# Posts by SARA

Total # Posts: 4,473

**Chemistry**

Balance the reaction using half reactions under BASIC conditions: Al + CrO4^-2 ---> Al(OH)3 + Cr(OH)3 I tried to solve this question and ended up with this: Here are the two half equations Al ---> Al(OH)3 CrO4^-2 ---> Cr(OH)3 For Al ---> Al(OH)3, I did 3OH^- + 3H2O...

*May 21, 2015*

**Macroeconomics**

If investors sell their stocks and increase their money holdings due to a bad economy then A. demand for loanable funds will increase. B. demand for loanable funds will decrease. C. supply of loanable funds will increase. D. supply of loanable funds will decrease. E. quantity ...

*May 20, 2015*

**cell notation**

Given the balanced net ionic equation Zn(s) + 2H^+(aq) <---> Zn^2+(aq) + H2(g) would the cell notation be: Zn|Zn^2+||2H^+|H2 (i'm not sure if hydrogen gas should be in the cell notation)

*May 20, 2015*

**Chemistry**

From the equation below, how many grams of barium sulfate can be produced from 20.8 g of barium chloride? BaCl2 + Na2SO4 -> BaSO4 + 2NaCl

*May 19, 2015*

**Chemistry**

When 2.05 moles of CH4 are mixed with 5.03 moles of O2 in the reaction below, the limiting reactant is CH4 + 2O2 -> CO2 + 2H2O

*May 19, 2015*

**Chemistry**

Balance the reaction using half reactions under BASIC conditions: Al + CrO4^-2 ---> Al(OH)3 + Cr(OH)3 I'm not sure how to do this question.

*May 19, 2015*

**chemistry- Check please**

I am also supposed to write out a balanced equation and cell notation equation for each reaction that produced a positive voltage, but all of mine were positive

*May 15, 2015*

**chemistry- Check please**

Well I'm a bit confused. I have an assignment where I am to do an online lab. First I'm supposed to find the highest and lowest voltage. For all of my Ecell, I got a positive answer. I have another question which says "Explain what a negative voltage on the volt ...

*May 15, 2015*

**chemistry- Check please**

I am given a question where I have to state which combination of electrodes will result in the greatest voltage and which will result in the lowest voltage. The metals given are Zinc, Copper, Silver and Hydrogen I calculated the Ecell for each combination and got the following...

*May 15, 2015*

**Math**

Can someone help me? If a and b are any two real numbers, explain how you calculate the difference a – b. Be sure to include the following in your explanation: a. A description of the relationship between addition and subtraction b. How you can use a number line to help ...

*May 14, 2015*

**Please help**

If there had not been a system of military alliances in place in Europe in 1914, would the assassination of Archduke Franz Ferdinand have resulted in World War I?

*May 13, 2015*

**Please help**

How did World War I and its aftermath contribute to the rise of fascism in Europe in the 1920s?

*May 13, 2015*

**Please help**

I think it is 2nd one?

*May 13, 2015*

**Please help**

Which best describes Hitler's beliefs as expressed in Mein Kampf? Revolution was needed to create a classless society. Germany could control the world with the help of the Japanese. All races could live peacefully under German domination. Jewish people were to blame for ...

*May 13, 2015*

**Please help**

Which is true about communism but is not true about fascism? uses secret police creates powerful leaders opposes democracy has the ultimate goal of equality is it the second?

*May 13, 2015*

**History**

Which best describes Vladimir Lenin's vision for Russia? Professional revolutionaries would seize power for the working class. The Red Army would achieve victory over Germany in World War I. Democratic revolution would depose the tsar. An alliance with Britain and France ...

*May 12, 2015*

**Lit**

sorry for late responses but im trying to work on the paper as much as i understand

*May 12, 2015*

**Lit**

use

*May 12, 2015*

**Lit**

how would puse ethos,pathos, and logos for this topic

*May 12, 2015*

**Lit**

I need help, we start to write a research paper and we picked our own topic, 1 requirement was to use (mlk letter from birmingham jail) how do i relate this to inequality in wealth distribution.

