Daskaranren ruwa(ice)

Ice ruwa ne da ke daskarewa zuwa wani yanayi mai ƙarfi, yawanci yana samuwa a ko ƙasa da yanayin zafi na 0 ° C, 32 ° F, ko 273.15 K. Yana faruwa ne ta halitta a duniya, a kan sauran taurari, a cikin abubuwan girgije na Oort, kuma a matsayin kankara mai tsaka-tsaki. A matsayin ƙwararren inorganic crystalline da ke faruwa ta halitta tare da tsari mai tsari, ana ɗaukar kankara a matsayin ma'adinai. Dangane da kasancewar ƙazanta irin su barbashi na ƙasa ko kumfa na iska, yana iya bayyana a fili ko fiye ko žasa da launin shuɗi-fari.

Kusan duk ƙanƙarar da ke duniya na wani tsari ne na crystalline hexagonal wanda ake nunawa da ƙanƙara Ih (ana magana da "kankara ɗaya h"). Ya danganta da yanayin zafi da matsa lamba, aƙalla matakai goma sha tara (ƙulla geometries) na iya wanzuwa. Mafi yawan canjin lokaci zuwa ƙanƙara Ih yana faruwa lokacin da aka sanyaya ruwan ruwa ƙasa 0 °C (273.15 K, 32 °F) a daidaitaccen yanayin yanayi. Lokacin da ruwa ya yi sanyi da sauri (quenching), har zuwa nau'i uku na ƙanƙara amorphous zai iya samuwa. Kankarar Interstellar ƙanƙara ce mai ƙarancin ƙarancin ƙima (LDA), wanda wataƙila ya sa LDA ƙanƙara ta zama nau'in da ya fi yawa a sararin samaniya. Lokacin da aka sanyaya a hankali, haɗin haɗin proton tunneling yana faruwa a ƙasa -253.15 °C (20 K, -423.67 °F) yana haifar da abubuwan mamaki masu yawa.

Kankara yana da yawa a saman duniya, musamman a yankunan polar da kuma saman layin dusar ƙanƙara, inda zai iya haɗuwa daga dusar ƙanƙara don samar da glaciers da zanen kankara. Kamar yadda dusar ƙanƙara da ƙanƙara, ƙanƙara nau'i ne na hazo na yau da kullun, kuma ana iya ajiye shi kai tsaye ta tururin ruwa azaman sanyi. Canji daga kankara zuwa ruwa yana narkewa kuma daga kankara kai tsaye zuwa tururin ruwa shine sublimation. Waɗannan matakai suna taka muhimmiyar rawa a cikin yanayin yanayin ruwa na duniya. A cikin 'yan shekarun nan, yawan kankara a duniya yana raguwa saboda sauyin yanayi. An sami raguwa mafi girma a cikin Arctic da kuma a cikin tsaunukan da ke wajen yankunan polar. Asarar ƙanƙara mai tushe (saɓanin ƙanƙarar ruwan teku) shine farkon wanda ke ba da gudummawa ga hawan teku.

Mutane sun yi amfani da ƙanƙara don dalilai daban-daban na dubban shekaru. Wasu gine-ginen tarihi da aka tsara don riƙe ƙanƙara don samar da sanyaya sun wuce shekaru 2,000. Kafin kirkiro fasahar sanyaya abinci, hanya daya tilo da za a iya adana abinci cikin aminci ba tare da an gyara shi ta hanyar abubuwan da ake adanawa ba ita ce amfani da kankara. Isasshen ƙanƙara mai ƙarfi yana sa magudanar ruwa su sami damar jigilar ƙasa a lokacin hunturu, kuma ana iya kiyaye hanyoyin kankara da aka keɓe. Ice kuma tana taka rawa sosai a wasannin hunturu.

 Bayyanannun Abubuwa 
Ice tana da tsarin crystalline na yau da kullun dangane da kwayoyin ruwa, wanda ya ƙunshi atom ɗin oxygen guda ɗaya wanda aka haɗa shi da atom ɗin hydrogen guda biyu, ko H-O-H. Duk da haka, yawancin abubuwan da ke cikin jiki na ruwa da kankara ana sarrafa su ta hanyar samar da haɗin gwiwar hydrogen tsakanin oxygen da ke kusa da kwayoyin hydrogen; alhali yana da rauni mai rauni, amma duk da haka yana da mahimmanci wajen sarrafa tsarin ruwa da kankaraBjerrum, N (11 April 1952). "Structure and Properties of Ice". Science. 115 (2989): 385–390. Bibcode:1952Sci...115..385B. doi:10.1126/science.115.2989.385. PMID 17741864..

Wani abu da ba a saba gani ba na ruwa shi ne cewa ƙaƙƙarfan sifarsa—kankara da aka daskare a matsa lamba na yanayi—ya kai kusan kashi 8.3 cikin ɗari fiye da sifar ruwansa; wannan yayi daidai da haɓakar girma na 9%. Yawan ƙanƙara shine 0.9167 Harvey, Allan H. (2017). "Properties of Ice and Supercooled Water". In Haynes, William M.; Lide, David R.; Bruno, Thomas J. (eds.). CRC Handbook of Chemistry and Physics (97th ed.). Boca Raton, FL: CRC Press. ISBN 978-1-4987-5429-0.9168 Voitkovskii, K. F., Translation of: "The mechanical properties of ice" ("Mekhanicheskie svoistva l'da"), Academy of Sciences (USSR), DTIC AD0662716 g / cm3 a 0 ° C da daidaitattun yanayin yanayi (101,325 Pa), yayin da ruwa yana da nauyin 0.9998  - 0.999863  g / cm3 a yanayin zafi da matsa lamba. Ruwan ruwa ya fi yawa, ainihin 1.00 g/cm3, a 4 ° C kuma ya fara rasa yawansa yayin da kwayoyin ruwa suka fara samar da lu'ulu'u masu tsayi na kankara yayin da aka kai ga daskarewa. Wannan ya faru ne saboda haɗin gwiwar hydrogen da ke mamaye rundunonin ƙwayoyin cuta, wanda ke haifar da tattara ƙwayoyin ƙwayoyin cuta marasa ƙarfi a cikin daskararru. Yawan ƙanƙara yana ƙaruwa kaɗan tare da rage zafin jiki kuma yana da ƙimar 0.9340 g/cm3 a -180 °C (93 K).Lide, D. R., ed. (2005). CRC Handbook of Chemistry and Physics (86th ed.). Boca Raton, Florida: CRC Press. ISBN 0-8493-0486-5.

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