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Assignment
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Teacher Comments
Practical 1 Write up: Testing acidity
Science experiment – Testing for Acidity
Introduction –
This experiment will show the pH levels in each of the different substances with the materials listed below. With this experiment we would be able to tell, which solution is acidic, alkaline or neutral.

Research Question – What would happen if I mix two solutions such as lemon juice and vinegar together?

Materials –
Vernie computer interface
1 x Smart Q pH Adapter and Electrode
a 400ml beakers
The various solution such as vinegar, water, alcohol and lemon juice
Water
Tissue paper
(2) 200ml beakers

Procedure –

1. Have all the materials listed above ready and working as they should.
2. Set all the beakers and other utensils on the table, each beaker should carry the different solutions listed to 20ml.
3. Have an extra beaker filled with water to clean to pH prode with after testing each solution.
4. Connect the pH sensor to the data logger
5. Pull the electrode out of its case but do not spill or throw away the liquid inside.

6. Start Vernie computer interface and click “collect” to begin collecting data.

7. Carefully place the pH electrode into the first solution and then click “collect”. The rode will stop collecting data when it has reach a maximum time of 10 seconds.

8. After, pull the electrode out of the solution and wash the tool off with the extra water you have on the table.

9. Repeat the process until you are finish testing each solution and then start to mix the solutions together carefully.

10. Keep a data sheet of your results from the test you have just done.

Results –
external image clip_image002.gif

The pH values for acid solution are measured from a scale from one to fourteen (1 – 14). They are divided into section three, such as acid solution, alkaline solution and neutral solution. Acid solutions are measured from one to six (1 – 6), Alkaline solution is eight to sixteen (8 – 16) and a neutral solution is seven (7). By this you will be able to tell where the solution that were tested, sit on the pH scale. Lemon juice, alcohol and vinegar tested to be acid solution. Even when mixed together. Water was the only solution that tested to be a neutral solution or any different. The reason you have to wash the electrode after testing each solution is so that you don’t have mix solutions together while testing other solutions.

Conclusion –

This experiment showed the pH levels of all the solutions and compared the solution against each other. The graph showed which solutions are acid, neutral and base and the pH after the vinegar and lemon juice were mixed, which made the solution even more acidic and very harm to drink. But also most of the solution were acidic acids and also very harmful to body (such as alcohol).

Limitation –

Although this lab showed the variety of pH levels during the experiment, I would have liked to be able to compare my data to more solutions. This would have given me more of an understanding of the solutions.

Modification –
To improve this experiment, you could have taken the temperature of the solution as well as taking the pH and also using different solutions.

Practical 2 Write up: pH and Temperature
change in Coca Cola
Task 1: Predication

I am predicting that the pH will increase due to the fact that the Alka Seltzer would be a base and the acids in cola would decrease while the pH increase, because as a acid decrease the pH goes up. Also the temperature would change to a cooler form than before.
Task 2:
Independent variables:


Alka Seltzer

Dependent variables:

pH
Temperature


Factors to be changed:

1. Make sure both of the colas have not been shaken.
2. Make sure both of colas have not been in the refrigerator.
3. Each cola should not have been open before the experiment.
4. Make sure each of the colas has the same amount of liquid in the container.
5. Make sure the cola is from the same brand.




Hypothesis:
If I have a coca cola, whole Alka seltzer and a crushed Alka Seltzer, then I believe that the crush Alka Seltzer will increased more than the whole Alka Seltzer in the pH scale. This is because the crushed Alka Seltzer will not have to take as much time to dissolve in the cola which increases in the pH.
Task 3: Materials –


Coca cola
Two (2) 100 ml beakers
400 ml beaker
Two (2) Alka Seltzer
Computer
pH rode
Data logger
Timer
Temperature robe
Water
Tissue paper


Task 4: Procedure:

1. Make sure you have all your supplies set up before proceeding.
2. Connect the data logger into your computer; also connect the temperature and pH probe into the senor.
3. Place two (2) 100ml beakers and a 400ml beaker on the table. Pour sixty milliliters (60 ml) of coca cola into one beaker first.
4. Then drop either one of the whole or crush tablets into the beaker with the coca cola. Then click the “collect” button and place the pH or temperature probe into the beaker for 60 seconds.
5. After pull out the probe out of the beaker and wash the probes after using them.
6. Collect the data you have received from the experiment onto a table and take notes.
7. Now repeat from step four to six (4-6) and analyze your results and what you have observed. Repeat step 4 with the probe you did not use before.



