Chemical Analysis Flashcards
How can you identify the purity of a substance using temperature?
A chemically pure substance will melt or boil at a specific temperature. You can test the purity of a sample by measuring its melting or boiling point and comparing it with the melting or boiling point of the pure substance (which you can find from a data book). The closer your measured value is to the actual melting or boiling point, the purer your sample is.
What is a formulation?
Formulations are useful mixtures with a precise purpose that are made by following a ‘formula’ (a recipe). Each component in a formulation is present in a measured quantity, and contributes to the properties of the formulation so that it meets its required function.
What is the test for chlorine?
Chlorine bleaches damp litmus paper, turning it white. (It may turn red for a moment first though - that’s because a solution of chlorine is acidic).
What is the test for oxygen?
If you put a glowing splint inside a test tube containing oxygen, the oxygen will relight the glowing splint.
What is the test for carbon dioxide?
Bubbling carbon dioxide through (or shaking carbon dioxide with) an aqueous solution of limewater causes the solution to turn cloudy.
What is the test for hydrogen?
If you hold a lit splint at the open end of a test tube containing hydrogen, you’ll get a s “squeaky pop” (the noise comes from the hydrogen burning quickly with the oxygen in the air to form water).
How can you test for carbonate ions?
You can test whether a mystery solution contains carbonate ions by putting a sample in a test tube and then using a dropping pipette to add a couple of drops of dilute acid. You should then connect the test tube to a test tube of limewater. If carbonate ions are present, carbon dioxide will be released that will turn the limewater cloudy when it bubbles through it.
How can you 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 your mystery solution. If sulfate ions are present, a white precipitate of barium sulfate will form.
How can you test for halides?
Add a couple of drops of dilute nitric acid, followed by a couple of drops of silver nitrate solution to your mystery solution.
A chloride gives a white precipitate of silver chloride.
A bromide gives a cream precipitate of silver bromide.
An iodide gives a yellow precipitate of silver iodide.
Lithium ions burn with a ______ flame.
Crimson
Sodium ions burn with a ______ flame.
Yellow
Potassium ions burn with a ______ flame.
Lilac
Calcium ions burn with a ______ flame.
Orange-red
Copper ions burn with a ______ flame.
Green
What colour precipitate does calcium form with sodium hydroxide?
White
