After the calorimeter constant is found we can move on to part two of the experiment, where we will test each of the four salts in the calorimeter to find out if the salt will be used for a hot or cold pack. Our goal is to first determine the q_dissolution and then to find the heat of dissolution. A -〖∆H〗_dissolution will be an exothermic reaction which indicates that the salt would go in a hot pack. While a 〖∆H〗_dissolution will be an endothermic which indicates that the salt would go in an ice pack. Calculations for determining the 〖ΔH〗_(dissolution ) of each salt Csolution = specific heat of water = 4.184 J/g°C ΔHdissolution=qdissolution/(moles of substance dissolved) -q_dissolution=-(m_solution×C_solution×〖∆T〗_solution )+(C_calorimeter×〖∆T〗_calorimeter) q_dissolution = the opposite of the answer you get for- q_dissolution. *For where M is the mass of the solution, C is the thermal Constant of water: 4.184 J/g°C, ∆T is the change in Co , Q is the energy of dissolution. In order to determine the mass of salt required for the ice pack to reach 0.0°C and hot pack to reach 65°C, we must set the ΔHdissolution which will be calculated from our trial equal to the ΔHdissolution of hot/cold pack containing 100 mL of water and reaching a temperature of 65°C/0.0°C. This equation is given below: (Cdissolution ×M dissolution × ΔT dissolution)/(moles of substance dissolved)=(Cdissolution(x+100g water)dissolution ΔTdissolution x g of substance dissolved )/█(g/mol of substance dissolved@) *The left side of the equation will represent the data from the experiment, and the right side represents our hypothetical calculations. By plugging in either 65°C or 0°C (depending on if were solving for the hot or cold pack), and the... ... middle of paper ... ...ited Stanton, B. ; Zhu, L. ; Atwood, C. H. Experiments in General Chemistry featuring MeasureNet,2nded.;Brooks/Cole Cengage Learning: Belmont, 2006; p 243-251, p 395-399 "Calcium Chloride MSDS." Science Lab. Science Lab, n.d. Web. 6 Apr. 2014. . "Material Safety Data Sheet Ammonium Nitrate MSDS." Science Lab. Science Lab, n.d. Web. 6 Apr. 2014. . "Material Safety Data Sheet Lithium Chloride MSDS." Science Lab. Science Lab, n.d. Web. 6 Apr. 2014. . "Potassium Nitrate MSDS." Science Lab. Science Lab, n.d. Web. 6 Apr. 2014. . Staudt, Maureen, and Michael Stranz, eds. General Chemistry for Engineering and Science II. Mason,Ohio: Cengage Learning, 2012. Print.
Using Equation 4, it can be inferred that the initial temperature of the hot water minus the change in temperature of the mixture equals the temperature of the cold water plus the change in temperature of the mixture (Equation 5). This is then rearranged to indicate that the initial temperature of the hot water is two times the change in temperature plus the initial temperature of the regular water. This is shown in Equation 6.
The complete experimental procedure is available in the General Chemistry Laboratory Manual for CSU Bakersfield, CHEM 213, pages 20-22, 24-25. Experimental data are recorded on the attached data pages.
Alka Seltzer Dissolving at Different Temperatures. The variable that I will change will be the temperature of the water. that the Alka Seltzer is put in. For my results I will measure the time taken for the Alka seltzer.
By adding fresh cold water it should cool the copper calorimeter. By making sure I do these checks before I do the experiment means that I should be able to get accurate results as the test will have been run fairly and hopefully successfully as there should not have been anything gone wrong. To make sure all the measurements are correct, I will also run checks. These checks when recording the data are. Make sure to check the thermometer to see what temperature the water is at the start, so I am able to see what it has to be when its been heated by 10 degrees.
The collected data indicated that the formula of the hydrate is CuSO4· 5H2O. In order to find this formula, we had to first calculate the mass of water lost from the hydrate. So we subtracted the mass of
Specific heat capacity of aqueous solution (taken as water = 4.18 J.g-1.K-1). T = Temperature change (oK). We can thus determine the enthalpy changes of reaction 1 and reaction 2 using the mean (14) of the data obtained. Reaction 1: H = 50 x 4.18 x -2.12.
Tf-Ti). Next, subtract the initial temperature, 25 degrees from the final temperature, 29 degrees putting the change in temperature at 4 °C. To calculate the heat absorbed by the water in calorimeter, use the formula (q = mCΔT). Plug in 50 mL for (m), 4.184 J for (C) and 4 °C for the initial temperature (ΔT), then multiply.
Start with the hot water and first measure the temperature. Record it. 8. Then pour 40 ml into the beaker. You can measure how much water was used by looking at the meniscus.
Temp: Mass of evap. dish: Mass of evap dish+contents: Mass of contents: Solubility g/100cm3 water
With a smaller quantity of water (50mls) and the same amount of Ammonium Nitrate added. After any period of time the mixture will be a cooler temperature than that of a mixture with a larger quantity of water.
Sweating and Heat Loss Investigation Aim To find out whether heat is lost faster over a sweaty body compared to a dry body. Apparatus 2 Boiling tubes 47ml max 2 Measuring jug 50ml max A Beaker 250ml max 2 thermometers Paper towels A kettle to boil water A stopwatch 2 magnifying glasses (8x) 2 corks with a small hole through the centre A test tube rack Preliminary work In my preliminary work, I need to find out how much water to use, whether the tissue should be wet with hot/cold water, how often the readings should be taken, how accurate should the readings be, how many readings should be taken and what my starting temperature should be. My results are as follows. Starting temperature of 40°c Time (secs) Wet towel (°c) Dry towel (°c) 30 36 38.9 60 35 38.5 90 34 37.9 120 33.9 37.5 150 33 37 180 32.6 36.9 210 32.3 36.8 240 31 36.5 270 30.4 36 300 30.3 35.9 Starting temperature of 65°c Time (secs) Wet towel (°c) Dry towel (°c) 30 51.1 53 60 48.2 51.9 90 46.4 51 120 46 50 150 44.3 49 180 42.9 48.4 210 42.6 46.9 240 41.7 48 270 40.2 47.5 300 39.3 47 Starting temperature of 60°c Time (secs) Wet towel (°c) Dry towel (°c)
Then comparing the initial temperature of the water to the temperature after the reaction between various salts has occurred, I was able to determine which salt resulted in an exothermic reaction when combined with water. The NaCl and KNO3 were both endothermic reactions because the final temperature was less than the initial temperature. This means that heat was lost by the surroundings, the solution, and gained by the system, the reaction. MgSO4 was exothermic because its final temperature was greater than its initial temperature, which means that heat was gained by the solution and lost by the reaction. Therefore, MgSO4 was the best salt to use for the heat pack because it was the only salt we tested that released heat. After this, we ran three trials with varying volumes of water in order to find the volume ratio of salt to water that would produce a reaction that could release enough heat to raise the temperature of the solution by about 20°C. From this information, I could find the changes of enthalpy of the reaction, which was able to be a substitute for changes in heat content because the reaction took place at a constant
Haynes, William M.., and David R. Lide. CRC handbook of chemistry and physics a ready-reference book of chemical and physical data : 2012-2013. 93e édition. ed. Boca Raton (Fla.): CRC Press, 2012. Print.
Methodology: A plastic cup was filled half way with crushed ice and mixed with four spoonfuls of 5 mL of sodium chloride. A thermometer was quickly placed inside the cup to take the temperature and the
... model for the thermodynamics and fluid mechanics calculations for this system need to be presented.