Data:
m (mass) = ?
MM (Molar Mass) of H2O2
H = 2*1 = 2u
O = 2*16 = 32u
----------------------
MM H2O2 = 34 g/mol
M (molarity) = ?
V = 1500mL → V = 1,5 L
n (molar solution) = 1,33 mol
[tex]M = \frac{n}{V} = \frac{1,33}{1,5} [/tex]
[tex]M\approx0,8mol/L[/tex]
Soon:
[tex]M = \frac{m}{MM*V} [/tex]
[tex]0,8 = \frac{m}{34*1,5} [/tex]
[tex]0,8 = \frac{m}{51} [/tex]
[tex]m = 0,8*51[/tex]
[tex]\boxed{m = 40,8g}[/tex]