Objective: Students will learn to write up a lab with components.
Students will be able find density using equipment and the density equation.
Students will be able to compare densities to known accepted values by mathematics.
Materials: 4 metal blocks graduated cylinder water ruler
Triple beam balance
Hypothesis - ________________________________________________________________________
Procedure: write in a step by step fashion – whole sentences!
Finding volume with a ruler:
Finding volume with a graduated cylinder
Data Tables: construct your own table for 4 blocks (Fe, Cu, Al, brass) and measure the following data: volume with a ruler, volume with a graduated cylinder, hand mass
Calculations:
Calculations: 4 density calculations, one for each bar
show general equation one time
substitutions
calculated answer with units
Density Calculation using mass and Ruler volume
Brass Copper Iron Aluminum
Density Calculation using mass and Displacement of Water method for volume.
Brass Copper Iron Aluminum
Percent Error of Ruler Volume vs Accepted Value : using the accepted values below, find the percent error for only one bar. When done there should be 2 calculations one for each volume type.
Write equation Density calculated compared to density accepted
Substitute numbers Accepted density for Cu = 8.9 g/cm3
Give answer with units Fe= 7.2 g/ cm3
Al = 2.7 g/ cm3
Brass= 8.7 g/cm3
Type of bar ________________________
Percent Error\
(Ruler) Density vs Accepted Value (Displacement) Density vs Accepted Value
Conclusion: Write a short paragraph. Within the paragraph do the following fluidly:
Accept or deny the hypothesis.
Restate the densities you calculated.
State the percent errors in your calculations.
Make a statement regarding volume found by the displacement method compared to
volume found by measurement. Identify which is more accurate and why.
Give reasons (other than human error) for discrepancies.
Elements of a Well Written Lab Special Note:All written work must be the student’s own words. It must be different from your lab partners. The concept can be discussed but your explanations should be your own. Objective: simple clear, concise, describes what the lab is designed to discover
Usually starts with words similar to: To find out… The student will be able to… Hypothesis: gives an educated guess as to what is expected to happen during the lab.
For our purposes it will often gives a comparison such as most, least, faster,
slower. All variable to be tested need to be identified. Never start with I think. Statement should start out with your variables or the process. Ex: The soil is expected to heat up faster than the water. Materials: should be listed clearly
Diagram: if necessary, should have set up with all equipment labeled. If there is
anything specific to be paid attention to it should be noted. For example: the distance between the lamp and the soil and water needs to be identical shown
with an arrow.
Data Table: should be neat and orderly. All columns should be labeled with what is being measured or the variable. All columns should also have a unit of measurement attached to it. Ex: Temperature (degrees C). Graph: Should appear on graph paper. Most graphs will be line graphs in high school. Elements to include:
Overall title in the top right corner of the paper – describing what the graph is showing
X and Y axis labeled with measurement and unit
Key supplied if multiple lines
The graph should take up at least 2/3rds of the paper provided so make sure to
gauge your axis’ correctly to take up most of the space and include all your
points.
Calculations: if required, must start with the general word equation written down.
Substitutions should be clearly made and shown. The answer should appear
with units attached. If multiple variables, each variable and its calculation should
be neatly labeled so you know (and I know) which variable goes with which
answer.
Conclusion: A well written paragraph which includes several elements:
Acceptance or denial of the hypothesis.
A restatement of the final data or final calculations to show tested relationships
An explanation or interpretation of the data
Appropriate vocabulary for the objective of the lab.
Elements of a Well Written Lab