What volume of iron (density 7.87 g/cm3) would be required to balance a 1.00 cm3 sample of lead (density 11.4 g/cm3) on a two-pan laboratory balance?

Question

What volume of iron (density 7.87 g/cm3) would be required to balance a 1.00 cm3 sample of lead (density 11.4 g/cm3) on a two-pan laboratory balance?

Answer 1

Calculate mass of lead:

1.00 cm³ lead x 11.4 g/cm³ = 11.4 g lead on one side of balance

 

To balance that, one needs 11.4 g of iron on the other pan.  Calculate volume of iron to give you 11.4 g:

11.4 g iron x 1 cm³/7.87 g = 1.45 cm³ of iron needed