Tuesday

October 21, 2014

October 21, 2014

Number of results: 76,387

**CHEMISTRY!**

A zero-order reaction has a constant rate of 3.4010−4 M/s. If after 80.0 seconds the concentration has dropped to 6.0010−2 M, what was the initial concentration?
*February 25, 2009 by Reese*

**Chemistry**

A zero-order reaction has a constant rate of 3.2010^−4 M/s. If after 35.0 seconds the concentration has dropped to 9.0010^2M , what was the initial concentration?
*April 30, 2010 by D.Walker*

**chemistry-rate of reaction**

The fictitious compound, arrhenium fluoride (AhF), reacts with itself to form a dimer with the formula Ah2F2. The reaction is second order in AhF. The value of the rate constant is 3.59110−3 M−1s−1. What is the initial rate of reaction in a reactor filled ...
*December 2, 2012 by Ron*

**Chemistry**

The fictitious compound, arrhenium fluoride (AhF), reacts with itself to form a dimer with the formula Ah2F2. The reaction is second order in AhF. The value of the rate constant is 4.09110−3 M−1s−1. What is the initial rate of reaction in a reactor filled ...
*November 29, 2012 by Odesa*

**chemistry**

The fictitious compound, arrhenium fluoride (AhF), reacts with itself to form a dimer with the formula Ah2F2. The reaction is second order in AhF. The value of the rate constant is 2.59110−3 M−1s−1. What is the initial rate of reaction in a reactor filled ...
*November 29, 2012 by mike*

**chemistry**

The fictitious compound, arrhenium fluoride (AhF), reacts with itself to form a dimer with the formula Ah2F2. The reaction is second order in AhF. The value of the rate constant is 5.59110−3 M−1s−1. What is the initial rate of reaction in a reactor filled ...
*November 30, 2012 by maliya *

**Science**

The fictitious compound, arrhenium fluoride (AhF), reacts with itself to form a dimer with the formula Ah2F2. The reaction is second order in AhF. The value of the rate constant is 1.09110−3 M−1s−1. What is the initial rate of reaction in a reactor filled ...
*December 5, 2012 by Shelly*

**chemistry**

The fictitious compound, arrhenium fluoride (AhF), reacts with itself to form a dimer with the formula Ah2F2. The reaction is second order in AhF. The value of the rate constant is 2.09110−3 M−1s−1. What is the initial rate of reaction in a reactor filled ...
*December 8, 2012 by Anonymous*

**chemistry**

The fictitious compound, arrhenium fluoride (AhF), reacts with itself to form a dimer with the formula Ah2F2. The reaction is second order in AhF. The value of the rate constant is 6.091×10−3 M−1s−1. What is the initial rate of reaction in a reactor ...
*November 29, 2012 by NIK*

**chemistry**

The fictitious compound, arrhenium fluoride (AhF), reacts with itself to form a dimer with the formula Ah2F2. The reaction is second order in AhF. The value of the rate constant is 6.091×10−3 M−1s−1. What is the initial rate of reaction in a reactor ...
*November 29, 2012 by sveta*

**chemistry**

1) The activation energy of a certain reaction is 35.3 kJ/mol. At 20 degrees C, the rate constant is 0.0130 s^-1. At what temperature would this reaction go twice as fast? Answer in units of degrees Celsius. i think the answer is around 34, but i keep in getting it screwed up...
*January 29, 2008 by Evets*

**Chemistry**

The decomposition of hydrogen iodide on a gold surface at 150 oC HI(g) H2(g) + I2(g) is zero order in HI. In one experiment, when the initial concentration of HI was 0.206 M, the concentration of HI dropped to 3.71E-2 M after 898 seconds had passed. Based on these data, ...
*March 22, 2014 by kait*

**chemistry**

The rate constants for a first order decay reaction are found to be: k287.3∘C=1 x 10−4 s−1 k327.4∘C=19.2 x 10−4 s−1 a) Determine the value, in s-1 of k250∘C (b) How long will it take, at 350 ∘C, for the reactant to decay to 1% of...
*January 11, 2013 by Anonymous*

