Question

Suppose now that you wanted to determine the density of a small crystal to confirm that it is graphite. From the literature, you know that graphite has a density of 2.25 g/cm^3. How would you prepare 20.0 mL of the liquid mixture having that density from pure samples of CHCl3 (d = 1.492 g/mL) and CHBr3 (d = 2.890 g/mL)? (Note: 1 mL = 1 cm^3.)

Answer 1

Answer:

The volume of first and second compound are 9.15 ml and 10.85 ml.

Explanation:

Given that,

Density of graphite = 2.25 g/cm³

Volume of mixture = 20.0 mL

Density of first compound = 1.492 g/ml

Density of second compound = 2.890 g/ml

Let the volume of first mixture = x

The volume of second mixture = (20-x)....(I)

We need to calculate the volume of first compound

Using formula of  density of mixture

$\rho=\dfrac{V_{1}\rho_{1}+V_{2}\rho_{2}}{V_{1}+V_{2}}$

Where, $V_{1}$ = volume of first compound

$V_{2}$ = volume of second compound

$\rho_{1}$ =density of first compound

$\rho_{1}$ = density of first compound

Put the volume into the formula

$2.25=\dfrac{x\times1.492+(20-x)\times2.890}{x+20-x}$

$45=1.492x+57.8-2.890x$

$45-57.8=1.492x-2.890x$

$12.8=1.398x$

$x=\dfrac{12.8}{1.398}$

$x=9.15\ ml$

We need to calculate the volume of second compound

Using equation (I)

$V_{2}=20-x$

Put the value of x

$V_{2}=20-9.15$

$V_{2}=10.85\ ml$

Hence, The volume of first and second compound are 9.15 ml and 10.85 ml.