Tuesday

March 3, 2015

March 3, 2015

Total # Posts: 957

**Chemistry**

Consider the following reaction: CO(g)+H2O(g)⇌CO2(g)+H2(g) Kp=0.0611 at 2000 K A reaction mixture initially contains a CO partial pressure of 1348torr and a H2O partial pressure of 1780torr at 2000 K. Calculate the equilibrium partial pressure of CO2. Calculate the ...
*February 25, 2015*

**Biology**

describe how a population is thought to evolve through natural selection. Provide an example (specifically, the peppered moth)
*February 20, 2015*

**Chemistry**

name all the possible isomers of methyl nitrobenzoate and nitroacetanilide which can be formed
*February 11, 2015*

**Organic Chem**

Why does the carotene elute from the column before the chlorophylls?
*February 11, 2015*

**Organic Chem**

Why does the carotene elute from the column before the chlorophylls?
*February 11, 2015*

**Organic Chemistry**

Why does the carotene elute from the column before the chlorophylls?
*February 11, 2015*

**Chemistry**

Why does the carotene elute from the column before the chlorophylls?
*February 11, 2015*

**Chemistry**

Why does the carotene elute from the column before the chlorophylls?
*February 11, 2015*

**Chemistry**

Why does the carotene elute from the column before the chlorophylls?
*February 11, 2015*

**Chemistry**

A solution of 4-methyl-3-penten-2-one in ethanol shows an absorbance of 0.52 at 236 nm in a cell with a 1-cm light path. Its molar absorptivity in ethanol at that wavelength is 12,600 M^-1 cm^-1. What is the concentration of the compound?
*February 11, 2015*

**Chemistry**

A solution of 4-methyl-3-penten-2-one in ethanol shows an absorbance of 0.52 at 236 nm in a cell with a 1-cm light path. Its molar absorptivity in ethanol at that wavelength is 12,600 M^-1 cm^-1. What is the concentration of the compound?
*February 11, 2015*

**Chemistry**

Why does the carotene elute from the column before the chlorophylls?
*February 11, 2015*

**Chemistry**

Why should a mixture to be separated by column chromatography be introduced onto the column in a minimum amount of solvent?
*February 11, 2015*

**Chemistry**

Arrange the following compounds in order of decreasing ease of elution from a column of silica gel: a) 2-octanol; b) 1,3-dichlorobenzene; c) tert-butylcyclohexane; d) benzoic acid
*February 5, 2015*

**Chemistry**

name* Thanks for help DR. Bob
*February 4, 2015*

**Chemistry**

Okay i'll keep my answers the same. What do you think is the answer. Tert-butylcyclohexane > 1,3-dichlorobenzene > 2-octanol > benzoic acid
*February 4, 2015*

**Chemistry**

What precautions must be taken when you introduce a mixture of compounds to be separated onto a liquid chromatography adsorbent column?
*February 4, 2015*

**Chemistry**

oh no man. i just want different answers to see if the answers are right. And if people agree. I just don't want to take chances. Do you have a background in chemistry or something? I have no background in chemistry so i don't know if i'm seeing a right answer or ...
*February 4, 2015*

**Chemistry **

Once the adsorbent is packed in a liquid chromatography column, it is important that the level of the elution solvent not drop below the top of the adsorbent. Why?
*February 4, 2015*

**Chemistry **

What precautions must be taken when you introduce a mixture of compounds to be separated onto a liquid chromatography adsorbent column?
*February 4, 2015*

**Chemistry **

Once the adsorbent is packed in a liquid chromatography column, it is important that the level of the elution solvent not drop below the top of the adsorbent. Why?
*February 4, 2015*

**physics**

a metal object is suspended from a spring balance scale. the scale reads 800 N when it is suspended in air and 700 N when the object is completely submerged in water. find the buoyant force, the volume and the density of the metal.
*February 3, 2015*

**world history**

why is the ability to debate still important todat
*February 2, 2015*

**chemistry**

In 100 mL of distilled water,1.0g of thallium cholirde is added. How much of the 1.0g of TlCl doen't dissolve? The Ksp of TlCl is 3.6 x 10-6
*February 2, 2015*

