Question

1) A piece of wood has a measured mass of 212.8 g. The wood is a cylinder of radius 4.5 cm and length 6.2 cm. What is the density of the wood? g/cm3 2) 23.0 mL of water are put in a graduated cylinder. The cylinder with the water in it has a mass of 149.6 g. The dry, empty cylinder has a mass of 127.2 g. What is the density of the water? g/mL 3) A jagged piece of iron has a mass of 19.5 g. After the iron is fully submerged in 25.0 mL of water, the water level is 27.5 mL. What is the density of the iron? g/mL 4) Final question: If the iron in #3 were only partially, not fully, submerged in the water, would the density result be GREATER, LESS, or the SAME as the result in #3 above? Explain why.

Answer 1

Q1. Volume of cylinder = (pi) * (radius)^2 * (length)

Volume of cylinder = (3.14) * (4.5 cm)^2 * (6.2 cm)

Volume of cylinder = 394.4 cm^3

density of wood = (mass of wood) / (volume of cylinder)

density of wood = (212.8 g) / (394.4 cm^3)

density of wood = 0.54 g/cm^3

Q2. mass of water = (mass of empty cylinder + water) - (mass of empty cylinder)

mass of water = (149.6 g) - (127.2 g)

mass of water = 22.4 g

density of water = (mass of water) / (volume of water)

density of water = (22.4 g) / (23.0 mL)

density of water = 0.974 g/mL

Q3. volume of iron = (volume of water + iron) - (volume of water)

volume of iron = (27.5 mL) - (25.0 mL)

volume of iron = 2.5 mL

density of iron = (mass of iron) / (volume of iron)

density of iron = (19.5 g) / (2.5 mL)

density of iron = 7.80 g/mL

Q4. when iron peice is not fully submerged, the volume of iron will be less than 2.5 mL and since mass remains same, the density will be higher as the result in #3 above.