From instant cold packs to flameless ration heaters and hand warmers, the energy changes accompanying physical and chemical transformations have many consumer applications.
This preview shows page 1 - 5 out of 5 pages. Subscribe to view the full document. Box All Rights Reserved. Catalog No. AP Publication No. The backbone of these applications is calorimetry—measuring heat transfer. Investigate the energy changes accompanying the formation of solutions for common laboratory salts, and then apply the results to design a hand warmer that is reliable, safe and inexpensive.
When the pack is activated, the solid dis— solves in water and produces a large temperature change. The energy or enthalpy change associated with the process of a solute dissolving in a solvent is called the heat of solution AHsoln. At constant pressure, this enthalpy change, AHsois equal in magnitude to the heat loss or gain, q, to the surroundings.
The overall process can be represented by the following equations. If the amount of energy released in the formation of hydrated ions is less than the amount of energy required to separate the solute and solvent particles, then the sum of the energy changes will be positive and the solution process endothermic absorbs heat.
Heats of solution and other enthalpy changes are generally measured in an insulated vessel called a calorimeter that reduces or prevents heat loss to the atmosphere outside the reaction vessel.
The process of a solute dissolving in water may either release heat into the resulting aqueous solution or absorb heat from the solution. When using a calorimeter, the reagents being studied are mixed directly in the calorimeter and the temperature is recorded both before and after the reaction has occurred.
A small amount of the heat will be absorbed by the calorimeter itself qw. The calorimeter constant has units. This calibration experiment is done by mixing equal volumes of hot and cool water in the calorimeter and measuring the temperature after 20 sec- onds.
The resulting value is assumed to be the instantaneous mixing temperature, Tm. The heat gained by the calorimeter. The investigation begins with an introductory activity to become familiar with the principles of calorimetry and heat of solution calculations.
The results provide a model for the guided-inquiry challenge, which is to design an optimum hand warmer for consumer applications.
Working in groups of four, each student group will be provided six different solids, along with their costs and individual Material Safety Data Sheets MSDS. Determine the heat of solution for each solid and analyze the cost and safety information to propose a design for the best all-around hand warmer.
Pre-Lab Questions 1. When chromium chloride, CrClz, is dissolved in water, the temperature of the water decreases. Is the heat of solution exothermic or endothermic?
Which is stronger—the attractive forces between water molecules and chromium and chloride ions, or the combined ionic bond strength of CrCl2 and intermolecular forces between water molecules? A solution was formed by combining In Question 2 above, the calorimeter was found to have a heat capacity of 8.
If a correction is included to account for the heat absorbed by the calorimeter, what is the heat of solution, qwm? The solid in Question 2 was aluminum sulfate, A12 SO4 3.
Calculate the molar heat of solution, Ame, for aluminum sulfate. First determine the heat released per gram of solid.
Reproduction pannssion is granted only to science teachers who have purchased Designing a Hand Wanner. Calcium chloride and ammonium chloride are slightly toxic.
Magnesium sulfate is a body tissue irritant.
Sodium acetate is a body tissue and respiratory tract irritant. Avoid contact of all chemicals with eyes and skin. Wear chemical splash goggles, chemical-resistant gloves, and a chemical-resistant apron.
Wash hands thoroughly with soap and water before leaving the laboratory. Please follow all laboratory safety guidelines. Introductory Activity PartA.Nov 17, · PURPOSE: to determine which of the 3 ionic compounds (NaCl, LiCl, or NaCH3COO) is most suitable for use as a hand warmer PROCEDURE: DAY 1 (Part 2 only): 1) Measure out 2 separate samples of mL of distilled water 2) Heat one to about 50˚C, and place other one in calorimeter (at around 20˚C) 3) Add heater water to calorimeter, cover top, wait 15 seconds, .
their costs and individual Material Safety Data Sheets (MSDS). Determine the heat of solution for each solid and analyze the cost and safety information to propose a design for the best all-around hand warmer.
Pre-Lab Questions 1. When chromium chloride, CrCl 2, is dissolved in water, the temperature of the water decreases. a. Is the heat of solution exothermic or endothermic? Salt is made up of sodium and chloride and is ionically bonded. Sugar, on the other hand, is composed of carbon, oxygen, and hydrogen and has covalent bonds.
D Introduction A salt molecule is made up of one sodium atom and one chlorine atom. For salt to be made, the sodium atom must lose an electron and become a sodium ion.
The purpose of second part in the lab was to determine which set of products would be best to use to make a hand warmer. The objective of the lab was to see which ionic solids in set A or B would produce the greatest heat for a hand warmer.
Determine the heat of solution for each solid and analyze the cost and safety information to propose a design for the best all-around hand warmer. Pre-Lab Questions 1. When chromium chloride, CrClz, is dissolved in water, the temperature of the water benjaminpohle.com: Beibei warmerblended inquiry lab for ap, designing a hand warmer lab course hero, active teaching strategies and learning activities, the warm teacher appreciation quotes on thank you teacher, ap chemistry designing an effective hand warmer, designing a hand warmer purpose to determine the best, best 25 hand warmers ideas on pinterest diy hand warmer, buy.