Saturday
December 20, 2014

Posts by Hank


Total # Posts: 37

Chemistry
Calculate the S(univ) for the following phase change at 25 deg celcius. The boiling point of heptane is 98.0 Celcius and has a Delta Hvap= +21.6kj/mol. C7H16(l)--> C7H16(g) Delta S= +79.0j/k I know that the equation is Delta Suniv= DSsys + DSsurr PLEASE SHOW ME HOW TO DO IT...
November 23, 2014

Chemistry
Calculate Ecell for reaction for the given info below.. O2(g)+2H2O(l)+4Ag(s)--> 4OH-(aq)+4Ag+(aq Ag+(aq)+ 1e ---> Ag(s) Ered= 0.80v O2(g)+2H2O(l) + 4e ---> 4OH- Ered= 0.40v My confusion is I have done problems similar to this when the Ered was negatives, but two ...
November 23, 2014

Chemistry
I.e Pb(NO3)2+NaI==> PbI2 + NaNO3 I know NO3 will dissolve in water, but if I didnt know if PbI2 was solid or aqueous, how would i figure that out? and Al(3+)+ 6F- ===> [AlF6]^3- (aq)
November 22, 2014

Chemistry
If I was taking an exam and I had no solubility rules given...
November 22, 2014

Chemistry
Equilibria* (complex ions Equilibria)
November 22, 2014

Chemistry
If I had a question about complex ions and the problem had a "mixture" of two compounds, how would I know if one of the products formed is going to be a solid or liquid? I know there are solubility rules, but is there something else you can use to tell?
November 22, 2014

Chemistry
79.0J/K- 21600/298k= +6.5
November 22, 2014

Chemistry
Could I just use the formula DSuniv= DSsys- (DHsys/T)
November 22, 2014

Chemistry
I did as you said and I got the wrong answer. the correct asnwer is supposed to be +6.5, and I am getting -25.8.. Can you just show me how to do it with numbers and steps. I am just more confused now.
November 22, 2014

Chemistry
DrBob222
November 22, 2014

Chemistry
So since Delta S= +79.0J/K is Delta S equal to Delta Ssys? I dont get the relationship of Delta S and sys and surr with delta S (entropy) that would make it become +79.0J/K DSsys and then DSurrs= (-21600J/mol*1mol)/298K= -72.5J/K Suniv= +79.0J/K+-72.5J/K= +6.5
November 22, 2014

Chemistry
Calculate the S(univ) for the following phase change at 25 deg celcius. The boiling point of heptane is 98.0 Celcius and has a Delta Hvap= +21.6kj/mol. C7H16(l)--> C7H16(g) Delta S= +79.0j/k I know that the equation is Delta Suniv= DSsys + DSsurr but for DSurr= -0.216J/371k...
November 22, 2014

Physics
Two charged particle are fixed on the x-axis 11 cm apart. The one on the left has a net charge of +25uc and the one on the right has a net charge of -11uc. What is the magnitude of the electric field 10 cm to the right of the negative charge? How do you solve this problem? ...
July 8, 2014

trig
Find all the solutions from [0, 2pi] cot^2x+csc=x
February 4, 2014

gen physics
An iron (ĉ = 7860 kg/m3) cube measuring 15.4 cm on a side is suspended from a wire. Find the tension in the wire when the block is completely submerged in water (ĉ = 1000 kg/m3).
July 16, 2013

physics
A hydraulic jack has an input piston with a diameter of 1.00 cm, and an output piston with a diameter of 6.00 cm. What weight (in N) can be lifted when a force of 45.8 N is applied to the input piston? Answer is 1650 N but I need someone walk me through the steps please.
July 16, 2013

physics
A tank contains mercury, whose density is 13 600 kg/m3. Find the force exerted by the mercury on a circular plug at the bottom of the tank. The plug has a diameter of 2.54 cm, and is located 37.6 cm below the surface of the mercury. The answer is 25.4 N but I don't know ...
July 16, 2013

Physics
An object (m=2.85 kg) is attached to a disk-shaped pulley. The diameter of the pulley is 0.242 and its weight is 7.272 N. Suppose the object is allowed to fall (a) What is its linear acceleration? (b) What is the angular acceleration of the pulley? (c) How far does the bucket ...
November 27, 2012

math
The scale factor for two similar retangles is 3. If the area of the smaller rectangle is 8m^2, what is the area of the larger rectangle.
October 16, 2012

Math-factoring
factor 5m^2-m-20
July 1, 2012

Math
Find relative extrema of f(x)=x^3-3x^2+4
June 24, 2012

Calculus
Given y=(x^2+2)sqrt(x^3-8x) Find dy/dx
June 24, 2012

Calculus
a)Find dy/x where y=tan(4=x^3)^4? B) Find relative extrema of f(x)=x^3-3x^2+4
June 24, 2012

chemistry
When a 0.5725 g sample of Lysol was titrated with 0.100 M NaOH, an endpoint was obtained at 15.00 mL. What is the percent of HCl in the Lysol sample?
March 22, 2012

Calculus
find the area under the curve y = x^2 + x from the origin to the line x = 3
February 12, 2012

Calculus
Find the derivative of y = 3x+2/x+1
February 10, 2012

calculus
When the area in square units of an expanding circle is increasing twice as fast as its radius in linear units, the radius is (a) 1/4pi (b) 1/4 (c) 1/pi (d) 1 (e) pi
December 26, 2011

Finite Math
Time-share sales provide an opportunity for vacationers to own a resort condo for 1 week (or more) each year forever. The owners may use their week at their own condo or trade the week and vacation elsewhere. Timeshare vacation sales usually require payment in full or ...
May 2, 2011

Graphing
I am plotting V/Vo vs 1/[C] and am asked to extrapolate to infinite concentration to obtain b/Vo, the intercept. How would I go about doing this?
April 2, 2011

chemistry
9.10-5.41=3.69 18.0152/3.69=??
November 28, 2010

chemistry
well i got 3.69% but that doesnt look right
November 28, 2010

chemistry
is the answer 40.5% or 59.5% ?
November 28, 2010

chemistry
a hydrated salt is a solid that includes water molecules within its crystal structure. a student heated a 9.10-gram sample of a hydrated salt to a constant mass of 5.41 grams. what percent by mass of water did the salt contain?
November 28, 2010

Math: Calculus
Does it mean, 0.5*10*70=350 m?
November 10, 2010

Cultural Anthropology
I'm having trouble coming up with a topic that'll expand to 10 pages for my final research project. I have to choose a culture and an issue within that culture. Any ideas will be appreciated! Thanks!
August 1, 2010

Statistics
A gas station manager thinks the average motorist changes their oil less than the recommended two times per year. In a survey 15 car owners were asked how many times they changed their oil in the past year. Here are the results: 1 1 2 1 2 2 0 1 0 1 2 3 1 3 0 The value of the ...
March 27, 2010

chemistry
the ans, is 45.6
June 18, 2009

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