**Chemistry**

The rate constants for a first order decay reaction are found to be: k287.3∘C=1 x 10−4 s−1 k327.4∘C=19.2 x 10−4 s−1 (a) Determine the value, in s-1 of k250∘C (b) How long will it take, at 350 ∘C, for the reactant to decay to 1% ...
*January 11, 2013 by selly*

**CHEMISTRY HELP NEEDED!!**

Given info: Reaction: 3A+2B--->2C+D {A] (mol/L) 1.0 10^-2 1.0 10^−2 2.0 10^−2 2.0 10^−2 3.0 10^−2 [B] (mol/L) 1.0 3.0 3.0 1.0 3.0 Rate of appearance of C (mol/L-hr) 0.3010^−6 8.1010^−6 3.2410^−5 1.2010^−6 7.3010^&#...
*March 11, 2012 by Kelly*

**chemistry**

The reactant concentration in a second-order reaction was 0.790 after 200 and 8.8010−2 after 740 . What is the rate constant for this reaction?
*May 20, 2012 by Anonymous*

**Chemistry**

Given info: A] (mol/L) [B] (mol/L) Rate of appearance of C (mol/L-hr) 1.0 10^-2 1.0 0.3010^−6 1.0 10^−2 3.0 8.1010^−6 2.0 10^−2 3.0 3.2410^−5 2.0 10^−2 1.0 1.2010^−6 3.0 10^−2 3.0 7.3010^−5 Reaction: 3A+2B--->...
*March 11, 2012 by Kelly*

**Bio Help Please **

1)How can you indicate that the bacteria have taken up the plasmid? 2)What is the purpose of the LB/amp(-) plate? Should there be bacterial growth on the plate? 3) Why would one compare plates LB/amp (-) and LB/amp (+)?
*March 30, 2013 by Melissa*

**Bio Help Please!!!**

1)How can you indicate that the bacteria have taken up the plasmid? 2)What is the purpose of the LB/amp(-) plate? Should there be bacterial growth on the plate? 3) Why would one compare plates LB/amp (-) and LB/amp (+)?
*March 31, 2013 by Melissa*

**biology**

Given the part of the molecule shown below, can the underlined atom participate in a hydrogen bond with an approriate bonding partner? −O−−−H −C−H−− −N−−−H −O−H−− −C−&#...
*March 12, 2013 by selly*

**Calculus**

Recall that the average velocity between times t1and t2 is calculated using vave = y(t2) − y(t1)/t2 − t1. We are given that y = 14t − 1.86t^2. Evaluating at t = 1, we have y(1) = 14(1) − 1.86(1)2 = 12.14. Thus, the average velocity between times 1 and 1...
*October 8, 2011 by Prater*

**Calc**

Recall that the average velocity between times t1and t2 is calculated using vave = y(t2) − y(t1)/t2 − t1. We are given that y = 14t − 1.86t^2. Evaluating at t = 1, we have y(1) = 14(1) − 1.86(1)2 = 12.14. Thus, the average velocity between times 1 and 1...
*September 4, 2013 by P*

**Chemistry**

In a given 1st order reaction A ---> products, the initial concentration of A is 0.40 M. What will be the concentration of A after 15 seconds if the half-life of the reaction is 3 seconds? I found the concentration to be 1.25 x 10-2 M But then how do I find the rate ...
*February 18, 2013 by Marcus *

**college chem**

Determine the rate of consumption of I− if the initial concentration of IO3− was 0.6634 M and decreased to 0.5745 M after 0.3964 hours. Use the reaction below. IO3− + 5I− + 6H+ ↔ 3I2 + 3H2O
*February 22, 2014 by hershi*

**biology**

Which bacterial plates control for: 1) If the E. coli cells were transferred correctly: 2) If the E. coli cells can grow on LB: 3) If the Ampicillin is working correctly: 4) If the stock E. coli cells were contaminated with plasmid: Possible choices for each number are: "-"...
*July 18, 2009 by Jenn*

**Chemistry**

The reaction 2NO2--->2NO+O2 has the rate constant k= 0.68 m-1s-1. If the initial concentration of NO2 is 9.3010−2 M, how long it would take for the concentration to decrease to 2.0010−2 M ? please answer and show the steps
*February 9, 2012 by Jeremy*

