When aqueous solutions of Pb(NO,h and Nal are combined a yellow solid results. W
ID: 590649 • Letter: W
Question
When aqueous solutions of Pb(NO,h and Nal are combined a yellow solid results. What is the chemical identity of the yellow solid? Write a balanced chemical equation consistent with this observation. To which general class does this chemical reaction belong? When heated to sufficiently high temperatures solid calcium carbonate (CaCO,) produces solid calcium oxide (CaO) and a gas. What is the chemical identity of the gas? Write a balanced chemical equation consistent with this observation. To which general class does this chemical reaction belong? Dissolution of solid ammonium nitrate (NH&NO;,) in water results in a measurable temperature decrease. Write a balanced chemical equation consistent with this observation. Did this reaction absorb or release heat? To which general class does this chemical reaction belong?Explanation / Answer
1. Pb(NO3)2 + 2 NaI ---> PbI2 + 2 NaNO3
The yellow precipitate is PbI2. The copound is insoluble in wate, so it precipitate out of the reaction.
This reaction belongs to precipitation reactions.
2.
CaCO3 ----------------> CaO + CO2
CaCO3 generates Co2 upon heating. The CO2 gas can be identifies by simple lime wate test. When you bubble carbon dioxide through the diluted solution of calcium hydroxide (slaked lime). , it forms a solid precipitate of calcium carbonate – chalk or limestone. Calcium carbonate is insoluble in water. Thus, if there is CO2 present in the sample, the limewater will turn milky, cloudy white.
It belongs to decomposition reaction
3.
NH4NO3(s) + H2O -----> NH4+(aq) + NO3-(aq) + H+ + OH-
When solid ammonium nitrate comes in contact with water, the polar water molecules will interact with these ions and attract individual ions from the lattice structure, which eventually breaks down. To break the ionic bonds holding the lattice together requires energy, which is absorbed from the surrounding environment, making the solution cold.
Therefore the overall dissolution of ammonium nitrate in water is strongly endothermic. This reaction absorb heat.
This is dissolution type of reaction
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