Name: ____________________________________________ Date: ________________ P___R___S___ CPA Chemistry Density Lab 25% of the grade 50 points total No late work is accepted! As a whole class: A) Finding the density of a regular shaped object: A rectangular solid is 5 cm long, 2 cm high and 4 cm wide. The mass of this solid is 30 grams. Calculate its density. 5 cm 2 cm 4 cm Density = ______________________________________ B) Finding the density of an irregular shaped object: The water level of a graduated cylinder is 20 cm3. A rock is dropped into the graduated cylinder. The water level rises to 23 cm3. It has a mass of 25 grams. Calculate the density of this rock. Density = ______________________________________ C) Compare the densities of two objects with same materials but different volumes and masses Given a small rubber stopper and a big rubber stopper (they are with same material). Estimate the following situations: 1) The small rubber stopper has (the same / bigger / smaller) density comparing to the big rubber stopper. 2) The small rubber stopper will (sink in / float on) the water. 3) The big rubber stopper will (sink in / float on) the water. A small rubber stopper has the mass of 1 g and volume of 2 cm3. What is its density? __________________________ A big rubber stopper has the mass of 2 g and volume of 4 cm3. What is its density? __________________________ Do they have the same densities? ____________________________ As a lab group of two: A) Find the density of a regular shaped object Material: Wooden block Ruler Electric balance Procedure: 1) Use the ruler to find the length, width and height in cm. length _________________ width __________________ height __________________ To determine the volume multiply length x width x height in cm3. Volume of the wooden block = ________________________ (work) = ________________________ (answer) 2) Use the electric balance to find the mass of the wooden block in g. Mass = _______________________ 3) Now calculate the density of the wooden block. Show all your work! Density = _________________________ B) Find the density of an irregular shaped object Material: Metal screw Electric balance 25-mL graduated cylinder Procedure: 1) Fill the graduated cylinder about halfway with water. At eye level, record the volume of the water. (Make sure you read the bottom of the meniscus) Volume of water = ____________________________ mL Now carefully slide the screw into the graduated cylinder. Be careful not to let any of the water splash out. Read and record the new volume of water and screw. Volume of water and screw = _______________________ mL Volume of just the screw = Volume of water and screw – Volume of water = ______________________________________ = ________________ mL = ______________ cm3 (1 ml = 1 cm3) 2) Dry off the screw. Use the balance to find the mass of the screw in g. Mass = _______________________ 3) Now calculate the density of the screw. Show your work! Density = _________________________ C) Compare the densities of two objects with same materials but different volumes and masses Material: Small cork Big cork Plastic beaker 25-mL graduated cylinder Electric balance Procedure 1) Estimate the following situations: The small cork has (the same / bigger / smaller) density comparing to the big cork. The small cork will (sink in / float on) the water. The big cork will (sink in / float on) the water. 2) Use the same procedure as the above C) to find: Small cork Big cork Volume of water (mL = cm3) Volume of water + cork (mL = cm3) Volume of cork (mL = cm3) 3) Dry off the corks. Use the balance to find the mass of the corks in g. Mass of the small cork = _________________ 4) Calculate the density (SHOW YOUR WORK): Density of the small cork = Mass of the big cork = __________________ Density of the big cock = 5) Now carefully put both the corks onto the beaker of water. a) Explain what happen. b) Does the experiment result match with your estimation? Why or why not? c) Do they have the same density? Why do you think if they have same or different density?