Answer
a) 11.063 mL
b) 0.78900 g/mL
c) 7.140 g/mL
Work Step by Step
a) To find the volume of the pycnometer, you need to find the mass of the water, and plug that into the density of the water that they give you to find the volume since $D=M\div V$. Therefore, volume is equal to $M\times D$. So knowing the density and the mass will allow you to find the volume. The density of the water is .99820 g/mL, and the mass of the water is the mass of the pycnometer when it is full of water minus the mass of the pycnometer when it is empty. Plugging in these numbers into $V=M\times D$, you find the volume to be 11.063 mL (make sure to round to the appropriate number of significant figures).
b) Part b of this question asks for the density of ethanol given the mass. Using what you figured out in the previous question (volume of the pycnometer), and knowing that $D=M\div V$, you can figure out the density of ethanol. Subtract the mass of the pycnometer (32.0764, as stated in question) from the total mass with ethanol (40.8051) to find the mass of just the ethanol. Then, divide this number by the volume you figured out in part a. You will end up with 0.78900 g/mL
c) To figure out this part of the question, you will have to find the volume of the water. You know the density of the water, so again, you can use the density formula. You find the mass of the water by subtracting the mass of the zinc and the mass of the pycnometer from the total mass. Then, you plug in the density and the mass of the water into the density formula and solve for the volume. Once you get the volume of the water, subtract that from the total volume of the pycnometer. The number you get will be the volume of the zinc. You then plug in the mass and volume into the density formula, and you will end up with 7.140 g/mL.