**chemistry**

In a reaction A to products, ,4.40 min after the reaction is started concentration of A is 0.588M. The rate of reaction at this point is rate= -change in concentration of A/change in time=2.2x10^-2Mmin^-1. Assume that this rate remains constant for a short period of time. A. ...
*January 18, 2014 by Temmi*

**Chemistry**

The rate constant for a certain reaction is = 4.3010−3 s^-1. If the initial reactant concentration was 0.400 M , what will the concentration be after 19.0 minutes? Rate would be first order therefore I used. A=A initial*e^-kt I keep getting .0030 M but supposely I am ...
*January 31, 2010 by Joanna*

**physics**

Four charges −8 10^−9 C at (0 m, 0 m), −7 10^−9 C at (5 m, 1 m), −1 10^−9 C at (−2 m, −3 m), and 2 10^−9 C at (−2 m, 4 m), are arranged in the (x, y) plane as shown. Find the magnitude of the resulting force ...
*January 29, 2014 by sarah*

**calculus-changing voltage**

V = IR V is increasing at the rate of 1 volt/sec while I is decreasing at the rate of 1/3 amp/sec. Let t = time in sec What is dV/dt? What is dI/dt? Find the rate at which R is changing when V = 12 volts and I = 2 amp. Thanks. Please ignore this. I got the answer.
*December 9, 2006 by Jen*

**Chemistry!**

The rate constant for a certain reaction is k = 5.0010−3 s-1 . If the initial reactant concentration was 0.950 M , what will the concentration be after 8.00 minutes?
*February 25, 2009 by Reese*

**Chemistry**

The rate constant for a certain reaction is = 8.0010−3 . If the initial reactant concentration was 0.400 , what will the concentration be after 16.0 minutes?
*September 29, 2012 by Dab353*

**Chemistry**

The rate constant for a certain reaction is k=8.9010^−3 s^-1. If the initial reactant concentration was 0.400M, what will the concentration be after 13.0 minutes?
*October 22, 2012 by Tasnim*

**Physics**

A 60 watt light bulb in a household circuit at 120 V carries a current of 0.500 amp. (An amp was defined in class as a way to measure charge movement. One amp is one coulomb per second.) How many electrons move through this light bulb in five minutes?
*March 7, 2011 by Anonymous*

**math**

(4 − 2x)−2 x=-2 y=4 z=-3 how do you solve this? i have solved it and gotten 6 for my answer many times and it says it's wrong. other equations are (y − z)−3 and (x − 5y)0. i cant get them right
*March 1, 2012 by krysta*

**Chemistry**

The degradation of CF3CH2F (an HFC) by OH radicals in the troposphere is first order in each reactant and has a rate constant of k=1.6108M−1s−1 at 4∘C. If the tropospheric concentrations of OH and CF3CH2F are 8.1105 and 6.3108 molecules cm−3, ...
*March 25, 2014 by Rebecca*

**Grade 12 Calculus **

Evaluate each of the following. Show all your calculations. a) f'(3) if f(x) = x^4 − 3x b) f' (−2) if f(x) = 2x^3 + 4x^2 − 5x + 8 c) f" (1) if f(X) = −3x^2 − 5x + 7 d)f" (−3) if f(x) = 4x^3 &#...
*April 15, 2013 by mandy*

**chem**

A certain first-order reaction has a rate constant of 2.75 10-2 s−1 at 20.C. What is the value of k at 50.C if Ea = 75.5 kJ/mol? i know to use the ln(k1/k2)= (ea/R)((1/T1)-(1/T2)) but how do i know what T2 is when i only have one temp? there is a b part to the question...
*February 10, 2013 by Hannah*

**calculus (gr 12)**

Evaluate each of the following. Show all your calculations. a) f'(3) if f(x) = x^4 − 3x b) f' (−2) if f(x) = 2x^3 + 4x^2 − 5x + 8 c) f" (1) if f(X) = −3x^2 − 5x + 7 d)f" (−3) if f(x) = 4x^3 &#...
*April 16, 2013 by Alexandra*

