Chemical Analysis Flashcards
What is a pure substance
A substance made of only one type of element or compound
What are fixed points
Fixed points are melting and boiling points of an element or compound
What happens to the melting point if a substance becomes impure
Melting point decreases
What happens to the boiling point if a substance becomes impure
Increases
What is a formulation
A mixture that is designed to be useful
Give two examples of formulations
Paint
Cleaning agents
What is the technique used to analyse unknown substances in solution
Chromatography
What are the two phases in chromatography
Mobile phase and stationary phase
What does Rf mean
Retention Factor
How can we work out the Rf value of a substance
Rf = Distance move by substance / Distance moved by solvent
How can a substance be identified by its Rf value
The Rf value can be matched against a database
What is the test for hydrogen and what is the positive result
Lighted splint is placed in test tube with hydrogen, produces a ‘pop’
What is the test for oxygen and what is the positive result
Glowing splint is placed in test tube with hydrogen, relights
What is the test for carbon dioxide and what is the positive result
Bubble through limewater, goes cloudy
What is the chemical name for limewater
Calcium hydroxide