Problem 157 - Chemistry An Atoms First Approach

Question

Which of the following statements about chemical equations is(are) true? a. When balancing a chemical equation, you can never change the coefficient in front of any chemical formula. b. The coefficients in a balanced chemical equation refer to the number of grams of reactants and products. c. In a chemical equation, the reactants are on the right and the products are on the left. d. When balancing a chemical equation, you can never change the subscripts of any chemical formula. e. In chemical reactions, matter is neither created nor destroyed so a chemical equation must have the same number of atoms on both sides of the equation.

Step-by-Step Solution

Answer

Statements d and e are true. Statement d is true because we should never change the subscripts of any chemical formula when balancing a chemical equation. Statement e is true because, according to the law of conservation of mass, a balanced chemical equation must have the same number of atoms for each element on both sides of the equation.

Step 1: Statement a

In a chemical equation, when balancing, we must change the coefficients to ensure that the number of atoms for each element is the same on both sides of the equation. Therefore, statement a is false.

Step 2: Statement b

The coefficients in a balanced chemical equation represent the stoichiometric amounts, i.e., the ratio of the number of molecules (or moles) of reactants and products. They do not refer to the number of grams of reactants and products. Therefore, statement b is false.

Step 3: Statement c

In a chemical equation, the reactants are on the left side, and the products are on the right side. Statement c contradicts this, meaning it is false.

Step 4: Statement d

When balancing a chemical equation, we should never change the subscripts of any chemical formula because doing so would change the identity of the substance. We can only change the coefficients in front of the chemical formulas to balance the equation. Therefore, statement d is true.

Step 5: Statement e

The law of conservation of mass states that matter is neither created nor destroyed in a chemical reaction. Hence, a balanced chemical equation must have the same number of atoms for each element on both sides of the equation. This means statement e is true. Conclusion: Statements d and e are true.