You are trying to determine the density of a piece of metal. You use a balance and find that the mass of the piece of metal is 56.72 g. To determine the volume of the metal, you fill a graduated cylinder to 31.0 mL and then drop the piece of metal into the graduated cylinder. The final volume is 38.9 mL. What is the density of the piece of metal?

On October 21, 1982, the Bureau of the Mint changed the composition of pennies (see Exercise 120). Instead of an alloy of 95% Cu and 5% Zn by mass, a core of 99.2% Zn and 0.8% Cu with a thin shell of copper was adopted. The overall composition of the new penny was 97.6% Zn and 2.4% Cu by mass. Does this account for the difference in mass among die pennies in Exercise 120? Assume the volume of the individual metals that make up each penny can be added together to give the overall volume of the penny, and assume each penny is the same size. (Density of Cu = 8.96 g/cm3; density of Zn = 7.14 g/cm3).

A student is trying to identify the composition of a pure metal block by determining its density. The student records the mass of the sample to be 30.0 g. The rectangular block is 2.00 cm × 3.00 cm × 1.40 cm.

Ethanol has a density of 0.789 g cm‐3. Calculate the volume in mL that must be poured into a measuring cylinder to give 19.8 g of ethanol. Note 1 mL = 1 cm3.