Thursday

October 27, 2016
Total # Posts: 2,479

**chemistry**

For the reaction A to products}, the following data were obtained: t=0 s, A}]=0.715 M; 22 s, 0.605 M; 74 s, 0.345 M; 132 s, 0.055 M. What is the half-life of the reaction? ive been posting this for awhile now...can someone just show me how to go about doing this problem? i ...

*February 28, 2010*

**chemistry**

For the reaction A to products}, the following data were obtained: t=0 s, A}]=0.715 M; 22 s, 0.605 M; 74 s, 0.345 M; 132 s, 0.055 M. What is the half-life of the reaction?

*February 28, 2010*

**chemistry**

For the reaction A to products}, the following data were obtained: t=0 s, A}]=0.715 M; 22 s, 0.605 M; 74 s, 0.345 M; 132 s, 0.055 M. What is the half-life of the reaction?

*February 28, 2010*

**chemistry**

for this one do i just plug in k A^2B^0 = rate?

*February 28, 2010*

**chemistry**

The reaction A + B to C + D is second order in A and zero order in B. The value of k is 1.10×10−2 M^{-1}\;min^{-1}. What is the rate of this reaction when A}]=0.124 M and B}]=3.89 M?

*February 28, 2010*

**Chem- follow up question**

Sorry i posted this as an answer after my question had been answered, this is continued from the qualitative analysis question: That reallly cleared some things up, but I do still have a few questions. Umm im not completely clear on the hyrogen peroxide subject. its added to a...

*February 28, 2010*

**Chemistry**

That reallly cleared some things up, but I do still have a few questions. Umm im not completely clear on the hyrogen peroxide subject. its added to a solution containing aluminum chloride and iron chloride, and you said it is ther eto make sure the ion is Al3+, can you please ...

*February 28, 2010*

**Chemistry**

HI, we conducted a qualitative analysis, to identify the cations in an unknown sollution..trying to determine whether it had Al 3+, Fe (3), and Lead ions..i am having trouble understanding some parts of the procedure. before testing for aluminum and iron, hydrogen peroxide was...

*February 28, 2010*

**chemistry**

For the reaction A to products}, the following data were obtained: t=0 s, A}]=0.715 M; 22 s, 0.605 M; 74 s, 0.345 M; 132 s, 0.055 M. What is the half-life of the reaction?

*February 28, 2010*

**chemistry**

The reaction A + B to C + D is second order in A and zero order in B. The value of k is 1.10×10−2 M^{-1}\;min^{-1}. What is the rate of this reaction when A}]=0.124 M and B}]=3.89 M?

*February 28, 2010*

**chemistry**

The reaction A to products is first order in A. 1.) If 2.00 g A is allowed to decompose for 42 min, the mass of A remaining undecomposed is found to be 0.50 g. What is the half-life, t_{1/2}, of this reaction? 2.)Starting with 2.00 g A, what is the mass of A remaining ...

*February 28, 2010*

**Art**

Does anyone know what the difference between analytical and expressive lines are and where I can find some art examples of each?

*February 26, 2010*

**physics**

0.490 mol of argon gas is admitted to an evacuated 50.0 cm^3 container at 60.0 C. The gas then undergoes an isochoric heating to a temperature of 400 C. What is the pressure?

*February 26, 2010*

**Accounting**

Given the data, would you have invested in Quality Department Store in 2006? Explain why or why not. Summarize your analysis of the financial data to support your reasoning. What recommendations would you make to improve the financial health of this company? Explain why.

*February 24, 2010*

**physics**

If 2.0J of work is done in raising a 180g apple, how far is it lifted?

*February 21, 2010*

**Crt/205 Critical Thinking**

I need help with this assignment: Argument Evaluation DUE: Day 7 Points: 100 · Read the essay “Bush’s Environmental Record” by Bob Herbert found in the “Appendix 1”, pgs. 461-462. To find this, click on the “Controlling Irrational Fears ...

*February 21, 2010*

**algebra**

5 yrs ago Montys age was 5 years less than twice Rachels age. In 3 years, one third of Rachels age will be 12 years less than Montys age. How old are they now?

*February 18, 2010*

**math**

No - that comes out to a negative number - doesnt it? Can you show the next steps?? I am not sure why it is not coming out -

*February 18, 2010*

**math**

5 yrs ago Montys age was 5 years less than twice Rachels age. In 3 years, one third of Rachels age will be 12 years less than Montys age. How old are they now?

