Chemical Reaction Lab

It is important to not change the quantity of the materials from one experiment to the next is because, the instructor told you and the worksheet says to only put a certain amount, mostly because that is a safe quantity and probably if you use more than the directed amount then it will become an unsafe reaction.

1. Calculate the change in temperature (T) for each trial. Record in Data Table 2.

In order to measure the heats of reactions, add the reactants into the calorimeter and measure the difference between the initial and final temperature. The temperature difference helps us calculate the heat released or absorbed by the reaction. The equation for calorimetry is q=mc(ΔT). ΔT is the temperature change, m is the mass, c is the specific heat capacity of the solution, and q is the heat transfer. Given that the experiment is operated under constant pressure in the lab, the temperature change is due to the enthalpy of the reaction, therefore the heat of the reaction can be calculated.

In this lab experiment our main focus was to get skillful in using tools such as the metric ruler, balances, thermometer, and graduated cylinder to capture measurements of length, mass, temperature and volume. Additionally, this lab helped us to become more familiar with the uncertainty of measurements, as well as becoming efficient with rounding our measurements to the correct numbers of significant figures. Our results are measured consistently with rounding to the closest answer we could possibly acquire as the data can tell you.

The control experiment for this investigation will be the experimental setup of 5 trials using 5oC as the temperature. All the steps in the method will be followed.

After the twenty minutes elapsed, the flask was cooled to room temperature and then titrated with the remaining NaOH until the colorless solution remained pink. The final volume was then recorded. While solution #1 was heating the same process was repeated with solution#2 and the second burette

2. The least precise measurement was the temperature but more specifically the freezing points of the solutions and solutes. Due to the freezing point only having two significant figures, the data is limited to two significant figures as well.

The cooling time caused error when calculating the moles of water because the actual result was seven moles instead of five moles which was what was calculated. The calculations could have been potentially miscalculated particularly due to the significant figures used in the data. The method for this experiment can be improved by maybe using another object rather than the crucible to allow a faster cooling time that way the calculations for the analysis have less of a chance of

This did not allow for all for the flames energy to be concentrated on one spot at the bottom of the beaker. This error would have decreased the precision and accuracy of the data gathered form the experiment. This chance of this error could be removed it the experiment was to take place somewhere were there would be not motion of the air to change the position of the flame (e.g. in a bomb calorimeter). 2. Variance in length and width of burner wicks.

Another error was that we did not measure the temperature of the water while it was boiling for the first trial. We used the boiling point of water, 100℃. Another possible error was that when measuring the temperature of the water in the calorimeter for the first trial, the thermometer was touching the bottom of the calorimeter instead of just the water. The lab procedure could have said to make sure that the thermometer touches

The change in the solution depends on the chemical being added. [1] “ For a exothermic reaction the  increase in temperature will cause the reverse reaction to occur. This causes a decreasing amount of the products and increases the amounts of reactants. Lowering the temperature will produce the opposite response.” As seen in the results, when the mixture was heated it produced less product.

Temperature: I can’t control the room or water temperature of the area studied. This may influence the amount of dissolved oxygen in water. However, as the measure are done at the same time I expect the temperature to be similar.

I thought that most of my results were very accurate. However there were a number of points out of place that I could improve on. On the '250ml experiment ' the reading between six and eight minutes appeared to be incorrect compared with the average heat loss in the same experiment. This could have been

• The water must then be heated to 70oC (the first temperature for the experiment)

During the experiment, the samples are placed in the water bath. The water tank has a large volume and it is an open system. The temperature of the water inside is difficult to keep constant. That makes the reaction in the sample cannot perform well at a suitable temperature, which is the body temperature. As there is a difference in the temperature, the reaction completeness in each sample may not be the same. The products formed may not be completed. That means there are some reactants were at complex form. This affects the result of the experiment. We cannot have an accurate measure of each sample. Thus, the accuracy of the experiment is not good enough.