Mass/Volume Calculation

• The simplest way to find object density (d) is to divide object mass (m) by volume (v). Mass is determined by weighing the object of interest. A "neat" shape, such as a sphere or cube, facilitates direct calculation of object volume.
  
  

Irregular Object Volume

• If an irregularly shaped rock raises the volume of a liquid by 2 mL when added to a liquid, then the rock has volume of 2 mL.
  
  

Density of Ideal Gas

• Ideal gas equation is PV = nRT, where P is pressure, V is volume, n is amount (moles), R is a substance-specific factor, and T is temperature. Also, mass (M) is the product of moles (n) and molecular weight (W). Therefore, M = nW. We calculate V = nRT/P. Since d = M/V, d = (nW)/ (nRT/P). This equation simplifies to d = WP/ (RT). No gas is completely "ideal," but this formula gives a good approximation.