Page 14 - Physical chemistry understanding our chemical world

CONTENTS xiii

9.4 Photophysics: emission and loss processes 472
How are X-rays made? 472
Why does metal glow when hot? 473
How does a light bulb work? 474
Why is a quartz–halogen bulb so bright? 474
What is ‘limelight’? 476
Why do TV screens emit light? 476
Why do some rotting fish glow in the dark? 478
How do ‘see in the dark’ watch hands work? 479
How do neon lights work? 480
How does a sodium lamp work? 481
How do ‘fluorescent strip lights’ work? 482
9.5 Other optical effects 483
Why is the mediterranean sea blue? 483
Do old-master paintings have a ‘fingerprint’? 485

10 Adsorption and surfaces, colloids and micelles 487
10.1 Adsorption and definitions 487
Why is steam formed when ironing a line-dried shirt? 487
Why does the intensity of a curry stain vary so much? 489
Why is it difficult to remove a curry stain? 492
Why is iron the catalyst in the Haber process? 494
Why is it easier to remove a layer of curry sauce than to remove a curry
stain? 496
How does water condense onto glass? 497
How does bleach remove a dye stain? 498
How much beetroot juice does the stain on the plate contain? 499
Why do we see a ‘cloud’ of steam when ironing a shirt? 503
10.2 Colloids and interfacial science 504
Why is milk cloudy? 504
What is an ‘aerosol’ spray? 505
What is ‘emulsion paint’? 506
Why does oil not mix with water? 508
10.3 Colloid stability 509
How are cream and butter made? 509
How is chicken soup ‘clarified’ by adding eggshells? 510
How is ‘clarified butter’ made? 510
Why does hand cream lose its milky appearance during hand rubbing? 511
Why does orange juice cause milk to curdle? 512
How are colloidal particles removed from waste water? 513
10.4 Association colloids: micelles 514
Why does soapy water sometimes look milky? 514
What is soap? 517
Why do soaps dissolve grease? 518