Question

Problema 8 va rooog urgeeent dau 13 puncte și coroana

Answer 1

ms1 = 200 g, c1 = 10% , c2 = 15%

stim ca c = mdx100/ms

=> md1 = ms1xc1/100 = 200x10/100 = 20 g

=> md2 = md1 + a , a = masa de dizolvat adaugata

    ms2 = ms1 + a

c2 = (md1+a)x100/(ms1+a)

15 = (20+a)100/(200+a)

15(200+a) = 2000 + 100a

=> 3000 + 15a = 2000 + 100a

=> a = 11,77 g

facem proba

ms2 = 200 + 11,77

md2 = 20 + 11,77

=> c2 = 31,77x100/211,77 = 15% ..............se verifica