Question

Liquid octane (CH) has a density of 0.7025 g/mL at 20 °C. Find the true mass (murue) of octane when the mass weighed in 18 air is 17.320 g. Assume the air density is 0.0012 g/mL and the balance weight density is 7.5 g/mL 17.35

Answer 1

Explanation:

According to Buoyance equation,

          m = $[m' \times \frac{1 - \frac{d_{a}}{d_{w}}}{1 - \frac{d_{a}}{d}}]$

where,      m = true mass

                 m' = mass read from the balance = 17.320 g

              $d_{a}$ = density of air = 0.0012 g/ml

              $d_{w}$ = density of the balance = 7.5 g/ml

                    d = density of liquid octane = 0.7025 g/ml

Now, putting all the given values into the above formula and calculate the true mass as follows.

      m = $[m' \times \frac{1 - \frac{d_{a}}{d_{w}}}{1 - \frac{d_{a}}{d}}]$    

          = $[17.320 g \times \frac{1 - \frac{0.0012 g/ml}{7.5 g/ml}}{1 - \frac{0.0012 g/ml}{0.7025}}]$

          = $17.320 g \times 0.999850$                

          = 17.317 g

Thus, we can conclude that the true mass of octane is 17.317 g.