Tuesday
September 30, 2014

Posts by SARA


Total # Posts: 3,672

English
Please track the errors by editing this passage of writing. This is an exercise for my English homework. I have made a couple of changes or editing to the writing piece already, but I am not sure if there are more editing that needs to be made. Also, please evaluate the ...
September 24, 2013

Chemistry
What volume of 0.01 M NaOH should be required to raise the pH of a litre of 25 mM H2SO4 to 4.0? I started out by attempting to find the initial pH of H2SO4 and determined I need 2.57 units of pH to raise it to 4. I know that somewhere I use the HH equation, but don't know ...
September 22, 2013

College Physics 1
A space probe has two engines. Each generates the same amount of force when fired, and the directions of these forces can be independently adjusted. When the engines are fired simultaneously and each applies its force in the same direction, the probe, starting from rest, takes...
September 17, 2013

pre calcalus
(x+4)^2/3=9
September 16, 2013

math
i didnt get how 16x^2 turned into 8x^2 16x^2 = 30x + 4 Solving for x, 8x^2 - 15x - 2 = 0
September 16, 2013

simple math
If a= 9990.9 and b= 9886.1. First, convert these to scientific notation. If only three significant digits are allowed in decimal portion (mantisa) of the scientific notation and chopping and not rounding is used, what is a-b?
September 14, 2013

Sociology
I need to break a folkway and write an essay on it - any ideas?
September 7, 2013

American Gov
What is the primary claim made by those who oppose hate crimes legislation?
September 6, 2013

Geography
thank you Ms.sue
September 5, 2013

Math
144
September 3, 2013

Math
if Kenneth has 22 problems of math to do for homework and had already done 12 problems done he would have to subtract 22-12=10 and then multiply 22 divide12 =10
August 27, 2013

physics
A car accelerates from 44 m/s to 52 m/s in 3.4 seconds. What distance is covered?
August 24, 2013

Maths
A ramp was built to move equipments into a shed. The ramp rises one foot. If the lower edge of the ramp is 8 feet from the base of the shed what is the approximate length in feet of the ramp Can someone please help me with this question
August 21, 2013

Sociology
Diane Kendall,9th edition, the question for assignment 1 is the review the top 10 values listed in textbook and decide which values are missing from the list and why were they not listed.
August 19, 2013

Pre Calculus 2
A ship regularly travels between two ports that are 350 miles apart. When traveling directly from A to B, the ship sails on a bearing of . However, to avoid a storm, one day the ship leaves A on a bearing of and travels for 6 hours at 17mph. When the bad weather has passed, it...
August 4, 2013

Calculus!!
Using the identity: L{f(t)/t}=integral F(p)dp (s -->infinity), find the integral of: sin(t)/t dt (0-->infinity)
July 28, 2013

Ehglish
How would you analyze an audience for the topic: Should regulations for home schools be changed?
July 27, 2013

Calculus HELP!
Use the fact that L{f'}=sF-f(0) to derive the formula for L{cosh at}
July 27, 2013

Chemistry
Okay, cool. So, the oxidation state of Co is 2+. Co2+ = [Ar]4s2 3d7 Metal cations get rid of the s orbital before the d, so can I say then the number of unpaired electrons is 7?
July 26, 2013

Chemistry
The complex [Co(ox)3]4- has a high-spin electron configuration. How many unpaired electrons are there in the complex? I know because it's a high-spin, it's tetrahydral shaped. But I don't know what (ox) is so, I'm stuck in finding the oxidation state of Co ...
July 26, 2013

Calculus
Find the Laplace transform of: f(t)=t-2e^(3t)
July 25, 2013

Chemistry
CoCl2<->CO+Cl2 Keq=7.6*10^-4 M CoCl2 is introduced in a closed container until its concentration is .890 M. What will be the concentration of Cl2 once the reaction has reached equilibrium?
July 20, 2013

Chemistry
How many liters of Cl2 has at a pressure of .950 atm and a temperature of 298K will be collected from the reaction of 25 mL of a .100 M aqueous solution of KMnO4 and an excess of HCI? KMnO4+HCI->MnCl2+Cl2+H2)+KCl
July 20, 2013