**calculus (gr 12)**

Evaluate each of the following. Show all your calculations. a) f'(3) if f(x) = x^4 − 3x b) f' (−2) if f(x) = 2x^3 + 4x^2 − 5x + 8 c) f" (1) if f(X) = −3x^2 − 5x + 7 d)f" (−3) if f(x) = 4x^3 &#...
*April 16, 2013 by Alexandra*

**Chemistry**

Consider the reaction A ==> B. If the reaction is first-order in A with the initial concentration A being 6.048M, what is the concentration of A after 1.986 seconds if the rate constant is 0.483s-1? Error tolerance: 0.5% Can someone explain how to do this? Thanks ln(Ao/A...
*February 6, 2007 by Marisol*

**Chemistry**

calculate the specific rate constant A] (mol/L) [B] (mol/L) Rate of appearance of C (mol/L-hr) 1.0 10^-2 1.0 0.3010^−6 1.0 10^−2 3.0 8.1010^−6 2.0 10^−2 3.0 3.2410^−5 2.0 10^−2 1.0 1.2010^−6 3.0 10^−2 3.0 7.3010^−5
*March 11, 2012 by Kelly*

**Chemistry**

calculate the specific rate constant A] (mol/L) [B] (mol/L) Rate of appearance of C (mol/L-hr) 1.0 10^-2 1.0 0.3010^−6 1.0 10^−2 3.0 8.1010^−6 2.0 10^−2 3.0 3.2410^−5 2.0 10^−2 1.0 1.2010^−6 3.0 10^−2 3.0 7.3010^−5
*March 11, 2012 by Kelly*

**Chemistry**

calculate the specific rate constant A] (mol/L) [B] (mol/L) Rate of appearance of C (mol/L-hr) 1.0 10^-2 1.0 0.3010^−6 1.0 10^−2 3.0 8.1010^−6 2.0 10^−2 3.0 3.2410^−5 2.0 10^−2 1.0 1.2010^−6 3.0 10^−2 3.0 7.3010^−5
*March 11, 2012 by Kelly*

**calculus**

Find an equation for the surface consisting of all points P(x, y, z) equidistant from the point P(0, 1, 0) and the plane x = 3. Answer Choices: 1. y2 + z2 − 6x + 2y − 8 = 0 2. x2 + z2 + 6y − 2z − 8 = 0 3. y2 + z2 + 6x − 2y − 8 = 0 4. x2 + z2...
*October 27, 2010 by Bob*

**chemistry**

The reaction A + B to C + D is second order in A and zero order in B. The value of k is 1.1010−2 M^{-1}\;min^{-1}. What is the rate of this reaction when A}]=0.124 M and B}]=3.89 M?
*February 28, 2010 by joe*

**chemistry**

The reaction A + B to C + D is second order in A and zero order in B. The value of k is 1.1010−2 M^{-1}\;min^{-1}. What is the rate of this reaction when A}]=0.124 M and B}]=3.89 M?
*February 28, 2010 by joe*

**Chemistry**

The decomposition of hydrogen iodide on a gold surface at 150 oC HI(g) H2(g) + I2(g) is zero order in HI with a rate constant of 1.20E-4 Ms-1. If the initial concentration of HI is 0.575 M, the concentration of HI will be 0.116 M after seconds have passed.
*March 22, 2014 by kait*

**Chemistry**

The decomposition of hydrogen iodide on a gold surface at 150 oC HI(g) H2(g) + I2(g) is zero order in HI with a rate constant of 1.20E-4 Ms-1. If the initial concentration of HI is 0.575 M, the concentration of HI will be 0.116 M after how many seconds have passed?
*March 22, 2014 by kait*

**Chemistry(Please check)**

1) The reaction A + B + C = products has a rate law rate = k times A times C squared. Which of the following will result in an increase in the rate constant for the reaction? #1 - increasing the temperature #2 - adding a catalyst #3 - doubling the concentration of reactant C I...
*February 19, 2012 by Hannah*

