Measurement and Density Purpose: In Part I of this lab, you will learn how to take and report measurements using different measuring devices for measurements of length, mass, and volume. You will be required to indicate the precision of your measurement using correct significant figures and proper units. Part II: You will learn how to determine the density of solids and liquids by measuring their mass and volume. Materials Needed: – AA size paper sheet (one) – Metric Ruler (Provided in the lab kit) – Balance (Provided in the lab kit) – Cube (Provided in the lab kit) – 10 mL graduated cylinder (Provided in the lab kit) – 25 mL graduated cylinder (Provided in the lab kit) – Water
The Correct Answer and Explanation is:
Measurement and Density Lab Report
Purpose:
In Part I of this lab, the purpose is to learn how to accurately take and report measurements using various measuring instruments. These include tools for measuring length, mass, and volume. The goal is to correctly express these measurements using appropriate significant figures and units, which reflect the precision of the measuring devices. In Part II, the objective is to determine the density of both solid and liquid substances. This is achieved by measuring the mass and volume of the substances and using the formula for density.
Correct Answer:
To measure length, use a metric ruler and report the result in centimeters or millimeters, using the appropriate number of significant figures based on the smallest division on the ruler. For mass, use the balance and record the mass in grams, again noting the precision based on the display. Volume of a liquid is measured using the graduated cylinders. Read the volume at eye level from the bottom of the meniscus and report it in milliliters with the correct number of significant figures.
To find density, use the formula:
Density = Mass / Volume
For example, if a metal cube has a mass of 12.35 grams and a volume of 4.10 cm³, the density would be:
Density = 12.35 g / 4.10 cm³ = 3.01 g/cm³
Explanation
Measurements are fundamental in science because they provide the basis for understanding physical properties. In this lab, you will learn to use different tools for measurement and how to express the values properly. Each measuring device has its own degree of precision. A ruler may allow measurement to the nearest millimeter, while a balance may provide mass to the nearest hundredth of a gram. It is important to include the correct number of significant figures in your results because they communicate the certainty of your measurements.
Volume measurements also require precision. Graduated cylinders must be read from eye level at the bottom of the meniscus to avoid parallax error. Each cylinder has different graduation marks, so the number of significant figures will differ. For example, a 10 mL graduated cylinder typically allows for more precise measurements than a 25 mL one.
In the second part of the lab, density is calculated using the ratio of mass to volume. This property helps identify materials and assess their purity. For solids, volume can be determined geometrically or by water displacement. For liquids, mass is found by weighing the liquid in a container and subtracting the mass of the container. Understanding how to measure and calculate density allows students to apply scientific principles to practical problems, such as material identification and quality control.