Chemistry
An aqueous solutions is 18.7% by mass Na3PO4. What is the boiling point of this solution? The Kb for water is .512 C/m. Consider if the solute is an electrolyte or a nonelectrolyte.
July 20, 2013

Chemistry
When the following reaction took place at 23.8 and a pressure of 758 torr, 3.9 L of o2 were collected. What mass of KCIO3 decomposed? KCIO3->KCI+O2
July 20, 2013

Chemistry
A mixture containing 5 g of H2 and 10 g of o2 is allowed to react in a 15 L rigid container at a constant temperature of 25 C. H2+O2->H2O Once the reaction is complete, what will be the pressure of the excess gas inside the container?
July 20, 2013

Chemistry
A sample of oxygen is collected over water at 22 C and 762 torr. What is the partial pressure of the dry oxygen? The vapor pressure of water at 22C is 19.8 torr.
July 20, 2013

Chemistry
A gas mixture containing N2 and O2 was kept inside a 2 L container at a temperature of 23 C and a total pressure of 1 atm. The partial pressure of oxygen was .722 atm. How many grams of nitrogen were present in the gas mixture?
July 20, 2013

Chemistry
A sample of oxygen is collected over water at 22 C and 762 torr. What is the partial pressure of the dry oxygen? The vapor pressure of water at 22C is 19.8 torr
July 20, 2013

Chemistry
Calculate the percent yield for the reaction if 76.8 g of H2O reacted and 125 g of NO were produced. NO2+H2O->HNO3+NO
July 20, 2013

Chemistry
Calculate how much acetylene (C2H2) can be produced from 358 g of H20 and an excess of CaC2 if the perfect yield for this reaction is 94.5% CaC2+H2)-> C2H2+C2H2+CA(OH)2
July 20, 2013

Chemistry
Calculate the number of moles of excess reactant that will be left-over when .350 g if HCN react with .500 g of 02: HCN+O2->N2+CO2+H20
July 20, 2013

Solution Set
The Y-coordinate of the solution of the system {x+y=3 {-3x+2y=-19 the answer is -2 how? I've done everything to try to solve!
July 18, 2013

Calculus
Find the complete solution to the 2nd ODE: 2y''+3y'+y=t^(2)+3sin(t)
July 18, 2013

Solution Set
Find the solution of |x-2|>8 The answer is {1,4} how?
July 17, 2013

Chemistry
Identify the type of structural isomerism that exists in each of the following pairs of compounds. (a) [CoCl2(NH3)4]Cl·H2O and [CoCl(NH3)4(H2O)]Cl2 coordination isomerism geometrical isomerism hydrate isomerism ionization isomerism linkage isomerism optical isomerism (b...
July 17, 2013

Chemistry
Identify the type of structural isomerism that exists in each of the following pairs of compounds. (a) [CoCl2(NH3)4]Cl·H2O and [CoCl(NH3)4(H2O)]Cl2 coordination isomerism geometrical isomerism hydrate isomerism ionization isomerism linkage isomerism optical isomerism (b...
July 17, 2013

Chemistry
1. Write the formula for these compounds: a) sodium tris(oxalato)rhodium(III) b) sodium tetrachloroplatinate(II) c) triamminetrichloronickel(IV) sulfate For a) I put: Na3Rh(C2O4)3, however got an error message of this: "Your answer appears to be missing required square ...
July 17, 2013

Simplify Math
m^(3/4)/m^(5/4)m^-2 hopefully you understand the equation.
July 13, 2013

Linear Equation
A gas station sells regular gas for $2.20 per gallon and premium gas for $2.70 a gallon. At the end of a business day 220 gallons of gas were sold and receipts totaled $519. How many gallons of each type of gas were sold? I know its a linear equation. just cant find out how to...
July 12, 2013

Chemistry
A couple questions here: 1. How do you expect nitriding to change the properties of iron? a) Nitriding makes iron stronger. b) Nitriding makes iron weaker. c) Nitriding makes iron more electrically conductive. d) Nitriding makes iron less electrically conductive. 2. Calculate ...
July 10, 2013

business communication
would you please rephrase it? my boss has given me to rewrite it for international employees. i want it to have in simple english so that every body can understand
July 10, 2013

business communication
can you plz correct it Howdy comrades! Shouldn’t surprise anyone that we took a beating this year, given the insane pricing moves our knucklehead competitors have been making. I mean how those clowns can keep turning a profit is beyond me, what with steel costs still ...
July 10, 2013

