What is the HCl concentration if 71.9 mL of 0.350 M NaOH is required to titrate a 30.0 mL sample of the acid?
1. Write and balance the equation.
NaOH + HCl --> NaCl + H2O
2. calculate mols NaOH used. mols = M x L = ?
3. Convert mols NaOH to mols HCl. The coefficients in the balanced equation tell you that mols NaOH = moles HCl
4. Convert to M. M = mols HCl/L HCl
To find the concentration of HCl, we can use the concept of stoichiometry and the balanced equation of the reaction between HCl and NaOH. The balanced equation is:
HCl + NaOH → NaCl + H2O
From the balanced equation, we can see that the mole ratio between HCl and NaOH is 1:1. This means that 1 mole of HCl reacts with 1 mole of NaOH.
First, let's find the number of moles of NaOH using its volume and concentration:
Number of moles of NaOH = Volume of NaOH (L) × Concentration of NaOH (M)
= 71.9 mL × (1 L / 1000 mL) × 0.350 M
= 0.025165 mol
Since the mole ratio is 1:1, the number of moles of HCl is also 0.025165 mol.
Next, let's calculate the concentration of HCl by dividing the number of moles of HCl by the volume of the acid sample:
Concentration of HCl = Number of moles of HCl / Volume of acid sample (L)
= 0.025165 mol / 0.0300 L
= 0.83883 M
Therefore, the HCl concentration is 0.83883 M.
To find the HCl concentration, we can use the concept of stoichiometry and the equation for the reaction between HCl and NaOH:
HCl + NaOH → NaCl + H2O
We know the volume and concentration of NaOH used in the titration, as well as the volume of the acid sample. By determining the moles of NaOH used, we can find the moles of HCl in the acid sample and calculate the concentration.
Here is how you can find the HCl concentration:
Step 1: Convert the volume of NaOH used from milliliters (mL) to liters (L):
71.9 mL = 71.9 / 1000 L = 0.0719 L
Step 2: Use the stoichiometry of the balanced equation to determine the moles of NaOH used:
Moles of NaOH = Volume of NaOH (in L) × Concentration of NaOH
Moles of NaOH = 0.0719 L × 0.350 mol/L = 0.025165 moles
Step 3: Since the reaction is 1:1 between HCl and NaOH, the number of moles of HCl in the acid sample is also 0.025165 moles.
Step 4: Calculate the concentration of HCl:
HCl Concentration = Moles of HCl / Volume of Acid Sample (in L)
HCl Concentration = 0.025165 moles / 0.0300 L = 0.8388 M
Therefore, the HCl concentration is 0.8388 M.