Help! I need to do this review question and don't know where to start !
The label on a bottle of vinegar claims that the bottle conatins 5% (m/v) of acetic acid. In order to test this claim, a 50ml sample is titrated with sodium hydroxide. 166ml of 0.25 mol/l is added when the indictor turns pink. What is the concentration of acetic acid in the vinegar?
First write and balance the equation.
CH3COOH + NaOH ==> CH3COONa + H2O
moles NaOH = M x L = 0.166*0.25 = ??moles
Look at the equation and you know moles NaoH = moles CH3COOH.
g CH3COOH = moles CH3COOH x molar mass CH3COOH.
That # grams is in 50 mL; you want the # grams in 100 mL. That will be the %CH3COOH m/v
Okay! Thank you for the help !
I got 6.80932 % ... is that correct?
I don't think so. Post your work and I'll find your error.
Nero-Crush on You
To determine the concentration of acetic acid in the vinegar, you can use the concept of titration. Here is how you can solve this question step by step:
Step 1: Understand the information given
In the problem, it is mentioned that a 50 mL sample of vinegar is titrated with sodium hydroxide (NaOH). It is also given that 166 mL of 0.25 mol/L NaOH is added until the indicator turns pink.
Step 2: Set up the balanced chemical equation
The reaction between acetic acid (CH3COOH) and sodium hydroxide (NaOH) can be represented by the following balanced chemical equation:
CH3COOH + NaOH -> CH3COONa + H2O
Step 3: Determine the moles of sodium hydroxide used
Using the concentration and volume of NaOH added, you can calculate the moles of NaOH used. The concentration is given as 0.25 mol/L, and the volume is 166 mL (remember to convert to liters by dividing by 1000):
Moles of NaOH = concentration * volume
Moles of NaOH = 0.25 mol/L * 166 mL / 1000 mL/L
Step 4: Convert moles of NaOH to moles of acetic acid
From the balanced equation, you can see that the mole ratio between NaOH and acetic acid is 1:1. This means that the moles of NaOH used are equal to the moles of acetic acid in the sample.
Step 5: Determine the concentration of acetic acid in the vinegar
The concentration of acetic acid can be calculated using the formula:
Concentration (m/v) = (moles of acetic acid / volume of vinegar sample) * 100
Substitute the values into the formula:
Concentration (m/v) = (moles of NaOH / volume of vinegar sample) * 100
Step 6: Calculate the final concentration
Substitute the moles of NaOH and the volume of the vinegar sample into the formula calculated in the previous step to find the concentration of acetic acid in the vinegar.
By following these steps, you should be able to determine the concentration of acetic acid in the vinegar.