Procedure #1
PLEASE NOTE: Titration requires several steps in order to obtain exact results. The procedures described in this lab assume that you have already done the TITRATION TUTORIAL and are familiar with the technique.
1. Take a clean Erlenmeyer flask from the Glassware shelf and place it on the workbench.
2. Add 25 mL HCl (of unknown concentration) to the flask.
3. Add 2 drops of phenolphthalein to the flask.
4.Take a burrete from the Glassware shelf and place it on the workbench.
5. Fill the burette with 50 mL of 1M NaOH solution. Record this initial volume.
6. Drag the flask to the lower half of the burette so that the two will be connected.
7. Open the Data window and click on the flask. Click the Pushpin icon in the blue bar of the Data window to lock its display to the contents of the flask.
8. Open the Properties window and click on the burette. Enter "1" in the amount to add, and click the flow button to drip 1 mL of NaOH into the flask.
9. Continue to add NaOH in 1 mL increments.
10. The pink color will appear in flask all at once when the endpoint is either reached or crossed. Record the burette volume at which this occurs.
11. Detach the flask from the burette and drag it to the recycling chute.
Question #1 :
1. Write a balanced equation for the neutralization equation.
2. Use the two volumes obtained from your two trials of Procedure #2 to calculate the average volume of NaOH used to neutralize the HCl. Why is it not recommended to use the volume measured in Procedure #1 as part of this calculation?
3. Why was it necessary to repeat Procedure #2 and average the two volumes?
4. Use the average value calculated above and the molarity of the NaOH to calculate the molarity of the HCl.
You have several posts here with no attempt at answering any of them. Tell us what it is you don't understand about this question.
Im not sure what the balanced equation is
and i dot get how to do the calculations
1. Write a balanced equation for the neutralization equation.
#1
NaOH + HCl --> NaCl + H2O
#4. mLNaOH x M NaOH = mL HCl x M HCl
Solve for the one unknown in the equation.
1. To write a balanced equation for the neutralization reaction between HCl and NaOH, we need to consider the stoichiometry of the reaction. In this case, the balanced equation is:
HCl + NaOH -> NaCl + H2O
This equation shows that one mole of HCl reacts with one mole of NaOH to produce one mole of NaCl and one mole of water.
2. The volume measured in Procedure #1 is not recommended to be used in the calculation because it was the initial volume of NaOH solution. The neutralization reaction occurs when the endpoint is reached, which is indicated by the appearance of a pink color due to phenolphthalein. The volume recorded at the endpoint (Procedure #2) is the actual volume of NaOH required to neutralize the HCl. Therefore, only the volumes obtained from Procedure #2 should be used in the calculation to determine the average volume of NaOH used.
3. It was necessary to repeat Procedure #2 and average the two volumes in order to obtain a more reliable and accurate result. By repeating the procedure and taking multiple trials, we can minimize random errors and obtain a more precise value for the volume of NaOH used. Averaging the two volumes helps to reduce any systematic errors and increases the confidence in the final calculated value.
4. To calculate the molarity of HCl, we can use the balanced equation and the molarity of NaOH.
First, calculate the number of moles of NaOH used by multiplying the average volume of NaOH (obtained from Procedure #2) by its molarity (given in the problem).
moles of NaOH = average volume of NaOH (in liters) * molarity of NaOH (in moles/liter)
Next, since the stoichiometry of the reaction is 1:1 between HCl and NaOH, the number of moles of HCl used is equal to the number of moles of NaOH used.
Finally, to calculate the molarity of HCl, divide the moles of HCl by the volume of HCl used in liters.
Molarity of HCl = moles of HCl / volume of HCl (in liters)