Calculus-HELP!!!
Find a general solution to the first – degree ordinary differential equation. If an initial condition is given, find the corresponding particular solution. Write solution explicitly if possible: dx/dt=sqrt(x+t+1)
July 8, 2013

Calculus-HELP PLZ !!!!
Find a general solution to the first – degree ODE. If an initial condition is given, find the corresponding particular solution. Write solution explicitly if possible. (9x^2+y-1)dx-(4y-x)dy=0, y(1)=0
July 7, 2013

Calculus
Find a general solution to each first – degree ODE. If an initial condition is given, find the corresponding particular solution. Write all solutions explicitly if possible. dr/dè = r^(2)/è
July 5, 2013

Calculus
Show that both functions y1=e^(-2x) and y2=xe^(-2x) are solutions to the differential equation y^''+4y^'+4y=0
July 2, 2013

Statistics
A company has developed a new type of light bulb, and wants to estimate its mean lifetime. A simple random sample of 12 bulbs had a sample mean lifetime of 692 hours with a sample standard deviation of 30 hours. It is reasonable to believe that the population is approximately ...
July 1, 2013

Chemistry
Dinitrogen pentoxide, N2O5, decomposes by first-order kinetics with a rate constant of 0.15 s-1 at 353 K. (a) What is the half-life (in seconds) for the decomposition of N2O5 at 353 K? (b) If [N2O5]0 = 0.0579 mol·L-1, what will be the concentration of N2O5 after 4.0 s...
June 28, 2013

Chemistry
a) 2A --> B + C b) 2A --> B + C c) 2A --> 3B + C
June 28, 2013

Chemistry
Determine the rate constant for each of the following first-order reactions. In each case, write the rate law for the rate of loss of A. (a) 2 A B + C, given that the concentration of A decreases to one-fourth its initial value in 57 min (b) 2 A B + C, given that A0 = 0.036 ...
June 28, 2013

Chemistry
The presence of a catalyst provides a reaction pathway in which the activation energy of a certain reaction is reduced from 125 kJ·mol-1 to 75 kJ·mol-1. (a) By what factor does the rate of the reaction increase at 293 K, all other factors being equal? (b) By what...
June 28, 2013

Chemistry
Ethane, C2H6, forms ·CH3 radicals at 700.°C in a first-order reaction, for which k = 1.98 h-1. (a) What is the half-life for the reaction? (b) Calculate the time needed for the amount of ethane to fall from 1.00 10-3 mol to 2.48 10-4 mol in a 500. mL reaction vessel...
June 28, 2013

Chemistry
When 0.13 g of H2 and 0.18 g of I2 are confined to a 150. mL reaction vessel and heated to 700. K, they react by a second-order process (first order in each reactant), with k = 0.063 L·mol-1s-1 in the rate law (for the rate of formation of HI). (a) What is the initial ...
June 28, 2013

Chemistry
Dinitrogen pentoxide, N2O5, decomposes by a first-order reaction. What is the initial rate of decomposition of N2O5 when 3.6 g of N2O5 is confined in a 0.77 L container and heated to 65°C? For this reaction, k = 5.2 x 10^-3 s-1 in the rate law (for the rate of ...
June 28, 2013

Chemistry
Dinitrogen pentoxide, N2O5, decomposes by first-order kinetics with a rate constant of 0.15 s-1 at 353 K. (a) What is the half-life (in seconds) for the decomposition of N2O5 at 353 K? (b) If [N2O5]0 = 0.0579 mol·L-1, what will be the concentration of N2O5 after 4.0 s...
June 28, 2013

Chemistry
a) 2A --> B + 2C b) A --> C + 2D
June 28, 2013

Chemistry
Determine the rate constant for each of the following second-order reactions. In each case, express your results in terms of the rate law for the loss of A. (a) 2 A B + 2 C, given that the concentration of A decreases from 2.74 mmol·L-1 to 1.46 mmol·L-1 in 122 s...
June 28, 2013

