Question

A 9.0 milliliter sample of hcl solution is exactly neutralized by 6.0 milliliters of a 3.0 m naoh solution. what is the concentration of the hcl solution

Answer 1

The correct answer is 2.0 M

Step-by-step explanation:

The equation for the reaction is

HCl + NaOH ⇒ NaCl + H₂O

The formula to be used for the question is

CaVa ÷ CbVb = na ÷ nb

where Ca is the concentration of the acid, HCl (which is unknown)

Cb is the concentration of the base, NaOH (3.0M)

Va is the volume of the acid, HCl (9 ml)

Vb is the volume of the base, NaOH (6 ml)

na is the number of moles of the acid (from the equation above, there is 1 mole of HCl)

nb is the number of moles of the base (from the equation above, there is 1 mole of NaOH)

Hence,

Ca × 9/ 3 × 6 = 1/1

Ca = 3×6×1/9×1

Ca = 2 M

The concentration of the acid is 2.0 M

Answer 2

Volume of base(NaOH)= Vb =6 mL
Concentration of base(NaOH)= Mb =3 M
Volume of acid(HCl)= Va =9 mL
Concentration of acid(HCl)= Ma = ?
Now,

Ma*Va = Mb*Vb
Ma*(9) = (3)*(6)
Ma= 2 M