Page 12 - Physical chemistry understanding our chemical world

CONTENTS xi

Why does a torch battery eventually ‘go flat’? 325
Why does E AgCl,Ag change after immersing an SSCE in a solution of salt? 326
Why ‘earth’ a plug? 328
7.5 Concentration cells 333
Why does steel rust fast while iron is more passive? 333
How do pH electrodes work? 336
7.6 Transport phenomena 339
How do nerve cells work? 339
What is a ‘salt bridge’? 342
7.7 Batteries 343
How does an electric eel produce a current? 343
What is the earliest known battery? 345

8 Chemical kinetics 349
8.1 Kinetic definitions 349
Why does a ‘strong’ bleach clean faster than a weaker one does? 349
Why does the bleaching reaction eventually stop? 351
Why does bleach work faster on some greases than on others? 354
Why do copper ions amminate so slowly? 356
How fast is the reaction that depletes the ozone layer? 358
Why is it more difficult to breathe when up a mountain than at ground
level? 359
8.2 Qualitative discussion of concentration changes 361
Why does a full tank of petrol allow a car to travel over a constant
distance? 361
Why do we add a drop of bromine water to a solution of an alkene? 362
When magnesium dissolves in aqueous acid, why does the amount of
fizzing decrease with time? 364
8.3 Quantitative concentration changes: integrated rate equations 368
Why do some photographs develop so slowly? 368
Why do we often refer to a ‘half-life’ when speaking about radioactivity? 378
How was the Turin Shroud ‘carbon dated’? 382
How old is ¨ Otzi the iceman? 385
Why does the metabolism of a hormone not cause a large chemical change
in the body? 387
Why do we not see radicals forming in the skin while sunbathing? 388
8.4 Kinetic treatment of complicated reactions 393
Why is arsenic poisonous? 393
Why is the extent of Walden inversion smaller when a secondary alkyl
halide reacts than with a primary halide? 394
Why does ‘standing’ a bottle of wine cause it to smell and taste better? 397
Why fit a catalytic converter to a car exhaust? 399
Why do some people not burn when sunbathing? 400
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How do Reactolite sunglasses work? 403