A 16.6 mL portion of an HBr solution of unknown strength is diluted to exactly 247 mL. If 102.1 mL of this diluted solution requires 87.8 mL of 0.37 M NaOH to achieve complete neutralization, what was the strength of the original HBr solution?
NaOH + HBr ==> NaBr + H2O
moles NaOH used in the titration = M x L = 0.37 x 0.0878 = 0.03249.
Using the balanced equation above, convert moles NaOH to moles HBr. The coefficients are 1:1; therefore, moles HBr = 0.03249
That = the moles in the 102.1 mL sample. How much was in the 247 mL. That will be
0.03249 x (247/102.1) = ?? moles HBr. That = the number of moles HBr in the 16.6 mL original sample.
Then M = moles/L soln.
just for clarification,it's
?? moles HBr/original sample (which is 16.6ml)
right?
To find the strength of the original HBr solution, we need to determine the concentration or molarity of the HBr solution.
First, let's calculate the number of moles of NaOH used in the neutralization reaction. We can use the formula:
moles = concentration (M) x volume (L)
Given that the volume of the NaOH solution used is 87.8 mL (which is equivalent to 0.0878 L) and the concentration of NaOH is 0.37 M, we can calculate the number of moles:
moles NaOH = 0.37 M x 0.0878 L = 0.0324 moles
According to the balanced equation of the neutralization reaction, 1 mole of HBr reacts with 1 mole of NaOH. Therefore, the number of moles of HBr in the original solution is also 0.0324 moles.
Next, we need to calculate the initial volume of the HBr solution. Since we diluted 16.6 mL of the original solution to a final volume of 247 mL, the initial volume can be found as follows:
initial volume (mL) = diluted volume (mL) / dilution factor
dilution factor = diluted volume (mL) / initial volume (mL)
dilution factor = 247 mL / 16.6 mL = 14.9
Now we can calculate the initial volume of the HBr solution:
initial volume (mL) = 16.6 mL x 14.9 = 246.34 mL
Finally, we can calculate the concentration of the original HBr solution using the formula:
concentration (M) = moles / volume (L)
concentration (M) = 0.0324 moles / 0.24634 L = 0.1316 M
Therefore, the strength of the original HBr solution is 0.1316 M.