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Topic: Pre-Lab Question Need HeLp  (Read 3818 times)

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Offline swtpnay860

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Pre-Lab Question Need HeLp
« on: November 14, 2006, 03:56:36 AM »
1. What is the pH of the micture if 10.00ml of 0.100M NaOH is added to 20.00 ml, 0.10M ascorbic acid solution?

2. What mass of a weak acid with a molar mass of 100.0g/mol is necessary to neutralize 35.0 ml of 0.100M NaOH solution?

3. What is the pH of 0.150g NaC2H3O2 in 100-ml H2O?

Thank YOu

Offline AWK

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Re: Pre-Lab Question Need HeLp
« Reply #1 on: November 14, 2006, 05:37:18 AM »
Show your attempt
AWK

Offline mdlhvn

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Re: Pre-Lab Question Need HeLp
« Reply #2 on: November 16, 2006, 10:47:19 PM »
Hard to answer.
1. You must have Keq of ascorbic acid to determine pH.

2. Hardly have I listened using a weak acid to neutralize a strong base. It is recommended to use strong acid since "neutralize" almost means to make a 7-pH solution. In this case, if you use  350mg weak acid to react sufficiently with NaOH, we scarely have a 7-pH solution but a weak base solution. However, If you have Keq of weak acid, you can calculate the amount of this to add to NaOH solution to make a nearly 7-pH solution

3.Similarily, we need Keq1 and Keq2 of H2CO3.

Offline AWK

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Re: Pre-Lab Question Need HeLp
« Reply #3 on: November 17, 2006, 03:14:02 AM »
1. You have ascorbate buffer based on pK1 (pH in this case eqals to pK1 exactly). Why?

2. Which weak acid you want to use - monobasic, dibasic? - answers will be different.

3. Calculate concentration, then pH of hydrolysis od sodium acetate
AWK

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