The purpose of this lab investigation is to determine which salt and at what quantity will produce the most effective and economical instant cold pack. A cold pack consists of two compartments, one containing water and the other containing a salt. Squeezing the cold pack gives off heat and breaks the barrier, allowing for the salt to dissolve in water and drop to 2°C. Many people use cold packs to reduce swelling and decrease blood flow of an injured area. Furthermore, cold packs absorb heat from their surroundings, making them endothermic systems that decrease/cool the temperature of their surroundings. Recording temperature changes and enthalpies of each ionic compound are needed to conclude which salt will produce the most effective cold pack. …show more content…
Heat or q of water is determined by the formula q = m x s x ∆ T, and q of the solution is q solution = - q water. In order to calculate ∆H, a calorimeter, an isolated system is used to calculate the heat of a chemical reaction. Using the heat found by the calorimeter, heat (kJ) is divided by the number of moles (n) in order to calculate ∆H of a solution. Enthalpy is used to determine if a system is endothermic or exothermic. If the ∆H of a system is negative then the system will be exothermic. If the ∆H of a system is positive then the system will be endothermic. The salt that yields the highest ∆H with the lowest cost per unit of grams needed to drop to 2 °C, will be the most effective and economical ionic compound to make the best cold
After each of the solids were completely dry, each was placed into a MelTemp device. The temperature at which each solid began to melt and completed melting was recorded.
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.
The mole is a convenient unit for analyzing chemical reactions. Avogadro’s number is equal to the mole. The mass of a mole of any compound or element is the mass in grams that corresponds to the molecular formula, also known as the atomic mass. In this experiment, you will observe the reaction of iron nails with a solution of copper (II) chloride and determine the number of moles involved in the reaction. You will determine the number of moles of copper produced in the reaction of iron and copper (II) chloride, determine the number of moles of iron used up in the reaction of iron and copper (II) chloride, determine the ratio of moles of iron to moles of copper, and determine the number of atoms and formula units involved in
The type of cold pack presented here contains ammonium nitrate, which is a white crystalline substance. When these crystals react with water they split into positive ammonium ions and negative nitrate ions. Due to the energy expended by the water in order to dissolve these crystals, the water becomes colder.
Through our data acquisition on day one our predicted values for the change in temperature of our NaCl solution in water was slightly off. This was most likely due to recording the freezing temperature sometime after the precise moment of the solution freezing. However, we predicted that as we doubled our concentration of NaCl in solution the freezing point depression would also double which is consistent with our results. Through our day one experiments we were able to better understand the ability of NaCl as a deicer by understanding how the freezing point depression changes based on concentration. We could further test these results by testing with different concentrations of NaCl.
PURPOSE: to determine which of the 3 ionic compounds (NaCl, LiCl, or NaCH3COO) is most
The purpose of this lab was to identify unknown bacteria cultures using various differential tests, and my unknown bacteria is #17. The identification of these unknown cultures was accomplished by separating and differentiating possible bacteria based on specific biochemical characteristics. Whether the tests performed identified specific enzymatic reactions or metabolic pathways, each was used in a way to help recognize those specifics and identify the unknown cultures. The differential tests used to identify the unknown cultures were Gram stain, Catalase, Mannitol Salt Agar (MSA), Blood Agar, Novobiocin, Coagulase, and DNAse (Alachi, 2007).
Hypothesis: The purpose of this experiment was to investigate the question will different food sources affect the level of activity of detoxification enzymes in bean beetles? The class alternate hypothesis is different food sources will affect the level of activity of the detoxification enzymes in bean beetles. The null hypothesis is the different food sources will not have any effect on the level of activity of the detoxification enzymes in bean beetles. Experimental design: The independent variables in this experiment were the types of beans (bean 1 was mung beans and bean 2 was adzuki beans) and enzymes assays used.
For our lab, we have six beakers of water. Three of the beakers contain high temperature water that range from 46 ℃ to 55 ℃, while the other three beakers contain room temperature water that range from 22 ℃ to 23 ℃. Then, we take six different colored Alka Seltzer tablets, and place them into the beakers one at a time. We record the length of time it takes for each Alka Seltzer to dissolve
In this unit we have conducted research and experiments on our chosen reactions to create the highest exothermic reaction for the The Heat-and-Eat meal pack will use a chemical reaction that involves two reactants. Reactant 1 is a solid and Reactant 2 is a liquid.
Secondly: The samples were only placed in the water bath for five minutes and as soon as any samples were removed the temperature
2. (5 pts) List and explain the names and affiliations of the various characters/stakeholders in this story – I’m looking for us to use the story to map out the complexities that are generally associated with solving public health puzzles – the stakeholders you list and explain here should apply to many of the cases we consider going forward.
Purpose: The purpose of this laboratory was to gain an understanding of the differences between the freezing points of pure solvent to that of a solvent in a solution with a nonvolatile solute, and to compare the two.
It’s predicted that when adding the chemical substance into the water, energy will be released or absorbed, this will be observed by a temperature change, therefore, there would be an exothermic or endothermic reaction.
As stated, our solvent in this lab will be tert-butanol. We start by recording the freezing point of this substance without anything added. Then, we add various