Recent content by Little Bear

Homework Statement How do California H.S. students compare to students nationwide in their college readiness, as measured by their SAT scores? The national average scores for the class of 2003 were 507 on the verbal portion and 519 on the math portion. Suppose that 100 California students...

1. Homework Statement (I forgot to write out the problem statement in previous post) How do California H.S. students compare to students nationwide in their college readiness, as measured by their SAT scores? The national average scores for the class of 2003 were 507 on the verbal portion...

I forgot the slash between 98 and sqrt(100)!. It was my typo. Sorry. Still I get the same answer of z = -0.816 instead of -3.33. I am only concerned about getting the z value because how can I answer yes or no, without knowing it. Also, it is asking for us to test using alpha = .05. Z-test...

Homework Statement Dissolved O2 Content. Industrial wastes and sewage dumped into our rivers and streams absorb oxygen and thereby reduce the amount of dissolved oxygen available for fish and other forms of aquatic life. One state agency requires a minimum of 5 parts per million (ppm) of...

Homework Statement a. Do the data provide sufficient evidence to indicate that the average verbal score for all California students in the class of 2003 is different from the national average? Test using alpha = .05. b. Do the data provide sufficient evidence to indicate that the average math...

Preparing a sample buffers using weak acid/strong base? Preparing a sample buffers using weak acid/strong base? You will be provided with 0,5 M acetic acid as a source of acetic acid and 0.2 M NaOH with which to prepare the same 0.1 M buffers. a) Calculate the number of moles of acetic acid...

Preparing a sample buffers using weak acid/strong base? Preparing a sample buffers using weak acid/strong base? You will be provided with 0,5 M acetic acid as a source of acetic acid and 0.2 M NaOH with which to prepare the same 0.1 M buffers. a) Calculate the number of moles of acetic acid...

Thanks so much. I've been ill and still am so I can't get my head to think straight. I really appreciate your help Hunt_.

How can you prepare a buffer with HH with an acid with a weak acid? Need to prepare buffer with Henderson-Hasselbalch Equation? Use the H-H equation to calculate the volume of 0.1 M acetic acid and 0.1 M Na acetate required to prepare 50 ml 0.1 M acetate buffer pH 4.0. HH: pH = pk +...

Thank you Thank you so much. :smile:

Getting the Theoretical Vol required to raise pH of an acid sol to its pK value I think I erred in my reasoning. I should be using the c1*v1 = c2*v2 formula There is 50 mL of 0.1 M Tris HCl acid So Let v1 = 50 mL = 0.050 L c1 = 0.01 M Tris HCl Then c2 = 0.2 M NaOH v2 = ? mL c1*v1 =...

pH = pKa + log [base/acid] (H-H equation) Using the H-H equation, calculate the theoretical volume of 0.2 M NaOH required to raise the pH of 0.1 M Tris HCl (pk = 8.1) to raise the pH to its pK value. The way I see it is to get pH = pK so using H-H equation: 8.1 = 8.1 + log[0.2 M NaOH/0.1...