Task 5: Safety and Precaution
Be sure to wear safety goggles and gloves while doing your experiment. DO NOT consume any of the Alka Seltzers. Make sure your utensils are clean and wash the probes after using them in each beaker.
Task 7: Results

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The coca cola when mixed with the Alka Seltzer seemed to have changed in its pH and temperature, but the pH and temperature was different from it’s original state due to the fact that one tablet was broken and the other a whole. The variables were the whole and broken Alka Seltzer tablets that were being compared in the experiment. When the whole Alka Seltzer tablet was dropped into the coca cola, the tablet took at least a few minutes to finish dissolve in the cola. It didn’t react to the coca cola at once like the broken tablet and did not have as much of a effect in the pH but better in temperature than of the broken tablet.
By the graph above it shows that coca cola before being mixed with the Alka Seltzer was pH 2.73* and Temperature 30.3*. Then after being mixed with the Whole tablet, its pH dropped to almost of neutral state and cooler than before. The pH after was 6.40* and temperature 28.7*. I think this is so because the whole tablet acted as a base to do as it should and lower the acids in the coca cola which cooled the coca cola down. When the broken tablet was mixed with the cola, as I said before the coca cola instantly when in contact with the cola begun to fuzz and bubble over the beaker. The pH after in contact with the cola was 6.33* and temperature 29.5. This shows that the broken tablet did the same as the whole tablet but faster and changed the pH by 3.60* and temperature by 0.8*. Therefore when comparing the variables, the broken Alka Seltzer changed the coca cola pH into more of a neutral but the Whole tablet’s temperature was cooler. The difference in pH between the whole and broken tablet was 0.07 which isn’t much but still a change. And the temperature is 0.8 of a difference.


Task 8: Conclusion
By my results it shows that if I have a coca cola, whole Alka seltzer and a crushed Alka Seltzer, then the thought process would be that the crush Alka Seltzer will increased more than the whole Alka Seltzer in the pH scale making it more neutral than acidic. This is because the crushed Alka Seltzer will not have to take as much time to dissolve in the cola which increases in the pH. Then I wondered by the difference in temperature and pH, why the broken Alka Seltzer tablet was hotter than the whole tablet? I predict this is so because the broken Alka Seltzer tablet didn’t have much time to cool the temperature of the coca cola due to the fact that it dissolved quickly, unlike the whole Alka Seltzer which took longer and was the cooler of the two.


Complete command terms table


Homework 6th September 2010:


Temperature probe
1. What is the mouth's temperature after eatting gum?
2. What is the temperature of the rain water while it is falling?
Blood pressure
1. What is your blood pressure when you stop breathing for two minutes?
2. What is the blood pressure when your either scared or surprise?
Bio chamber
1. Does different types of plants produce oxygen differently?
2. What is the breathing rate of a plant?
Please leave a comment down below. :)
Students:
Comments:
Improvement:
Penny
In overall, I think that these questions are really well formulated, however a little short. The questions you want to know answers to, are easy questions however written a little confusing. I think that these questions show that you are wondering about a lot of things, and you show a good way of wanting to know these things as they all seem interesting.
As an improved for most questions I suggest that you try and be more detailed, e.g. temperature: q. 1 - what part of the mouth? q. 2 - how will you catch a drop of rain without the wind affecting your outcome? blood pressure: q. 1 - it is hard for a person not to breathe for a full 2 minutes, so maybe consider lowering the number a little. q. 2 - why not choose both, since both are different, and then compare them? Bio-chamber: q. 2 - plants release CO2, so maybe you should calculate the rate of the CO2 release and maybe compare that to the O2 intake?
Chad


