A student completes a titration by adding 12.0 milliliters of NaOH(aq) of unknown concentration to 16.0 milliliters of 0.15 M HCl(aq). What is the molar concentration of the NaOH(aq)?

Запишем уравнение реакции:

NaOH + HCl = NaCl + H2O
C NaOH*V NaOH = C HCl*V HCl
где: C NaOH и C HCl - мол�рные концентрации гидрок�ида натри� и хлорида водорода �оответ�твенно, моль/л; V NaOH и V HCl - объемы ра�творов гидрок�ида натри� и �ол�ной ки�лоты �оответ�твенно, л.
Мол�рна� концентраци� NaOH равна:
C NaOH*V = C HCl*V HCl/V NaOH = 0,016*0,15/0,012 = 0,2 моль/л

We write the reaction equation:
NaOH + HCl = NaCl + H2O
C NaOH * V NaOH = C HCl * V HCl
where: C NaOH and C HCl - molar concentration of sodium hydroxide and hydrogen chloride, respectively, mol / l; V NaOH and V HCl - volumes of the solutions of sodium hydroxide and hydrochloric acid, respectively, l.
Molar concentration of NaOH is:
C NaOH * V = C HCl * V HCl / V NaOH = 0,016 * 0,15 / 0,012 = 0,2 mol / l

To find the molar concentration of NaOH(aq), we can use the concept of stoichiometry and the balanced chemical equation for the reaction between NaOH and HCl.

The balanced chemical equation for the reaction is:

NaOH(aq) + HCl(aq) → NaCl(aq) + H2O(l)

From the balanced equation, we can see that the mole ratio of NaOH to HCl is 1:1. This means that for every 1 mole of NaOH, there is 1 mole of HCl.

Given that the volume of HCl(aq) used is 16.0 milliliters and the molar concentration of HCl(aq) is 0.15 M, we can determine the number of moles of HCl using the formula:

moles of HCl = volume (in liters) × molarity

Converting the volume of HCl to liters:

16.0 milliliters = 16.0 × 10^(-3) liters = 0.016 liters

Substituting the values into the formula:

moles of HCl = 0.016 liters × 0.15 M = 0.0024 moles

Since the mole ratio between NaOH and HCl is 1:1, the number of moles of NaOH is also 0.0024 moles.

To find the molar concentration of NaOH(aq), we divide the number of moles of NaOH by the volume of NaOH used (12.0 milliliters) converted to liters:

12.0 milliliters = 12.0 × 10^(-3) liters = 0.012 liters

molar concentration of NaOH = moles of NaOH / volume (in liters)

molar concentration of NaOH = 0.0024 moles / 0.012 liters

molar concentration of NaOH = 0.2 M

Therefore, the molar concentration of NaOH(aq) is 0.2 M.

To find the molar concentration of NaOH(aq), we'll use the equation for the balanced chemical reaction between NaOH(aq) and HCl(aq), which is:

NaOH(aq) + HCl(aq) → NaCl(aq) + H2O(l)

From the balanced equation, we can see that the molar ratio between NaOH and HCl is 1:1. This means that every mole of NaOH reacts with exactly one mole of HCl.

Now let's calculate the number of moles of HCl(aq) used in the reaction:

Moles of HCl = volume (in liters) × molarity of HCl
= 0.016 L × 0.15 mol/L
= 0.0024 mol

Since the molar ratio is 1:1, the number of moles of NaOH used in the reaction is also 0.0024 mol.

Now calculate the molar concentration of NaOH(aq):

Molar concentration of NaOH = moles of NaOH / volume of NaOH (in liters)
= 0.0024 mol / 0.012 L
= 0.2 mol/L

Therefore, the molar concentration of NaOH(aq) is 0.2 M.