Why is a styrofoam cup used as a calorimeter?
A coffee cup calorimeter is a useful, simple device that can be used to measure the temperature change that accompanies a reaction. A Styrofoam™ cup is used because it is a good insulator. The cup will absorb (or supply) negligible amounts of heat during most General Chemistry experiments.
Polystyrene is an insulating material, which means that it does not conduct heat very well. This means that it can prevent the heat released by the neutralization reaction from leaving the cup. On the other hand, glass is not quite as good of an insulator as polystyrene.
Answer and Explanation: Option A (styrofoam cup) is a better calorimeter than glass because it is a better insulator. This is because we want the system to be as isolated from the surroundings as possible when doing a calorimetry experiment where the reaction occurs inside the container.
A styrofoam cup is used because styrofoam is a relatively good insulating material. Heat given off within it as a result of some physical or chemical change will not be lost to the surrounding environment.
Safer to Use for Hotter Drinks:
This can lead to burnt fingers and dropped drinks, which could cause an injury. A foam cup is insulated from heat, and it's easy to pick one up with a hot beverage in the cup.
Foam cups are the most efficient way to keep your drinks warm in the winter and cold in the summer. Foam is also a valuable industrial product. In fact, most hospitals use foam products because foam products minimize exposure to bacteria and other foodborne pathogens.
The benefits of polystyrene packaging are numerous: Superior insulation which protects produce from temperature changes. Dimensional stability and recovery. Light weight and easy to stack.
Measuring cylinders are designed more specifically for accurate measurements of liquids with a much smaller error than beakers. They have many more graduation marks and have close to 0.5-1% error, which can be precisely used to measure liquids ranging from 1ml- 1L.
The volume marks on a beaker are only approximate values, and therefore only provide whole numbers. For example, a 100 mL beaker might only have marks for every 20 mL, so it would be tricky to gauge the exact volume of a liquid sample falling between the 60 mL and 80 mL marks.
Polystyrene and plastic foam are both used as insulators as they have small air bubbles trapped inside them. This makes them very good insulators because heat energy can't flow through them. The same idea is used to keep the inside of buildings warm.
Why would two styrofoam cups be an economical way of determining these heat values and what is the of the major pitfalls of using this system?
The two styrofoam cups are economical way because these cups have proper and well insulated. walls that help in preventing the exchange of heat from the environment. It reduces the exchange of heat that occurs between the surroundings and the liquid that is present in the coffee cup.
Styrofoam absorbs more heat per gram than steel, but the steel calorimeter is probably heavier. With a fast reaction there is the additional fact that the styrofoam calorimeter probably never comes up to the full temperature of the reaction before you quit recording temperatures.
Answer: This is because metals are good conductors of heat and have low specific heat capacity.
The calorimeter is a small container made of a metal, such as gold or copper, with good thermal conductivity. It has a well for a temperature sensor, which always has to be at exactly the same temperature as the calorimeter and its contents.
Styrofoam is an insulator, making it very poor at conducting heat. Heat can't pass on through to the water, so the Styrofoam disintegrates.
EPS is resistant to water and moisture. This means that it does not absorb them and that its insulating performance is not compromised when in contact with these elements. Insulation boards made of expanded polystyrene can make a home healthier because they will not contribute to mildew formation.
The polystyrene cup serves to insulate the reaction mixture, and slows heat losses from the side and bottom. Heat is still lost from the surface of the liquid mixture, of course, and that can be reduced by using a polystyrene lid with a hole for a thermometer.
The use of Styrofoam or other foamed polystyrene products is a personal choice. If used properly, it is an economical, sanitary product, with low environmental risks. However, used improperly, it can quickly become an unsightly environmental nuisance and does have potential health risks.
- Light Weight. Comprised of about 98 percent air, expanded polystyrene is extremely lightweight, making it ideal for transport and installation. ...
- Moisture Resistant. ...
- Durability. ...
- Thermal Efficiency. ...
- Versatility. ...
- On-Site Ease of Use. ...
- Environmental Sustainability.
Air is fine at convection, but the heat transfer is minimal because the low mass can't store much amount of heat. Thus it blocks the flow of the heat energy. Styrofoam reduces conduction and convection. In this way, it is one of the best existing insulators.
Which glassware is considered as the most accurate when measuring liquids explain why?
Volumetric flasks, burets and pipets are the most accurate with tolerances of less than 0.2%. To achieve these accuracies the person using the device needs to use the proper technique and the measurements need to made at the temperature for which the glassware was calibrated (usually 20 degrees C).
Graduated Cylinders and Beakers
Graduated cylinders, beakers and Erlenmeyer flasks have less accuracy than volumetric glassware. Graduated cylinders can generally be considered reliable to within 1 percent.
Graduated Cylinders
They also have glass bottoms that function as a spout to pour the liquid out. Unlike beakers, graduated cylinders are used for measuring liquid volumes. They range within the size of about 5ml to 2000ml. These cylinders are highly accurate & measure liquids within 1%.
Beakers and Flasks
Beakers are generally little more than glass jars that have a small spout that is used for pouring out the contents. Most beakers will have graduations marked on the outside, but they lack accuracy, and therefore beakers should not be relied upon when precision is vital.
The biggest drawback of glassware is breakage. Accidental breakage results in loss of valuable samples, harmful spillages, leakages of toxic chemicals, radioactivity, harmful bacteria or injuries to the laboratory chemist.
Both graduated cylinders and beakers are pieces of laboratory glassware that have a specific function. Graduated cylinders typically are more accurate at reading the volumes of the liquid inside. Beakers are better for stirring and mixing liquids.
