# Posts by SARA

Total # Posts: 4,514

**English**

Alright, thanks for your help!

**English**

I am not sure either. I haven't written this piece. It was an exercise for my homework assignment.

**English**

Thankyou Writeacher :) I don't know #4 either. Would this work?: Toxicity assessment of oil sands use process affected water for fish cell lines.

**English**

Thanks Anonymous! I need help with paraphrasing this sentence: Toxicity assessment of oil sands process-affected (process affected) water using fish cell lines.

**English**

- Yes, Take oil out of the sands is much more smoother. - AB means Alberta. - This phrase seems akward to me: Natives get sick from eating to (too) many fish from mercury and air pollution is another big problem.

**English**

I need help with editing these sentence structures shown below, which is used in this writing piece. For example, can we break it into two sentences. This way it would make or sense. 1). Natives get sick from eating to (too) many fish from mercury and air pollution is another ...

**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 ...

**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 ...

**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...

**pre calcalus**

(x+4)^2/3=9

**math**

i didn't get how 16x^2 turned into 8x^2 16x^2 = 30x + 4 Solving for x, 8x^2 - 15x - 2 = 0

**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?

**Sociology**

I need to break a folkway and write an essay on it - any ideas?

**American Gov**

What is the primary claim made by those who oppose hate crimes legislation?

**Geography**

thank you Ms.sue

**Math**

144

**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

**physics**

A car accelerates from 44 m/s to 52 m/s in 3.4 seconds. What distance is covered?

**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

**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.

**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...

**Calculus!!**

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

**Ehglish**

How would you analyze an audience for the topic: Should regulations for home schools be changed?

**Calculus HELP!**

Use the fact that L{f'}=sF-f(0) to derive the formula for L{cosh at}

**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?

**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 ...

**Calculus**

Find the Laplace transform of: f(t)=t-2e^(3t)

**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?

**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

**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.

**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

**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?

**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.

**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?

**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

**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

**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

**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

**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!

**Calculus**

Find the complete solution to the 2nd ODE: 2y''+3y'+y=t^(2)+3sin(t)

**physics**

ok

**Solution Set**

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

**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...

**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...

**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 ...

**Simplify Math**

m^(3/4)/m^(5/4)m^-2 hopefully you understand the equation.

**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...

**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 ...

**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

**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 ...

**mathematics**

(5,400) the actual value of y-the predicted value 400-471.44=-71.44 big difference between the actual value and predicted value of y therefore the regression equation is not very reliable.

**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)

**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

**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

**Calculus**

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

**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 ...

**physics**

a) μ = Fc/FN (i) FN =(950x9.8)+12000= 21310 Fc =(950)(46)^2/120= 16751 Putting values in (i) μ=0.7860 (no unit) b) v= sqrt(rμg)= sqrt[(120)(0.7860)(9.8)] v= 30.40 m/s^2

**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...

**Chemistry**

a) 2A --> B + C b) 2A --> B + C c) 2A --> 3B + C

**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 ...

**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...

**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...

**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 ...

**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 ...

**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...

**Chemistry**

a) 2A --> B + 2C b) A --> C + 2D

**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...

**Chemistry**

I understand, but what is K or how can I determine K?

**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.

**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 ...

**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 ...

**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.

**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 ...

**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?

**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...

**Chemistry**

Sorry, for the oxidizing, I put this: Fe^2+

**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 ...

**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!

**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?

**maths**

a sum of money trebles in 9years 4 months.in how many years will it double

**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.

**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 ...

**Chemistry**

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

**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

**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

**physics**

12

**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

**Calculus - HELP plz!**

Find all of the first partial derivatives of f(x,y,z)=arctan y/xz

**vectors**

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

**vectors**

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

**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

**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

**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?

**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

**Physical Science**

Thank you

**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 ofƒâblood = 1.0x103kg/m3

**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?

**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? ...

**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?

**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?