Question

Consider two solids, one (A) with a density of 2.79 g/mL, and the other (B) with a density of 7.91 g/mL.

a) If you mix 1.00 mL of each of the two substances together, what is the density of the mixture?............g/ml

b) If you mix 1.00 g of each of the two substances together, what is the density of the mixture?..........g/ml

Answer 1

a)

Masses of each sample are:

$m_A=D_A\times{V_A}=2.79g/mL\times1.00mL=2.79g$

$m_B=D_B\times{V_B}=7.91g/mL\times1.00mL=7.91g$

Therefore, the density of the mixture is:

$D_{AB}=\frac{m_A+m_B}{V_A+V_B}=\frac{2.79g+7.91g}{1.00mL+1.00mL}=5.35g/mL$

Answer: 5.35 g/mL

b)

Volumes of each sample are:

$V_A=\frac{m_A}{D_A}=\frac{1.00g}{2.79g/mL}=0.3584mL$

$V_B=\frac{m_B}{D_B}=\frac{1.00g}{7.91g/mL}=0.1264mL$

Therefore, the density of the mixture is:

$D_{AB}=\frac{m_A+m_B}{V_A+V_B}=\frac{1.00g+1.00g}{0.3584mL+0.1264mL}=4.13g/mL$

Answer: 4.13 g/mL