Skip to main content
Ch.4 - Chemical Quantities & Aqueous Reactions
Chapter 4, Problem 103

People sometimes use sodium bicarbonate as an antacid to neutralize excess hydrochloric acid in an upset stomach. What mass of hydrochloric acid (in grams) can 2.5 g of sodium bicarbonate neutralize? (Hint: Begin by writing a balanced equation for the reaction between aqueous sodium bicarbonate and aqueous hydrochloric acid.)

Verified step by step guidance
1
Write the balanced chemical equation for the reaction: \( \text{NaHCO}_3 (aq) + \text{HCl} (aq) \rightarrow \text{NaCl} (aq) + \text{H}_2\text{O} (l) + \text{CO}_2 (g) \).
Calculate the molar mass of sodium bicarbonate (NaHCO₃) using the atomic masses: Na (22.99 g/mol), H (1.01 g/mol), C (12.01 g/mol), and O (16.00 g/mol).
Determine the number of moles of sodium bicarbonate in 2.5 g by dividing the mass by its molar mass.
Use the stoichiometry of the balanced equation to find the moles of hydrochloric acid (HCl) that react with the moles of sodium bicarbonate. The mole ratio from the equation is 1:1.
Calculate the mass of hydrochloric acid by multiplying the moles of HCl by its molar mass (36.46 g/mol).

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Balanced Chemical Equation

A balanced chemical equation represents a chemical reaction with equal numbers of each type of atom on both sides of the equation. For the reaction between sodium bicarbonate (NaHCO3) and hydrochloric acid (HCl), the balanced equation is: NaHCO3 + HCl → NaCl + H2O + CO2. This equation is essential for determining the stoichiometric relationships between reactants and products.
Recommended video:
Guided course
01:32
Balancing Chemical Equations

Stoichiometry

Stoichiometry is the calculation of reactants and products in chemical reactions based on the balanced equation. It allows us to determine how much of one substance is needed to react with a given amount of another. In this case, stoichiometry will help us find out how many grams of hydrochloric acid can be neutralized by 2.5 g of sodium bicarbonate.
Recommended video:
Guided course
01:16
Stoichiometry Concept

Molar Mass

Molar mass is the mass of one mole of a substance, typically expressed in grams per mole (g/mol). It is crucial for converting between grams and moles in stoichiometric calculations. For sodium bicarbonate and hydrochloric acid, knowing their molar masses allows us to calculate the number of moles present in the given mass, which is necessary for applying stoichiometry to find the mass of hydrochloric acid that can be neutralized.
Recommended video:
Guided course
02:11
Molar Mass Concept