CH EM I S T R Y OF WATE R
WAT ER IS A C HEMI C AL M OLE C ULE THA T C O NTAI N S TWO
HYD R OGE N ATO MS A ND ON E OX YGE N AT O M. THE TE RM
WAT ER OFT EN ALL U DES TO T HE COM P OUN D ' S LIQ U ID
CON D ITI O N. T HE SO LID PHA SE IS R E FERR ED T O AS ICE , W HILE
TH E GAS PH ASE IS RE F ERRE D TO AS S T EAM . WA TER MA Y ALSO
PR O DUC E A S U P ERC R I TICA L FLU ID UND E R S P ECI F IC
CON DIT ION S.
ALT E RNA T IVE NAM E S FOR WAT ER
AC T UA LLY , T HE I UPAC NOM E NC L ATU RE FOR WATER IS W AT ER. O XID ANE IS
AN OTH E R NAME FO R IT . IN C HEM I ST R Y, OXI DAN E IS E X CLU SIV E LY USED AS TH E
MO N ONU CLE AR PAR ENT H YDR IDE TO DES IGN ATE W ATE R D ER I VAT IVE S.
TH E TERM " WA TE R" IS DER IVE D FROM TH E OLD E NG LIS H WOR D WAE TER ,
PR OTO - GERM AN IC WAT AR , OR GER MA N WAS SER . THE SE TE RM S ALL I MPL Y
" WA TE R" OR " WET ."
CO M POS ITI ON OF W AT ER
WA TER IS MADE UP OF SOL ELY H YDR OGE N AND O XYG EN. B OT H E LE MEN TS HAVE
ST ABL E AND RAD IOA C TIV E I SOT OPE S IN NAT URE . W AT ER MOL ECU LES WI TH
WE I GH T S R AN GIN G F RO M 18 ( H 216 O) TO 22 ( D 218 O) ARE PR OJE CTE D TO
DE V EL O P AS A RES UL T OF T HESE ISO TOPES .
TH E MAI N WAT ER M O LE C UL E S H 216 O HAVE A M ASS OF 18 AM U, H O WE V ER
MO L EC ULE S W ITH M ASS ES 19 AN D 20 AR E ALSO PR E SE NT IN L AR GE QU A NTI TIE S.
TH E ISO TOP IC DIS TRIB UTI ON OF WA TER M OLE CU L ES RE LIE S ON IT S SOU RC E
AND AGE S INC E ISO TOP IC ABU NDA NCE S ARE NOT A LW AYS T HE SAME D UE TO
TH EIR AS TRO NOM I CAL OR IGI N.
PR O PER TIE S OF WAT ER
WA TER E XISTS N A TU R AL LY IN ALL TH REE S TATES ON THE P LA NET . W AT ER
BE C OM E S A SO LI D WHE N THE TEMP ERA TUR E FALLS BELOW FR E EZ ING ( 32
DE G RE E S F AHR ENH E IT ) . IT I S A L IQU ID BE T WE EN THE F RE E ZI NG AND B OI LIN G
PO INT S. AND IT IS A GAS A BOV E TH E BOI LING POI NT ( 212 DEG REE S
FA H REN HEI T). AP ART F RO M THE THR EE ST A TE S, WAT ER HA S A VA RIE TY OF
DI STI NCT CH A RAC TER I ST I CS. MO ST LI QUI DS SH R IN K AS T HE Y COO L, BUT NOT
WA TER . WAT ER W ILL S TO P S HR I NK ING AB OU T 39 DEG REE S F AHR ENH E IT, TH EN
RE V ER S E AND BEG IN TO G RO W AS IT BEC OME S C OL DER . A NOT HER AT TRI BUT E IS
CO H ESI ON , W HI CH IND ICA TES T HAT W AT ER IS D RAW N TO OT HER W AT ER.
WA T ER IN OUR B ODI ES
WA TER A CCO UN T S FOR A LM OST TWO- TH IR DS OF AN AD UL T HUM AN' S WEI GH T .
TW O- TH IR DS OF THI S WAT ER IS FO UND W ITH IN CE LLS , W IT H THE R EM A IN ING
TH IRD F OUND E XT R ACE LLU LAR L Y, MOS TLY IN BLO OD PL ASM A AND TH E
IN T ERS TIT IAL FLU ID TH AT B ATH ES TH E CE L LS . T HIS W AT ER, WH ICH AC CO U NT S
FO R ROU GHL Y 5 % OF BO DY WE IG HT ( ABOU T 5 L IN AN AD ULT ), SER VE S AS A
SU S TAI NIN G F LU ID FOR BLO OD CE LLS AS WE LL AS A WAY OF MO V IN G
CH E MI C AL S B ETW EEN CE LLS AND T HE EX TER NA L E N VIR ONM ENT . IT IS
ESS ENT IAL LY A 0 . 15 M S OLU TIO N OF S ODI UM CH LOR I DE ( NAC L) WI TH TR AC E
QU A NTI TIE S OF A DD I TIO NAL EL E CT R OLY TES , THE MO ST IM POR TA N T OF WH ICH
BE ING BI CAR BON A TE ( HCO 3 -) AND PR O TE I N ANI ONS .