Chemistry
I understand, but what is K or how can I determine K?
June 28, 2013

Chemistry
I don't understand how to figure out K. I used the information in the problem given to solve for k, and then plug that k in to solve for t, but it's not the correct answer.
June 28, 2013

Chemistry
The half-life for the second-order reaction of a substance A is 58.2 s when A0 = 0.63 mol L-1 Calculate the time needed for the concentration of A to decrease to the following values. (a) one-third of its original value (b) one-sixth of its original value (c) one-seventh of ...
June 28, 2013

Chemistry
A total charge of 96.5 kC is passed through an electrolytic cell. Determine the quantity of substance produced in each of the following cases. (a) the mass (in grams) of silver metal from a silver nitrate solution (b) the volume (in liters at 273 K and 1.00 atm) of chlorine ...
June 21, 2013

Chemistry
Predict the standard emf of each of the following galvanic cells. (a) Sn(s)|Sn2+(aq)||Sn4+(aq),Sn2+(aq)|Pt(s) (b) Pt(s)|Fe3+(aq),Fe2+(aq)||Ag+(aq)|Ag(s) I don't want the answer, I want the procedure/methods of how to do these types of problems.
June 21, 2013

Chemistry
Balance the reaction of plumbate ions and hydrochlorite ions: Pb(OH)42-(aq) + ClO-(aq) → PbO2(s) + Cl- I put: Pb(OH)3-(aq) + ClO-(aq) → PbO2(s) + Cl-(aq) + H2O(l) + OH-(aq) It said: The reaction described in your answer is not balanced. One or more of your ...
June 21, 2013

Chemistry
Reaction of hydrazine with chlorate ions N2H4(g) + ClO3-(aq) → NO(g) + Cl-(aq) Balanced: 3N2H4(g) + 4ClO3-(aq) → 6NO(g) + 6H2O(l) + 4Cl-(aq) Reducing agent: ClO3- Oxidizing agent: N2H4 Right?
June 21, 2013

Chemistry
Either my online portal hates me, or I don't understand how to balance properly. QUESTION Balance reaction of arsenic(III) sulfide with nitric acid As2S3(s) + NO3-(aq) → H3AsO4(aq) + S(s) + NO(g) Is this the correct balanced equation? 32 H2O + 24 As2S3(s) + 80 H+(aq...
June 21, 2013

Chemistry
Sorry, for the oxidizing, I put this: Fe^2+
June 21, 2013

Chemistry
Balance each of the following skeletal equations by using oxidation and reduction half reactions. All the reactions take place in acidic solution. Identify the oxidizing agent and reducing agent in each reaction. (Use the lowest possible coefficients. Include states-of-matter ...
June 21, 2013

Physics (trig)
The height of an outdoor basketball backboard is 12 1/3 feet and the backboard casts a shadow 19 1/5 feet. Find the angle of elevation of the sun (answer in units of degrees). Can someone help me with the formula? Thank you!
June 19, 2013

Physics (algebra)
the sonar of a navy cruiser detects a submarine that is d=4601 ft from the cruiser. the angle between the water level and the submarine is 0=32 degrees. What formula should I use to solve?
June 18, 2013

maths
a sum of money trebles in 9years 4 months.in how many years will it double
June 15, 2013

Chemistry
The pH of 0.40 M HF(aq) is 1.93. Calculate the change in pH when 0.301 g of sodium fluoride is added to 53.7 mL of the solution. Ignore any change in volume.
June 14, 2013

chemistry
Suppose that 0.483 g of an unknown monoprotic weak acid, HA, is dissolved in water. Titration of the solution with 0.250 M NaOH(aq) required 42.0 mL to reach the stoichiometric point. After the addition of 21.0 mL, the pH of the solution was found to be 3.75. (a) What is the ...
June 14, 2013

Chemistry
moles of H2SO3 = 0.0246 moles of 2NaOH = 0.04925 Second stiochiometric point volume: 400. mL First stiochiometric point volume: 200. mL Thanks!
June 14, 2013

Chemistry
What volume of 0.123 M NaOH(aq) must be added to 125 mL of 0.197 M H2SO3(aq) to reach the following points? (a) the first stoichiometric point (b) the second stoichiometric point
June 14, 2013

