Wednesday
September 2, 2015

Posts by dave


Total # Posts: 707

World History
farming
November 14, 2010

chemistry
(1)acid+base=.1M potassium dibasic phosphate: 7=12.67 + log(base/acid) (base/acid)=2.138x10^-6 subst. in (1) base+base/2.138x10^-6=.1 solving base=2.13x10^-7M Mass of base=2.13x10^-7 x (174.18g)=3.71x10^-5g Now I can find the mass of the acid as well by substituting for the ...
November 14, 2010

chemistry
I should have given more info. I figured that I would use the H-H equation and the total conc., but what I don't get is why do I need two pka's. I can get to the mass easily, but it seems that I could use either pka=7.21 or 12.67 with the base +acid =.1M.
November 14, 2010

chemistry
Calculate the mass of salts needed for constructing a buffer using potassium monobasic phosphate and potassium dibasic phosphate with the total concentration of 100 mM. The solution is to be prepared in DI water and the pKa value for potassium monobasic phosphate is 7.21 and ...
November 14, 2010

geometry
what are the possible coordinate of the midpoint of the given segment
November 8, 2010

algebra
factors
November 7, 2010

Algerbra
10,000(1-n/20)=6500 please show work
November 7, 2010

english
8. In Frost’s poem “Mending Wall,” the lines “I see him there, / Bringing a stone grasped firmly by the top / In each hand, like an old-stone savage armed” uses which poetic device?
November 7, 2010

math
log8 4(square root sign) 1/2
November 7, 2010

Math
you werent supposed to include the 1-
November 6, 2010

Math
Write the following logarithmic equation in exponential form? 1- log0.001 = -3
November 6, 2010

math
thank you
November 6, 2010

math
a baseball team buys 15 bats for $405. aluminum bats cost $25 and wooden bats cost $30. how many of each type did they buy? Please show work
November 6, 2010

6th grade
Your stupid...
November 3, 2010

Chem.
Acetic acid (CH3COOH) reacts with isopentyl alcohol (C5H12O) to form isopentyl acetate (C7H14O2), a fragrant substance with the odor of bananas. CH3COOH + C5H12O -> C7H14O2 + H2O If the yield for the reaction is 45%, how many grams of the product are formed when 3.58 g of ...
October 31, 2010

Chem
Acetic acid (CH3COOH) reacts with isopentyl alcohol (C5H12O) to form isopentyl acetate (C7H14O2), a fragrant substance with the odor of bananas. CH3COOH + C5H12O -> C7H14O2 + H2O If the yield for the reaction is 45%, how many grams of the product are formed when 3.58 g of ...
October 31, 2010

Chemistry
A 2.50 gram sample of bronze was dissolved in sulfuric acid. The copper in the sample reacted with sulfuric acid to form copper sulfate. Cu (s) +2 H2SO4 (aq) -> CuSO4 (aq) +2 H2O (l) The copper sulfate formed in this reaction was mixed with I to form copper iodide: CuSO4 (...
October 31, 2010

math
A tugboat can go 10 miles upstream in the same time as it can go 15 miles downstream. If the tugboat goes 12 miles per hour in still water, what is the speed of the current?
October 27, 2010

algebra
While shopping, Jill spent six times as much as Nan. If they spent a total of $112, how much did each person spend?
October 24, 2010

physics
actually the other guy has it right except that he has sin instead of cosine
October 22, 2010

physics
Thank you. I figure out the answer for this one. I do have another one.
October 21, 2010

physics
A large boulder is ejected vertically upward from a volcano with an initial speed of 41.0 . Air resistance may be ignored.
October 21, 2010

physics
Hi: I need help with the following physics problem. Can you explain it to me? Thank you, The fastest measured pitched baseball left the pitcher's hand at a speed of 50.0 . If the pitcher was in contact with the ball over a distance of 1.50 and produced constant ...
October 21, 2010

physics
Hi: I need help with the following physics problem. Can you explain it to me? Thank you, The fastest measured pitched baseball left the pitcher's hand at a speed of 50.0 . If the pitcher was in contact with the ball over a distance of 1.50 and produced constant ...
October 21, 2010

