Stoichiometry of Chemical Reactions in Solution

Solving stoichiometry problems for reactions in solution requires the same approach as before, with the additional step of converting the volume of reactant or product to moles (1) balance the equation, (2) find the number of moles of one substance, (3) relate it to the stoichiometrically equivalent number of moles of another substance, and (4) convert to the desired units. 

Calculating Amounts of Reactants and Products for a Reaction in Solution 

Problem Specialized cells in the stomach release HCI to aid digestion. If they release too much, the excess can be neutralized with an antacid to avoid discomfort. A common antacid contains magnesium hydroxide, Mg(OH)2, which reacts with the acid to form water and magnesium chloride solution. As a government chemist testing commercial antacids, you use 0.10 M HCI to simulate the acid concentration in the stomach. How many liters of stomach acid react with a tablet containing 0.10 g of Mg(OH)2  

Plan We know the mass of Mg(OH)2 (0.10 g) that reacts and the acid concentration (0.10 A4), and we must find the acid volume. After writing the balanced equation, we convert the grams of Mg(OH)2 to moles, use the molar ratio to find the moles of HCI that react with these moles of Mg(OH)2, and then use the molarity of HCI to find the volume that contains this number of moles. The steps appear in the roadmap. 

Check The size of the answer seems reasonable a small volume of dilute acid (0.034 L of 0.10 4/) reacts with a small amount of antacid (0.0017 mol). 

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