*May 12, 2015*

**Chemistry-check answer please**

I am given a question where I have to state which combination of electrodes will result in the greatest voltage and which will result in the lowest voltage. The metals given are Zinc, Copper, Silver and Hydrogen I think that silver and copper would give the greatest voltage ...

*May 12, 2015*

**Chemistry**

I'm not sure where to start. Is this correct so far? I first write a balanced chemical equation using HF and water HF+ H2O <->H3O^+ + F^- The use the ICE table where the E row is: HF=0.50-x H30+= x F-= 0.75+x Then the Ka equation Ka=[H3O+][A-]/[HA] where Ka=(x)(0.75+...

*May 12, 2015*

**Chemistry**

Determine the pH of a buffer made from 250 ml of 0.50M HF and 150 ml of 0.75 M NaF.

*May 12, 2015*

**Chemistry**

thanks!

*May 12, 2015*

**Chemistry**

How would I find the pH of 0.25 M carbonic acid? also the pH for 0.075 M CN^-?

*May 12, 2015*

**Chemistry**

Determine the molar solubility of Y for XY2 if Ksp is 2.2x10^-4. The 2 in Xy2 is a subscript. I found the Ksp equation which is ksp=[x^2+][Y^-]^2 Then I did the ICE table and got x and 2x for the equilibrium concentrations. Then I did: 2.2x10^-4=(x)(2x)^2 I solved for x and ...

*May 12, 2015*

**Chemistry**

the answer is supposed to be 7.5x10^-5 but I don't know how

*May 12, 2015*

**Chemistry**

Determine Ksp if the equilibrium concentration of X is 0.02 M and Y is 0.05 M given that X2Y(s)<-->2X^+(aq)+Y^(2-)(aq). The 2 in X2Y is a subscript.

*May 12, 2015*

**SOLVED**

solved this question

*May 12, 2015*

**Chemistry**

Determine Qsp if 8.7 ml of 2.1 M AgNO3 is added to 1.7 ml of 1.5 M CaCl2 .The Ksp of AgCl is 1.77 x 10^-10.

*May 12, 2015*

**English**

1.D 2.D 3.D I'm not sure

*May 11, 2015*

**English**

Story : The Ethanol Debate Natalie Stewart What feature of the selection BEST illustrates that it is a persuasive essay? A) < -- A? the chart showing the rise in corn prices B) the information on how farmers feed their herds C) the description of how ethanol use costs ...

*May 11, 2015*

**Chemistry**

hmm ok thanks though!

*May 11, 2015*

**Chemistry**

I think it is the percent yield. the answer is 86.029411764706 but i'm not sure how

*May 11, 2015*

**Chemistry**

The reaction N2(g)+3H2(g)<-->2NH3(g) begins with 1.15 M N2 and 1.36 M H2. At equilibrium the concentration of NH3 is 0.78 M. Determine the extent of reaction.

*May 11, 2015*

**Math**

Select the inequality that models the problem. The length of a rectangle is four times its width. If the area of the rectangle is less than 100 square meters, what is the greatest width of the rectangle? 4w + w < 100 4 + 4w < 100 4w < 100 4w • w < 100

*May 11, 2015*

**English**

Researchers from around the world have declared this fast-acting, appetite suppressant as a modern medical miracle for Americans who struggle with weight loss. A)transfer B)plain folks C)testimonial D)name calling C ?

*May 11, 2015*

**general math**

if 3 1/2 bags of seed cost $35, what will 4 1/2 bags cost?

*May 8, 2015*

**Math**

Eduardo started a business selling sporting goods. He spent $7500 to obtain his merchandise, and it costs him $300 per week for general expenses. He earned $850 per week in sales. What is the minimum number of weeks it will take for Eduardo to make a profit? Write an ...

*May 7, 2015*

**Math**

The length of a rectangle is four times its width. If the perimeter is at most 130 centimeters, what is the greatest possible value for the width? 13 cm 21.7 cm 26 cm 52 cm

*May 7, 2015*

**math 0312**

The current in a stream moves at a speed of 9 mph. A boat travels 17 mi upstream and 17 mi downstream in a total time of 13 hrs. What is the speed of the boat in still water?

