Question

a 30.00 mL sample of NaOH solution with unknown molarity is neutralized by 35.00 mL of a 0.400 M H2SO4 solution. Determine the unknown molarity.The balanced chemical equation is H2SO4 + 2 NaOH → 2 H2O + Na2SO4

Answer 1

The molarity of NaOH is 0.933 M

Step-by-step explanation

Given that;

The volume of NaOH is 30.00mL

The volume of H2SO4 is 35.00mL

The molarity of H2SO4 is 0.400 M

The number of moles of the acid (nA) = 1

The number of moles of the base(nB) = 2

The balanced equation of the reaction is

`\text{ H}_2SO_4\text{ + 2NaOH }\rightarrow\text{ Na}_2SO_4\text{ + 2H}_2O`

Follow the steps below to find the molarity of NaOH

Step 1; Apply the dilution formula

`\text{ }\frac{\text{ C}_{A\text{ }}V_A}{\text{ C}_B\text{ V}_B}\text{ = }\frac{\text{ n}_A}{\text{ n}_B}`
`\begin{gathered} \text{ }\frac{0.4\text{ }*\text{ 35}}{\text{ C}_B*\text{ 30}}\text{ = }\frac{\text{ 1}}{\text{ 2}} \\ \text{ cross multiply} \\ \text{ 0.4 }*\text{ 35 }*\text{ 2 = C}_B*\text{ 30 }*\text{ 1} \\ \text{ 28 = 30C}_B \\ \text{ Divide both sides by 30} \\ \text{ C}_{B\text{ }}\text{ = }\frac{\text{ 28}}{\text{ 30}} \\ \text{ C}_{B\text{ }}\text{ = 0.933 M} \end{gathered}`

Therefore, the molarity of NaOH is 0.933 M