Here is my data Flask 1: - Add 25 mL hydrochloric acid (HCl) of unknown concentr

Question

Here is my data

Flask 1:

- Add 25 mL hydrochloric acid (HCl) of unknown concentration Add 2 drops of phenolphthalein ( The volume is 25.1 mL)

*Intial pH = 0.95*

Burret 1:

- Add 50 mL of 1 M sodium hydroxide (NaOH) solution

0 mL dispensed= 0.95 pH

-1mL dispensed = 1.16 pH

-2mL = 1.53 pH

<<2.85 mL = 11.25 pH *Color Change to Pink*>>

-3mL = 11.85 pH

-4mL = 12.61 pH

-5mL = 12.85 pH

-6mL = 13.00 pH

-7mL = 13.10 pH

-8mL = 13.18 pH

-9mL = 13.24 pH

2. Find the equivalence point on the graph. What is the pH and equivalence volume of NaOH at this point? (How did you come up with this answer because I have another experiment I have to do and answer the same question)

3. At the equivalence point, how many moles of 1 M NaOH were added to the flask. To get the number of moles, multiply the molarity by the number of LITERS of NaOH added. And At the equivalence point, the number of moles of NaOH equals the number of moles of HCl in the flask. How many moles of HCl were in the flask?

Could you show the answers however also your work an explain the answers so I can understand:) Because I have another lab very similar to do. Thanks for your help :)

Explanation / Answer

2) Equivalence point is the point at which the moels of acid is equal to moles of base. So in the graph the equivalence point is determined as the point at which the straight line parallel to x-axis is formed.

The point is 2.85 mL (volume of base) and 11.25 as pH.

3)

Moles of NaOH = concentration of NaOH*volume of NaOH

= 1 M*2.85 mL

= 2.85*10^(-3) mol

Number of moels of HCl in the flask = 2.85*10^(-3) mol before the reaction is taking place.

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