Ba(OH)2(aq) + HCl(aq) BaCl2(aq) + H2O (g)
Consider the unbalanced equation above. What is the concentration of the original hydrochloric acid solution if 18.0 mL of the acid reacts with 45.5 mL of 0.280 M barium hydroxide?
Ba(OH)2(aq) + 2HCl(aq) BaCl2(aq) + 2H2O (g)
molBa(OH)2 = M x L = ?
Now using the coefficients in the balanced equation, convert mols Ba(OH)2 to mols HCl.
Finally, M HCl = mols HCl/L HCl.
To find the concentration of the original hydrochloric acid solution, we can use stoichiometry and the balanced equation.
Step 1: Write and balance the equation:
Ba(OH)2(aq) + 2HCl(aq) → BaCl2(aq) + 2H2O(g)
Step 2: Convert the volume of barium hydroxide solution to moles:
To convert the volume to moles, we need to use the given concentration of barium hydroxide.
Moles of Ba(OH)2 = Volume (in liters) × Concentration (in M)
= (45.5 mL / 1000 mL/L) × 0.280 M
= 0.01274 moles
Step 3: Use the stoichiometry of the balanced equation to find the moles of HCl:
From the balanced equation, we can see that each mole of Ba(OH)2 reacts with 2 moles of HCl. Therefore, the number of moles of HCl can be calculated:
Moles of HCl = 2 × Moles of Ba(OH)2
= 2 × 0.01274 moles
= 0.02548 moles
Step 4: Convert the moles of HCl to concentration:
To find the concentration of HCl in the original solution, we need to convert the moles of HCl to liters and divide by the volume of the original solution.
Concentration (in M) = Moles of HCl / Volume (in liters)
= 0.02548 moles / (18.0 mL / 1000 mL/L)
= 1.4156 M
Therefore, the concentration of the original hydrochloric acid solution is approximately 1.4156 M.