**chemistry**

HCOOH(aq) <-----> H^+ (aq)+ HCOO^-(aq) The equilibrium constant (Ka) for Reaction 3 at 25 C is 1.80 10−4 mol dm−3. Calculate the equilibrium concentration of hydrogen ions if the concentration of formic acid at equilibrium is 0.00500 mol dm−3
*February 10, 2013 by Mark*

**Chemistry**

Given the two reactions 1.PbCl2 <--->Pb^2+ + 2 Cl^-, K1= 1.8210^−10 2. AgCl <----> Ag^+ + Cl^-, K2 = 1.1510−4 what is the equilibrium constant Kfinal for the following reaction? PbCl2+ 2 Ag^+ <---> 2AgCl+ Pb^2+ This is what i have soo far: PbCl2...
*February 5, 2009 by Saira*

**Calculus**

If V volts are measured across a resistance of R ohms in a circuit carrying a current of I amperes, V=IR. At a certain instant, the voltage is 250 and is increasing at a rate of 4 volts/min, while the current is 0.5 AMP and is increasing at a rate of 0.01 amp/min. Find the ...
*February 28, 2013 by Trevor*

**AP CHEMISTRY**

A voltaic cell is constructed that uses the following half-cell reactions. Cu+(aq) + e− -> Cu(s) I2(s) + 2 e− -> 2 I−(aq) The cell is operated at 298 K with [Cu+ ] = 2.7 M and [I− ] = 2.7 M. (a) Determine E for the cell at these concentrations. (b...
*April 6, 2012 by MIKE*

**AP CHEMISTRY**

A voltaic cell is constructed that uses the following half-cell reactions. Cu+(aq) + e− -> Cu(s) I2(s) + 2 e− -> 2 I−(aq) The cell is operated at 298 K with [Cu+ ] = 2.7 M and [I− ] = 2.7 M. (a) Determine E for the cell at these concentrations. (b...
*April 14, 2012 by DAN*

**science**

The equilibrium constant (Ka) for Reaction 3 at 25 C is 1.80 10−4 mol dm−3. Calculate the equilibrium concentration of hydrogen ions if the concentration of formic acid at equilibrium is 0.00500 mol dm−3. (Show all of your working and give your answer to ...
*February 10, 2013 by Mark*

**vector**

For any two numbers a and b, the product of a−b times itself is equal to a2−2ab+b2. Does this familiar algebraic result hold for dot products of a vector u − v with itself? In other words, is it true that (u − v) (u − v) = uu−2uv+vv? ...
*April 11, 2010 by sarah A*

**Chemistry**

The fictitious compound, arrhenium fluoride (AhF), reacts with itself to form a dimer with the formula Ah2F2. The reaction is second order in AhF. The value of the rate constant is 8.591x10-3 M-1s-1. What is the initial rate of reaction in a reactor filled with AhF to a ...
*December 10, 2012 by Please Help Me!!!!!!!!*

**Calculus**

Calculus If V volts are measured across a resistance of R ohms in a circuit carrying a current of I amperes, V=IR. At a certain instant, the voltage is 250 and is increasing at a rate of 4 volts/min, while the current is 0.5 AMP and is increasing at a rate of 0.01 amp/min. ...
*February 28, 2013 by Trevor*

**Algebra**

1.Solve 2x = 5x2 for x. A. 2.322 B. 0.431 C. 0 and 2.322 D. 0 and 0.431 2.Which of these is a factor of 2x100 − x7 − 1? A. x B. x − 2 C. x + 1 D. x − 1 3.If P(x) is a polynomial with P(6) = 1.12 and P(5) = 0.6 then which of the following must be true...
*May 5, 2012 by nash*

**CHEMISTRY**

Urbium (Ur) is an upscale element found in big cities. Its oxide (UrO2) is not very stable and decomposes readily at temperatures exceeding 66∘ C. The figure below shows how the rate of reaction varies with the concentration of UrO2 at 75∘ C. The rate r is in units...
*November 29, 2012 by OLEG*

**chemistry**

Urbium (Ur) is an upscale element found in big cities. Its oxide (UrO2) is not very stable and decomposes readily at temperatures exceeding 66∘ C. The figure below shows how the rate of reaction varies with the concentration of UrO2 at 75∘ C. The rate r is in units...
*December 1, 2012 by lisa*