*May 4, 2015*

**Statistics**

SAT scores are distributed with a mean of 1,500 and a standard deviation of 300. You are interested in estimating the average SAT score of first year students at your college. If you would like to limit the margin of error of your 95% confidence interval to 25 points, how many...

*May 2, 2015*

**Chemistry**

A flask contains 25.0 mL of diethyl ether weighth 18.74 µg (micrograms). What is the density of the diethyl ether and grams per liter? I'm not sure how to set this problem up correctly.

*May 1, 2015*

**Chemistry**

Sulfur dioxide reacts with chlorine to produce thionyl chloride and dichlorine oxide S: 32.0 amu O: 16.0 amu Cl: 35.45 amu SO2 + 2Cl2 --> SOCl2 + Cl2O If 0.400 moles of chlorine gas reacts excess sulfur dioxide, how many moles of dichlorine oxide are forme?

*May 1, 2015*

**Chemistry**

Aluminum metal reacts with iron (III) oxide to produce aluminum oxide and iron metal. Answers the following three questions note: you will need to write a balanced equation to answer them Al: 26.9 amu Fe: 55.8 amu O: 16 amu 1 How many moles of iron (III) oxide are required to ...

*May 1, 2015*

**Chemistry**

Solutions of sodium hypochlorite, NaClO are sold as bleach. They are prepared by the following reaction: 2NaOH + Cl2 --> NaCl + NaClO + H2O If you have 2.32 mol of NaOH and 2.74 mol of Cl2 ga available to react, answer the following questions Na: 23.0 amu Cl:35.5 amu O: 16....

*May 1, 2015*

**Chemistry**

A flask contains 25.0 mL of diethyl ether weighth 18.74 µg (micrograms). What is the density of the diethyl ether and grams per liter?

*May 1, 2015*

**Chemistry**

In an experiment, 13g of methanol and 11 g of carbon monoxide were placed in a reaction vessel. Given the following reaction C:12.0 amu O:16.0 amu H:1.0 amu CH3OH + CO --> HC2H3O2 1 What is the theoretical yield of acetic acid? 2 If the actual yield of acetic acid is 19.1 g...

*May 1, 2015*

**Chemistry**

How can you write this formula? I'm stuck

*May 1, 2015*

**Chemistry**

A mixture containing 11.9 g of calcium fluoride and 10.3 g of sulfuric acid is heated to drive off hydrogen fluorid. Given the following reaction what is the me maximum number of grams of hydrogen fluoride that can be obtied? Ca: 40.0 amu F: 19.0 amu H: 1.0 amu S 32.0 amu CaF2...

*May 1, 2015*

**Chemistry**

Molarity What is the final volume (in Liters) of a solution prepared by diluting 25 mL of 8.25 M sodium hydroxide to a concentration of 2.40 M?

*May 1, 2015*

**Chemistry**

An organic compound consists of only carbon, hydrogen, and oxygen. Through combustion analysis, 5.671g of water and 36.933g of carbon dioxide are formed from 17.422g of sample. C:12.0 amu O: 16.0 amu H:1.0 amu In the space provided please write the empirical formula and, if ...

*May 1, 2015*

**chemistry**

Calculate the mass of oxygen gas required to occupy a volume of 6 L at a pressure of 20.9 kPa and a temperature of 37◦C.

*April 30, 2015*

**Calculus**

What is the solution to the following system of equations -2x+3y+z=5 x+5y+2z=17 To do this, I used elementary operations and isolated x to get 13y+5z=37. Is that correct so far? How would I continue?

*April 30, 2015*

**Calculus**

How would I find the equilibrant of three vectors? I am given a graph of three different vectors which meet at the point (0,0)

*April 30, 2015*

**Calculus**

If 3(a,3,2)-2(3,b,b)=(-3,1,-2) determine a and b. Describe the set spanned by the vectors. I don't know how to answer this

*April 30, 2015*

**Solved?**

I found the derivative of y=3x-1 which is y=3. Then I had the two differentiated equations equal one another: 2x+3=3 and solve for x: x=0 Then I subbed x into f(x)=x^2+3x+2 and got y=2 So the coordinate is (0,2)?

