Determining variables involved in Calorimetry Equations (Jake Dickerman)

Research Question and Hypothesis

How will differing masses of the same fluid impact the time taken to raise temperature of water?

How will changing the concentrations of salt, while keeping a consistent mass, change the rate of temperature growth in a fluid?

(The goal here is to have students discover the variables involved in the equation Q = mC_pΔT)

Standards

Experimental Design

This is two separate experiments, each adding another piece of the Q = mC_pΔT formula.

In the first experiment, students are all given a different volume of water. Students put their volumes of water onto hot plates, attempting to have each hot plate at approximately the same temperature. Students measure the temperature of the water for up to ten minutes, checking temperatures using an immersion thermometer every thirty seconds. Data is collected on the google form below:

In the second experiment, students all have the same mass that they are heating, but there is salt introduced into the water. For every gram of salt added, one gram of water is removed. Beyond that, the experimental design remains the same, students record data every thirty seconds for ten minutes.

Independent variable

The independent variable in the first experiment is the mass of water being heated. It is measured in a graduated cylinder. In this circumstance, the volume of the water stands in for the mass of water.

The independent variable in the second experiment is the ratio of salt to water. In this case, the mass of salt is measured using a gram scale and then the volume of salt is measured using a graduated cylinder. In each beaker, there is 200 grams of substance.

Dependent variables

The dependent variable in each experiment is the temperature growth. It is measured using an immersion thermometer.

Series

The series examined in this experiment is the temperature against time. This allows students to see how the rates of temperature were varied based upon the independent variable.

Constants and Controls

Constants in this experiment were the level of the hot plates, although this was imprecise. All students were given the same type of pyrex beaker. In the first experiment, an additional constant was the composition of each fluid.

In the second experiment, an additional constant was the mass of each fluid.

Materials

• Immersion Thermometers

• Course sea salt

• Beakers

• Hot plates

• Water

• Graduated cylinders

• Timer (phones will do or teacher can create a communal timer)

• Device to access google forms

Procedures

• Fill beakers to proscribed levels

• Using an immersion thermometer, get the initial temperature of fluid in beakers - mark that as "zero" time level

• Turn all hot plates to 300 °C

• Place the beaker onto the hot plate

• After 30 seconds, record the temperature of the fluid

• Repeat every 30 seconds for 10 minutes

• Record data on the google form

Sample data and graphs

Analysis & Conclusions

There is a clear relationship in the mass experiment's chart. It is easy to see that as the mass of water decreased, the temperature growth increased. This supports the idea that mass is a vital part of understanding the amount of energy required to change the temperature of a substance.

Unfortunately, the data collection was not as strong in this experiment. I assumed that as the ratio of salt to water increased, the rate of temperature growth would increase as well. However, this did not occur as expected. There may have been issues in the data collection. As can be seen, almost every group input data for the first experiment. Unfortunately, students had a much greater difficulty massing salt in beakers in the second experiment, and thus the degree of data collected was greatly decreased, lowering the efficacy of the data collected.

Photos & Movies

Include photos and movies of your longitudinal research. Post your photos in the class photo album and your movies in your Youtube account.

References

Include links to all relevant references.