Problem: Baking soda (sodium bicarbonate, NaHCO3) reacts with acids in foods to form carbonic acid (H2CO3), which in turn decomposes to water and carbon dioxide gas. In a cake batter, the CO2(g) forms bubbles and causes the cake to rise.The density of baking soda is 2.16 g/cm3. Calculate the concentration of lactic acid in one cup of sour milk (assuming the rule of thumb applies), in units of mol/L. (One cup = 236.6 mL = 48 teaspoons).

FREE Expert Solution

We are asked to calculate the concentration of lactic acid in one cup of sour milk (assuming the rule of thumb applies), in units of mol/L

The rule of thumb in baking is that 1/2 teaspoon of baking soda is neutralized by one cup of sour milk. 

Recall that molarity is the ratio of the moles of solute and the volume of solution (in liters). In other words:


Molarity (M)=moles solute (mol)liters of solution (L)


We’re given the density of baking soda is 2.16 g/cm3. Recall that density is given by:



density=massvolume


The steps we need to do for this solution are:

Step 1: Convert teaspoon (tsp) to cubic centimeters (cm3) and 1 cup to liters (L).

Step 2: Calculate the moles of baking soda (sodium bicarbonate, NaHCO3)

Step 3: Perform a mole-to-mole comparison between lactic acid and sodium carbonate (1 mol lactic acid:1 mol sodium carbonate).

Step 4: Calculate the molarity of the solution.


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Problem Details

Baking soda (sodium bicarbonate, NaHCO3) reacts with acids in foods to form carbonic acid (H2CO3), which in turn decomposes to water and carbon dioxide gas. In a cake batter, the CO2(g) forms bubbles and causes the cake to rise.

The density of baking soda is 2.16 g/cm3. Calculate the concentration of lactic acid in one cup of sour milk (assuming the rule of thumb applies), in units of mol/L. (One cup = 236.6 mL = 48 teaspoons).

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