Put the pictures of the moon from the 11th, the 12th, and today the 13th together to see if you are any closer to figuring out the pattern of the phases and the times of rising and setting.
13 October 2017 New Delhi 5:10 am (facing east)
Find the mass of the two steel wool bottles and enter the data if you have not done so.
Complete the vinegar and baking soda reaction in a bottle if you have not done so. Enter the data in the class spreadsheet.
Begin working on question 1 below.
- Mass before and after the reaction of Magnesium Sulfate and Sodium Carbonate:
- Mass before and after the reaction of vinegar and baking soda in an open container:
- Mass before and after burning steel wool in an open container:
- Mass before and after reaction of steel wool in air
- Mass before and after reaction with steel wool in vinegar
- Mass before and after reaction with vinegar (5% solution of acetic acid) and baking soda (sodium hydrogen carbonate)–also mass after opening bottle
- Examine the class data from the reactions. Be sure you have entered your results. Pick out the data that surprise you the most. Make a histogram of the relevant findings (like the change in mass). Follow good graphing guidelines. Explain in sentences what surprises you about the findings. Discuss what you expected before you conducted the experiments and before you looked at the class data. How do you explain the data? How do you explain the reaction? What do you think happens with the atoms and molecules?
- What can you find out about The Conservation of Mass? https://www.youtube.com/watch?v=t1b1S31xGFc How do the results in the video clip compare to our class results? What are your ideas?
- We will extract and test the gas from both experiments with the steel wool. You will see a gas-testing technique and will learn a property of the gas that has remained in the bottle and/or has been produced by the reaction. It will be important to contrast the gas(es) in the bottles with air. Think about the importance of establishing a comparison case–called a control.
- We will generate the gas from the vinegar and baking soda reaction, capture it in an inverted cylinder filled with water and inverted test-tubes, and test the gas.
- We will, if time, demonstrate with a molecular model the reaction of vinegar (5% acetic acid) and baking soda (sodium hydrogen carbonate). See information and photographs below.
With reference to the reaction of vinegar and baking soda:
- What do you think happens to the vinegar?
- What do you think happens to the baking soda?
- What do you think the gas might be?
- Where do you think the gas came from–the vinegar, the baking soda, both?
- How could you find out by experimentation?
- Based on your previous experiments what mass of gas can be released from 2 grams of baking soda and 60 ml of vinegar? Think of a workable procedure.
- What volume of gas can be released from 1 gram of baking soda and 30 ml of vinegar? Think of a workable procedure.
- What are the properties of the gas? Think of a workable procedure to collect and test the gas.
- What proportions of vinegar and baking soda are needed for a complete reaction–where no baking soda is left over and no vinegar is left over? What are the tests to know if you have reached a complete reaction? Think of a workable procedure.
- What remains in the solution after the reaction is completed? Think of a workable procedure.
- Other questions–pose some.
- SOME NOTES ON THE VINEGAR AND BAKING SODA REACTION
- Ingredients before the reaction (reactants)
- Baking soda (Sodium Hydrogen Carbonate) + Vinegar (5% acetic acid in water) —>
- Some products that are not Baking soda and vinegar
- What are these products?
- A gas–what might the gas be? what are its properties? How much gas is produced?? How much volume? Is the gas made from the baking soda only, from the vinegar only, or does each compound contribute something that then comes together to make the gas?
- A liquid (water? something dissolved in the water? more than one thing dissolved in the water?
- What are the relative amounts of baking soda and vinegar that will completely react with each other so that no baking soda is left AND no vinegar is left.
The simplest set of changes to get from vinegar and baking soda to the reaction products.
NaHCO3 + CH3COOH —-> CO2 + H2O + CH3COONa
(this is a description of the overall reaction which occurs in several steps)
Review this from the beginning of the year: Fundamental-questions-about-matter
There is a very interesting project from MIT which uses LEGOS to represent atoms and molecules. Take a look: http://mindandhand.mit.edu/educators/educators.shtml
Student and molecular models
More information on the reaction
A paper by Sarkar and Frazier (Dr. F) about the complication that arises when using a certain technique to try to observe the conservation of mass with the vinegar and baking soda reaction. Read this, see what you understand, ask questions: conmass