NATURFAGPRØVE FOR 8A, KAPITTEL 7 og 8, 27.03.2015. NAVN:___________________ Svar på oppgavearket. Dersom det ikke er satt av tilstrekkelig med plass, kan du bruke siste side. Svar med penn eller blyant. 1: I en demo brukte vi sukker og konsentrert svovelsyre. Fortell hva som skjedde. Hvilken egenskap ved svovelsyre så vi demonstrert? Svar: ___________________________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________ 2: Forklar pH-skalaen. Svar: ___________________________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________ 3: Hva er en syre-base-indikator. Nevn fire eksempler på syre-base-indikatorer. Svar: ___________________________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________ 4: Hvilke to gasser er det mest av i luft? Hvor mye er det av de to gassene? Svar: ___________________________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________ 5: I en elevøvelse framstilte vi hydrogengass. Forklar hva vi gjorde i denne øvelsen. Hvilke egenskaper har hydrogengass? Svar: ___________________________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________ 6: Nevn fire egenskaper for en sur løsning. Svar: ___________________________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________ 7: Nevn tre egenskaper for en basisk løsning. Svar: ___________________________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________ 8: Hva mener vi med at en syre og en base nøytraliserer hverandre? Svar: ___________________________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________ 9: Hvorfor kan eddik brukes som middel til konservering av mat? Svar: ___________________________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________ 10: Hvordan endres pH hvis vi tilsetter vann til en sur eller basisk løsning? Svar: ___________________________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________ 11: Hvorfor kan karbondioksid brukes som brannslokkingsmiddel? Svar: ___________________________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________ 12: Hvorfor er en basisk løsning farlig for øynene? Svar: ___________________________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________ 13: Hvilket fellestrekk har vi i den kjemiske formelen for syrer? Svar: ___________________________________________________________________________ 14: Forklar fotosyntesen. Svar: ___________________________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________ 15: VURDER PÅSTANDENE OG KRYSS AV FOR RETT ELLER GALT. NR 1 2 3 4 5 6 7 8 9 10 11 12 PÅSTAND Karbondioksid ble tidligere kalt kvelstoff. Hvis vi fortynner en base med vann, blir den etterhvert sur. BTB er en indikator som er blå i basisk løsning. Syre i vann går an – vann i syre er uhyre. pH-verdien i en sitron er litt over 7. Hvis pH i regnvannet er over 5,6, har vi sur nedbør. Nitrogengass blakker kalkvann. Andrée landet med en ballong, fylt med hydrogengass, på Nordpolen i 1897. Når du blåser på et bål, tilfører du energi som får bålet til å brenne bedre. Bakepulver reagerer med surt stoff og danner karbondioksid. Når SO2 løses i vann, dannes det svovelsyre. Kalsiumkarbonat (CaCO3) løst i vann, er en syre. RETT GALT