*April 30, 2015*

**Calculus**

What are the coordinates of the point on the graph of f(x)=(x+1)(x+2) at which the tangent is parallel to the line with equation 3x-y-1=0? a)(-3,2) b)(-1,0) c)(0,2) d)(1,6) To answer this, I put f(x)=(x+1)(x+2) into the form f(x)=x^2+3x+2 and found the derivative which is f&#...

*April 30, 2015*

**Calculus**

What does it mean to span in R2? I have this question: Which of the following sets if vectors span R2? a) {(1,1),(-2,-2)} b) {(1,1),(1,2)} c) {(1,2),(1/2,2)} d) {(-1,1),(1,-1)}

*April 29, 2015*

**Calculus**

Thanks! I was overthinking the question

*April 29, 2015*

**Calculus**

An airplane is heading due east with an airspeed of 220km/h when it encounters a wind from the south at 76km/h. What is the direction of the resultant velocity of the airplane The answer is E19.06°N but I don't know how

*April 29, 2015*

**SOLVED**

I made a mistake... i figured it out

*April 29, 2015*

**calculus**

For the function f(x)=x^3e^x, determine intervals of increase and decrease and the absolute minimum value of f(x) To do this I found the derivative which is f'(x)=3x^2e^x. Then I set it to zero: f'(x)=0 0=3x^2e^x How would I isolate x? And when I do, I would sub that x...

*April 29, 2015*

**Calculus**

Can you please explain how I would solve these questions? 1) Which point is 2 units from the line 12x-9y-5=0? a)(8,3) b)(7/6, -7/3) c)(14,6) d)(1,1) 2.) Which of the following sets of vectors spans R2: a) {(1,1),(-2,-2)} b) {(1,1),(1,2)} c) {(1,2),(1/2,2)} d) {(-1,1),(1,-1)}

*April 29, 2015*

**Calculus**

Susan pulls on a rope sleigh with a force of 120 N. If the rope makes an angle of 25 degrees with the horizontal, what is the force that tends to lift the sleigh? a)120.00 N b)108.76 N c)50.71 N d)84.85 N how would you know?

*April 28, 2015*

**Help**

What are some things you can skip?

*April 28, 2015*

**Calculus**

How would I find the second derivative if f(x)= √(x^3+2) using the quotient rule. I got to the step where [(12x√(x^3+2))-(9x^4/√(x^3+2))]/4(x^3+2) how would i go from that to: (3x(x^3+8))/(4(x^3+2)^3/2)

*April 27, 2015*

**critical numbers**

thanks!

*April 27, 2015*

**critical numbers**

How would I find the critical numbers of f'(x)=(x-3)^3(x+4)(x^2+1)? The answer is x=-4, x=3

*April 27, 2015*

**English**

What does Georgiana represent in "The Birthmark"? feminine perfection<----- evil and greed the rewards of hard work the price of madness

*April 24, 2015*

**AP CHEM**

The pKa of acetic acid is 4.74. What is the buffering range of this acid and its conjugate base? Explain.

*April 22, 2015*

**Laboratory Chemistry**

The activity of a stock isotope is 10,000 DPM/0.10mL. If 0.25 ml of this stock is placed in 2.50 ml of water, what is the activity in the diluted specimen? My guess is that I just multiply the 10,000 DPM by the 1/10 dilution factor. I then come up with 1,000DPM/0.10ml. Does ...

*April 20, 2015*

**Vectors**

correction, the two planes are coincident that the other intersects in line

*April 19, 2015*

**Vectors**

What is the nature of intersection of these three planes: 5x+3y-z=11 -2x-7y+10z=2 6x+21y-30z=-6 I know that the answer is two parallel planes and the other one intersecting in a line. my question is how would you know that the first equation intersects in a line? Would you use...

*April 19, 2015*

**Vectors**

Determine the vector equation of a plane that contains the line with symmetric equation (x+3)/-2=(y+1)/5=(z+2)/4 and the point P(1,3,0). For this question to find the direction vector you would use subtraction with the points (-3,-1,-2) and (1,3,0). Why would it be (1,3,0)-(-3...

