PLEASE READ CAREFULLY THERE ARE SEVERAL STEPS AND QUESTIONS.
Have you ever thought about the elements salt is made up of? Salt is made up of two elements: sodium and chlorine. One atom of sodium forms an ionic bond with one atom of chlorine, and sodium chloride (aka table salt) is formed. However, sodium (by itself) is toxic for human consumption, as is chlorine. How in the world does combining two toxic substances form something that is essential for human survival? As you have been learning, chemical reactions often form products that have characteristics that are dramatically different from those of the reactants, and salt is a perfect example of that. No toxic substances are used in this experiment, but you will have the opportunity to observe a chemical reaction up close.
In this experiment, you will be exploring how the concentration of reactants affects the rate of a chemical reaction. Specifically, you will add varying amounts of baking soda to bottles containing vinegar and observe the length of each reaction. At the same time, you will also be trapping one of the products (carbon dioxide) by affixing a balloon to the top of each bottle. If needed, here is the link to a downloadable document that shows the expected lab report format.
Follow the steps of the scientific method
Apply vocabulary terms correctly
Create a formal lab report to communicate findings
Explain the relationship between the rate of reaction and quantity of reactants used
Endothermic: a reaction that absorbs energy
Exothermic: a reaction that releases energy
Heat of reaction: the change in enthalpy (heat content) that occurs in the process of converting reactants to products in a chemical reaction
FIRST STEP: Pre-Lab Questions
Before beginning this lab, take time to thoughtfully answer the questions below. The pre-lab questions are designed to prepare you for the
concepts presented in the lab. It is recommended that you type your answers in a digital document, as you will need to include these responses in your formal lab report. Also, you may use your lessons as a resource, but do not copy your lessons (or any other sources) word-for-word.
Taking a source and presenting it as your own work is plagiarism and may result in a zero on the assignment.
In the virtual lab (link below), you have the opportunity to observe a reaction and then to change the variables and observe the results. After
launching the simulation, click “RUN REACTION” and observe the rate and results of the reaction; this will be your baseline for comparison.
Next, click “SELECT VARIABLES,” choose a variable to change, choose whether to decrease or increase that variable (where applicable), and
click “RUN REACTION.” Compare the results to those of the original reaction, and use your observations to answer the pre-lab questions.
Note: Most variables can be both increased and decreased (e.g., temperature), while the catalyst can only be added.
COPY AND PASTE THE FOLLOWING LINK into your browser toBEGIN THE VIRTUAL LAB TO ANSWER THESE QUESTIONS:
https://teachchemistry.org/periodical/issues/may-2018/reaction-rates
Using your observations in the virtual lab, summarize how the rate of reaction changes when a catalyst is used. Explain why the rate changes. (Describe what is occurring at the molecular level.)
Using your observations in the virtual lab, summarize how the rate of reaction changes when the concentration is changed. Explain why the rate changes. (Describe what is occurring at the molecular level.)
Using your observations in the virtual lab, summarize how the rate of reaction changes when the surface area of the reactants is changed. Explain why the rate changes. (Describe what is occurring at the molecular level.)
Using your observations in the virtual lab, summarize how the rate of reaction changes when the temperature of the reactants is changed. Explain why the rate changes. (Describe what is occurring at the molecular level.)
Read through the “Conducting the Experiment” section, and then identify the independent (i.e. manipulated), dependent, and controlled variables in this experiment. (List at least 5 controlled variables.)
2ND PART OF ASSIGNMENT Research Question
How does increasing the amount of baking soda combined with a fixed amount of vinegar affect the rate of reaction?
Hypothesis
In general, hypotheses are written using the “If…then…” format. The hypothesis gives a clear statement of the experimenter’s prediction, and the statement must be disprovable. For this experiment, write a hypothesis that predicts how the rate of reaction will change as the amount of baking soda used in the reaction increases.
Materials
Baking soda
White vinegar
4 plastic, water bottles (must all be same size)
Funnel
Teaspoon
Tablespoon
4 balloons
Food coloring (optional)
Stopwatch or phone timer
Piece of string (at least 12 inches long)
Ruler or meter stick
INSTRUCTIONS
Measure 1 teaspoon of baking soda, and use the funnel to add the baking soda to the first balloon; shake the balloon gently so that the baking soda settles in the balloon. Next, measure 2 teaspoons of baking soda and use the funnel to add it to the second balloon; shake the balloon gently. Now, measure 3 teaspoons of baking soda and use the funnel to add it to the third balloon; shake the balloon gently. The fourth balloon will act as the control, and no baking soda will be added to it.
Prepare your water bottles by cleaning them thoroughly. (Note: You can use the same bottle for each trial, but it must be rinsed thoroughly between trials. If you use multiple bottles, they all must be the same shape and size; if they are not, you are adding another variable to the experiment.)
Add 10 tablespoons of vinegar to each bottle. If you want to add food coloring to the vinegar, it will help you see the bubbles during the reaction; add 3 – 5 drops of coloring to each bottle, if desired.
Stretch the mouth of the first balloon over the opening of the bottle, but make sure that no baking soda drops into the bottle yet! The balloon should hang down on the side of the bottle. Do the same for all four bottles.
Set your timer up so that it is ready to record the length of the reaction. When ready, lift one balloon straight up and gently shake it to allow the baking soda to drop into the bottle, and immediately start the timer. Hold the base of the bottle to ensure that it doesn’t tip while the reaction takes place. (Also, pay attention to how the temperature of the bottle changes.)
Once the reaction is complete, stop the timer; the balloon will remain inflated. Loop the string around the widest part of the balloon, and then lay that portion of the string along a ruler or meter stick and measure the length in centimeters; this is the circumference of the balloon.
Repeat steps 4 – 6 for all four balloons and record your data. When finished, clean up your supplies and begin compiling your lab report.
Data
Analysis Questions
What evidence is there that a chemical reaction took place in this experiment? List as many indicators as possible.
Is the reaction between baking soda and vinegar an exothermic or endothermic reaction? Explain your answer using evidence from the lab.
Balance the following chemical equation (which is for this reaction) and list the number of atoms of each element present before and after the reaction: NaHCO3 + CH3COOH → CO2 + H2O + CH3COONa
Do you think the baking soda or the vinegar is the limiting reactant? Why? Explain what is occurring at the molecular level.
If you were to weigh the bottle with the balloon before and after the reaction took place, would the total mass change? Why or why not?
Conclusion
Begin by stating whether the hypothesis was supported or disproved. Use data to support your statement.
Consider the following questions as you write your conclusion:
What do your results mean or how might the principles be used in daily life?
Did you learn anything new? If not, what previous concepts did this lab reinforce?
Is there anything you would or could do differently that would improve the experiment?
What did this experiment reveal about God or His creation?
Heading and unique title
Pre-lab, hypothesis, procedure, data, analysis, and conclusion section headings
Each section is thorough
All work is typed
Completed lab report submitted through TurnItIn
Ignitia assignment submitted with TurnItIn Submission ID
Livebinders
Downloadable lab report document
Lab report format with section descriptions
HS lab report rubric
Steps of the scientific method image and article