Question

Define the following: limiting reagent, theoretical yield, actual yield, percent yield, enthalpy of reaction, exothermic reaction, endothermic reaction.

Answer 1

Limiting Reagent:- the reactant that is completely consumed in a chemical reaction.

Theoretical yield:- the amount of product that can be made in a chemical reaction based on the amount of limiting reactant.

Actual yield:- the amount of product actually produced by a chemical reaction. the actual yield is usually less than the theoretical yield because at least a small amount of product is lost or does not form during a reaction.

Percent yield:- (actual yield/theoretical yield)*100%.

Enthalpy of a reaction:-it is the amount of thermal energy (or heat) that flows when a reaction occurs at constant pressure. i.e ΔHrxn.

Exothermic reaction : An exothermic reaction is a chemical reaction that releases energy in the form of light or heat.It gives net energy to its surroundings. That is, the energy needed to initiate the reaction is less than the energy that is subsequently released.

reactants → products + energy

Examples of exothermic reactions:

Calcium oxide reacts vigorously with water to produce slaked lime(Calcium hydroxide) used in white washing releasing large amount of heat.

Endothermic reaction : An endothermic reaction is any chemical reaction that absorbs heat from its environment.

reactants + energy → products

Example of endothermic reactions :

Melting of ice: Ice takes heat from the surroundings and turns in to liquid water.

Decomposition of Calcium Carbonate: When limestone is heated at above 900 ºC it decomposes into quick lime and releases carbondioxide.

CaCO3(limestone)-------------> CaO(quick lime) + CO2