Question

which statement(s) is/are true for all chemical reactions?
select all that apply
a energy is released when bonds are
formed.
b reactant elements and/or compounds
rearrange to form chemically new
products.
c energy is absorbed when bonds are
broken.
d there is an overall energy release during
all chemical reactions.
check it

Explanation:

• Option A: In chemical reactions, bond - formation is an exothermic process (releases energy). For example, when \(H - H\) bonds are formed in the synthesis of \(H_2\) from \(H\) atoms, energy is released.
• Option B: By definition, a chemical reaction involves the rearrangement of atoms (from reactant elements and/or compounds) to form new substances (products). For instance, in the reaction \(2H_2+O_2 = 2H_2O\), \(H_2\) and \(O_2\) (reactants) are rearranged to form \(H_2O\) (a new product).
• Option C: Bond - breaking is an endothermic process (absorbs energy). Consider the decomposition of water \(2H_2O

ightarrow2H_2 + O_2\), energy is required to break the \(O - H\) bonds in \(H_2O\).

• Option D: Not all chemical reactions are exothermic (overall energy release). Some reactions are endothermic (overall energy absorption). For example, the reaction \(N_2O_4

ightarrow2NO_2\) is endothermic under certain conditions.

Answer:

A. Energy is released when bonds are formed.
B. Reactant elements and/or compounds rearrange to form chemically new products.
C. Energy is absorbed when bonds are broken.