Chemical analysis Flashcards
What is a formulation?
.Useful mixtures with precise purposes
.Made by following a formula
.Each component is in a measured quantity and it contributes to the properties of the formulation so it meets the required function
Test for chlorine
Chlorine bleaches damp litmus paper white
Test for oxygen
Put a glowing splint inside a test tube containing oxygen then the oxygen will relight the glowing splint
Test for carbon dioxide
Bubbling carbon dioxide through an aqueous solution f calcium hydroxide (lime water) causes the solution to turn cloudy
Test for hydrogen
Hold a burning splint at the open end of the test tube, if a squeaky pop is heard then hydrogen is present in the tube (the pop is from the oxygen and hydrogen reacting quickly in the air to form water)
What are carbonates?
Substances that contain CO3^2- ions
Test for carbonate ions
.Use a dropping pipette and add a few drops of dilute acid to a test tube containing your mystery substance
.Connect the test tube to a test tube containing lime water, if carbonate ions were present then CO2 would have been released from reaction with the acid which will turn the lime water cloudy when it bubbles through
What is a sulfate ion?
SO4^2-
Test for sulfate ions
.Use a dropping pipette to add a couple of drops of dilute hydrochloric acid followed by a couple of drops of barium chloride solution to a test tube containing the mystery solution, if sulfate ions are present then a white precipitate of barium sulfate will form
Ba^2+ + SO4^2- –>
BaSO4
Why is hydrochloric acid added in the test for sulfate ions?
Get rid of any traces of carbonate ions as these would also produce a precipitate and confuse the results
Give 3 examples of halide ions
Cl-, Br-, I-
Test for halide ions
.Add a couple of drops of dilute nitric acid
.Add a couple of drops of silver nitrate solution
.A certain colored precipitate will form depending on the halide
Ag+(aq) + ‘HALIDE-‘(aq) –>
Ag’HALIDE’(s)
In the test for halide ions, what color precipitate does a chloride ion give
White, silver chloride