Endothermic and Exothermic Reaction Experiment
Two students, Andre and Betsy, were completing a lab in which they investigated temperature changes in two reactions. They made a hypothesis for what they expected to happen in each reaction, and then they tested each hypothesis by observing the reactions conducted according to the experimental procedure below.
Read the lab report (below) and watch the video (above) to see the data Andre and Betsy used. Then answer the questions.
LAB REPORT
Experimental Questions:
Question A: When baking soda and vinegar react, is the reaction endothermic or exothermic?
Question B: When hydrogen peroxide reacts in the presence of yeast, is the reaction endothermic or exothermic?
Hypothesis:
Hypothesis A: If baking soda and vinegar react, the reaction will be endothermic.
Hypothesis B: If hydrogen peroxide reacts in the presence of yeast, the reaction will be endothermic.
Background:
When baking soda and vinegar react, one of the new substances formed is carbon dioxide. The other is a type of salt, but it is not the same as table salt. (As a reminder, NEVER taste anything you are using in lab!)
When hydrogen peroxide is treated with yeast, the hydrogen peroxide decomposes and oxygen is one of the products that is formed. (The yeast actually just acts as a catalyst to make the reaction go faster.)
If a reaction is endothermic…
the temperature goes down
the surroundings feel colder
thermal energy is absorbed
If a reaction is exothermic…
the temperature goes up
the surroundings feel warmer
thermal energy is evolved (given off)
Materials (You do NOT need these materials. You will get the get the data by watching the video.)
graduated cylinder (if you have one; you can use your teaspoon for liquid and solid measurements)
teaspoon
thermometer (a kitchen thermometer that will measure around room temperature, not a health thermometer)
safety goggles
baking soda (from the grocery store; usually located near baking supplies)
vinegar (from the grocery store; usually located near baking supplies OR near salad dressing)
3% hydrogen peroxide (from the store; usually located near first aid and health supplies)
dry active yeast (from the grocery store; usually located near baking supplies; you can get the small packet because you won’t need much)
reaction vessel (a container such as glass measuring cup)
larger pan for catching spills
Safety Procedure
Do not taste any substance that you are using for this experiment.
3% hydrogen peroxide is not safe to eat or taste.
Have adult supervision.
Wear closed-toe shoes!
If your learning coach approves, wear an apron that fits properly and is correctly tied so as to not be too loose.
Wear safety goggles.
Have long hair tied back away from the face.
Use care when handling chemicals and the thermometer.
Experimental Procedure (You will NOT have to complete this on your own. You will follow the video.)
Steps 1-5 are for part A. Steps 6-10 are for part B.
Use your graduated cylinder or teaspoon to measure 10 mL (2 teaspoons) of vinegar. Pour the vinegar into your reaction vessel. Place the reaction vessel inside your larger pan or other spill-catching container. Rinse and dry the teaspoon, if you used it.
Place the thermometer in the reaction vessel with the vinegar and record the temperature. Read the thermometer very, very carefully.
Add two teaspoons of baking soda to the reaction vessel. Use the thermometer to gently stir the vinegar and baking soda while watching the temperature on the thermometer.
Record the new temperature. (All temperature measurements for this lab should be done in degrees Celsius.) If the temperature is going down, read the lowest temperature it reaches before it goes back up. If the temperature is going up, read the highest temperature it reaches before it goes back down. It may only change by a little bit. Watch carefully!
Wash the reaction vessel, spill-catching pan, teaspoon, and the graduated cylinder (if you used one). Carefully wash the thermometer and let it return to room temperature.
Use your graduated cylinder or teaspoon to measure 10 mL (2 teaspoons) of hydrogen peroxide. Pour the hydrogen peroxide into your reaction vessel. Place the reaction vessel inside your larger pan or other spill-catching container. Rinse and dry the teaspoon, if you used it.
Place the thermometer in the reaction vessel with the hydrogen peroxide and record the temperature. Read the thermometer very, very carefully.
Add one teaspoon of dry active yeast to the reaction vessel. Use the thermometer to gently stir the yeast and hydrogen peroxide while watching the temperature on the thermometer.
Record the new temperature. If the temperature is going down, read the lowest temperature it reaches before it goes back up. If the temperature is going up, read the highest temperature it reaches before it goes back down. It may only change by a little bit. Watch carefully!
Wash the reaction vessel, spill-catching pan, thermometer, and the graduated cylinder.
Question 1
Completing a data table:
For this item, move the temperatures (data from the video) into the correct locations in the table.
You will drag and drop one temperature value into each blank box. You may use a value more than one time, but you should only put one temperature value in each box.
(4 points)
Put responses in the correct input to answer the question. Select a response, navigate to the desired input and insert the response. Responses can be selected and inserted using the space bar, enter key, left mouse button or touchpad. Responses can also be moved by dragging with a mouse.
starting temperature in degrees C ending temperature in degrees C
reaction A (vinegar and baking soda)
reaction B (hydrogen peroxide)
Question 2
Completing Conclusions
A proper conclusion should restate the hypothesis and compare that hypothesis to the data observed during the experiment. If the data agree with the prediction, we say the hypothesis was supported. If the data don't agree with the prediction, we say the hypothesis was refuted. When deciding whether the hypothesis is supported or refuted, it is important to consider the data and the background information.
Use the drop down menus to complete the conclusion A.
(6 points)
For experiment A, the hypothesis predicted the reaction would be
. The temperature changed from
to
. Because the temperature
, the reaction must be
. The hypothesis was
by the data.
Question 3
Use the drop down menus to complete conclusion B.(6 points)
For experiment B, the hypothesis predicted the reaction would be
. The temperature changed from
to
. Because the temperature
, the reaction must be
. The hypothesis was
by the data.
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Question 1:
The temperatures for reaction A (vinegar and baking soda) and reaction B (hydrogen peroxide) are not provided in the lab report or video. Thus, the answer cannot be determined with the given information.
Question 2:
For experiment A, the hypothesis predicted the reaction would be endothermic. The temperature changed from [temperature before the reaction] to [temperature after the reaction]. Because the temperature [increased/decreased], the reaction must be [endothermic/exothermic]. The hypothesis was [supported/refuted] by the data.
Question 3:
For experiment B, the hypothesis predicted the reaction would be endothermic. The temperature changed from [temperature before the reaction] to [temperature after the reaction]. Because the temperature [increased/decreased], the reaction must be [endothermic/exothermic]. The hypothesis was [supported/refuted] by the data.
Question 1:
The data has to be obtained from the video, so it's not possible to drag and drop the temperature values into the correct locations in the table without watching the video.