{"id":5918,"date":"2018-05-21T21:33:37","date_gmt":"2018-05-21T19:33:37","guid":{"rendered":"http:\/\/agora.xtec.cat\/ies-merce-rodoreda\/?p=5918"},"modified":"2018-05-21T21:33:37","modified_gmt":"2018-05-21T19:33:37","slug":"determinacio-dels-fosfats-duna-beguda-de-coca-cola","status":"publish","type":"post","link":"https:\/\/agora.xtec.cat\/ies-merce-rodoreda\/general\/determinacio-dels-fosfats-duna-beguda-de-coca-cola\/","title":{"rendered":"Determinaci\u00f3 dels fosfats d’una beguda de Coca-Cola"},"content":{"rendered":"

\"\"<\/a><\/p>\n

En l’assignatura de Qu\u00edmica Anal\u00edtica del cicle superior de Qu\u00edmica Ambiental tenim l\u2019oportunitat de fer pr\u00e0ctiques al laboratori. D\u2019entre les 13 pr\u00e0ctiques realitzades\u00a0durant el curs 2017-2018, vam fer una que em va semblar molt interessant, en la qual vam determinar la quantitat de fosfats que contenia una beguda de Coca-cola.<\/p>\n

Aquesta pr\u00e0ctica es basa en una colorimetria en la qu\u00e8 es pot determinar la quantitat de fosfats d\u2019una mostra d\u2019aquesta beguda refrescant. \u00c9s una pr\u00e0ctica que cal realitzar amb\u00a0molta cura a l\u2019hora ja que la sensibilitat de la recta de calibratge \u00e9s molt important per tal que la concentraci\u00f3 de fosfats de la beguda de Coca-cola sigui coherent amb la concentraci\u00f3 real.<\/p>\n

<\/p>\n

En primer lloc, vam fer un arbre de dilucions a partir d\u2019un patr\u00f3 de 250 ppm de fosfats. En les dues dilucions interm\u00e8dies no vam afegir reactiu cromog\u00e8nic. Per tant, vam enrasar directament amb aigua destil\u00b7lada. En canvi, en les quatre dilucions final, vam afegir 15mL de reactiu cromog\u00e8nic per cada 200mL de volum final abans d\u2019enrasar el matr\u00e0s. Aix\u00ed, vam obtenir quatre dilucions de 5, 12.5, 25 i 37.5 ppm de fosfats. Tamb\u00e9 vam fer un blanc de patr\u00f3, en el qual vam utilitzar aigua destil\u00b7lada en lloc del patr\u00f3 de 250ppm.<\/p>\n

En segon lloc, vam realitzar les dilucions de la mostra de Coca-cola. Pr\u00e8viament, per\u00f2, vam eliminar el CO2<\/sub> ja que podia causar un error al pipetejar. Aix\u00ed, vam preparar dues dilucions de la mostra (2\/100 i 5\/100) i vam haver de preparar un BLANC DE MOSTRA, ja que la mostra inicial presentava\u00a0color propi i podia generar una interfer\u00e8ncia positiva en el resultat final. A les dilucions de la mostra vam afegir reactiu cromog\u00e8nic abans d\u2019enrasar per\u00f2 en el blanc de mostra no.<\/p>\n

En tercer lloc, vam realitzar la recta de calibratge fent un espectre d\u2019absorci\u00f3 a partir de\u00a0la diluci\u00f3 m\u00e9s concentrada, per tal d\u2019escollir la longitud d\u2019ona de m\u00e0xima absorb\u00e0ncia i que\u00a0la recta de calibratge fos el m\u00e9s sensible possible. Despr\u00e9s, vam ajustar al cero d\u2019absorb\u00e0ncia amb el blanc de patr\u00f3 i vam anar afegint a la cubeta els patrons des del m\u00e9s dilu\u00eft al m\u00e9s concentrat. Entre les dilucions vam netejar la cubeta ambientant-la tres cops amb la diluci\u00f3 a mesurar.<\/p>\n

Per \u00faltim, vam mesurar l\u2019absorb\u00e0ncia de les dilucions de la mostra i dels blanc de mostra. Restant l\u2019absorb\u00e0ncia dels blanc de mostra a la diluci\u00f3 de la mostra corresponent, vam poder obtenir l\u2019absorb\u00e0ncia NETA de cada diluci\u00f3 i aix\u00ed la concentraci\u00f3 REAL de fosfats de la mostra.<\/p>\n

\"\"<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

En l’assignatura de Qu\u00edmica Anal\u00edtica del cicle superior de Qu\u00edmica Ambiental tenim l\u2019oportunitat de fer pr\u00e0ctiques al laboratori. D\u2019entre les […]<\/p>\n","protected":false},"author":227,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"categories":[1],"tags":[],"class_list":["post-5918","post","type-post","status-publish","format-standard","hentry","category-general"],"post_mailing_queue_ids":[],"_links":{"self":[{"href":"https:\/\/agora.xtec.cat\/ies-merce-rodoreda\/wp-json\/wp\/v2\/posts\/5918","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/agora.xtec.cat\/ies-merce-rodoreda\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/agora.xtec.cat\/ies-merce-rodoreda\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/agora.xtec.cat\/ies-merce-rodoreda\/wp-json\/wp\/v2\/users\/227"}],"replies":[{"embeddable":true,"href":"https:\/\/agora.xtec.cat\/ies-merce-rodoreda\/wp-json\/wp\/v2\/comments?post=5918"}],"version-history":[{"count":3,"href":"https:\/\/agora.xtec.cat\/ies-merce-rodoreda\/wp-json\/wp\/v2\/posts\/5918\/revisions"}],"predecessor-version":[{"id":6219,"href":"https:\/\/agora.xtec.cat\/ies-merce-rodoreda\/wp-json\/wp\/v2\/posts\/5918\/revisions\/6219"}],"wp:attachment":[{"href":"https:\/\/agora.xtec.cat\/ies-merce-rodoreda\/wp-json\/wp\/v2\/media?parent=5918"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/agora.xtec.cat\/ies-merce-rodoreda\/wp-json\/wp\/v2\/categories?post=5918"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/agora.xtec.cat\/ies-merce-rodoreda\/wp-json\/wp\/v2\/tags?post=5918"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}