Question

A 250cm cube flask of glass filled with sea water weighs 350g. Calculate the density of sea water if empty flask weighs 100g.

Answer 1

$m_{water} = m - m_{flask}; \\ \rho_{water} = \frac{m_{water}}{V} = \frac{m - m_{flask}}{V} = \frac{350\text{ g}-100\text{ g}}{250\text{ cm}^3} = 1\frac{\text{g}}{\text{cm}^3}.$