Math
Reduce each rational expression x^3-4xy^2/3x^3-2x^2y-8xy^2
October 21, 2010

5th grade math
A marathon race has 522 runners divided into 6 groups. What is a reasonable number of runners in each group? A 112, because 522/6 is about 550/5=110 B 98, because 522/6 is about 500/5=100 C 87, because 522/6is about 540/6=90 D 82, because 522/6 is about 480/6=80
October 21, 2010

algebra
find function value f(x)=x
October 20, 2010

CHEM
the pressure and temp being constant, you would add 8.00g of helium to the 8.00g to double its volume. If pressure or temp were varied this would not be true.
October 19, 2010

vector proofs math 536
*******Prove that AM/BM = MC/MD
October 19, 2010

vector proofs math 536
if the diagonals of quadrilateral ABCD intersect at their midpoints, then the quadrilateral is a parallelogram. Prove that AM MC --- = --- MB MD Ive tried figuring out this question for a while now and I cant figure it out.
October 19, 2010

physics
really stuck, a 90 kg skier has 140 KJ of total mechanical energy when he is at a height of 120m above the bottom of the hill. calculate the skiers kinetic energy. calculate his speed?
October 16, 2010

Finance(trying to dichper)
How would you read these two formulas? The 1/4 and 1/6 are throwing me off. These are example problems from what I need to do. Variance=1/4[(0.03 – 0.1)2 + (–0.14 – 0.1)2 + (0.27 – 0.1)2 + (0.22 – 0.1)2 + (0.12 – 0.1)2] Geometric average return...
October 13, 2010

General Chemistry
A student dissolved 4.00 g of Co(NO3)2 in enough water to make 100. mL of stock solution. He took 4.00 mL of the stock solution and then diluted it with water to give 275. mL of a final solution. How many grams of NO3- ion are there in the final solution? 0.0197 g 0.0394 g 0....
October 12, 2010

Chemistry
Why do Oxygenated fuels contain less energy than hydrocarbons?
October 12, 2010

chem
Why do oxygenated fuels contain less energy than hydrocarbons?
October 11, 2010

Science
If the acceleration gravity is 1.6m/2 on the moon and you weigh 539 N on earth, how much do weigh on the moon?
September 29, 2010

science
D.
September 29, 2010

calculus
a right circular cylinder has a volume 600cubic cm. if it costs $2 for the material needed to make the top and bottom and $3 for the material needed to make the sides, what is the radius and height of the cylinder that would cost the least?
September 20, 2010

chemistry
For which of these elements would the electron affinity process shown be least favorable? 1. H + e− ! H− 2. Li + e− ! Li− 3. F + e− ! F− 4. O + e− ! O− 5. N + e− ! N−
September 15, 2010

chemistry
The first ionization potential of the elements B, C, and N (atomic numbers 5, 6, and 7) steadily increases, but that of O is less than that of N. The best interpretation of the lower value for O is that: 1. the ionization potential of N is a maximum and the values decrease ...
September 15, 2010

chemistry
For which of these elements would the electron affinity process shown be least favorable? 1. H + e− ! H− 2. Li + e− ! Li− 3. F + e− ! F− 4. O + e− ! O− 5. N + e− ! N−
September 15, 2010

chemistry
That weird symbol was supposed to be quantum number l.
September 14, 2010

chemistry
In an atom, the maximum number of electrons having the quantum numbers n=5 and §¤ = 3 is: 1. 9. 2. 14. 3. 50. 4. 25. 5. 7. Shouldn't the maximum number be a lot bigger than the answer choices?
September 14, 2010

12th Grade Maths
simplify (e is positive) (24e)^1/3 / (3e)^1/3
September 13, 2010

chemistry
Thank you, sir.
September 3, 2010

chemistry
The electron in the n = 5 level of a hydrogen atom emits a photon with a wavelength of 1280 nm. To what energy level does the electron move?
September 3, 2010

science/acceleration
Due to a cart's sudden acceleration, a 200g wooden block remains on the front of the cart and does not slide or fall off. The mass of the cart is 10kg. The coefficient of static friction between the block and the front of the cart is 0.30. Calculate the cart's minimum ...
September 2, 2010

physics
at on time, the velocity of a rifle bullet was measured using a ballistic pendulum made up of a wooden block suspended from a string. the block used here has a mass of 20kg. a 50g rifle bullet is fired into the block, penetrating it by 10cm and causing it to swing upwards, ...
September 2, 2010

calculus
The limit as x approaches infinity of (e^x+x)^(1/x). I got that it diverges, but I'm not sure if I made a mistake. My work: lim(e+x^(1/x)) lim(e+(1/x^x)) lim(ex^x+1)/x^x l'hopital:lim(e^(e(lnx+1))+1)/e^(lnx+1) diverges?
September 1, 2010