**chemistry**

Please help !? Knowing that the concentration of Ag+ in a silver chromate solution is 1.5 x 10-3 M, calculate its solubility product at 25°C.
*February 2, 2015*

**chemistry**

Stuck on this one please help ! The solubility of barium sulphate, BaSO4, is 2.4 x 10-4 g/100 mL of solution. Calculate the Ksp of this solution.
*February 2, 2015*

**chemistry**

In 100 mL of distilled water,1.0g of thallium cholirde is added. How much of the 1.0g of TlCl doen't dissolve. The Ksp of TlCl is 3.6 x 10-6.
*February 1, 2015*

**chemistry**

Please help?! if 600 mL of a 0.04M KCl solution is mixed with 50mL of a 0.03M Na2SO4 solution, will a precipitate be formed? Explain your reasoning and/or show all calculations?
*February 1, 2015*

**chemistry**

I have no idea how to go about this question, please help! A clumsy chemist accidentally pours 100 mL of a 0.004 M Na2SO4 solution into a beaker containing 500 mL of 0.050 M CaCl2. Will a precipitate be formed? Explain your reasoning and/or show all calculations?
*February 1, 2015*

**chemistry**

Stuck on this questions ?! please help The solubility of barium sulphate, BaSO4, is 2.4 x 10-4 g/100 mL of solution. Calculate the Ksp of this solution.
*February 1, 2015*

**physics**

A ball is dropped from an upper floor, some unknown distance above your apartment. As you look out of your window, which is 1.5 m tall, you observe that it takes the ball 0.18 seconds to traverse the length of the window. Determine how high above the top of your window the ...
*January 30, 2015*

**AP Chemistry**

A sample of air contains 12.8 µg/m3 of beryllium dust. How many atoms of beryllium are present in a room with dimensions of 8 feet by 13 feet by 15.1 feet? Answer in units of atoms
*January 20, 2015*

**Chemistry**

You have a tank of helium with a volume of 10 liters that is currently under 40 atm of pressure. If you open the valve on the tank and release the helium into a room with a volume of 10,000 liters, how many atmospheres of pressure will the helium now be under? Second, what ...
*December 18, 2014*

**math**

A boat traveled 210 miles downstream and back. The trip downstream took 10 hours. The trip back took 70 hours. What is the speed of the boat in still water. What is the speed of the current?
*December 15, 2014*

**Math**

(13.98 + 3.96)=17.94/6=2.99
*December 12, 2014*

**Chemistry, Vapor Pressure**

Select the pair of substances in which the one with the higher vapor pressure at a given temperature is listed first. 1. C7H16, C5H12 2. CCl4, CBr4 3. H2O, H2S 4. CH3CH2OH, CH3-O-CH3 5. Xe, Kr
*December 11, 2014*

**Analytical Chemistry**

Calculate the ppm of the sodium ions when 2.91 g of sodium triphosphate are added to 2.33 L of solution. I earnestly have no idea how to solve this...
*December 9, 2014*

**Math**

) A car dealership advertises a 15% discount on all its new cars. In addition, the manufacturer offers a $1000 rebate on the purchase of a new car. Let x represent the sticker price of the car. a. Suppose only the 15% discount applies. Find a function f that models the ...
*December 4, 2014*

**ratio proportions**

The ratio of apples to oranges is 4:5. I have 200 apples and oranges total. How many are apples?
*November 18, 2014*

**math**

a basketball team needs 5 players. the team can choose from a group of 7 players. explain how to find the combinations of players that can be on the team.
*November 18, 2014*

**chemistry**

The vapor pressure of liquid chloroform, CHCl3, is 100. mm Hg at 283 K. A 0.198 g sample of liquid CHCl3 is placed in a closed, evacuated 400. mL container at a temperature of 283 K. Assuming that the temperature remains constant, will all of the liquid evaporate? What will ...
*November 11, 2014*

