Barium hydroxide and ammonium chloride reaction

Two Examples Thermodynamics: Entropy In this module: Two Examples In the introduction to this tutorial you encountered two reactions that were endothermic yet still product-favored. The second reaction was between barium hydroxide and ammonium chloride: Ba(OH) 2• 8H 2O (s) + 2 NH 4Cl (s) BaCl 2• 2H 2O (s) + 2 NH 3 (aq) + 8 H 2O ( l) Three moles of two solids react to form one mole of a solid, eight moles of liquid, and two moles of an aqueous solution. Using Calculate DS univ for the reaction and verify that it is, indeed, positive, making the reaction product-favored. DS univ = DHº = 1 mol • DH fº(BaCl 2• 2H 2O(s)) + 2 mol • DH fº(NH 3(aq)) + 8 mol • DH fº(H 2O(l)) - 1 mol • DH fº(Ba(OH) 2• 8H 2O(s)) - 2 mol • DH fº(NH 4Cl)(s) DHº = 1 mol • -1460.1 kJ/mol + 2 mol • -80.29 kJ/mol + 8 mol • -285.83 kJ/mol - 1 mol • -3342 kJ/mol - 2 mol • -314.4 kJ/mol DHº = 63 kJ DSº = 1 mol • Sº(BaCl 2• 2H 2O(s)) + 2 mol • Sº(NH 3(aq)) + 8 mol • Sº(H 2O(l)) - 1 mol • Sº(Ba(OH) 2• 8H 2O(s)) - 2 mol • Sº(NH 4Cl)(s) DSº = 1 mol • 203 J/mol•K + 2 mol • 111 J/mol•K + 8 mol • 69.91 J/mol•K - 1 mol • 427 J/mol•K - 2 mol • 94.6 J/mol•K DSº = 368 J/K DSº univ = DSº - DHº/T DSº univ = 368 J/K - 63 kJ/(273.15 + 25)K • 1000 J/1 kJ = 157 J/K > 0 When ice melts to liquid water, there is a similar increase in entropy in the system that offsets its increase in enthalpy: H 2O (s) H 2O ( l) Thus, this reaction is also product-favored at 25 ºC. Two Examples

Entropy Debriefing Welcome to the Entropy debriefing Answer the questions below, and click on the Check buttons when you are ready. 1. The barium hydroxide and ammonium chloride reaction has positive values for both DSº and DHº, implying that at some temperatures it is product-favored and at others reactant-favored. Calculate the temperature at which the reaction switches from one to the other. Ba(OH) 2• 8 H 2O (s) + 2 NH 4Cl (s) BaCl 2• 2 H 2O (s) + 2 NH 3 (aq) + 8 H 2O ( l) The correct answer is shown below. This demonstration would be ineffective for teaching a class of chemistry students in outer space! DHº = 63 kJ DSº = 368 J/K (from the previous page) DS univ = 0 = DS syst + DS surr 0 = DS syst - DH syst/T DH/T = DS T = DH/ DS T = 63 kJ/368 J/K • 1000 J/1 kJ = 170 K = -100 ºC 2. Chemical cold packs used in athletic medicine are designed to lower the temperature at the injury site when ammonium nitrate is dissolved in water: NH 4NO 3 (s) NH 4NO 3 (aq) a. What is DHº for the reaction? b. What is DSº for the reaction? c. Is the reaction product-favored at 25 ºC? Yes d. Is it product-favored at -40 ºC? Yes No No The solution is shown below. Dissolving ammonium chloride in water is an endothermic process, which produces the cold needed to reduce swelling in injuries. DHº = 1 mol • DHº f(NH 4NO 3(aq)) - 1 mol • DHº f(NH 4NO 3(s)) DHº = 1 mol • (-339.87 kJ/mol) - 1 mol •(-365.56 kJ/mol) DHº = -339.87 kJ + 365.56 kJ = 25.69 kJ The solution is shown below. Dissolving ammonium...

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Ammonium chloride and sodium hydroxide reaction| NH 4Cl + NaOH = NH 3 + NaCl + H 2O Ammonia, sodium chloride (NaCl) and water are given as products when ammonium chloride is heated with aqueous sodium hydroxide ( NaOH (aq) ). Aqueous ammonium chloride has weak acidic charactristics. Ammonium salt and alkali reaction mechanism Hydrohen atoms of ammonium ion have a small positive charge. Therefore electrons of oxygen atom in the hydroxyl ion attacks that hydrogen atom. Then, one N-H bond is broken and that N-H electrons go towards the nitrogen atom. It forms an ammonia molecule. Also broken hydrogen atom is taken by oxygen atom which forms new O-H bond to form a water (H 2O) molecule. Ammonium chloride and barium hydroxide reaction - NH 4Cl + Ba(OH) 2 When barium hydroxide is added to the ammonium chloride on heating, ammonia is released. As other product barium chloride (BaCl 2) and water are given. What are the safety tips you should aqare of before this experiment? You know, ammonia gas is released in this reaction. First, read MSDS ( Material Safety Data Sheets ) to get what are the effects of ammonia and take the actions to prevent those accidents or injuries. • Wear gloves, masks and goggles to protect your hands and eyes. Questions weak bases when react with ammonium chloride Calcium hydroxide is a weak base. But, when aqueous calcium hydroxide solution is added to ammonium chloride solution, ammonia gas can be released. Heating is required to occur the reaction and e...

The reaction between Ammonium Chloride and Barium hydroxide:- • Barium Hydroxide is a strong base and Ammonium Chloride is an acidic salt. • The reaction between these two compounds will yield another base and another salt. • The Ammonium hydroxide disintegrates into ammonia and water. The ammonia gas evolves with a pungent smell. • Both of these compounds are strong electrolytes and will completely dissociate in water. • This reaction is an endothermic reaction. • Endothermic reactions are chemical reactions in which the reactants absorb heat energy from the surroundings to form products • Here is a reaction to demonstrate the above-explained statements. Ba ( OH ) 2 ( aq ) Barium Hydroxide + 2 NH 4 Cl ( aq ) Ammonium Chloride → BaCl 2 ( aq ) Barium Chloride + 2 NH 3 ( g ) Ammonia + H 2 O ( l ) Water

The reaction may be summarized as follows: #Ba(OH)_2*8H_2O(s) + 2NH_4Cl(s) rarr 2BaCl_2(aq) + 8H_2O(l) + 2NH_3(g)uarr# Now, as you know, this reaction is spontaneous, but as it proceeds it extracts energy from the surroundings; so much so that the reaction vessel becomes visibly icy. Why should the reaction be spontaneous when bonds are being broken? Because the reaction is Gaseous ammonia and aqueous barium chloride supply a thermodynamic driving force to the reaction by their increased entropy, by the greater potential for disorder. I do not have the thermodynamic parameters to hand but #DeltaH# is positive, but #DeltaS# is also strongly positive. In this case, entropy wins, and the reaction proceeds spontaneously. And as always entropy is the fundamental driving force for the spontaneity of chemical change.