Question
5. The following equations represent chemical reactions. Chemical Reactions Which equation shows . that the total mass during a chemical reaction stays the same? A. 1 B. 2 C. 3 D. 4
Answer
4.5
(277 Votes)
Vance
Professional · Tutor for 6 years
Answer
The correct answer is B.
Explanation
## Step1This problem involves the law of conservation of mass in chemical reactions. According to this law, the total mass of the reactants (the substances that start a chemical reaction) is equal to the total mass of the products (the substances that are produced by the reaction). Therefore, in a balanced chemical equation, the number of atoms of each element is the same on both sides of the equation.## Step2Let's examine each of the given equations:A. The equation is not balanced because there are 2 atoms of sodium (Na) and 2 molecules of water (H2O) on the left side, but only 1 molecule of sodium hydroxide (NaOH) and 1 molecule of hydrogen (H2) on the right side.B. The equation is balanced because there are 2 atoms of hydrogen (H2) and 1 molecule of oxygen (O2) on the left side, and 2 molecules of water (H2O) on the right side.C. The equation is not balanced because there are 2 ions of magnesium (Mg2+) and 1 molecule of chlorine (Cl2) on the left side, but only 1 molecule of magnesium chloride (MgCl2) on the right side.D. The equation is not balanced because there are 1 molecule of sodium hydroxide (NaOH) and 1 molecule of magnesium chloride (MgCl2) on the left side, but only 1 molecule of sodium chloride (NaCl) and 1 molecule of magnesium hydroxide (MgOH) on the right side.