EXPERIMENT 7: decision OF THE certain HEAT of A METAL
Lansing ar College basic invernessgangshow.netistry laboratory I
LEARNING OBJECTIVE
Determine the certain heat volume of a steel using a coffee cup calorimeter.
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INTRODUCTION
Heat is a kind of power that is transferred in between objects with different temperatures. Heat constantly flows native high temperature to low temperature. The lot of heat soaked up or released (q) by the object depends on its mass (m), details heat (Cs), and also the adjust in temperature (ΔT).
Specific heat have the right to be characterized as the lot of heat compelled (q) to raise the temperature that one gram the the substance by one degree Celsius.
Equation 1
Rearranging Equation 1: Equation 2
Each pure substance has actually a certain heat the is a characteristic physical residential or commercial property of the substance. The specific heats the some usual substances are provided in Table 1.
Table 1. certain Heat of Some usual Substances
| Substance | Specific heat (J/g°•C) |
| Water | 4.184 |
| Wood | 1.76 |
| Concrete | 0.88 |
| Mercury | 0.14 |
| Iron | 0.451 |
| Copper | 0.385 |
The size of details heat varies greatly from huge values like that the water (4.184 J/g°•C) to little values like that the mercury (0.14 J/g°•C). When equal masses of objects room heated to absorb an same amount the heat, the object with smaller the certain heat value would reason the greatest increase in temperature.
Heat power is either soaked up or progressed during nearly all invernessgangshow.netical and also physical changes. If heat is absorbed or start the system, the procedure is endothermic and if warm is developed or exits the system, the procedure is exothermic. In the laboratory, heat circulation is measure up in one apparatus called a calorimeter. A calorimeter is a an equipment used come determine heat flow throughout a invernessgangshow.netistry or physical change. A doubled Styrofoam cup fitted through a covering in i m sorry a feet is boring to accommodate a thermometer can serve well as a calorimeter (See Figure 7.1.)
Figure 7.1 Coffee Cup Calorimeter
In this experiment friend will warmth a well-known mass the a steel to a recognized temperature and then carry it come a calorimeter that contains a known amount the room temperature water (Tc). The preferably temperature reached by the water in the calorimeter (Tmax) will certainly be recorded and the temperature adjust of the water (Tmax - Tc) and also the temperature readjust of the steel (100.0°C - Tmax) calculated.
The circulation of power (heat) in between a metal and also its environment is explained by Equations 3 and also 4.
|qlost by metal|= qgained by water + qgained through calorimeter Equation 3
mmetal x Csmetal x |Tmax – 100.0°C| =
Equation 4
(Note: warm capacity that coffee cup is calorimeter = 15.9 J/°C)
Rearranging Equation 4 to resolve for the certain heat the the metal:
Csmetal = Equation 5
EXPERIMENTAL PROCEDURE
This experiment is done in a team the two. Ar 200 mL that room temperature water indigenous a carboy in a 250 mL beaker and collection it next for later use. Next place around 250 mL of tap water into a 400 mL beaker. Add 4-5 boil chips into the insanity water to avoid bumping. Carry the insanity water to a tenderness boil utilizing a hot plate. Achieve three clean dry 18 by 175 mm test tubes. Brand them runs 1 – 3. Tare one of the check tubes in a beaker. Carefully add around 30 g that the metal sample come the check tube and record the fixed of the metal in DATA TABLE I. If you space at the balance, fixed two additional samples into the check tubes 2, and 3. Put all the 3 test pipe containing the unknown steel in the water bath. Heat to boiling, and also then keep the temperature for about 5 minutes. Assume the the temperature of the steel is 100.0°C after the has been in the boiling water bath for at the very least 5 minutes.
While the steel is gift heated, achieve two Styrofoam cups, a lid, a thermometer and also a timer. Utilizing a i graduated cylinder, measure up 50.0 mL of the room temperature water and also transfer right into the double Styrofoam cup. Allow 5 minutes for this system to with thermal equilibrium. ~ 5 minutes, document the temperature the the water, Tc, in DATA TABLE I and in DATA TABLE II for time 0 seconds.
