Calorimetry Assume you mix 100.0 mL of 0.200 M CsOH with 50.0 mL of 0.400 M HCl in a coffee-cup

Calorimetry Assume you mix 100.0 mL of 0.200 M CsOH with...

Calorimetry Assume you mix 100.0 $\mathrm{mL}$ of $0.200 \mathrm{M}$ CsOH with $50.0 \mathrm{mL}$ of $0.400 \mathrm{M} \mathrm{HCl}$ in a coffee-cup calorimeter. The following reaction occurs: $$ \mathrm{CsOH}(\mathrm{aq})+\mathrm{HCl}(\mathrm{aq}) \rightarrow \mathrm{CsCl}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{O}(\ell) $$ The temperature of both solutions before mixing was $22.50^{\circ} \mathrm{C},$ and it rises to $24.28^{\circ} \mathrm{C}$ after the acid-base reaction. What is the enthalpy change for the reaction per mole of CsOH? Assume the densities of the solutions are all $1.00 \mathrm{g} / \mathrm{mL}$ and the specific heat capacities of the solutions are $4.2 \mathrm{J} / \mathrm{g} \cdot \mathrm{K}.$

Calorimetry
Assume you mix 100.0 $\mathrm{mL}$ of $0.200 \mathrm{M}$ CsOH with $50.0 \mathrm{mL}$ of $0.400 \mathrm{M} \mathrm{HCl}$ in a coffee-cup calorimeter. The following reaction occurs:
$$
\mathrm{CsOH}(\mathrm{aq})+\mathrm{HCl}(\mathrm{aq}) \rightarrow \mathrm{CsCl}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{O}(\ell)
$$
The temperature of both solutions before mixing was $22.50^{\circ} \mathrm{C},$ and it rises to $24.28^{\circ} \mathrm{C}$ after the acid-base reaction. What is the enthalpy change for the reaction per mole of CsOH? Assume the densities of the solutions are all $1.00 \mathrm{g} / \mathrm{mL}$ and the specific heat capacities of the solutions are $4.2 \mathrm{J} / \mathrm{g} \cdot \mathrm{K}.$

Key Concepts

Heat Transfer Calculation

Heat transfer calculations in calorimetry involve determining the energy change using the formula Q = m × c × ?T, where Q is the heat transferred, m is the mass of the substance, c is the specific heat capacity, and ?T is the change in temperature. This calculation is fundamental for connecting temperature changes observed in an experiment with the heat absorbed or released during the reaction.

Stoichiometry in Chemical Reactions

Stoichiometry involves using the quantitative relationships among reactants and products in a chemical reaction. In the context of thermochemistry, stoichiometry is used to relate the amount of heat exchanged to the number of moles of reactants or products involved, thereby enabling the calculation of enthalpy change per mole of a specific substance.

Enthalpy Change

Enthalpy change, denoted as ?H, represents the total heat absorbed or released by a system at constant pressure during a chemical reaction. It is a central concept in thermochemistry that helps to determine whether a reaction is exothermic or endothermic and provides data useful for assessing reaction spontaneity and feasibility.

Specific Heat Capacity

Specific heat capacity is a material property that indicates the amount of heat energy required to raise the temperature of one gram of a substance by one degree Celsius. In calorimetry, knowing the specific heat capacity of the solution or material being studied is essential for calculating the total heat absorbed or released during a process.

Coffee-Cup Calorimeter

A coffee-cup calorimeter is a simple, constant-pressure device used to measure the heat of reactions, particularly those occurring in aqueous solutions. Its design minimizes heat loss and is ideal for reactions that undergo small temperature changes, making it a popular tool in educational and research laboratory settings.

Calorimetry

Calorimetry is the study of measuring the amount of heat released or absorbed during a chemical or physical process. It is a fundamental technique in thermochemistry that allows scientists to quantify energy changes under controlled conditions, providing insight into reaction energetics and stability of compounds.

Transcript

00:01 Okay, so the first thing that we should do is we should calculate the mass of the solution.

00:06 Right, so the mass of solution is equal to the total volume, which is 100 milliliters, plus 50 milliliters, right, 150.

00:21 And they tell us that the density is one gram per millimeter right here in the question.

00:31 So one gram per millimeter per one millimeter.

00:35 And we get 150 grams and that is the mass of the solution.

00:41 Now the next thing that we can do is we can convert the celsius into kelvin.

00:47 So in order to convert celsius to the kelvin, all we need to do is add 273.

00:52 Right.

00:55 So 22 .25 plus 273 is, oops, the, oh, give me a second.

01:09 Okay, the answer is 295.

01:12 0 .5 kelvin and our 24 .28 plus 273 is 297 .28 kelvin.

01:23 Now what we can do is we can calculate the change in temperature.

01:27 So delta t is equal to t final minus t initial.

01:34 So t final is 297 .28 kelvin minus 295.

01:40 Kelvin.

01:43 And we should get the answer.

01:45 To be equal to 1 .78, 1 .78 kelvin .78.

01:53 Okay, so i'm going to circle these because we're going to need these values eventually.

02:01 Okay.

02:03 Now the next thing that we should do is calculate the q.

02:07 So q is equal to mass times it by the specific heat and then times it by the change in temperature.

02:18 Right? so we have the mass as 150 grams.

02:22 We have c as 4 .2 joules per grams times kelvin and we have the change in temperature as 1 .78 kelvin.

02:37 Right, kelvin crosses out, grams crosses out, and we're left for jewels and q has units of jewels...

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