Effect of Temperature on Diffusion (Gloria Hernandez Scipio)

Research Question and Hypothesis

What is the effect of temperature on the rate of diffusion of food coloring in distilled water?

Hypothesis: If the temperature is high, then the food coloring will dissolve faster because heat causes molecules to speed up, causing the rate of diffusion to increase.

Standards

MS-PS1-4.

Develop a model that predicts and describes changes in particle motion, temperature, and state of a pure substance when thermal energy is added or removed. [Clarification Statement: Emphasis is on qualitative molecular-level models of solids, liquids, and gases to show that adding or removing thermal energy increases or decreases kinetic energy of the particles until a change of state occurs. Examples of models could include drawing and diagrams. Examples of particles could include molecules or inert atoms. Examples of pure substances could include water, carbon dioxide, and helium.]

Science and Engineering Practices:

Analyzing and Interpreting Data

Analyzing data in 6–8 builds on K–5 and progresses to extending quantitative analysis to investigations, distinguishing between correlation and causation, and basic statistical techniques of data and error analysis.

Analyze and interpret data to determine similarities and differences in findings. (MS-PS1-2)

Scientific Knowledge is Based on Empirical Evidence

Science knowledge is based upon logical and conceptual connections between evidence and explanations. (MS-PS1-2)

Energy and Matter

Experimental Design

There will be 3-500mL beakers. In each beaker, pour 300mL of water. Heat up beaker #1 until it boils; keep beaker #2 at room temperature; put beaker #3 in an ice bath 10-15 minutes prior to demonstration. Have 3 students keep time; one student per beaker. Put 3 drops of food coloring in beaker #3 (cold) and have the student start time once the first drop hits. Repeat for #2 and #1. Have the students stop the time once it is fully dissolved in the water. Have students speculate what occurred. At this time, #

2 and #3 have not yet dissolved- it will take them at least an hour to fully diffuse throughout the water.

Questions to have students think about:

Why did the food coloring diffuse so fast in the hot water?
Do you think that the food coloring in the warm and cold water will eventually fully dissolve completely over time? Why/why not?
Do you think the food coloring will eventually separate from the water again?
What can we do to speed up the diffusion for #2 and #3? Why?
Do molecules ever stay still?
Are the molecules still moving in beaker #1?

Independent variable

The independent variable is the temperature of the water. I will measure the independent variable with a thermometer

Dependent variables

The dependent variable is the rate of diffusion. This will be measured by timing how long it takes for the food coloring to fully dissolve in the water.

Series

Study of rate of diffusion (dependent variable) as a function of temperature (independent variable.

Constants and Controls

Constants: beaker size, amount of water, method of collecting time, same color of food coloring, same amount of drops, same location in the room

Control: The room temperature water

Materials

Materials:

3- 500mL beakers (supply cabinet. Can use a regular glass cup- preferably clear.)
hot plate (supply cabinet. May use microwave or stove)
ice bath (a bowl with water and ice. Place beaker in the ice bath)
water (tap water or distilled)
food coloring (grocery store-$3)
Thermometer (Supply cabinet or grocery store)

Procedures

Label beaker #1- hot water; beaker #2- room temperature water; beaker #3- cold water
Pour 300mL of water into each beaker. (May want to add slightly more to beaker #1 to account for some water evaporating once it begins to boil.)
Fill a bowl (bigger that the beaker) with about 10 cm of water. Put ice in the bowl of water.
Place beaker #3 in the ice bath. Do not mix the water in the beaker and the ice bath.
Let sit for 10-15 minutes or longer.
Record the temperature
Place beaker #1 on hot plate and set temperature to high
Once it starts to boil, turn off the hot plate
Record the temperature.
Have timer ready to press start once drops hit the water. Because they are timed individually, you do not need to drop them in at the same time.
Put 3 drops of food coloring of choice into beaker #3. Have timer start their timer once first drop hits.
Proceed to beaker #2 and repeat step 11
Proceed to beaker #1 and repeat step 11
Once the food coloring has fully dissolved in the water, stop the timer. Record the time.
Beakers #2 and #3 may take longer than the class period. Continue timing and share results the next day.