Using a test tube holder, elevator the test pipe containing the heated metal from the boil water bath. Conveniently remove the lid and pour the hot metal (labeled run 1) into the calorimeter. Make certain no warm water indigenous the exterior of the test pipe drips right into the calorimeter. Change the lid the the calorimeter and also the thermometer. Swirl the device gently. Document the temperature every 5 seconds for a minute and also then every 15 secs for around 2-3 minute or until you observe a preferably temperature (Tmax) for about four continuous readings. Continue to swirl the calorimeter gently while record temperatures. Drainpipe the metal and also water right into a big filter funnel in the hood. Repeat the above procedure utilizing two additional samples. Dried the calorimeter between each trial.
Plot time (x- axis) vs. Temperature time because that each that the three runs making use of Excel. Please incorporate all 3 runs top top one graph. Column A is time and also columns B, C, and D will be temperatures for Runs 1-3. Give the graph a title and also label the x and y axes. Determine the Tmax indigenous the graph and label the on the graph by inserting a double headed arrowhead shape Figure 7.2.
Figure 7.2
Finally, calculate the specific heat that the metal using Equation 5.
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Clean increase & waste Disposal to water the metal sample and warm water right into the labeled bottles fitted through funnels in the hood. Wash the test tubes and place lock in the tray beside the oven. Please rotate off the digital thermometers, and also the timer. Return them come the side bench. Shut down the laptop computer and return it come its numbered space in the Dry-Dock. Plugin the correct laptop charging cable. Very closely unplug the hot plate and leave it the end on the bench. Please clean the bench peak with a moist document towel
DATA SHEET for EXPERIMENT 7 – decision OF THE particular HEAT the A METAL
Your Name: ______________________ Lab companion Name: _______________________
DATA TABLE i (2 pts.)
(Record the dimensions with units and also the correct number of far-reaching figures.)
| Quantity | Run 1 | Run 2 | Run 3 |
| Volume of water in the calorimeter | 50.0 mL | 50.0 mL | 50.0 mL |
| Mass of metal | |||
| Temperature the metal | 100.0 °C | 100.0 °C | 100.0 °C |
| Temperature the water in calorimeter, Tc | |||
| Maximum Temperature, Tmax | |||
| Temperature adjust of the cold water, Tmax - Tc |
DATA TABLE II (2 pts.)
| Time Seconds | Temperature °C Run 1 | Temperature °C Run 2 | Temperature °C Run 3 | |||||
| 0 | ||||||||
Plot time (x-axis) vs. Temperature for each of the 3 runs in DATA TABLE II making use of Excel. Offer each graph a title and label the x and y axes. Mark the ∆T’s (Tmax – Tc) on her graph. (2 pts.)
TABLE III – Tabulated results (2 pts.)
| Quantity | Run 1 | Run 2 | Run 3 |
| Calculated specific heat | |||
| Average particular heat | |||
| Average deviation | |||
| Known details heat | 0.222 J/g oC | ||
| Relative % error for average specific heat |
Calculations: display your calculations below. Be certain to include units in your set up and also report your answer come the exactly number of far-reaching figures.
Calculated details heat for run 1: (2 pts.) Average particular heat: (1 pt.) mean deviation: (2 pts.) relative % error for average specific heat: (1 pt.)POST activities for EXPERIMENT 7 - decision of the specific HEAT of a METAL
Name: _________________________________________
discuss the precision and also accuracy of your details heat determination. Usage your calculated mean deviation and relative error in her discussion. (An typical deviation of 0.02 J/g°C and also a family member error of less than 10% space considered great in this experiment.) (4 pts.) Explain plainly how the 2 errors below would boost or decrease her calculated value for particular heat by referring to the equation:Error #1: The student offered 25.372 g for this experiment however recorded 23.372 g in the data table and used the incorrect value once calculating the particular heat. (Hint: the error is making use of the 23.372 g data point.) (2 pts.)
Error #2: The initial temperature of the steel was 98 °C, no 100 °C, together we have assumed. (Hint: The error is using the 100 °C.) (2 pts.)
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