For the following questions, consider the definition of ?Hrxn and how it differs

Question

For the following questions, consider the definition of ?Hrxn and how it differs from q.

8. If 0.50 M HCl had been used in this experiment instead of 1.0 M HCl, predict (in generalterms) the value for the amount of heat (q) lost by the chemical reaction. Explain yourreasoning.

9.  If 0.50 M HCl had been used in this experiment instead of 1.0 M HCl, predict (in generalterms) the value for the ?Hrxn that would have been observed. Explain you reasoning.

Heat of Reaction Purpose The objective of this laboratory exercise will be to determine the heat of reaction for two acid-base reactions using a coffee-cup calorimeter and a temperature sensor. Theory A coffee-cup calorimeter is constructed of two polystyrene coffee cups inside one another nested inside a 400 mL beaker with a foam lid. The lid supports a plastic stirrer and a rubber stopper to hold the thermometer. This simple calorimeter utilizes polystyrene and trapped air to minimize any heat loss from the calorimeter to the environment. In this lab, a temperature sensor will be used to monitor the temperatures during the experiment via the computer. Although relatively efficient for the cost, the calorimeter will absorb a small amount of heat. This amount of heat is unique to each cup calorimeter, but you will use Ccal 26.14 J/K, which is an average value. In this experiment, the heat lost during the reaction of two different acids with sodium hydroxide will be determined. Part one is with hydrochloric acid and part two is with acetic acid. [These are acid base reactions. Review the textbook chapter 4, section 44 BEFORE coming to the lab.] For both parts, you will mix aqueous solutions of HCl and NaOH in the calorimeter and measure the corresponding change in temperature. The heat (q) that is lost during this chemical reaction by the chemicals is gained by the total volume of water in which the chemicals were dissolved and the calorimeter: q released by the reaction-qgained by both the solution (water) and the calorimeter. Note that q released will be a negative value, while q gained will be a positive value. 0 Qrxn qwater + Qcalorimeter Substituting in the equation for heat transfer, the heat lost by the chemical reaction can be calculated: -qreaction _ + (mC water + (ccaT)calorimeter NOTES: I. T in K is the SAME as AT in °C 2. There is no m value for the calorimeter term, since the calorimeter mass is constant. 3. Every one of the calorimeters has a slightly different Ccal, so you will use a representative value of 26.14 J/K for this calculation. Since the volume of water is measured rather than the mass, a density for water of 1.00 g/ml will be assumed to obtain mass measurements for the solutions, which are essentially water. The

Explanation / Answer

QUESTION 8

The heat lost by the chemical reaction would be less as a lower concentration corresponds to a lesser no. of moles. This generates lesser heat.

Related Questions

Navigate

• Browse (All)
• Browse F
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.