Glass is far inferior to paper, plastic and Styrofoam in terms of insulation. Thermal conductivity in terms of BTU/(feet - hour - degrees F) is 1.82 for glass, 0.09 for paper, 0.06 for Styrofoam.
In its expanded form, polystyrene has low thermal conductivity which makes it a great insulator. Polystyrene foam contains a lot of small pockets of air within its structure, and this is an important key to its insulating properties.
Styrofoam is a material that is made of expanded polystyrene foam (EPS). It is generally used to make food containers, coffee cups etc. The specific heat capacity of Styrofoam is calculated experimentally as 0.27calgm−1oC−1 or 1131Jkg−1K−1.
Styrofoam coffee cups do a better job of insulating, because the material does not conduct heat well. Also, A Styrofoam cup is several times thicker than a paper coffee cup, adding to its insulating properties.
What are the limitations of a Styrofoam cup calorimeter in measuring heats of reactions?
A coffee cup calorimeter is great for measuring heat flow in a solution, but it can't be used for reactions that involve gases since they would escape from the cup. The coffee cup calorimeter can't be used for high-temperature reactions, either, because they would melt the cup.
A constant pressure calorimeter is also known as a coffee cup calorimeter. It is a very simple device; basically it can be made from two styrofoam cups, a stirrer and a thermometer.
Answer and Explanation: Option A (styrofoam cup) is a better calorimeter than glass because it is a better insulator. This is because we want the system to be as isolated from the surroundings as possible when doing a calorimetry experiment where the reaction occurs inside the container.
Polystyrene is an insulating material, which means that it does not conduct heat very well. This means that it can prevent the heat released by the neutralization reaction from leaving the cup. On the other hand, glass is not quite as good of an insulator as polystyrene.
Polystyrene was the best insulator followed by paper, porcelainand then metal.
The glass calorimeter is used to determine the ΔH of most chemical reactions. Reactants in stoichiometric amounts are placed in the calorimeter. As the reaction proceeds, the heat energy evolved or absorbed will either warm or cool the system.
A calorimeter is composed of an insulated container, a thermometer, a mass of water, and the system to be studied. The use of an insulated container (Styrofoam cup in this experiment) allows us to assume that there is no heat transferred through the calorimeter walls.
Calorimeters are made up of metal only because they are good conductor of heat and hence the heat exchange is quick which the basic requirement for the working of calorimeter.
The role of the Styrofoam in a coffee cup calorimeter is that it reduces the amount of heat exchange between the water in the coffee cup and the surrounding air. The value of a lid on the coffee cup is that it also reduces the amount of heat exchange between the water and the surrounding air.
The foam cup acts as an insulator. This means that less, if any, heat can escape. This will allow the calorimeter to be more precise.
Why do you use a Styrofoam cup when measuring the specific heat of a metal?
A styrofoam cup is used because styrofoam is a relatively good insulating material. Heat given off within it as a result of some physical or chemical change will not be lost to the surrounding environment.
The foam cup acts as an insulator. This means that less, if any, heat can escape. This will allow the calorimeter to be more precise.
Styrofoam absorbs more heat per gram than steel, but the steel calorimeter is probably heavier. With a fast reaction there is the additional fact that the styrofoam calorimeter probably never comes up to the full temperature of the reaction before you quit recording temperatures.
When a chemical reaction occurs in the coffee cup calorimeter, the water absorbs the heat of the reaction. Since the styrofoam cup insulates the reaction from the outside world (adiabatic), we can assume all the reaction's energy is absorbed into the water.
The cup is partially filled with a known volume of water and a thermometer is inserted through the lid of the cup so that its bulb is below the water surface. When a chemical reaction occurs in the coffee cup calorimeter, the heat of the reaction is absorbed by the water.
Glass is far inferior to paper, plastic and Styrofoam in terms of insulation. Thermal conductivity in terms of BTU/(feet - hour - degrees F) is 1.82 for glass, 0.09 for paper, 0.06 for Styrofoam.
Polystyrene and plastic foam are both used as insulators as they have small air bubbles trapped inside them. This makes them very good insulators because heat energy can't flow through them. The same idea is used to keep the inside of buildings warm.
Thus, if the heat had been determined using a glass beaker instead of a polystyrene sample, most of the heat would be used up by glass to heat it. Thus, this amount of heat will be lost. Hence the temperature change (ΔT) will be lower, resulting in lower heat of neutralization.
Calorimeters are made of thin sheet of copper. For a calorimeter to be effective it must have two properties. (1) Although any object will use or loose some heat in experiments, a calorimeter should not absorb / loose too much of heat, otherwise it would affect the readings and final results.
It traps the air in its small pockets. Styrofoam has millions of small air bubbles trapped inside the foam. Since air is a bad conductor of heat Styrofoam efficiently prevents heat transfer. Air is a mixture of gases, and it is not a good conductor or a radiator.
What containers can be used as a calorimeter?
Simple calorimeters are made with a metal container of water, positioned above a combustion chamber. A thermometer is used to measure the heat change in the amount of water. The simplest versions of the device can be made at home using two coffee cups or styrofoam cups, though it is not as accurate as lab equipment.
The specific heat capacity of Styrofoam is calculated experimentally as 0.27calgm−1oC−1 or 1131Jkg−1K−1.
The two styrofoam cups are economical way because these cups have proper and well insulated. walls that help in preventing the exchange of heat from the environment. It reduces the exchange of heat that occurs between the surroundings and the liquid that is present in the coffee cup.
Use the same mass of water in the calorimeters for each experiment. Position the calorimeter the same distance above the flame for each experiment. Use the same thermometer in each experiment. Use a pipette to measure the water into the copper calorimeter instead of a measuring cylinder.
