Purpose
The purpose of this lab is to find mole ratios of reactants in a chemical reaction.
Data Table of Temperature Change in Chemical Reactions
mL NaClO |
mL NaOH |
Initial Temperature |
Final Temperature |
Change in Temperature |
0
10 20 30 40 50 |
50
40 30 20 10 0 |
21.75 degrees Celcius
21.75 degrees Celcius 21.75 degrees Celcius 21.75 degrees Celcius 21.75 degrees Celcius 21.75 degrees Celcius |
22.00 degrees Celcius
26.50 degrees Celcius 31.00 degrees Celcius 36.50 degrees Celcius 41.50 degrees Celcius 21.50 degrees Celcius |
0.25 degrees Celcius
4.75 degrees Celcius 9.25 degrees Celcius 14.75 degrees Celcius 19.75 degrees Celcius 0.25 degrees Celcius |
Conclusion
The data table shows a numerical listing of the collected data. The graph shows the collected data visually. One must review both of the datas to spot the optimum ratio. The optimum ratio in this data happens to be four to one. This is 40mL of NaClO and 10 mL of Solution ‘B’, or sodium hyposulfite. The reaction has to be 4 NaClO + 1 Na2S2O3 --> Products and set up in a stoichiometric mole to mole ratio to find the largest amount of reactants used and the greatest amount of products produced.
Discussion of Theory
Though the method of continuous variations in this lab, the optimum ratio is able to be found. In the method of continuous variations, different ratios of two reactants were tested. The controlled variable in this experiment was the volume. The controlled volume is 50mL. The independent variable is the temperature. The reactants were poured into the cup and then the thermometer was placed in the cup to measure the final temperature. The final temperature is then subtracted from the initial temperature to find the delta. The delta recordings were recorded to the graph according to their corresponding ratio. A best-fit line was made on each side of the graph: an increasing line and a decreasing line. The point where the two lines intersects marks the highest temperature change corresponding to a ratio which would be the optimum ratio of the reaction.
Analysis Questions
1. You must keep a constant volume of reactants so that the measurements are proportional. The quantity of the reactants could then be compared to the resulting changes in the temperature.
2. The term limiting reagent is the reactant that will be completely used up in a chemical reaction before all the other reactants are used up. This, therefore, causes the reaction to stop.
3. The measurement of volume limits the precision of the data rather than the measurement of temperature. Temperature is what’s being measured (or tested for) and the amount of volume set for the lab affects the change in temperature. For example, if the constant volume was 80mL instead of 50mL, the temperature might have increased a lot more.
4. Along the upward sloping line of the graph, the limiting reagent is NaClO. Along the downward sloping line of the graph, NaOH is the limiting reagent.
5. Other physical properties that could use the method of continuous variations may be the color intensity of a reactant or product, the mass of a precipitate that forms, or the volume of gas evolved.
6. It is more accurate to use the point of intersection of the two lines to find the mole ratio rather than the ratio associated with the greatest temperature change because it shows the maximum of both of the lines. The highest of the upward sloping line only tells the highest for that, and not both of the lines.
2. The term limiting reagent is the reactant that will be completely used up in a chemical reaction before all the other reactants are used up. This, therefore, causes the reaction to stop.
3. The measurement of volume limits the precision of the data rather than the measurement of temperature. Temperature is what’s being measured (or tested for) and the amount of volume set for the lab affects the change in temperature. For example, if the constant volume was 80mL instead of 50mL, the temperature might have increased a lot more.
4. Along the upward sloping line of the graph, the limiting reagent is NaClO. Along the downward sloping line of the graph, NaOH is the limiting reagent.
5. Other physical properties that could use the method of continuous variations may be the color intensity of a reactant or product, the mass of a precipitate that forms, or the volume of gas evolved.
6. It is more accurate to use the point of intersection of the two lines to find the mole ratio rather than the ratio associated with the greatest temperature change because it shows the maximum of both of the lines. The highest of the upward sloping line only tells the highest for that, and not both of the lines.