Learning Objectives:

• Learning the applications and limitations of laboratory glassware.
• Learning to apply dimensional analysis and the metric system
• Learning proper technique for making accurate measurements of mass, temperature, and volume.
• Using dimensional analysis for dosage calculation

In this lab, we will practice the measurement and calculation skills that we use this session.  Specifically, we will learn how to make accurate measurements, use dimensional analysis in a real world/lab setting, and calculate density.  We will also determine the strengths and limitations of common scientific tools.  

• Read the lab before coming to class.  The expectation at Chamberlain (CCN/CU) is that you come to class fully prepared for lab.
• Always dress properly for lab.  Be sure to wear closed toed shoes and long pants to lab.  In lab, ware your safety equipment including goggles, lab coat, and gloves.
• Always check with your instructor regarding proper waste disposal
• Listen carefully  to the professor’s instructions and work safely
• Always follow the rules outlined in the safety contract
• If in doubt of how to use a piece of lab equipment, as you instructor.  Improper use of lab equipment can be dangerous or could damage lab materials.
• If you have any safety concerns, see your instructor.
• Use deionized water (DI water) in your experiments.

Exploration 1: Volume Measurements

Materials: 100 ml beakers, 250 ml or smaller beakers, graduated cylinder, pipettes, pipette bulb, balance, DI water

Method: 100 ml beakers, 250 ml or smaller beakers, graduated cylinder, pipettes, pipette bulb, balance, DI water

Questions:

1. Which volume measurement instrument is the most accurate?
2. What may be causing variation in the volume measured?

Exploration 2: Measuring density of an object

In this exploration, we will learn how to calculate the density of a small object using the displacement method.

Materials: 50 ml graduated cylinder, 25 ml of water, and one small, solid object such as a metal bar.

Method: 50 ml graduated cylinder, 25 ml of water, and one small, solid object such as a metal bar.

Question:

1. This method of determining density can be used to measure the densities of even irregularly shaped objects.  Why?

Exploration 3: Dimensional Analysis

In dimensional analysis, we use the relationships between physical quantities to convert between units.  We perform dimensional analysis in everyday life when we calculate how much gasoline we will require for a trip, or how many days of medication we have in our pill bottles before we require a refill. In chemistry, we use dimensional analysis for a wide range of tasks such as calculating product yields, preparing solutions, and comparing results. In our final exploration today, we will practice using the principles of dimensional analyses.

1. In a classroom, students are completing a reaction that requires 500 ml of water per student.  How many liters of water will the class use if there are 18 students in class? Show all work below.(1 point)
2. You are giving your child a medicine that has a dosage of 2 tsp a dose.  The instructions indicate that you are to give the child 3 doses day.  How many days will a 100 ml bottle of medication last?  Show all work below (1 point)

100 ml = 20.2884 tsp

3. A chemical process dissolves 500 milligrams of iron oxide every 20 mins.  How long would it take this reaction to dissolve 2 lbs of iron oxide? Show all work below (1 point)