# Search results

1. ### Determining appropriate range from test data

Hello all. I am performing chemistry experiments and recording the times of various observed results. What I am doing currently is performing the test several times in order to determine what result is "normal." My goal is to determine a range as a standard by which all future tests will...
2. ### Method to remove salt from water (Not distillation or RO)

IX Resin is a cool idea. I don't suppose it's possible to do a "homemade" resin, so in that case from where would be a good place to purchase some that can exchange typical Na and Cl ions? (hopefully not to expensive!) Thanks.
3. ### Method to remove salt from water (Not distillation or RO)

Hello all. I'm tutoring a high school student and am having trouble with a seemingly simple science project that was assigned: How to remove table salt from water. Having graduated as a Chemical Engineer, I said distillation! But the problem statement says you can't be that boring. Then I said...
4. ### Multiple Linear Regression (2 factors, 1 output)

http://imgur.com/mciGw" [Broken]
5. ### Multiple Linear Regression (2 factors, 1 output)

Hello all; I'm doing work for my job, and I've forgotten my statistics =(. I first want to know if what I'm trying to do is possible. I want to create a linear regression of the form Y = a * x1 + b * x2 + c. http://imgur.com/Q4vGP" [Broken] As you can see, there is space that is...
6. ### Need help setting up integral. (Doesn't have to be solved)

What have you tried so far? Please post your attempt and any rough work that pertains to this problem.
7. ### Integration of cos

bad.. BAD Dorumon!! =P sqrt(a + b) =/= a + sqrt(b) You should have some trigonometric substitutions in your notes/textbook that involve cosine. Take a look at them, and see if they make the integrand a little nicer.
8. ### Lin Alg Question: Cross-Product Proof

I'm not sure why you don't agree. I end up with the statement: a X (b - c) = 0 And for that statement to hold, the following must necessarily be true: b - c = 0 since we know that a is nonzero. a is parallel to 2a, so taking the cross-product of two parallel vectors yields the...
9. ### Lin Alg Question: Cross-Product Proof

http://imgur.com/mceBq" [Broken] I'm curious to see if my conclusion is correct. thanks in advance.
10. ### Purging air from system

Yes, that is a catch indeed. The tube system will be a closed loop, and therefore the nitrogen or helium would act as diluents; reducing the performance of the cell. FYI: The pressure build-up is very small, so that is not a concern. There is a gauge which reads from 0 to 5 psig, and the...
11. ### Purging air from system

Here is the situation: We are building a small model car (roughly 8 in wide by 18 in long) whereby hydrogen is produced in a chemical reaction, travels through some tubing to our fuel cells, which in turn powers the motor. The issue lies in the start-up procedure; it is required to purge...
12. ### Fairly basic integral failing to become solved. O:-)

when you see a square root in your integrand, you will likely want to attempt trig substitution if there is no other obvious route. There are 3 different trig substitutions possible based on the form under the root: x = z * [email protected] x = z * [email protected] x = z * [email protected] you should know which one to use based...
13. ### Fuel Cell Voltage Calculation

thanks for your replies. I did some research on this topic myself and found out where some of my confusion lies. on the site http://www.fuelcellknowledge.org/research_and_analysis/cell_performance/index.html", it does clearly say in the Gibbs and Nernst Potential document that the Nernst...
14. ### Fuel Cell Voltage Calculation

Hello, I'm doing work in Fuel Cells and am having difficulty with a simple issue; the Nernst Voltage (E) is greater than the Standard Potential (EO) The only electrochemical reaction considered is H2 + 0.5O2 --> H2O The Nernst equation for this reaction is E = EO - (RT / 2F) ln (PH2O / (PH2...
15. ### Recommended Physical Chemistry Text

Hello, I'm taking Physical Chemistry I in second year, and my prof does not have a required book for the course and everything will be based off his notes (which are very good by the way) However, I would like a deeper understanding of the material, and the prof did recommend two books. What...
16. ### Recommended Physical Chemistry Text

Hello, I'm taking Physical Chemistry I in second year, and my prof does not have a required book for the course and everything will be based off his notes (which are very good by the way) However, I would like a deeper understanding of the material, and the prof did recommend two books. What...
17. ### Capillary Tubes (purchase in Canada)

VWR does offer what I'm looking for, however it comes at a high price http://www.vwrcanlab.com/catalog/product/index.cgi?object_id=0008810&class_id=5005843 [Broken] over \$400 for all types of glass tubing.
18. ### Capillary Tubes (purchase in Canada)

Hey everybody I'm looking to buy a set of these: http://www.sciencelab.com/page/S/PVAR/10615/10-2410 the 5mm OD tubes that become malleable when subjected to heat (for a little project I want to do). Unfortunately, this website does not ship to Canada. Anyone know of any brick & mortar...
19. ### Derivitives of Trig.

For #3, sec^2(x) - tan^2(x) = 1. the rest is easy.
20. ### Schools U.S. versus Canadian Universities

You can't simply say Harvard>UofT always, forever and ever in everything; period. If you have attend both universities, or did some comparison between the layout of their programs, then you could say math is better here, engineering is better there or w/e conclusion you want to draw. That...
21. ### Summation Proof with Binomial Theorem

Prove the following statement: $\sum\limits_{r + s = t} {\left( { - 1} \right)^r \left( \begin{array}{c} n + r - 1 \\ r \\ \end{array} \right)} \left( \begin{array}{c} m \\ s \\ \end{array} \right) = \left( \begin{array}{c} m - n \\ t \\ \end{array} \right)$ Any initial...
22. ### Is this integral correct?

Wayy to complicated $\begin{array}{l} \int {\frac{{e^x }}{{\sqrt {4 - e^{2x} } }}} dx \\ {\rm{let }}u = e^x \\ {\rm{ }}du = e^x dx \\ \int {\frac{{du}}{{\sqrt {4 - u^2 } }}} \\ {\rm{let }}u = 2\sin \theta \\ {\rm{ }}du = 2\cos \theta d\theta \\ \end{array}$ What would you...
23. ### Trig Limit

As a general rule, you can't really compare different operators together. For example, each of the following types of operations: polynomial, trigonometric, logarithmic, exponential - if any two appear in the same equation, you can only solve it numerically. Give me an exact solution for...
24. ### Area of a Triable with three vertices

yes, you would be right in thinking this. look at points A,B,C; maybe try making vectors out of those points? then crossing some of them?
25. ### Area of a Triable with three vertices

1. this isn't calculus 2. you should really explain where you got vectors a and b from. 3. why are you dotting when you should be crossing? 4. do you know the definition of area for a triangle with vertices A,B,C?
26. ### Help me separate this equation

remember: ln(a^b) = b*ln(a) what does that allow you to do?
27. ### Trigonometric derivatives

The video was more than sufficient. If you still are unable to complete the problem, seek help from your teacher, peers, or get a tutor.
28. ### Sine and cos functions

dessert =/= a mathematical constant, Ry
29. ### Addition of sin and cos

Please only post calculus questions in this forum.
30. ### A trig equation

I didn't really look at your work too closely, but this way seems more obvious to me. (tan(x) + sqrt(3))(cos(x) + 2) = 0 This is equation is factored, i.e. in the form you need to solve the problem. Therefore, this equation equals 0 when: 1) tan(x) + sqrt(3) = 0 or 2) cos(x) + 2 = 0...