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The aim of this experiment is to measure the change in temperature during chemical reactions and to conclude whether the reaction is exothermic or endothermic.
Here, hydrochloric acid reacts with sodium hydroxide to form sodium chloride and water. The solution becomes hot as some heat energy is also get released in this reaction. When barium hydroxide and ammonium chloride are mixed together, heat energy is supplied from outside, as this is an endothermic reaction. The products formed during this reaction are barium chloride and aluminium hydroxide.
Let us take a look at the identification of exothermic and endothermic reactions in a virtual lab.
Apparatus Required-
- Beakers
- Glass rods
- Thermometer
Chemicals Required-
- Sodium hydroxide (aq)
- Hydrochloric acid (aq)
- Barium hydroxide (s)
- Ammonium chloride (s)
To check whether a reaction is exothermic or endothermic, we have to follow the following procedure:
- Measure the room temperature and record it.
- Measure the temperature of 20 mL hydrochloric acid, 20 mL sodium hydroxide, 5.35 g ammonium chloride, and 15.75 g barium hydroxide present in the beakers and record them.
- First, perform the neutralisation reaction between hydrochloric acid and sodium hydroxide.
- Place the beaker containing HCl on the retort stand and mount the thermometer.
- Pour NaOH into the beaker containing HCl.
- Immediately note the initial temperature.
- Gently stir the solution using a glass rod and note down the final temperature.
- Calculate the temperature change.
- Next, perform an acid-base reaction between barium hydroxide and ammonium chloride.
- Place the beaker containing ammonium chloride on the retort stand and mount the thermometer after cleaning.
- Add Ba(OH)2 and note down the initial temperature of the reactant mixture.
- Stir the mixture well using a glass rod.
- Note the final temperature and calculate the temperature change.
While performing the experiment, kindly follow these precautions:
- Wear protective gear, which includes a lab coat, goggles and gloves, while performing this experiment.
- Handle the concentrated solutions of hydrochloric acid and sodium hydroxide with care.
- Stir the reaction mixture gently to prevent heat loss.
- Use a clean and dry thermometer.
- A thermometer with a wide range must be chosen.
FAQs on Exothermic or Endothermic Reactions
Q1. Identify whether the given statement is true or false.
Heat energy is released during an exothermic reaction.
Answer: The reactions in which energy is released are called exothermic reactions
Q2. Which type of reaction occurs between sulphuric acid and calcium hydroxide?
Answer: Sulphuric acid reacts with calcium hydroxide to form calcium sulphate and water. The solution becomes hot as some heat energy is also get released in this reaction.
H2SO4(aq) + Ca(OH)2(aq) ? CaSO4(s) + 2H2O(l)
Q3. What are endothermic reactions?
Answer: The reactions in which energy is absorbed are called endothermic reactions. The participating species in such reactions absorb thermal energy from the surroundings and hence, the temperature decreases during such reactions.
Q4. Which type of reaction occurs between ammonium chloride and barium hydroxide?
Answer: The reaction between ammonium chloride (NH4Cl) and barium hydroxide (Ba(OH)2.8H2O) is a type of endothermic reaction, since, heat energy is required to carry out the reaction.
Ba(OH)2.8H2O (s) + 2NH4Cl (s) ? BaCl2 (aq) + 10H2O (l) + 2NH3 (aq)
Q5. How can you recognize an exothermic reaction?
Answer: One of the main signs of an exothermic reaction is a noticeable increase in temperature in the reaction environment. Additionally, the reaction might produce light or sound, indicating the release of energy.
JEE Main