Chemistry
What volume of 0.123 M NaOH(aq) must be added to 125 mL of 0.197 M H2SO3(aq) to reach the following points? (a) the first stoichiometric point (b) the second stoichiometric point
June 14, 2013

physics
12
June 14, 2013

CALCULUS
Find the gradient and directional derivative of f at P in the direction of v: f(x,y)=ln(x^2 + y^2 +1)+ e^(2xy) P(0,2) v=5i-12j
June 2, 2013

Calculus - HELP plz!
Find all of the first partial derivatives of f(x,y,z)=arctan y/xz
June 2, 2013

vectors
why are the answers in the back of my textbook,[3,4,-1], [4,5,-5], [2,3,3]
May 27, 2013

vectors
find three points on each plane [x,y,z]= [3,4,-1]+s[1,1,-4]+ t[2,-5,3]
May 27, 2013

physics
a horizontal force of 600Npulls two masses 10kg lying on a frictionnnnless surface connected by a light string .what is the tension in the string?Does the answer depend on which mass end the pull is applied
May 26, 2013

physics
explai biot-savart,law.an electron with velocity 3*107ms1 describe a circular path in a uniform magnetic field of 0.2T,perpendicular to it.calculate the radius of path
May 23, 2013

math
at a certain factory each worker either drives to work or take the bus. the ratio of worker who take the bus to those who drive to work is 2:5. if 120 worker drive to work how many workers are there at the factory?
May 16, 2013

Physical Science
my dear , how did you get this formula of KE, KE=mv2/2 and the mass is equal to (rho)(volume ) so KE=(RHO)(VOLUME)(V2)/2 ,, I confused , can you explain more please
May 13, 2013

Physical Science
Thank you
May 13, 2013

Physical Science
- What is the kinetic energy ,KE, per unit volume V of blood that has a speed of 0.5 m/s. Take density ofĉblood = 1.0x103kg/m3
May 13, 2013

Microbiology
How can lab practices and safety precautions help reduce hazards in a lab setting? How do you handle blood cultures and pathogenic strains in a lab to minimize contamination?
May 3, 2013

maths
Consider the following system of inequalities: {(c−1)x^2+2cx+c+4≤0 cx^2+2(c+1)x+(c+1)≥0 The sum of all real values of c, such that the system has a unique solution, can be written as ab, where a and b are coprime positive integers. What is the value of a+b? ...
May 3, 2013

statistics
the probability that a house in an urban area will develop a leak is 5%. if 23 houses are randomly selected, what is the probability that none of the houses will develop a leak?
April 28, 2013

Chemistry
What is the pH of a solution of 40.0 ml of 0.800 M HCl titrated with 4.00 ml of 1.00 M Hydroxyl amine?
April 24, 2013

Physics :(( help please TT
thanxxxxxxx hero.........
April 23, 2013

chemistry
how many gram of h2 needed to react with 3.10 n2
April 18, 2013

chemistry
how many gram of h2 needed to react with 3.10 n2
April 18, 2013

PHYSICS
The only force acting on a particle is conservative force F. If the particle is at point A, the potential energy of the system associated with F and the particle is 39 J. If the particle moves from point A to point B, the work done on the particle by F is +25 J. What is the ...
April 17, 2013

CALCULUS-plz help!
For the curve r = 2 sin 3(theta): Find the arc length of one petal
April 16, 2013

CALCULUS-plz help!
For the curve r = 2 sin 3(theta): Find the arc length of one petal
April 16, 2013

Math
I think I figure it out. The answer is: 12 A ^2 * 2 A * - 31 + 4 A * 6 + / I figured that that the square sign and the number 2 count as one operator. For ^2 I just use the x^2 button on the calculator and it gave me the same answers.
April 15, 2013

Math
I need to change this expression to postfix form. (12*A^2-2*A+31)/(4*A+6) I know how to do this except for the squaring part. I got stuck. This is my try. 12 A 2 ^ * 2 A * - 31 + 4 A * 6 + / When I test this in a calculator, it gives different results. Another problem is that ...
April 15, 2013

biology
i am researching an article and am having trouble understanding the title. can someone please explain to me in simple terms: Deficiency of a Beta-arrestin-2 signal complex contributes to insulin resistance. so what is a beta arrestin 2 signal complex?
April 15, 2013

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