*February 18, 2010*

**science **

it has less density

*February 17, 2010*

**Math**

The week before a big concert, five friends (Alvin, Bert, Chip, Dennis, and Ethan) stood in line to buy tickets. There were other people between them, but the five friends were in line in the order listed above. The line was really long, and they were pretty bored. Chip ...

*February 16, 2010*

**math**

5 Hundredths.

*February 16, 2010*

**Health**

Which one of the following subcategories of the E/M section has separate codes for new and established patients? A. Office or Other Outpatient Services B. Hospital Observation Services C. Initial Inpatient Consultation D. Emergency Department Services

*February 15, 2010*

**7th grade essay writing**

What's with the stupid mama joke?

*February 15, 2010*

**Physics**

The acceleration due to gravity on planet X is one fifth that on the surface of the earth. If it takes 3.9 s for an object to fall a certain distance from rest on earth, how long would it take to fall the same distance on planet X?

*February 14, 2010*

**chem**

That's the problem, I have to make a diagram using only the data made available to me, and I have no idea how to make use of the critical point to solve this. If 179 is indeed equilvalent to 1 atm or 760 mm Hg, i can conclude that at 125 degrees its 0.1-0.9 atm, i just don...

*February 12, 2010*

**chem**

Benzaldehyde, C6H5CHO}, has a normal boiling point of 179.0 C and a critical point at 422 C and 45.9 atm. Using a phase diagram, estimate its vapor pressure at 125 Degrees I'm directing it up again to Dr. Bob. (or anyone else who can help) **** If the boiling point (179) ...

*February 12, 2010*

**chemistry**

that was me who posted the comment above. my friend had the same question.

*February 12, 2010*

**chemistry**

1.) How much ethanol, C2H5OH, in liters (d=0.789g/ml) must be dissolved in water to produce 190.5 of 1.65 M C2H5OH? (Molarity problem.) 2.) How much concentrated hydrochloric acid solution (36.0% HCl by mass, d = 1.18g/mL}), in milliliters, is required to produce 11.0 L of 0....

*February 12, 2010*

**english**

I'm black,approx. 6" square,I have a hole in the middle ,and my sides go round and round

*February 11, 2010*

**History-PLEASE HELP**

Thank you soooo much!!

*February 11, 2010*

**History-PLEASE HELP**

I am stuck on a homework assignment and am having a hard time finding information on this topic. Can someone please please help!! Why is Kenneth Clark’s interpretation of the African mask ethnocentric?

*February 11, 2010*

**math**

ok, I realize that I should cut each remaining square into 9 quadrants leaving the middle open of each of them. Now, I just don't know how to get the percent of the original square that remains in stage 3.

*February 10, 2010*

**math**

Hello, Here is a question with something i've never heard of. These are the first two stages of a fractal known as the Sierpinski carpet. The carpet begins with a square (stage 1). The square is cut into 9 congruent squares and the middle square is removed (stage 2). Draw ...

*February 10, 2010*

**MATH**

On the xy-coordinate plane, point O is the origin. Suppose vector OE=(3,8) and vector OF=(-2,-4). What ordered pair represents vector EF? I tried graphing them but they don't even end up in the same quadrant. Not sure what to do..

*February 10, 2010*

**MATH**

Oh, so you had to find a pattern... Thanks

*February 10, 2010*

**MATH**

Hello, This figure shows the number of segments used to form longer and longer rows of squares. It shows that 1 square has 4 segments 2 squars has 7 segments and 3 squares has 10 segments. The question is how many segments will be in a row with 100 squares? Thought maybe a ...

*February 10, 2010*

**Math**

Oh thanks!

*February 10, 2010*

**Math**

For 5 consecutive days, the price of a lamp in jill's store is reduced by 10% from the previous day's price. At the end of the fifth day, by what percetage will the price of the lamp have been reduced from its initial price? I'm not sure where to begin since I don...

*February 10, 2010*

**MATH**

Hello I have to draw a pentagon with 30 square units on graph paper. My question is how can I get 30 square units if the slanted sides are not full squares?

*February 7, 2010*

**math repost Please Help!**

Hello, In a class of 24 students, every student flips fairly two coins 40 times each and records the results. Assume that the class obtained the expected results when they conducted the experiment. a. Make a bar graph illustrating the combined class results b. explain why an ...

*February 7, 2010*

**Math**

Patricia's teacher asked her to find the perimeter of the school's rectangular parking lot. After school, patricia walks along the short side of the lot and finds it is 50 yards long. She then walks diagonally from one corner of the rectangle to the other and throught ...

