Volume and Pressure Lab – 2.5 days

Objectives

  • Show the difference between high pressure and low pressure using a particle diagram
  • Correctly use tools for measuring the pressure of a gas
  • Explain the relationship between the volume of a gas and pressure in a closed system

Teacher notes and overview of daily lessons

Day 1

  1. Revisit demo of expanding marshmallow in plastic syringe
  2. Pre-lab

Day 2

  1. Demo how to use probe-ware
  2. Collect data and graph

To set up VernierLabQuest:

  1. Pre-charge computer interface for 8 hours.
  2. Plug Gas Pressure Sensor in to CH 1 dock.
  3. Using stylus, tap House icon and go to LabQuest App.
  4. You should see a red box showing a pressure reading. If not, go to Sensor Setup in Sensors menu and select Gas Pressure (or Biology Gas Pressure) for CH 1.
  5. For this lab, student do not need to do timed data collection. They can manually record their numbers and graph in their journals.

Day 3 (35-min periods)

  1. Data analysis
  2. Write conclusion

Detailed Daily Plan

Day 1

Warm-up/Entry Task

In our Volume of a Heated Liquid lab, what do you think would have eventually happened if there was NO HOLE in the stopper and we kept heating the liquid? Why?

Materials

Marshmallow demo (re-visited)

1 mini marshmallow

1 plastic syringe

Student Handout: Volume and Pressure Lab Sheet

  1. Direct instruction: pressure and how to show pressure using a particle diagram
  2. Revisit demo of expanding marshmallow in plastic syringe
  3. Have mini marshmallow and syringe ready and show again as quick demo. For students who did this last semester, they can connect back to the previous demo.
  4. Ask students: what does the marshmallow show us about the air pressure inside our closed system? In this lab, we’ll be looking at how to measure the exact relationship between pressure and volume of gas (air) in a closed system.
  5. Pre-lab
  6. Go over question and variables with students
  7. Define and identify variables (controlled, manipulated, responding)
  8. Write down hypotheses

Day 2

Warm-up/Entry Task

When a person says “I’m under a lot of pressure,” what do they mean? How is this the same or different than our scientific definition of pressure?

Materials (per group of 4 students)

1 mini marshmallow

1 plastic syringe

gas pressure sensor and computer interface

  1. Demo how to use probeware
  2. Show students how to take out plunger of syringe, insert marshmallow, and return plunger to syringe.
  3. Show students how to read syringe and air volume.
  4. Demo the “start”: put marshmallow in, push plunger to 15mL, screw plunger on to Gas Pressure Sensor.
  5. Show students how to turn on LabQuest and get to pressure display (House icon LabQuest App)
  6. Collect data and graph
  7. Options: students can decide their own data points, or teacher can assign data points (volume).

Exit Slip

What is the relationship between the volume and the pressure of a gas in a closed system?

  1. When you increase the volume, the pressure stays the same.
  2. When you increase the volume, the pressure increases.
  3. When you increase the volume, the pressure decreases.

Day 2.5

The analysis/conclusion format follows what students will see on the Biology EOC. In their words:

Write a conclusion for this controlled experiment.

In your conclusion, be sure to:

  • Answer the experimental question.
  • Including supporting data from the X vs Y data table
  • Explain how these data support your conclusions.
  • Provide a scientific explanation for the trend in the data.

Example conclusion for this lab using sentence frames(colors match bullet points above):

We hypothesized that if we increased the volume in our system, the gas pressure would decrease. Our hypothesis was supported by the data. According to the data, when the volume of gas was 10mL, the pressure of the system was 123kPa. When the volume of gas was 20mL, the pressure of gas in the system was 83kPa. Our data show that as volume increased, pressure decreased. It’s possible that pressure decreased because the particles were not hitting the sides of the syringe as often in a larger container because they had to travel farther.

Possible Sentence Frames

Answer the experimental question. Was your hypothesis supported or not supported?

We hypothesized ______.

Our hypothesis was [supported/not supported] by the data.

Include supporting data from your data table.

According to the data, when the volume of gas was ______, the pressure of the system was ______. ______.

Explain how these data support your conclusions.

Our data show that as volume ______, pressure ______.

Provide a scientific explanation for the trend in the data.

______

Volume and Pressure LabNames: ______

Research Question: What is the relationship between volume and pressure of a gas in a closed system?

In other words, how does volume of gas (manipulated variable) affect pressure (responding variable) in a closed system?

Hypothesis

If (manipulated variable is changed)______

then(effect on responding variable)______

because (the scientific reason ______

______

Variables

Manipulated Variable: ______Responding Variable: ______

Controlled Variables: ______

Materials and Diagram

Material List
Syringe
Gas pressure sensor
LabQuestcomputer interface
marshmallow / Diagram Of Set Up

Experimental Method/Procedure

  1. Carefully take plunger out of syringe and put marshmallow in.
  2. Re-insert plunger and adjust so you have 15mL of air in the syringe.
  3. Screw the syringe into the Gas Pressure Sensor.
  4. Turn on the LabQuest computer and go to the data collection window (house icon LabQuest App)
  5. If you DO NOT see the red box that shows a pressure reading, go to Sensors  Sensor Setup  CH 1  Pressure Bio Gas Pressure
  6. Change the volume of gas (air) in the syringe by gently pushing down or pulling up on the plunger. Record the changes in volume and pressure in your data table.
  7. Clean up: turn offLabQuest, unscrew syringe, remove mini marshmallow, and return all materials to the tray.

Data Table

Volume of gas in syringe (mL) / Pressure of gas in syringe
(kPa) / Observations of marshmallow Before / Observations of marshmallow After
15
10
5
17
20

On your graph paper in your journal:

  1. Draw a graph of your data
  2. What happened to the pressure of your system when the volume DECREASED?