chem analysis

Question 1

what is a pure substance?

Answer 1

• in chemistry - pure substances - single element or compound not mixed with any other substance
• everyday language - pure substance can mean substance with nothing added to it - unadulterated + in natural state
• pure elements and compounds melt + boil at specific temps - MP and BP data can be used to distinguish between pure substances and mixtures

Question 2

what are formulations?

Answer 2

• complex mixtures that have been designed as a useful product
• quantity of each component - carefully measured to ensure product has properties needed

Question 3

calculate Rr value

Answer 3

distance travelled by substance/ distance travelled by solvent

Question 4

test for chlorine?

Answer 4

• chlorine bleaches damp litmus paper turning it white

- may turn red for a moment first though - because a solution of chlorine is acidic

Question 5

test for oxygen?

Answer 5

if put a glowing splint inside test tube containing oxygen - oxygen will relight the glowing splint

Question 6

test for hydrogen?

Answer 6

if hold a lit splint at the open end of a test tube containing hydrogen - get a squeaky pop

• noise comes from hydrogen burning quickly with oxygen in air to form H2O