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

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

Step-by-step 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=(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=(x*1.492+(20-x)*2.890)/(x+20-x)`

`45=1.492x+57.8-2.890x`

`45-57.8=1.492x-2.890x`

`12.8=1.398x`

`x=(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.