Question

Liquid octane (C8H18) has a density of 0.7025 g/mL at 20°C. Find the true mass (mtrue) of octane when the mass weighed in air is 17.660 g. Assume the air density is 0.0012 g/mL and the balance weight density is 7.5 g/mL.

Answer 1

Given that

Liquid octane (C8H18) has a density = 0.7025 g/mL at 20°C.

air density = 0.0012 g/mL and the balance weight density is 7.5 g/mL.

To solve this problem we use Buoyance equation:

Equation is :

m = [ m’{1-(da/dw)}/ {1-(da/d)}]

here m is the true mass ( we have to determine )

m’ mass which is read from the balance = 17.660 g

d a = density of air = 0.0012 g /mL

dw = density of the balance = 7.5g / mL

d = density of the liquid octane = 0.7025 g /mL

lets plug all of these value and get m

m={17.660(1-(0.0012/7.5)}/{1-(0.0012/0.7025)}

m={17.660(1-(0.00016)}/{1-(0.00171)}

m=17.657/0.99829

m = 17.69 g