**Math**

A marine biologist is testing a new under water probe. The probe is catapulted from the ship into the air, descends under water to a predetermined depth, and then returns to the surface where it can be collected. The function that models the probe’s path is f(x) = 15t2...
*October 30, 2014*

**Chemistry**

what is the limiting reagent in these two reactions Reaction 1: CuSO4+2NaOH=Cuo+Na2SO4+H2O Reaction 2: CuSO4+NaCO3=CuCO3+Na2SO4
*October 22, 2014*

**Calculus**

An inverted conical tank is being filled with water, but it is discovered that it is also leaking water at the same time. The tank is 6 meters high and its diameter at the top is 4 meters. The water is being added to the tank at a constant rate. Some of this water is found to ...
*October 19, 2014*

**Calculus**

A bright light on the ground illuminates a wall 12 meters away. A man walks from the light straight toward the building at a speed of 2.3 m/s. The man is 2 meters tall. When the man is 4 meters from the building, how fast is the length of his shadow on the building decreasing?
*October 19, 2014*

**Calculus**

A pulley system on a pier is used to pull boats towards the pier for docking. Suppose that a boat is being docked and has a rope attaching the boat's bow on one end and feeding through the pier's pulley system on the other end. The pulley system is 1 meter higher than ...
*October 19, 2014*

**Check my answer?**

Conditional statement based on a Venn diagram 2 circles: large circle says quadrilaterals smaller inner circle says squares If a shape is a square then it is a quadrilateral.
*September 29, 2014*

**physics**

A ball is thrown straight upward. At 4.36 m above its launch point, the ball's speed is one-half its launch speed. What maximum height above its launch point does the ball attain?
*September 21, 2014*

**Math**

I don't know it
*September 15, 2014*

**Math**

Help please
*September 15, 2014*

**Math**

Find the distance between points (6, 16) and (–1, 14) to the nearest tenth
*September 15, 2014*

**Math**

Find the other endpoint given the first endpoint and the midpoint A = (3, 5) B = (5, -11) find C
*September 15, 2014*

**Maths**

A boy is flying a kite on a string 33m long. The string which is being held at 1.5m above the ground, makes an angle of 39* with the horizontal. How high is the kite above the ground (nearest cm)
*September 14, 2014*

**Calculus**

Suppose the area under the curve y=xe^(-mx) from 0 to 1 is 0.4. Find m.
*September 8, 2014*

**Calculus**

I am trying to find the total area under the curve, not just the integral...
*September 7, 2014*

**Calculus**

Suppose the total area under the curve y=x^2-mx+1 from 0 to 5 is 11.3024. Find m. I know that this means that i need to find the integral of the absolute value of x^2-mx+1 from 0 to 5 and set it equal to 11.3024, but I am not sure where to go from there.
*September 7, 2014*

**math**

56.67 is correct?
*September 3, 2014*

**math**

Find each unit rate. Round to the nearest hundredth if necessary. 357 miles in 6.3 hours
*September 3, 2014*

**math**

Find each unit rate. Round to the nearest hundredth if necessary. 5 pounds for $ 2.49
*September 2, 2014*

**math**

What is the slope of the budget line from trading with Friday (coconuts for fish)?
*August 24, 2014*

**calculus 2**

use the simpsons rule with n=10, arc length y=^3sqaure root x, for 1<=x<6
*July 29, 2014*

**calc 2**

find the maclaurin series for: f(x) = (1-3x)^-5. What is the radius of convergence?
*July 27, 2014*

**Physics (HEELPPP)**

A coin with a diameter of 1.90 cm is dropped on edge onto a horizontal surface. The coin starts out with an initial angular speed of 14.4 rad/s and rolls in a straight line without slipping. If the rotation slows with an angular acceleration of magnitude 1.88 rad/s2, how far ...
*June 27, 2014*

**chemistry**

At a certain temperature, Keq is 4.13 x 10^-5 for the equilibrium: 2IBr(g) ↔ I2(g) + Br2(g) Assume that the equilibrium is established at the above temperature by adding only the reactant to the reaction flask. What are the concentrations of I2 and Br2 in equilibrium ...
*June 5, 2014*

