What is the molarity of the HCl solution?

Question

A 24.6 mL sample of HCl reacts with 33.0 mL of 0.222 M NaOH solution. What is the
molarity of the HCl solution? (note: write the balance chemical equation)

Answer 1

The balanced reaction is:

HCl + NaOH --> H2O + NaCl

 

Some things to note: 

Molarity = moles solute/liter of solution (M=n/V)

In this reaction, 1 mol of NaOH reacts with 1 mol of HCl

 

From the information given, we can find how many moles of NaOH reacted. Becuase NaOH and HCl react in a 1:1 ratio, finding the number of moles of NaOH that reacted also tells us how many moles of HCl reacted. 

Once we know how many moles of HCl reacted, we can find Molarity of the HCl solution since we have it's volume. 

 

So:

M = n/V ---> n = M*V

M NaOH = 0.222

n NaOH = ?

V NaOH = 33mL = 0.033 L

 

n NaOH = 0.222*0.0333L = 0.007326 mol = n HCl

 

n HCl = 0.007326

V HCl = 24.6mL = 0.0246 L

M HCl = ?

 

M HCl = 0.007326 mol/ 0.0246 L = 0.298 M HCl