**Chemistry **

A first order reaction has a rate constant of 0.0733 s−1. What is the half life for this reaction in seconds? when I plug in the numbers in the formula, my answer was 9.45. But on the computer it says the answer is wrong. How do I find the right answer?
*March 20, 2011 by Alex*

**Chemistry**

H6P6: Urbium Oxide First Part of the Question: Urbium (Ur) is an upscale element found in big cities. Its oxide (UrO2) is not very stable and decomposes readily at temperatures exceeding 66∘ C. The figure below shows how the rate of reaction varies with the concentration...
*November 29, 2012 by Odesa*

**chemistry**

The following data were obtained at 25 C for the reaction [1+2+2] C2H5Br + OH- C2H5OH + Br- Determine the rate law for the reaction from these data. [C2H5Br] [OH-] Rate 0.150 0.200 4.8 x 10-5 0.300 0.200 9.6 x 10-5 0.450 0.200 14.4 x 10-5 0.300 0.600 28.8 x 10-5 (ii) The ...
*February 8, 2012 by ranu*

**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 by dave*

**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 by dave*

**Chem2**

A reaction in which A, B, and C react to form products is zero order in A, one-half order in B, and second order in C. If the concentration of C is increased by a factor of 4.95 (and all other concentrations are held constant), how much will the rate of reaction increase?
*May 2, 2011 by Ryan*

**Second order half life**

At 100 degrees C , a certain substance undergoes second-order decomposition with a half-life of 26 minutes. If the initial concentration of the substance is 3.910−2M , what is the value of the rate constant at 100degrees C? So I put in (1560seconds) 1/2 = 1/ k (3.910&#...
*September 21, 2010 by Sar*

**Chemistry(Please check)**

A reaction has a rate law, rate = k times A times B squared. What is the overall order of the reaction. I think that the order is 0. Is this correct?
*February 19, 2012 by Hannah*

**chemistry ASAP please!!**

The reaction of CO(g) + NO(g) is second-order in NO2 and zero-order in CO at temperatures less than 500K. (a) Write the rate law for the reaction. (b) How will the reaction rate change if the NO2 concentration is halved? (c) How will the reaction rate change is the ...
*March 15, 2011 by Maria*

**chemistry kinetics**

Decomposition of an organic compound A follows first order kinetics. Initial concentration of A is 2 M. If rate constant of the decomposition is 3.58 10^−6 min^-1 , calculate the rate after 3 hours.
*May 24, 2012 by swa*

**Chemistry**

Determine the rate constant for the following second-order reaction: A=C+2D given that the initial concentration of A is .3 M and that the concentration of C increase to .01 M in 200 seconds. Express the result in terms of the rate law for the loss of A.
*March 14, 2014 by Anonymous*

**Chemistry**

Determine the rate constant for the following second-order reaction: A=C+2D given that the initial concentration of A is .3 M and that the concentration of C increase to .01 M in 200 seconds. Express the result in terms of the rate law for the loss of A.
*March 16, 2014 by Anonymous*

**math**

The number 27+200−−−√−−−−−−−−−√ can be simplified to the form a+b√, where a and b are positive integers. Find the product ab.
*June 20, 2013 by raja harishchandra*

**Chemistry**

biochemists consider the citric acid cycle to be the central reaction sequence in metabolism. One of the key steps is an oxidation catalyzed by the enzyme isocitrate dehydrogenase and the oxidizing agent NAD+. Under certain conditions, the reaction in yeast obeys 11th-order ...
*June 19, 2014 by Lety*

**Math - PreCalc (12th Grade)**

If Sn = 1 + 6 + 11 + 16 + 21 + 26...... where an = (5n − 4), what would be the mathematical expression represented by Sk + ak + 1? A) (k(5k − 3)/2)+ 5k + 1 B) (k(5k − 3)/2)+ 5k − 4 C) (k(5k − 3)/2)+ 5k + 2 D) (k(5k − 3)/2)+ 5k − 3 E) (...
*March 20, 2014 by Shawna*