**Global history**

Compare and contrast European colonization of the Americas in the 16th and 17th centuries with European colonization of Africa and Asia in the 18th and 19th centuries. Be sure to address the motives for colonization and the impact that colonization had on native peoples. (Just...
*May 28, 2014*

**Math**

I think your answer looks fine. We are doing this in my school as well. The question is rather open for personal opinion, so as long as you can back it up, it is fine. Sorry if this does not help
*May 28, 2014*

**Physics**

an electron is sitting 10cm away from a small object -5nc it is let go and moves away from the charged object when it reaches a distance of 15 cm away find its speed
*May 26, 2014*

**geometry**

if a cone is 7.5 cm high and has a vertical angle of 70 degree calculate the diameter of its base.
*May 16, 2014*

**Logic**

Even if you know only some of them please help! 1. Give a proof of the following: (∀F)( (P)( [ιxGx][Px] ⊃ F(P) ) ⊃ F(G)) (∃F)( (P)( F(P) ≡ [ιxGx][Px]) Therefore, E!(ιxGx) 2. Prove the following: [ιxMx][Thales believed that Bx...
*May 14, 2014*

**Trigonometry**

Two radar stations are 50 miles apart. Both are tracking the same plane. At this moment, the angle between station 1 and the plane is 73 degrees and the angle between station 2 and the plane is 46 degrees. How far is the plane from station 2?
*May 6, 2014*

**physics**

Sunlight strikes the surface of a lake at an angle of incidence of 44.5°. At what angle with respect to the normal would a fish see the Sun?
*May 4, 2014*

**physics**

How would a diamond look if there were no dispersion?
*May 4, 2014*

**physics**

Question Part Points Submissions Used 1 2 3 4 0/0.37 0/0.37 –/0.37 –/0.37 4/15 1/15 0/15 0/15 Total 0/1.48 ...A diamond in air is illuminated with white light. On one particular facet, the angle of incidence is 46.05°. Inside the diamond, red light (ë = 660...
*May 4, 2014*

**physics**

A diamond in air is illuminated with white light. On one particular facet, the angle of incidence is 46.05°. Inside the diamond, red light (ë = 660.00 nm in vacuum) is refracted at 17.38° with respect to the normal; blue light (ë = 470.00 nm in vacuum) is ...
*May 4, 2014*

**physics**

Sunlight strikes the surface of a lake at an angle of incidence of 44.5°. At what angle with respect to the normal would a fish see the Sun?
*May 4, 2014*

**Economics**

Based on the Nielsen ratings, the local CBS affiliate claims its 11 p.m. newscast reaches 41% of the viewing audience in the area. In a survey of 100 viewers, 36% indicated that they watch the late evening news on this local CBS station. What is the alternate hypothesis? H1...
*April 27, 2014*

**Statistics**

The claim that "38% of those persons who retired from an industrial job before the age of 60 would return to work if a suitable job was available," is to be investigated at the 0.02 level of risk. If 86 out of the 200 workers sampled said they would return to work, ...
*April 27, 2014*

**Statistics**

An accelerated life test on a large number of type-D alkaline batteries revealed that the mean life for a particular use before they failed is 19.0 hours. The distribution of the lives approximated a normal distribution. The standard deviation of the distribution was 1.2 hours...
*April 11, 2014*

**Statistics**

You take a trip by air that involves three independent flights. If there is an 67% chance each specific leg of the trip is on time, what is the probability all three flights arrive on time? (Round your answer to 3 decimal places.) Probability= ? My answer is 0.301 3 decimal ...
*April 5, 2014*

**Statistics **

A survey of top executives revealed that 37% of them regularly read Time magazine, 21% read Newsweek and 38% read U.S. News & World Report. Eleven percent read both Time and U.S. News & World Report. What is the probability that a particular top executive reads either Time or ...
*April 4, 2014*

