Question

1) Calculeaza masa de solutie 25% ce contine 7,5 kg de sare de bucatarie.
2) Determina masa de substanta dizolvata din 250 L solutie de CuSO 4 1,2M.
Mase atomice: Cu-64, S-32, O-16
3) Calculeaza volumul solutiei 1,5M ce contine 300g de CaCO 3 .
Mase atomice: Ca-40, C-12, O-16
4) Determina masa de substanta dizolvata din 3kg solutie 20% .

VA MULTUMESC IN AVANS!!

Answer 1

1)

c% = mdx100/ms

=> ms = mdx100/c% = 7,5x25/100 = 1,875 kg sare

2)

Cm = md/MxVs ; M.CuSO4 = 64+32+4x16 = 160 g/mol

=> md = CmxVsxM

= 1,2x0,25x160 = 48 g CuSO4

3)

Cm = md/MxVs ; M.CaCO3 = 40+12+3x16 = 100 g/mol

=> Vs = md/CmxM

= 300/1,5x100 = 2 L sol.

4)

c% = mdx100/ms

=> md = msxc%/100

= 3x20/100 = 0,6 kg