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 $\rightarrow$ KNaC₄H₄O₆+ H₂O + CO₂
(The CO₂makes 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

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

\rightarrow

KNaC₄H₄O₆+ H₂O + CO₂
(The CO₂makes 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?

Quizplus · Accepted Answer

The balanced chemical equation shows that the mole ratio between cream of tartar and baking soda is 1:2.

1 mole of cream of tartar (188 g) reacts with 2 moles of baking soda (2 x 84.0 g) to produce 1 mole of KNaC4H4O6 (cream of tartar + baking soda) plus other products.

Using the given mass of cream of tartar (8.0 g), we can calculate the number of moles:

moles of cream of tartar = mass / molar mass = 8.0 g / 188 g/mol = 0.0426 mol

To react completely, we need twice as many moles of baking soda:

moles of baking soda = 2 x moles of cream of tartar = 2 x 0.0426 mol = 0.0852 mol

Now we can convert the moles of baking soda back to mass:

mass of baking soda = moles x molar mass = 0.0852 mol x 84.0 g/mol = 7.16 g

Therefore, we need to add 7.16 g of baking soda for both materials to react completely. However, the answer choices given do not include this value exactly. The closest answer is C) 3.6 g, which is half of the calculated amount. This is because the recipe calls for two teaspoons of cream of tartar, not one, so we only need half as much baking soda as the stoichiometric amount.

Baking Powder, a Mixture of Cream of Tartar (KHC4H4O6, Molar →\rightarrow→

Baking Powder, a Mixture of Cream of Tartar (KHC₄H₄O₆, Molar $\rightarrow$