Math
Thanks! Connor looks like he nees some help too.
August 31, 2010

Math
2x+2=8 Solve for x
August 31, 2010

Pre Calc
thats supposed to be a fraction all equel to f(x).
August 31, 2010

Pre Calc
thats supposed to be a fraction all equel to f(x).
August 31, 2010

Psychology
No need to shout Jen. I misunderstood her question. I would like help finding an article that is peer reviewed that pertains to my original question. I have searched my university's library and cannot find any related articles.
August 19, 2010

Psychology
Yes. Please!
August 19, 2010

Psychology
• Find a peer reviewed article which discusses the effects of optimism on physical and psychological health. • Write a 1400 to 1600-word paper summarizing the article and stating your opinion on the validity of the study or studies.
August 19, 2010

Math
How would I calculate the area of a sector of a circle with radius 2 m that subtends an angle pi/3
August 14, 2010

college math
I do not understand a problem from a text book or how to solve the problem for the answer. Could shomeone show me the steps (show work) on how to solve this question. The sum of the intergers from 1 through n is n(n+1)/2. the sum of the squares of the intergers from 1 through ...
August 13, 2010

math-college algebra
Thank you Reiny. I see where I was making my mistake. I was multiplying 1/2*2 and 1/2*-6. instead of 2-6 then multiplying 1/2. Thank you for your help.
August 11, 2010

math-college algebra
y-3=1/2(x-6) "finding the value of a variable" x=2 I know the answer is 1, but how do I work the problem to get 1. This problem is in our text book and in the back it states the answer is 1. I tried working the problem serval times and I do not come up with one.
August 11, 2010

Algebra
I need a home test corrected before I turn it in on Monday. Can anyone help?
July 31, 2010

math
what is the probability of a six card hand cantoning no fives?
July 29, 2010

math
a group of hockey officials consists of 6 referees and 5 linesmen. the probability that the youngest referee and linesman would be selected if one referee and two linesman are required is a) 1/15 b)1/30 c) 1/60 d)1/120
July 29, 2010

trig
A Ferris wheel has a radius of 15 meters and takes 20 seconds to complete one full revolution. The seat you are riding in, takes 7 seconds to reach the top which is 35 meters above the ground. Write a sine or cosine equation for the height of your seat above the ground as a ...
July 26, 2010

math
A committee of 2 teachers and 3 students is to be randomly chosen from a group of 5 teacher and 6 students. the total number of different committees is?
July 26, 2010

math
the number of ways in which 18 students in Mr. Garr grade 3 class can line up for a photo if the the Armstrong triplets cannot all be together is n x16! what is n?
July 26, 2010

Physics
A 2.9 kg body is at rest on a frictionless horizontal air track when a horizontal force F acting in the positive direction of an x axis along the track is applied to the body. A stroboscopic graph of the position of the body as it slides to the right is shown in the figure. ...
July 22, 2010

physic
1.74 m/s
July 20, 2010

Trigonometry
Hi,how do I find both solutions of the equation cos41 = 0.35 between degrees 0 and 360? Many thanks
July 8, 2010

Math
How do I find the x intercepts of the parabola y=x^2-6x-7? Thanks
July 7, 2010

physics
An astronaut on a distant planet wants to determine its acceleration due to gravity. The astronaut throws a rock straight up with a velocity of +13 m/s and measures a time of 20.5 s before the rock returns to his hand. What is the acceleration (magnitude and direction) due to ...
July 4, 2010

algebra
Ticket Sales Living in or near a metropolitan area has some advantages. Entertainment opportunities are almost endless in a major city. Events occur almost every night, from sporting events to the symphony. Tickets to these events are not available long and can often be ...
June 24, 2010

Calculus
P= r - c p= (5000-30x)(80+x)-300x p'= -60x + 2300 x = 38.3 therefore 38.3 * 30 = 1150 per person
June 19, 2010

algebra
1570536900 x 3966.848485^-2 =
June 13, 2010

Math
function y = 4-2(2t+pi/2), where t is measured in radians. A.choose one option which gives the value of the function when t=pi radians B.choose one option which gives the period of the function in radians. a)0 b)1 c)2 d)4 e)pi/4 f)pi/2 g)pi h)2pi
June 12, 2010

