hey i was wondering, i have this question:

Sketch a pH curve for the titration of 40.00mL of 0.100 M hydrazine, H2NNH2, having a K of 3.0x10^-6 by 0.100 M HCIO4
i know you can t sketch but could you tell me what to do with the "K of 3.0x10^-6" i could sketch the curve without the "K" but i don t know if its an important part for the sketch

Here is a site that sketches MANY titration curves. Look at the left column, third one down from the top. That is a weak acid vs strong base titration curve.

If you know how the strong acid vs strong base looks, for a weak acid/strong base, just start the curve about 3 instead of 1 and slope it a little more.
http://www.google.com/search?q=titration+curves&hl=en&client=firefox-a&hs=2ud&rls=org.mozilla:en-US:official&prmd=imvnsfda&tbm=isch&tbo=u&source=univ&sa=X&ei=vAEGUNjfMOT02wWdtOC7BQ&ved=0CFwQsAQ&biw=683&bih=403

To sketch a pH curve for the titration of hydrazine (H2NNH2) with HCIO4, the value of the equilibrium constant (K) is indeed important. In this case, the given K value of 3.0x10^-6 indicates the acidity of the reaction.

Here's a step-by-step guide on how to sketch the pH curve:

1. First, determine the stoichiometry of the reaction between hydrazine and HCIO4. The balanced equation for the reaction is:

H2NNH2 + HCIO4 -> CIO4- + H3NNH3+

In this equation, one mole of hydrazine reacts with one mole of HCIO4 to produce one mole of CIO4- and one mole of the protonated form of hydrazine, H3NNH3+.

2. Calculate the initial moles of hydrazine in the 40.00 mL solution using the given concentration. Remember that:

Moles = concentration x volume
Moles of hydrazine = 0.100 M x 0.04000 L

3. Since the stoichiometry shows that one mole of hydrazine reacts with one mole of HCIO4, the initial moles of HCIO4 will be equal to the initial moles of hydrazine.

4. Start titrating the hydrazine solution with the HCIO4 solution. As the titration proceeds, the initial amounts of hydrazine and HCIO4 will react until either limit is reached. At this point, the pH of the solution changes due to the formation of the protonated form of hydrazine (H3NNH3+).

5. The pH curve will have three distinct regions:

a. Before the equivalence point: Initially, only hydrazine is present, and the pH will be higher (basic) due to the hydrolysis of hydrazine. As HCIO4 is added, the pH will remain relatively stable.

b. At the equivalence point: The moles of HCIO4 added will be equal to the initial moles of hydrazine. The pH will be almost neutral, around 7, as the H3NNH3+ concentration increases.

c. After the equivalence point: Excess HCIO4 will start to dominate the solution, making it acidic. The pH will decrease rapidly as more HCIO4 is added.

6. To determine the exact pH values at different points in the curve, you will need to carry out additional calculations based on the pKa value of hydrazine and the concentrations of the different species present in the solution.

Remember to consider the effects of dilution and volume changes during the titration. This process should give you an idea of how to sketch the pH curve for the given titration.