The manufacturing of these little soldiers for athletes relies on the principles of thermochemistry. The mixture of ammonium nitrate and water relies on endothermic properties or in this case when heat is absorbed to create the cold sensation in an ice pack. A device used to measure the quantity of heat transferred to or from an object is called a calorimeter. In most science labs it is more commonly referred to as a Styrofoam cup or a coffee cup calorimeter. In our lab we use a more sophisticated one which included a lid on the cup with an inserted thermometer and a stirrer.
The salts will be dissolved in distilled water by small quantities until the reaction reaches When ionic compounds dissolve in water, they either absorb energy from or release energy to the surroundings. If a chemical reaction absorbs heat from the surroundings, it is an endothermic reaction. If a solution releases heat to its surroundings, it is an exothermic reaction. The enthalpy of dissolution is the enthalpy change associated with the dissolution of a substance in a solvent at a constant pressure. The change in enthalpy relies on the concentration of the salt solution, because different concentrations will produce different enthalpies.
Chapter Two: Freezing Point Depression Measurements Purpose: The purpose of this lab is to measure freezing points and freezing point depression for several solutions. The freezing point depression constant (Kf) for p-xylene was calculated from freezing point measurements and used to estimate the molar masses of three unknown solutes in a p-xylene solution. The end goal of this lab experiment is to correctly identify these three unknown solutes. The molar mass of a solute is able to be determined through freezing point depression measurements because the increase in solutes disrupts crystal formation, requiring a lower temperature to form a lattice. This colligative property is important in many industries, but is clear to see when using ordinary salt to remove ice from steps or a driveway.
In the discussion section of this lab report, you will want to discuss the importance for heating the hydrate for a sufficient amount of time. Also address the following questions in your discussion: How would you expect the final measured mass of the anhydrate to change if the hydrate was not heated for a sufficient length of time, and why? How would this change in the measured final mass affect the calculated formula of the hydrate? Explain your
Making Hot and Cold Packs: Endothermic and Exothermic Chemical Reactions Background Hot and cold packs are frequently used by athletes and trainers to treat minor injuries, such as, inflammations, sprains, muscle spasms, head-aches, etc. Hot and cold packs consist of two separate compartments, one containing water and the other containing a salt. When you break the seal between the chambers and shake the pack vigorously, the two compartments combine and the salt dissolves in the water. This generates a chemical reaction. Depending on the type of salt, this reaction can either release or absorb heat energy.
Lab: I Scream, We All Scream for …Colligative Properties!? Introduction: When a solute is added to water the physical properties of freezing point and boiling point change. Water normally freezes at 0oC and boils at 100oC. As more solute is added, the freezing point drops (“freezing point depression”) and the boiling point increases (“boiling point elevation”). This property is useful in our lives.
Thermal decomposition of carbonates Introduction: Carbonates decompose when they are heated, producing calcium oxide and carbon dioxide. Carbon dioxide can be detected using lime water. Calcium carbonate calcium oxide + carbon dioxide CaCO3 CaO + CO2 Other metal carbonates decompose in the same way. Here are the equations for the thermal decomposition of copper carbonate: copper carbonate copper oxide + carbon dioxide CuCO3 CuO + CO2 Hypothesis: some metal carbonates decompose more easily than others when they are heated. Aim: The times taken for a chemical reaction to take place metals high up in the reactivity series (such as calcium) have carbonates that take a lot of energy to decompose them.
This hypothesis was chosen because it’s easier to digest hot water than it cold. Materials and Methods There were multiple materials and methods used for this particular latent lab. For example, the groups used the hot plate to heat up the water to different temperatures. Another material that was used was the thermometer used to check the temperature
Introduction: Stoichiometry is the branch of chemistry concerned with measuring the proportions of elements that combine during chemical reactions (Bing). The mole ratio, which is the comparison of moles of a given reactant or product in an equation, is essential to the proper usage of stoichiometry. In the following experiments, stoichiometry and mole ratios were used to accurately predict and obtain missing proportions from the given equations. In the stoichiometry of a neutralization reaction experiment, the molarity and type of acid were predicted by the titration of an unknown acid using .1 molar (M) Sodium Hydroxide (NaOH). In the other, aluminum leftovers, the activity series was used to understand how and why the reaction took place and stoichiometry was used to predict the amount of aluminum that should have reacted in the following equation: 3CuCl2 * 2H2O (aq) + 2Al (s) 2AlCl3 (aq) + 3Cu (s) + 6H2O Stoichiometry’s importance in the laboratory is well defined in the results of the previously mentioned experiments.
Name: 6.03: Calorimetry Data and Observations: Part I: Insert a complete data table, including appropriate significant figures and units, in the space below. Also include any observations that you made over the course of part I. (4 points) I observed that when the metal is placed inside the calorimeter, it transfers heat to the water making the water increase temperature while the metal will decrease temperature. I also noticed that the system was the metal and the surroundings is the water, this is because the water is taking in the heat from the metal making the water warm. Metal Name Mass of Metal Volume of water Initial temp.