What volume of 75% alcohol by mass (.d=0.8g/cm3.) must be used to prepare 150 cc of 30% alcohol by mass (.d=0.9g/cm3.) ?

Question

What volume of 75% alcohol by mass (.d=0.8g/cm3.) must be used to prepare 150 cc of 30% alcohol by mass (.d=0.9g/cm3.) ? (A) 44.44 mL (B) 56.25 mL (C) 67.5 mL (D) 33.56 mL

Tardigrade Admin · Accepted Answer

M1V1=M2V2 ρ =(Wr/V4) Vr=(Wr/ρ ) (75/100)× V× 0.8=(30/100)× 150× 0.9 V=67.5 ml

Q. What volume of 75% alcohol by mass $(d = 0.8 g / c m^{3})$ must be used to prepare 150 cc of 30% alcohol by mass $(d = 0.9 g / c m^{3})$ ?

44.44 mL

56.25 mL

67.5 mL

33.56 mL

$M_{1} V_{1} = M_{2} V_{2}$

$ρ = \frac{W _{r}}{V _{4}}$

$V_{r} = \frac{W _{r}}{ρ}$

$\frac{75}{100} \times V \times 0.8 = \frac{30}{100} \times 150 \times 0.9$

$V = 67.5$ ml

Q. What volume of 75% alcohol by mass (d=0.8g/cm3) must be used to prepare 150 cc of 30% alcohol by mass (d=0.9g/cm3) ?