*February 7, 2010*

**math**

Ok you have to write a system of equations. x+y=40 2x+4y=100 y=40-x 2x+4(40-x)=100 solve: X=30 Y=10 then 30+y = 40 y=10

*February 7, 2010*

**MATH**

Hello, In a class of 24 students, every student flips fairly two coins 40 times each and records the results. Assume that the class obtained the expected results when they conducted the experiment. a. Make a bar graph illustrating the combined class results b. explain why an ...

*February 7, 2010*

**algebra**

Jennifer is twice as old as Ramon. The sum of their ages 7 years ago was 13. How old are they now?

*February 6, 2010*

**math**

Hello, A ship's movements are being tracked on a radar screen. The ship is first seen on point a with coordinates (-5,8) 1. It moves along vector AB represented by the ordered pair (-6,-1) 2. Then it travels along vector BC represented by the ordered pair (4,-3) 3. Finally...

*February 6, 2010*

**Math**

Ok, thanks. But how did you get 12 and 5?

*February 6, 2010*

**Math**

Hello, I'm not sure how to go about this question. To get to work on the first day, Jose has the following directions. Travel 15 miles due East. Turn right and travel 12 miles due south. Turn right again and travel 10 miles due West. If Jose could travel in a straight line...

*February 6, 2010*

**Math**

ahh, so simple in hind sight

*February 6, 2010*

**Math**

Hello, I can't find a pattern to answer this question, can you help? The beginning of the fibonacci number sequence is listed below: 1,1,2,3,5,8,13,...... What is the smallest term in the sequence which has a value greater than 100?

*February 6, 2010*

**physics**

PE=(13/3)k(Q^2)/a

*February 3, 2010*

**Math**

Solve by the elimination method. 2r-5s = -11 5r + 2s = 16

*January 31, 2010*

**Math**

Find the indicated outputs for f(x)= 5x^2-5x. F(0) = 0 f(-1)= 1 f(2)= 45 is this right?

*January 31, 2010*

**Elimination Method...**

Solve by eliminatin method. 2r-5s= -11 5r+2s= 16

*January 31, 2010*

**equal group riddles**

i am a number between 20 and 30.when you put me into 6 equal groups;there is an even number in each group and 1 is left over.what number am i

*January 30, 2010*

**Finance**

2142

*January 27, 2010*

**Calculus**

eeee

*January 27, 2010*

**math**

In how many ways can 7 basketball players of different heights line up in a single row so that no player is standing between 2 people taller than she is?

*January 27, 2010*

**chemistry**

22%

*January 24, 2010*

**Math-Fractions**

How would I solve these two problems. (We have to simplify our answer) 5/7 divided by 8/21 12/7 divided by 9/21

*January 19, 2010*

**Elementary Math**

On a number where would 4/3 go? Would it go one third the way between 3 and 4? Where would 5/3 go?

*January 17, 2010*

**Molarity**

Determine the molarity and normality of a solution prepared by dissolving 55 mg of sodium bicarbonate (NaHCO3) in 750 mL of water.

*January 14, 2010*

**Precal**

use graphic techiques in radians I found that it is roughly equal to -.5 sin [ 20.42036^-1(x + 40.84071)pi ] + 1

*January 14, 2010*

**Precal**

I do not understand how to do this problem ((sin^3 A + cos^3 A)/(sin A + cos A) ) = 1 - sin A cos A note that all the trig terms are closed right after there A's example sin A cos A = sin (A) cos (A) I wrote it out like this 0 = - sin^6 A - cos^6 A + 2sin^3 A cos^3 A - ...

*January 14, 2010*

**Physics**

I'm having some trouble with this question A 4200-kg rocket is traveling in outer space with a velocity of 120m/s toward the Sun. It needs to alter its course by 23 degrees, which can be done by shooting is rockets briefly in a direction perpendicular to it’s original...

*January 13, 2010*

**Physics**

A 16.0 - kg descends a slide 2.50 m high and reaches the bottom with a speed of 2.25 m/s. How much thermal energy due to firciton was generated in the process? for this I keep on getting 432.5 J but the back of the book tells me that the answer is 352 J and I do not see how to...

*January 12, 2010*

**physics**

A charge of 2.4 nC and a charge of 5.0 nC are separated by 33.30 cm. Find the equilibrium position for a -4.1 nC charge.

*January 11, 2010*

**physics**

Calculate the net charge on a substance consisting of a combination of 6.8 multiplied by 1013 protons and 4.6 multiplied by 1013 electrons.

*January 11, 2010*

**precal**

given cscx= -3 and tanx>0 find cosx

*January 10, 2010*

**precal**

from {0,2pie} what are the solutions of tan x/4= square root of 3/3

*January 10, 2010*

**precal**

from {o, 2pie} what are the solutions of cos(squared)x- cos2x=0

*January 10, 2010*

**urgent precal**

What is cosx/ (secx-1) not in fractional form?