**Chemistry**

The following rearrangement reaction is first order: C3H6 CH3CH=CH2 The rate constant for this reaction is 6.7 ~ 10−4. How many minutes will it take for the concentration of C3H6 to drop to 11.75% of its initial value? How do I calculate this step by step. My answer ...
*March 20, 2011 by Alex*

**Product of Roots of Sums of Products of Difference**

What is the product of all roots to the equation ++(x−1)(x−2)(x−3)+(x−2)(x−3)(x−4)(x−3)(x−4)(x−5)+(x−4)(x−5)(x−6)(x−5)(x−6)(x−7)+(x−6)(x−7)(x−8)=0?
*March 25, 2013 by i need help from anyone!*

**Product of Roots of Sums of Products of Difference**

What is the product of all roots to the equation ++(x−1)(x−2)(x−3)+(x−2)(x−3)(x−4)(x−3)(x−4)(x−5)+(x−4)(x−5)(x−6)(x−5)(x−6)(x−7)+(x−6)(x−7)(x−8)=0?
*March 28, 2013 by please help me out!!*

**CHEMISTRY**

A second-order reaction has a rate constant of 1.65 M1 s1. If the initial reactant concentration is 1.0 M, calculate the time (in seconds) required for the reaction to become 90% complete. i got 0.06734 seconds but thats incorrect i have no idea what i am doing wrong! HELP!!!!
*March 28, 2012 by Maya *

**math**

3. Reduce the fraction −20t 5u 2v 3 48t 7u 4v . A. −5t 2v 2 12u 2 C. −5v 2 12t 2u 2 B. 5t 2v 2 12u 2 D. 5v 2 12t 2u 2 4. Reduce the fraction w 2 + 5w + 6 w 2 − w − 12 . A. w − 2 w − 4 C. w + 2 w + 4 B. w + 2 w − 4 D. w − 2 ...
*October 20, 2009 by jalisaj*

**math**

Consider the following 6 relations on the set of real numbers: A) y=2x−5, B) x2+y2=1, C) x=20−2y, D) y=10−x2−−−−−−√, E) y=2x2−3x+4 and F) y=|x| How many of these relations define y as a function of x in the ...
*June 9, 2013 by Anonymous*

**Chemistry**

The reaction 2B--->C + 2D is found to be zero order when run at 990 degrees C. If it takes 3.3X110^2 s for an initial concentration of B to go from 0.50 M to .20 M what is the rate constant for the reaction? what is the half life of the reaction under these conditions?
*February 29, 2008 by Lauren*

**Chemistry**

A certain first-order reaction has a rate constant of 2.6010−2 s-1 at 18 C. What is the value of k at 55 C if Ea = 90.0 kj/mol?
*February 6, 2012 by gary*

**algebra**

Which of the following is equivalent to the expression (t2 − t − 6)(t − 3)−1 ? a. t3 − 9t +18 b. (t − 2)(t + 3) c. (t + 2)(t − 3) d. (t − 2) e. (t + 2)this is the answer how is the problem worked out?
*May 23, 2010 by Mary*

**Rate Laws**

If the initial concentration of AB is 0.210 M, and the reaction mixture initially contains no products, what are the concentrations of A and B after 75 s? The reaction is in the second order: rate=k[AB]^2 The rate constant is k=5.4*10^2 M*s I don't understand how to find A and...
*February 20, 2010 by Kyle*

**AP Chemistry**

Which solution has the highest pH? 1. 0.1 M C6H5NH3Cl, Kb C6H5NH2 = 4.2 10−10 2. 0.1 M NH2(OH)2Cl, Kb NH2OH = 6.6 10−9 3. 0.1 M NaCl, Kb zero 4. 0.1 M NH4Cl, Kb NH3 = 1.8 10−5 5. 0.1 M CH3NH3Cl, Kb CH3NH2 = 5.0 10−4
*February 25, 2014 by Anonymous*

**Math - PreCalc (12th Grade)**

What value must be defined for f(4) to remove the discontinuity of this function at x=4? f(x)=(x^2−16)/(x−4) A) 0 B) 4 C) -4 D) 8 E) -8 f(4)=(4^2−16)/(4−4) f(4)=0/0 you can't divide by zero. I don't understand the question.
*March 20, 2014 by Shawna*

