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Unformatted text preview: Experiment #3: Pressure, Volume, & Temperature: Discovery of the Gas Laws A. SUMMARY In this lab we measured the different relationships between pressure, volume and temperature. In part A we took a section of air and then decreased the volume with a syringe. We also simultaneously measured the change in pressure along with the change in volume. After taking several measurements, we compared the relationship of the change between volume and pressure. In this comparison a conclusion was reached that further proved the Laws established by Robert Boyle and others in the 17th century that as volume increases pressure decreases, and visa versa. In part B we measured the change in pressure as temperature changes. We started with water at 0C and heated it slowly until it reached 90C. Every 5C we would measure the pressure and record it. At the end of this slow heating process you could see the almost perfect line showing that as temperature increases pressure increases as well, again in line with the Laws established by Robert Boyle and others in the 17th century. B. RESULTS Part A: k (Constant) 994.10 867.15 972.29 966.79 987.04 982.80 995.98 Pressure (kPa) 99.41 173.43 132.47 87.89 61.69 54.60 52.42 Volume (mL) 10.0 5.0 7.0 11.0 16.0 18.0 19.0 C. GRAPHS AND CALCULATIONS k=P*V k = 99.41 kPa * 10 mL :: k = 994.10 (Graphs on attached sheets) D. DISCUSSION Questions to Consider: Part A: 1. From the shape of the curve in your plot of pressure versus volume, do you think the relationship between the pressure and volume of a confined gas is direct or inverse? It's more inverse than direct because a plot of the points of direct would be a straight line and this is more like an exponential equation. 2. Based on your data, what would you expect the pressure of your air sample to be if the volume of the syringe were somehow increased to 60 mL? 165.54 kPa 3. Based on your data, what would you expect the pressure to be if the volume of the syringe were decreased to .20 mL? 0.55 kPa 4. What experimental factors were assumed to be constant in this experiment? Can you identify any potential sources of error in the experimental design? Does your data seem to show any effects of these factors? The environmental pressure and temperature were assumed to be constant. If the experimental environment were kept constant, like no doors being opened to prevent any pressure or temperature changes. The room would basically have to be sealed. These factors did not seem to effect the experiment too much because there was little variation, but it is present. 5. Choose one formula and calculate k for the ordered pairs in your data table. k=P*V k = 99.41 kPa * 10 mL :: k = 994.10 6. How constant were the values for k you obtained for question 5? The were all relatively constant with the exception of the second measurement. 7. Using P, V and k, write an equation representing Boyle's law. Write a verbal statement that correctly expresses Boyle's law. P*V=k Pressure multiplied by volume equals the constant. 8. Would the results of the experiment be improved if we used a sample of pure nitrogen? Of course the results would improve, with air you have a mixture of several different gases that all react differently to changes presented. If there was a single gas it would only react one certain way. Part B: 1. In order to perform this experiment, what two experimental factors were kept a constant? I have no idea what were kept constant 2. Based on the data and graph that you obtained for this experiment, express in words the relationship between gas pressure and temperature. As temperature increases pressure increases as well. 3. Explain this relationship using the concepts of molecular velocity and collisions of molecules. As you heat a substance the molecules begin expanding and moving around rapidly, this movement of particles causes an expansion in the gas, thus creating an upward change in pressure. 4. Write an equation to express the relationship between pressure and temperature. k=P/V 5. As you did in Part A, find a value for k using P, T data pair. How constant were your values? I cannot do this because in all of the printouts I have I cannot see the values for pressure. 6. According to this experiment, what should happen to the pressure of a gas if the Kelvin temperature is doubled? The pressure is not doubled however it is increased by a multiple of 1.87 7. You performed the experiment using air, which we know is actually a mixture of several gases. Would the results of the experiment be improved if we used a sample of pure nitrogen? Of course the results would improve. Like previously stated, every gas reacts differently to the same change. The results would be considerably improved if there was a single gas used in the experiment. ...
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This note was uploaded on 04/21/2008 for the course CHEM 107 taught by Professor Generalchemforeng during the Fall '07 term at Texas A&M.
- Fall '07