*January 10, 2010*

**precal**

yes i meant to have it with parantheses

*January 10, 2010*

**precal**

rewrite cosx/secx-1 not in fractional form

*January 10, 2010*

**chemistry**

In any chemical reaction, the quantities that are preserved are what? A. the number of moles and the volumes B. the number of molecules and the volumes C. mass and number of atoms D. mass and moles

*January 8, 2010*

**AP World History**

How can I show Change and Continuity in the American Environment between 600 AD - 1750 AD?

*January 6, 2010*

**Biology**

the first one is b. there is no general relationship.

*January 6, 2010*

**Math**

A group of nine students has a mean of 3.5 people in their households. Make a line plot showing an example of this data set

*January 5, 2010*

**science**

When is the Earth farthest from the sun?

*January 5, 2010*

**Physics**

The Olympic diver completes 3.5 somersaults in 1.7 seconds. What is the average angular speed (in rad/s) of the diver?

*December 21, 2009*

**chemistry**

The addition of a dilute hydrobromic acid would clearly distinguish solutions of a. barium nitrate and sodium sulfate b. lead nitrate and silver nitrate c. mercury(I) nitrate and silver nitrate d. silver nitrate and calcium sulfate e. calcium nitrate and barium nitrate

*December 18, 2009*

**AP Physics B (Heat Engines)**

I know that efficiency is e = |W|/|QH| were the H is the subscript I know that 900 MW is a value of power which is not work I know that |QH| is 2.8 E8 J/kg but I do not like the units for this, J/kg, as I thought Q was measured in joules only... How do I find the work done?

*December 16, 2009*

**AP Physics B (Heat Engines)**

18. (II) At a steam power plant, steam engines work in pairs, the heat output of the first one being the approximate ehat input of the second. Th eoperating temeprautres of the first are 680 degrees C and 430 degrees C, and of the second 415 degrees C and 280 degrees C. If the...

*December 16, 2009*

**pre al**

how do you find surface area

*December 15, 2009*

**SCIENCE**

What is the movement of a water particle in a wave called?

*December 14, 2009*

**science**

The movement of a water particle in a wave is called what?

*December 14, 2009*

**physics**

An aluminum cylinder weighs 1.03 N. When this same cylinder is completely submerged in alcohol, the volume of the displaced alcohol is 3.90 x 10-5 m3. If the cylinder is suspended from a scale while submerged in the alcohol, the scale reading is 0.730 N. What is the specific ...

*December 13, 2009*

**History**

Why do we need taxes? Could someone tell me in two paragraphs besides that we need it for roads and schools

*December 12, 2009*

**college**

what strategies can be incorporate into effective visual element into business presentations

*December 11, 2009*

**algebra 1**

Use the point-slope form to write an equation of the line with the given slope and point. m = 4, passes through (4, 6)

*December 10, 2009*

**PreCalc**

please h t t p : / / w w w . j i s k h a . c o m / d i s p l a y . c g i ? i d = 1 2 6 0 4 8 7 4 9 0

*December 10, 2009*

**Pre Calc**

I do not see why I got two different equations for my answer A weight attached to the end of along spring is bounicng up and down. As it bounces, its distance from the floor varies sinusoidally with time. You start a stopwatch. When the stopwatch reads 0.3 s, the weight first ...

*December 10, 2009*

**biology**

what functional groups appear in CH3CH2CH2Br

*December 10, 2009*

**algebra**

3[5-(2x+1(2))]= 3[5-(2x+2)] 3[5-2x-2]= 3[3-2x]= 9-6x

*December 10, 2009*

**spanish**

what is the correct possessive adjective for ¿Es mi clase de español?

*December 9, 2009*

**english**

Did you like “Usher”? How successful was Poe’s use of Gothic devices in creating an atmosphere of dread?

*December 7, 2009*

**Calc 3**

The actual span of the base of the dome is 143 feet. 1) Use cylindrical coordinates to write the surface of the dome as a function of the distance from the center of the base; that is find z = f (r) . 2) Use your function to find the height of the dome; that is what is f (0...

*December 7, 2009*

**Pre Calc**

Naturalists findthat the populations of some kinds of predatory animals vary periodically. Assume that the population of foxes in a certain forext vareis sinusoidally iwth time. REcord started being kept when time t = 0 years. A minimum number, 200 foxes, occurred when t = 2.9...

*December 6, 2009*