*April 19, 2015*

**Vectors**

At what point does the line r=(-2,3,1)+s(2,3,-1) intersect the y-axis?

*April 18, 2015*

**Vectors**

thanks!

*April 17, 2015*

**Vectors**

What is the distance between the parallel lines having equations 2x+2y=16 and x+y=0? I'm getting 2 as my answer but the answer is supposed to be 4√2

*April 17, 2015*

**Vectors**

why does this equation 3xy +y = 0 represent two planes?

*April 17, 2015*

**Project help please!!**

but I don't know how to make it into a video/commercial :(

*April 16, 2015*

**Project help please!!**

I have to come up with a product (such as soap, face cream, shampoo, cleaning spray, etc) and make a commercial for it. and I have to make up a name for it and the stuff that's found in it. I can't think of any products, I was thinking a shampoo commercial but I don&#...

*April 16, 2015*

**calc**

If f(x) = 3x^2 − 2x, 0 ≤ x ≤ 3, evaluate the Riemann sum with n = 6, taking the sample points to be right endpoints.

*April 16, 2015*

**socials**

We're the sons of liberty justified in their treatment of the loyalists

*April 15, 2015*

**Vectors**

How would I convert cartesian equation to parametric? For example: 2x-y+3z-6=0

*April 14, 2015*

**calc**

A boat leaves a dock at 3:00 PM and travels due south at a speed of 20 km/h. Another boat has been heading due east at 15 km/h and reaches the same dock at 4:00 PM. How many minutes after 3:00 PM were the two boats closest together? (Round your answer to the nearest minute.)

*April 14, 2015*

**Math**

Some number added to -12 is 45. Add this number to 30. Multiply the answer by 3. What is the final number?

*April 14, 2015*

**science**

The answer is A. ventral tegmental area

*April 13, 2015*

**Science**

What does the electron shell rotate around?

*April 13, 2015*

**Vectors**

How are these two lines coincident? 1) r=(1,7)+s(2,5) 2) x=4t+3 y=10t+12

*April 12, 2015*

**business math**

Jen purchased a condo in Naples Florida for $699,000. She put 20% down and financed the rest at 5% for 35years. What are Jens total finance charge?

*April 12, 2015*

**algebra**

Factor: X^4 y-y^5

*April 11, 2015*

**math**

an airplane is flying 120 km south and 130km west of an airport. It is flying at a height of 10 km . what is the straight line distance to the airport?

*April 10, 2015*

**linear algebra urgent**

^ each of those 3 sets are vectors

*April 9, 2015*

**linear algebra urgent**

Use the Gram-Schmidt process to transform the basis 1 1 1 , 0 1 1 , 2 4 3 for the Euclidean space R3 into an orthonormal basis for R3.

*April 9, 2015*

**Social Studies**

The revolutionary war was fought on american soil. how do you think this fact influenced the role of women in war?

*April 9, 2015*

**linear**

Let W be the subspace of R5 spanned by the vectors w1, w2, w3, w4, w5, where w1 = 2 −1 1 2 0 , w2 = 1 2 0 1 −2 , w3 = 4 3 1 4 −4 , w4 = 3 1 2 −1 1 , w5 = 2 −1 2 −2 3 . Find a basis for W ⊥.

*April 9, 2015*

**Ib math**

The marks of 2376 students in an IB exam are normally distributed with mean 49 marks and variance 225 A) if the mark is 45 estimate the number of candidates who passed the exam? B) if top 7% of students are awarded a 7, find the minimum mark required to obtain a 7? mean=49 ...

*April 9, 2015*

**World History**

Thanks

*April 6, 2015*

**World History**

could you please explain what i'm suppose to do and give me some websites i can get information from.

*April 6, 2015*

**World History**

I need help. In a brief essay, explain three ways in which the Roman Catholic Church responded to the spread of Protestantism in the sixteenth century. Describe each part of the church’s response using specific facts.

*April 6, 2015*