Baking powder, a mixture of cream of tartar (KHC₄H₄O₆, molar mass 188 g/mol) and baking soda (NaHCO₃, molar mass 84.0 g/mol) , undergoes the following reaction at baking temperatures:
KHC₄H₄O₆ + NaHCO₃ → KNaC₄H₄O₆ + H₂O + CO₂
(The CO₂ makes the cake rise.) A recipe calls for two level teaspoons (a total of 8.0 g) of cream of tartar. How much baking soda must be added for both materials to react completely?

Question

Quizplus · Accepted Answer

The balanced chemical equation tells us that there is a 1:1 stoichiometric ratio between cream of tartar and baking soda. This means that for every mole of cream of tartar, we need exactly one mole of baking soda to react completely. To find out how much baking soda we need, we first need to convert the mass of cream of tartar we have (8.0 g) to moles. Using the molar mass of cream of tartar: 8.0 g KHC₄H₄O₆ × (1 mol / 188 g) = 0.0426 mol KHC₄H₄O₆ Since the stoichiometry is 1:1, we need exactly 0.0426 mol of baking soda to react with the cream of tartar. Using the molar mass of baking soda: 0.0426 mol NaHCO₃ × (84.0 g / 1 mol) = 3.58 g NaHCO₃ Therefore, the answer is (C) 3.6 g.

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Baking Powder, a Mixture of Cream of Tartar (KHC₄H₄O₆, Molar