Math
: PROGRAM: PYTHAG : Prompt A, B :Fix 2 ã : (A2 +B2) ¨ C :Disp "C=",C : Float Choose the three true options concerning this program. Options A) The program can be used to find the length of the hypotenuse of a right-angled triangle. B) The ...
June 12, 2010

Math
Find the equation of the straight line that passes through the points (−1, 5) and (5, −1). Find the coordinates of the point where this line crosses the y-axis
June 11, 2010

Math
How do you find the vertical and horizontal assymptotes of the graph of the rational function? f(x)= 3x^2-5x+2/6x^2-5x+1 f(x)= 2x+3/(ãx^2-2x+3)
June 6, 2010

communication
In my opinion i find that C is also the best answer choice here.
June 2, 2010

SCIENCE 1
thankyou so much
May 11, 2010

SCIENCE 1
the van der waals equation incorperates coreections for the ideal gas law in order to account for the properties of real gases. one of the corrections accounts for A.the average kinetic energy being inversely proportional to temperature B. the possibility of chemical reaction ...
May 11, 2010

SCIENCE 1
thankyou so much
May 11, 2010

SCIENCE 1
Which of the following is a true statement about chemical equilibria in general A.there is only one set of equilibrium concentrations that equal teh Kc value B.eqauilibrium is the result of cessation of all chemical change C.at equilibrium the rate of the forward reaction is ...
May 11, 2010

SCIENCE 1
Actually you are 100% correct and i agree with C. thankyou so much
May 11, 2010

SCIENCE 1
for following reaction at equilibrium if we increase the reaction temperature the equilibrium will 2SO3(g)<-->2SO2(g)+O2(g)(deltaH degrees=198kJ) A. not shift B.the question can not be answered because Keq is not given C.shift to the right D. shift to the left I am going...
May 11, 2010

SCIENCE 1
thanks
May 11, 2010

SCIENCE 1
The van der waals equation incorporates corrections to the ideal gas in order to account for the properties of real gases one of the correcctions accounts for A.attractions between molecules B.the quantum behavior of molecules C.that average kinetic energy is inversely ...
May 11, 2010

CHEMISTRY
d.29
May 9, 2010

chemistry
533.0666 kj
May 4, 2010

Trig
How do i set this trig problem up? PLEASE help me. Find tan (s + t) given that sin s = 1/4, with s in quadrant 2, and sin t = -1/2, with t in quadrant 4.
May 3, 2010

trig
how do i set this problem up? Find tan (s + t) given that sin s = 1/4, with s in quadrant 2, and sin t = -1/2, with t in quadrant 4.
May 2, 2010

physics
With what speed must a muon travel so that its correct (relativistic) momentum is 8.0 percent greater than the value that would be computed nonrelativistically? Give your answer as a ratio to the speed of light
April 26, 2010

4th grade math
how do i mutipli fractoins
April 22, 2010

Calculus
Need an answer to this Calculus Question. I keep getting this type of question wrong. Thanks. Differentiate the Function: y = (3x-1)^2(2-x^4)^2 y =
April 19, 2010

Physics Help Please!
If the price of electrical enegy is $0.10 per kilowatt *hour, find the cost of using electrical energy to heat the water in a 12.0m * 9.00m * 1.5m swimming pool from 15 degrees C to 27 degrees C. So the change in temperature is 285.15 , the volume is 162m^3, the specific heat ...
April 6, 2010

physics helpppp
Okay, dude your velocities are ridiculous, does 150 m/s even make ANY sense to you?
March 30, 2010

physics help!!!
In February 1955, a paratrooper fell 365 m from an airplane without being able to open his chute but happened to land in snow, suffering only minor injuries. Assume that his speed at impact was 60 m/s (terminal speed), that his mass (including gear) was 90 kg, and that the ...
March 26, 2010

us history
Is there a good online source of information to compare and contrast the initial formation of two states—Virginia and Pennsylvania—by evaluating and listing the similarities and differences of the first state constitution for each state.
March 23, 2010

English
escaped; broke loose from; slipped out of
March 23, 2010

Math
P=I/rt Where P=principal(amount invested) I=Interest(amount earned) r=rate t=time So in order to fin the rate the formula can be written: r=I/Pt
March 23, 2010

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