Chloe


Caitlin


Ebony


Zayne


Nick
I think that you put a lot of thought into these questions and they are all very interesting.
For temp: q.2 how are you going to test the temperature of rainwater when it is falling, for blood pr: q.2 are you going to take the blood pressure before scaring or surprising the victim, Bio-chamber: q.1 how are you going to measure the amount of oxygen a plant produces anyway.
And plants do release oxygen, so ignore Penny.
Joe




Graphing with Excel



Basic Graphing in Excel

Table of Contents

  1. Entering and Formatting the Data in Excel
  2. Creating the Initial Scatter Plot
  3. Creating a Scatter Plot of Titration Data
  4. Changing the Scatter Plot to a Line Graph

Introduction

  • Beer's Law states that there is a linear relationship between concentration of a colored compound in solution and the light absorption of the solution. This fact can be used to calculate the concentration of unknown solutions, given their absorption readings. First, a series of solutions of known concentration are tested for their absorption level. Next, a scatter plot is made of this empirical data.

Entering and Formatting the Data in Excel

  • Open Excel and begin by formatting the spreadsheet cells so the appropriate number of decimal places are displayed (see Figure 1a).
    • Click and drag over the range of cells that will hold the concentration data (A5 through A10 for the sample data)
    • Choose Format > Cells... (this is shorthand for choosing Cells... from the Format menu at the top of the Excel window)
    • Click on the Number tab
    • Under Category choose Number and set Decimal places to 5
    • Click OK
    • Repeat for the absorbance data column (B5 through B10 for the sample data), setting the decimal places to 4
  • external image lwr-cap1a.gif
  • Figure 1a.
  • Your data will go in the first two columns in the spreadsheet. Type what is seen in Figure 1b in the appropriate cells.
    • Title the spreadsheet page in cell A1
    • Label Column A as the Concentration (M) of the known solutions in cell A3. This is the independent variable
    • Label Column B as the Absorbance readings for each of the solutions in cell B3. This is the dependent variable
    • Enter the independent and dependent variable values
    • Finally, enter the information shown in rows 12 and 13. These are absorbance values from two samples of unknown concentrations (more on this later).
  • external image lwr-cap1b.gif
  • Figure 1b.
  • The concentration data is probably better expressed in scientific notation.
    • Highlight the concentration data and choose Format > Cells....
    • Choose the Scientific Category and set the Decimal places to 2.The last step before creating the graph is to choose the data you want to graph.
    • Highlight the data in both the concentration and absorbance columns (but not the unknown data)This is shown in Figure 2.
  • external image lwr-cap2b.gif
  • Figure 2.
  • Return to Top

