Question

un concentrat de lamaie, contine aproximativ 6,5% acid citric. se cere a) concentratia acidului citric in solutia obtinuta prin amestecarea a 20 g concentrat lamaie cu 30g apa, b) cantitatea(g) de apa ce trebuie adaugata la 20 g concentrat lamaie pentru a obtine o solutie de 2% acid citric, multumesc

Answer 1

a) 

md = 20 g
ms = 30 g apa
----------------------
c%=?

ms = md + m apa
ms = 20 + 30
ms = 50 g solutie
c% = md / ms * 100
c% = ( 20 * 100 ) / 50
c% = 40 %


b)

md = 20 g
c% = 2 %
----------------
m apa = ?


c% = md / ms * 100
c / 100 = md / ms
2 / 100 = 20 / ms
ms = ( 20 * 100 ) /2
ms = 1000 g solutie
ms = md + m apa
m apa = ms - md
m apa = 1000 - 20
m apa = 980 g apa