11th Grade Chemistry Concepts Quiz

Avogadro's law states that equal volumes of gases at the same temperature and pressure contain the same number of molecules. An example to illustrate this law is the reaction between hydrogen and chlorine gases to form hydrogen chloride gas. According to Avogadro's law, the volumes of hydrogen and chlorine gases consumed are in a simple ratio of 1:1, and the volume of the hydrogen chloride gas produced is also in a 1:1 ratio with the volumes of the reactant gases.

Equilibrium in chemical reactions occurs when the rate of the forward reaction is equal to the rate of the reverse reaction, resulting in no net change in the concentrations of the reactants and products. An example of a reversible reaction that reaches equilibrium is the formation of ammonia from nitrogen and hydrogen. When nitrogen and hydrogen gases are reacted under suitable conditions, they form ammonia. At equilibrium, the rates of the forward and reverse reactions are equal, and the concentrations of nitrogen, hydrogen, and ammonia remain constant.

Exothermic reactions release heat energy to the surroundings, resulting in an increase in temperature. An example of an exothermic reaction is the combustion of methane, which releases heat and light energy. Endothermic reactions absorb heat energy from the surroundings, causing a decrease in temperature. An example of an endothermic reaction is the thermal decomposition of calcium carbonate, which absorbs heat from the surroundings to form calcium oxide and carbon dioxide.