Analía Bellizzi – Chemistry Classes

Ronald Reagan Senior High School

Determining the Density of Irregular Solids

Introduction

The purpose of this experiment is to understand the meaning and significance of the density of a substance. Density is a basic physical property of a homogeneous substance; it is an intensive property, which means it depends only on the substance’s composition and does not vary with size or amount. The determination of density is a nondestructive physical process for distinguishing one substance from another. Density is the ratio of a substance’s mass to its own volume.

In the metric system the unit of density for a liquid or solid is measured in g/mL or g/cm3 . The cm3 volume unit used with solids is numerically equal to mL volume unit used with liquids. That is, 1 mL = 1 cm3

In this experiment you will determine the density of several liquids and compare the physical properties of those liquids.

Which is heavier, a pound of aluminum or a pound of lead? The answer, of course, is neither, but many people confuse the words “heavy” and “dense” “Heavy” refers to mass only. Density is the mass of a substance contained in a unit of volume. Lead is a very dense metal and contains a large quantity of matter in a small
volume, while aluminum, being much less dense, contains a smaller quantity of matter in the same volume.

1- DENSITY OF IRREGULAR SOLIDS

 

Purpose of the lab

Determine the density of three different IRREGULAR SOLIDS

Materials

    • 50 mL Graduated Cylinder
    • Digital Balance
    • 3 rubber Stoppers of each size (00, 0 and 1)
    • tap water

Procedures: 

 
For each set of 3 rubber stoppers, repeat the same procedures
    1. Measure the mass rubber stoppers (#00) using the triple beam balance.
    2. Record this value in your data table
    3. Fill the 50 cm3 graduated cylinder with SOME water (between 25 and 35 cm3)
    4. Record the exact initial volume of water with the correct amount of significant figures (one decimal).
    5. Carefully insert the rubber stopper in the graduated cylinder. (be careful not to splash any water)
    6. Measure the volume of water + objects.
    7. Record the final volume in your table. (objects + water)
    8. Calculate the volume of the object based on your measurements.
    9. Calculate the density of the rubber stopper.
    10. Repeat the procedure for all the combinations in the table below

Lab Setup

Draw snapshots of the step by step for one of the trials.

LAB SETUP IS NOT A COLLECTION OF LAB EQUIPMENT . You need to show HOW those items were arranged in order to perform the lab.

Data Table

Data tables in you lab reports MUST BE DONE USING RULER on GRAPH PAPER.

You should PASTE data tables on your lab report using glue or tape DO NOT USE STAPLES!

How to record your measurements

In order to record your measurements properly and with the correct amount of significant figures, follow the instructions in the link below:

MEASUREMENTS – HOW TO SHOW THEM – HOW MANY SIG FIG?

Calculations

Calculations that lead to filling out the data table must be shown here. 

You need to specify what you are calculating so I can follow your reasoning. 

1- DENSITY OF LIQUIDS

 

Purpose of the lab

Determine the density of three different LIQUIDS

Materials

    • 10 mL Graduated Cylinder
    • Digital Balance
    • DISTILLED water
    • ALCOHOL
    • ACETONE (not done this year) 

Procedures:

For each liquid follow the instructions below:

    1. Using a triple beam balance, measure the mass of the empty graduated cylinder.
    2. Record the mass in your data table.
    3. Fill the graduated cylinder with some DISTILLED WATER. (between 8 and 10 mL.
    4. Record the volume in your data table
    5. Find the mass of the water and graduated cylinder by subtracting the final mass from the original one.
    6. record the mass of the water on your data table.
    7. Find the density of water at room temperature.

empty and dry the graduated cylinder. 

Repeat the steps for ALCOHOL and then for ACETONE

Data Table

Calculations

Calculations that lead to filling out the data table must be shown here. 

You need to specify what you are calculating so I can follow your reasoning. 

ANALYSIS QUESTIONS

Remember that:

      1. mL is numerically equivalent to cm3
      2. To receive full credit for every question, you need to show:
        1. Formula that you used, and how you isolated the correspondent variable needed.
        2. Plugin numbers with units
        3. Simplification of units or numbers if necessary
        4. Calculations leading to the answer shown on the problem.
      1. A solid has a mass of 31.2 g and is placed into a graduated cylinder with an initial volume of 25.3 mL. The volume of the water rises to 29.3 mL. What is the density of the solid? (Ans: 7.8 g/mL)
      1. A liquid is placed in a graduated cylinder that has a mass of 40.3 g. The liquid and cylinder have a mass of 80.3 g. The volume of the liquid is 20 ml. What is its density? (Ans: 2.0 g/mL)
      1. Calculate the density of a liquid in a graduated cylinder. The graduated cylinder has a mass of 25 grams when empty. The graduated cylinder plus an unknown liquid has a mass of 58 grams. What is the density of the liquid if its volume is 36.6 mL? (Ans: 0.90 g/mL)
      1. A graduated cylinder has a mass of 80 g when empty. When 20 mL of water is added, the graduated cylinder has a mass of 100 g. If a stone is added to the graduated cylinder, the water level rises to 45 mL and the total mass is now 156 g. What is the density of the stone? (Ans: 2.24 g/mL)
      1. Below the dark circles represent particles of matter (all the same mass). Which box below has the greatest density? (Analyze the two columns separately)

      1. (In the boxes All the same size) below the dark circles represent particles of matter (all the same mass). Which box below has the greatest density?

      1. Calculate the volume for the following object. If you know that the object has a mass of 18 g and the density is 12 g/cm3. (Ans: 1.5 mL)

         

      2. Calculate the density of a 480 g rectangular block with the following dimensions: length=8 cm, width=6 cm, height=5 cm. (answer = 2.0 g/cm3)
      3. Calculate the mass of a solid metal cylinder with a density of 2.65 g/cm3, and a volume of 10 cm3. (answer = 26.5 g)
      4. An irregular object with a mass of 18 kg displaces 2.5 L of water when placed in a large overflow container. Calculate the density of the object. (answer = 7.2 kg/L or 7.2 g/mL or 7.2 g/cm3)

Your LAB REPORT should include

      • TITLE
      • PURPOSE
      • MATERIALS
      • PROCEDURES
      • LAB SETUP
      • DATA TABLE
      • CALCULATIONS (NO CALCULATIONS WILL RESULT IN AN “I” (INCOMPLETE)
      • ANALYSIS QUESTIONS 

Below you will find pictures of a sample lab report and how to present the information↓