Creating the Initial Scatter Plot

  • With the data you want graphed highlighted, start the chart wizard
    • Choose the Chart Wizard icon from the tool bar (see Figure 3 for two examples). If the Chart Wizard is not visible, you can also choose Insert > Chart...
  • external image lwr-cap3.gif external image lwr-cap3a.gif
  • Figure 3.
  • The first dialogue of the wizard comes up
    • Choose XY (Scatter) and the unconnected points icon for the Chart sub-type (Figure 4a)
  • external image lwr-cap4a.gif
  • Figure 4a.
    • Click Next >
  • Return to Top
  • The Data Range box should reflect the data you highlighted in the spreadsheet. The Series option should be set to Columns, which is how your data is organized (see Figure 4b).
  • external image lwr-cap4b.gif
  • Figure 4b.
    • Click Next >
  • The next dialogue in the wizard is where you label your chart (Figure 4c)
    • Enter Beer's Law for the Chart Title
    • Enter Concentration (M) for the Value X Axis
    • Enter Absorbance for the Value Y Axis
  • external image lwr-cap4c.gif
  • Figure 4c.
    • Click on the Legend tab
    • Click off the Show Legend option (Figure 4d)
  • external image lwr-cap4d.gif
  • Figure 4d.
    • Click Next >
  • Return to Top
  • Keep the chart as object in Sheet 1 (the current sheet). See Figure 4e.
  • external image lwr-cap4e.gif
  • Figure 4e.
    • Click Finish
  • The initial scatter plot is now finished and should appear on the same spreadsheet page (called a sheet) as your original data. Your chart should look like Figure 5. A few items of note:
    • Your data should look as though it falls along a linear path
    • Horizontal reference lines were automatically placed in your chart, along with a gray background
    • Your chart is highlighted with square 'handles' on the corners. When your chart is highlighted, a special Chart floating palette should also appear, as is seen in Figure 5. Note: If the Chart floating palette does not appear, go toTools>Customize..., click on the Toolbars tab, and then click on the Chart checkbox. If it still doesn't show up as a floating palette, it may be 'docked' on one of your tool bars at the top of the Excel window.With your graph highlighted, you can click and drag the chart to a wherever you would like it located on the spreadsheet page. Grabbing one of the four corner handles allows you to resize the graph. Note: the graph will automatically adjust a number of chart properties as you resize the graph, including the font size of the text in the graph. You may need to go back and alter these properties. At the end of the first part of this tutorial, you will learn how to do this.
  • external image lwr-cap5.gif
  • Figure 5.
  • Go to the tutorial on creating regression lines to find out how to use a regression line with this scatter plot to calculate the concentrations of the two unknowns.
  • Return to Top

Creating an Initial Scatter Plot of Titration Data

  • In this next part of the tutorial, we will work with another set of data. In this case, it is of a strong acid-strong base titration (see Figure 10 for the final plot). With this titration, a strong base (NaOH) of known concentration is added to a strong acid (also of known concentration, in this case). As the strong base is added to solution, its OH- ions bind with the free H+ions of the acid. An equivalence point is reached when there are no free OH- nor H+ ions in the solution. This equivalence point can be found with a color indicator in the solution or through a pH titration curve. This part of the tutorial will show you how to do the latter.
  • Note that there should be two columns of data in your spreadsheet:
  • Column A: mL of 0.1 M NaOH added
  • Column B: pH of the 0.1 M HCl / 0.1M NaOH mixture
    • Using a new sheet in the spreadsheet workbook, enter your titration data as shown in Figure 6.
    • Go to the Data Input Tutorial if you need hints on formatting the cells to the proper number of decimal places
  • external image lwr-cap10.gif
  • Figure 6.
  • Now, create a scatter plot of titration data, just as you did with the Beer's Law plot (Figure 7).
    • Highlight the titration data and the Column headers
    • Click on the Chart wizard icon
    • Choose XY (Scatter) and the Scatter Chart sub-type
  • external image lwr-cap11.gif
  • Figure 7.
  • Continue through steps 2 through 4 of the Chart wizard:
    • The defaults for step 2 should be fine if you properly highlighted the data
    • In step 3 enter the chart Title and x and y axis Labels and turn Off the Legend
    • In step 4, leave as an object in the current page
  • The resulting plot should look like Figure 8:
  • external image lwr-cap12.gif
  • Figure 8.
  • Return to Top

Changing the Scatter Plot to a Line Graph

  • All of the points of the titration data can be connected to form a smooth curve. With this approach, the curve is guaranteed to go through all of the data points. This option can be used if you have only one pH reading per amount of NaOH added. If you have multiple pH readings for each amount added on the scatter plot, you will not end up with a smooth curve. To change the scatter plot to a (smoothed) line graph (Figure 9):
    • Choose Chart > Chart Type...
    • Select the Scatter connected by smooth lines Chart subtype
  • external image lwr-cap14a.gif
  • Figure 9.
  • The result should look like Figure 10:
  • external image lwr-cap14b.gif
  • Figure 10.
  • This smooth, connected curve helps locate where the steep part of the curve passes through pH 7.