**Chemistry**

In a reversible reaction, chemical equilibrium is attained when ? 1. Rate of the forward reaction is greater than the rate of the reverse reaction. 2. Rate of the reverse reaction is greater than the rate of the forward reaction, 3. Concentration of the reactants reaches zero ...
*March 9, 2011 by Jazmin F. *

**MATHS**

The number 2+3√+5√−−−−−−−−−−√ is algebraic because it is a root of a monic polynomial of degree 8, namely x^8+ax^7+bx^6+cx^5+dx^4+ex^3+fx^2+g^x+h. Find |a|+|b|+|c|+|d|+|e|+|f|+|g|+|h|.
*May 23, 2013 by SOmebody*

**CHEMISTRY**

Thiosulfate ion S2O32− is oxidized by ioidine according to the following reaction. 2S2O32−(aq) + I2(aq) S4O62−(aq) + 2I−(aq). If in a certain experiment, 0.0020mole of thiosulfate ion is consumed in 1.0 L of solution in 1 second, what is the rate of ...
*April 22, 2014 by Juan Pablesteban Gonzalez*

**Chemistry**

In a given 1st order reaction A ---> products, the initial concentration of A is 0.40 M. What will be the concentration of A after 15 seconds if the half-life of the reaction is 3 seconds?
*February 17, 2013 by Marcus *

**Chemistry**

Consider the following reaction: PbCl2 + 2 NaOH -> Pb(OH)2 + 2 NaCl What would be the major species observed floating in solution after one mole of PbCl2 and 2 moles of NaOH are mixed in aqueous solution? 1. Na+ ions, Cl− ions and H+ ions 2. Pb2+ ions, Cl− ions ...
*April 5, 2010 by Cher*

**CHEM**

1.) At what temperature will the rate constant for the reaction H2 + I2 to 2HI have the value 5.210−3 M^{-1}s^{-1}? (Assume k=5.4 *10^{-4}M}{-1)s}^{-1} at 599 K and k=2.8 * 10^{-2}M}^{-1}s}^{-1} at 683 K.) 2.)For the first-order reaction N2O5 to 2NO2 + 1/2O2 t_{1/2}=22....
*March 3, 2010 by anonymous*

**chemistry**

1.) At what temperature will the rate constant for the reaction H2 + I2 to 2HI have the value 5.210−3 M^{-1}s^{-1}? (Assume k=5.4 *10^{-4}M}{-1)s}^{-1} at 599 K and k=2.8 * 10^{-2}M}^{-1}s}^{-1} at 683 K.) 2.)For the first-order reaction N2O5 to 2NO2 + 1/2O2 t_{1/2}=22....
*March 3, 2010 by anonymous*

**Math, HELP!! URGENT!**

Please Simplify: (1/8)(40v−24y)−(1/7)(21v−35y+9)−(1/6) (1/11)(55x−22)−(1/2)(18x−2v)
*August 29, 2013 by Lucas*

**chemistry **

The equilibrium constant (Ka) for equation 3 at 25 C is 1.80 10−4 mol dm−3. Calculate the equilibrium concentration of hydrogen ions if the concentration of formic acid at equilibrium is 0.00400 mol dm−3. (Show all of your working and give your answer to ...
*May 17, 2013 by riddler *

**Physics-friction problem**

A 0.170 kg hockey puck is initially moving at 21.2 m/s [W] along the ice. The coefficient of kinetic friction for the puck and the ice is 0.005. (a) What is the speed of the puck after traveling 58.5 m? my solution: Fnet=Fk ma=μk.Fn ma=μk.mg a=(0.05)(0.170kg)(9.8m/s2...
*April 1, 2013 by LG*

**Chemistry**

The gas phase decomposition of dinitrogen pentoxide at 335 K N2O5(g) 2 NO2(g) + O2(g) is first order in N2O5. During one experiment it was found that when the initial concentration of N2O5 was 0.218 M, the concentration of N2O5 dropped to 2.96E-2 M after 282 s had passed. ...
*January 24, 2014 by Breauna*

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