
How can negative halide ions be identified?
-Nitric acid then silver nitrate solution is added.
-If a precipitate forms, halides are present.
Which ions produce a white precipitate with silver nitrate?
Which ions produce a cream precipitate with silver nitrate?
Which ions produce a yellow precipitate with silver nitrate?
How can negative sulfate ions be identified?
-Hydrochloric acid then barium chloride is added.
-If a white precipitate forms, sulfate ions are present.
What is titration used for?
To measure how much acid and alkali react completely.
What is the end-point of a reaction?
The point at which the acid and alkali have reacted completely.
What is a pipette used for?
Measure out a fixed solution.
What is a burette used for?
Measuring the volume added.
How is the concentration of a solution calculated?
-Calculate the mass in 1cm3 of solution.
-Calculate mass of solute in 1000cm3 of solution.
-Convert the mass to moles.
How is the mass of solute calculated?
-Calculate the mass of the solute in 1dm3.
-Calculate mass in 1cm3.
-Calculate the mass in the given volume.
What technique is used to analyse DNA?
Give two examples of chemical analysis in medicine.
-DNA can be matched to find suitable donors.
-Metal concentrations can be analysed to indicate joint failures.
What is the point of equilibrium?
When the rate of forward and reverse reactions are equal.
What happens when a system of equilibrium is changed?
When a system of equilibrium is subjected to a change then the position of equilibrium will shift to oppose the change.
How does changing the pressure affect reversible reactions involving gases?
-Increasing the pressure favours the reaction with the least number of molecules of gas formed.
-Decreasing the pressure favours the reaction with the greater number of molecules of gas formed.