Report Sheet: Pre-lab Questions (pay attention to significant figures) I. A stud
ID: 1082538 • Letter: R
Question
Report Sheet: Pre-lab Questions (pay attention to significant figures) I. A student placed a metal cube in a pre-weighed 50-mL beaker and measured the combined mass of the beaker and solid. She then measured the length of each side of the cube and found it to be identical. Her mcasurements are shown below. Use these measurements to calculate the density of the solid? Show work Mass of 50-mL beaker Mass of the 50-mL beaker + solid cube Length of the side of the cube: 4.930 g 42.120 g 2.15 cm 2. An irregularly shaped solid was carefully lowered into a 1000-mL graduated cylinder containing 536 mL of water. When the solid was completely under water, the water level rose to 712 mL. What is the volume of the solid? Show work 3. In an experiment, a student transferred 4.50 mL of a liquid into a pre-weighed beaker (the weight of which was determined to be 35.986 g). The combined weight of the beaker and the liquid was found to be 40.785 g. Calculate the density of the liquid. Show work! 4. In an experiment, a student determined the density of a liquid to be 0.875g/mL. Suppose the actual density of the liquid at that temperature is 0.840 g/mL. Calculate the percent error in the student's experimental value. Show work!Explanation / Answer
Density = mass/ volume
1.
mass of solid = mass of solid + beaker - mass of beaker
= 42.120g - 14.930g = 27.19g
volume of cube = a3 = (2.15 cm)3 = 9.93875 cm3
denisty = 27.19g / 9.93875 cm3 = 2.73575 g/cm3 ~ = 27.7358 g/cm3 upto 4 decimal places
correct answer should be reported with least significant figure(present in 2.15)) = 27.7 g/cm3
2.
volume of solid = volume of liquid raise in the beaker
volume of solid = 712 mL - 536 mL = 176 mL
3.
weight of liquid = weight of beaker + liquid - weight of beaker = 40.785g - 35.986g = 4.799g
volume given = 4.50 mL
density = mass/volume = 4.799g / 4.5 mL =1.066 g/mL ~ 1.07 g/mL
4.
(determined value - actual value) / actual x 100 = % error
(0.875- 0.840) / 0.840 x 100 = 4.17 %