1)
Se amestec 250 g sirop de c% = 25% cu 150 g sirop de c% = 15%. Ce concentratie finala are solutia obtinuta?
Rezolvare:
ms1 = 250g, c1% = 25%
ms2 = 150g , c2% = 15%
-------------------------------/-------
c%final = ?%
------------------------------//------
c% = mdx100/ms
=> md1 = ms1xc1/100 = 250x25/100 = 62,5g
=> md2 = ms2xc2/100 = 150x15/100 = 22,5g
=> md.final = md1+md2 = 62,5+22,5 = 85g
=> ms.final = ms1+ms2 = 250+150 = 400g
=> c%final = md.finalx100/ms.final
= 85x100/400 = 21,25%
2)
La 300g saramura de c% = 15% se adauga 250 g apa. Ce conc. procentuala finala are solutia dupa adaugarea apei?
Rezolvare:
ms1 = 300g, c1% = 15%
m.apa.adaugata = 250g
---------------------------------/-----
c%.finala = ?%
--------------------------------//----
din c% => md = msxc%/100 = 300x15/100 = 45g
ms.final = ms1 + m.apa.adaugata = 300+250 = 550g
=> c%finala = mdx100/ms.finala
= 45x100/550 = 8,2% (rotunjit)
3)
In 250g ceai cu zahar de c% = 10% se mai adauga o lingurita cu 10 g zahar. Ce concentratie are ceaiul dupa adaugarea zaharului?
ms = 250g, c% = 10%
md1 = 10g zahar
-----------------------------/---
c%finala = ?%
-----------------------------//----
din c% => md.initial = msxc%/100
= 250x10/100 = 25g
=> md.final = md.initial + md1 = 25+10 = 35g
=> ms.final = ms + md1 = 250+10 = 260g
=> c%finala = md.finalx100/ms.final
= 35x100/260 = 13,5% (rotunjit)