**Statistics**

You take a trip by air that involves three independent flights. If there is an 67% chance each specific leg of the trip is on time, what is the probability all three flights arrive on time? (Round your answer to 3 decimal places.) Probability=
*April 4, 2014*

**Statistics**

A survey of top executives revealed that 37% of them regularly read Time magazine, 21% read Newsweek and 38% read U.S. News & World Report. Eleven percent read both Time and U.S. News & World Report. What is the probability that a particular top executive reads either Time or ...
*April 4, 2014*

**Statistics**

Thank you
*April 4, 2014*

**Statistics**

The National Center for Health Statistics reported that of every 894 deaths in recent years, 25 resulted from an automobile accident, 185 from cancer and 309 from heart disease. What is the probability that a particular death is due to an automobile accident? 25/309 or 0.081 ...
*April 4, 2014*

**Chemistry**

Complete ionic equation and net ionic equation for 2 K3PO4 + 3 Fe(NO3)2 --> 6 KNO3 + Fe3(PO4)2
*March 26, 2014*

**Chemistry**

CIE and NIE for 2 K3PO4 + 3 Fe(NO3)2 --> 6 KNO3 + Fe3(PO4)2
*March 26, 2014*

**CHemistry**

SO2(g) + H2O(l)= H2SO(l) What mass of sulfur dioxide is needed to prepare 36.86 g of H2SO3(l)
*March 26, 2014*

**Chemistry**

CIE and NIE for 2 K3PO4 + 3 Fe(NO3)2 = 6 KNO3 + Fe3(PO4)2
*March 26, 2014*

**physics**

How long will it take a watch dropped from a bridge (20.3 meters above the water) to hit the water?
*March 26, 2014*

**grammar**

Thank you Writeacher
*March 18, 2014*

**grammar**

In The Space Before Each of the Following items, place a C if the capitalization is correct, a zero (0) if it is incorrect. Then insert capitals where should be, and draw a line through capitals that should be small letters. 1.the Rocky Mountains i got C 2.my spanish course i ...
*March 18, 2014*

**Calculus Check my answer **

Find the area between the curves y= x^2/2 +2 and y = –x – 3 on the interval –4 ≤ x ≤ 4. I got 40/3 is that correct?
*March 11, 2014*

**Calculas**

Find the area of the region under the curve y = 12 e ^{3 x} between x = -2.6 to x =2.6
*March 8, 2014*

**Calculas**

The slope of the tangent line to the graph of a function, h(t) is 7/2t The function passes through the point (5,3) Find h(4)
*March 2, 2014*

**IT**

Write a program that asks for the name of the employee, an hourly pay rate and hours worked. Compute gross pay (hours X rate), withholding tax, and net pay (gross pay minus withholding tax). Withholding tax is computed as a percentage of gross pay based on the following: Gross...
*February 23, 2014*

**physics**

Drag-race tires in contact with an asphalt surface have a very high coefficient of static fric.tion. Assuming a constant acceleration and no slipping of tires, estimate the coefficient of static friction needed for a drag racer to cover 2.1 km in 8 s, starting from rest. ...
*February 21, 2014*

**physics**

A person stands on a bathroom scale on a motionless elevator. When the elevator begins to move, the scale briefly reads 200 percent of the person's regular weight. Calculate the acceleration of the elevator, a_{elevator}. Use SI units
*February 21, 2014*

**Middle School Math Help Please**

You have a glass of juice in front of you, and you drink 1/6 of it. Then you pour as much water into the glass as you drank of the juice. Your drink 1/3 of this mixture and again you pour as much water into the glass as you drank of the mixture. Now you drink 1/2 of the ...
*February 19, 2014*

**calculas**

Consider the function f(x) = 7 xe^{-7.5 x}, 0<_x<_2. This function has an absolute minimum value equal to: which is attained at x=
*February 19, 2014*

**calculas**

A landowner wants to fence in a rectangular area of 60000 square metres and divide it into three parts with two parallel fences both parallel to one side of the rectangle. Each part will have a different grazing crop for the herds. What is the shortest total length of fence ...
*February 19, 2014*

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