National League for Nursing (NLN PAX) Practice Exam

Which type of reaction results in the formation of a solid from a liquid solution?

1. Precipitation reaction

2. Neutralization reaction

3. Combustion reaction

4. Redox reaction

The correct answer is: Precipitation reaction

The formation of a solid from a liquid solution is characteristic of a precipitation reaction. In this type of chemical reaction, two solutions containing soluble salts are mixed, and an insoluble product, or precipitate, forms and separates from the solution. This occurs when the product of the reaction has a lower solubility than the reactants, leading to the solid particles forming in the liquid mixture. For example, when solutions of silver nitrate and sodium chloride are combined, silver chloride precipitates out of the solution as it is insoluble in water. The identification of a precipitation reaction is generally indicated by observable changes, such as the appearance of a cloudy or solid mass in the otherwise clear liquid. In contrast, neutralization reactions involve the combination of an acid and a base to form water and a salt, which doesn’t necessarily produce a solid unless specific conditions are met. Combustion reactions typically involve the rapid reaction of a substance with oxygen, resulting in heat and light, and usually produce gaseous products. Redox reactions involve the transfer of electrons between substances, which may not lead to solid formation from liquids in all instances. Therefore, the unique characteristic of precipitating a solid from a liquid solution makes precipitation reactions the correct answer in this context.