1. Bestem den molære masse af urinstof:
* Carbon (c):12,01 g/mol
* Hydrogen (H):1,01 g/mol
* Nitrogen (n):14,01 g/mol
* Oxygen (O):16,00 g/mol
Molær masse urinstof (ch₄n₂o) =(12,01) + (4 * 1,01) + (2 * 14,01) + (16,00) =60,06 g/mol
2. Beregn molen af urinstof:
* Mol =masse / molær masse
* Mol urinstof =5,6 g / 60,06 g / mol =0,0932 mol
3. Beregn antallet af molekyler:
* Avogadros nummer =6,022 x 10²³ molekyler/mol
* Antal urinstofmolekyler =0,0932 mol * 6,022 x 10²³ molekyler/mol =5,61 x 10²² molekyler
4. Beregn antallet af atomer for hvert element:
* brint (H): Hvert urinstofmolekyle har 4 hydrogenatomer.
* Antal H -atomer =5,61 x 10²² molekyler * 4 atomer/molekyle =2,24 x 10²³ atomer
* carbon (c): Hvert urinstofmolekyle har 1 carbonatom.
* Antal C -atomer =5,61 x 10²² molekyler * 1 atom/molekyle =5,61 x 10²² atomer
* nitrogen (n): Hvert urinstofmolekyle har 2 nitrogenatomer.
* Antal N -atomer =5,61 x 10²² molekyler * 2 atomer/molekyle =1,12 x 10²³ atomer
* ilt (O): Hvert urinstofmolekyle har 1 iltatom.
* Antal O -atomer =5,61 x 10²² molekyler * 1 atom/molekyle =5,61 x 10²² atomer
Derfor:
* brint: 2.24 x 10²³ atomer
* carbon: 5,61 x 10²² atomer
* nitrogen: 1,12 x 10²³ atomer
* ilt: 5,61 x 10²² atomer