Question

One method used commercially to peel potatoes is to soak them in a solution of NaOH for a short time and then remove them from the NaOH. The peel will have separated from the potato and so it can then easily be sprayed off to yield beautifully peeled potatoes! The NaOH solution however, must be analyzed periodically to make sure its concentration is adequate for the reaction In one such analysis, 45.7 mL of 0.500 M H2SO4 is required to react completely with a 20.0 mL sample of the NaOH solution. The products of the reaction are Na2SO4 and water. What is the concentration of the starting NaOH solution?a. 1.14 M b. 2.28 M c. 0.438 M d. 0.500 M e. 0.571M

Answer 1

b. 2.28 M

Step-by-step explanation:

The reaction of neutralization of NaOH with H2SO4 is:

2NaOH + H2SO4 → Na2SO4 + 2H2O

Where 2 moles of NaOH react per mole of H2SO4

To solve the concentration of NaOH we need to find the moles of H2SO4. Using the chemical equation we can find the moles of NaOH that react and with the volume the molar concentration as follows:

Moles H2SO4:

45.7mL = 0.0457L * (0.500mol/L) = 0.02285 moles H2SO4

Moles NaOH:

0.02285 moles H2SO4 * (2moles NaOH / 1 mol H2SO4) = 0.0457moles NaOH

Molarity NaOH:

0.0457moles NaOH / 0.020L =

2.28M

Right option:

b. 2.28 M