Friday

May 6, 2016
Total # Posts: 701

**Chemistry-please help**

Posted by anne on Friday, October 14, 2011 at 6:30pm. Hi, I have a question on HPLC (high performance liquid chromatography). The procedure says to use a 4.6 x 150mm x 3um column. The relative retention time of Impurity B with reference to the main peak is about 0.5min. If I ...
*October 14, 2011*

**Chemistry**

Hi, I have a question on HPLC (high performance liquid chromatography). The procedure says to use a 4.6 x 150mm x 3um column. The relative retention time of Impurity B with reference to the main peak is about 0.5min. If I use a 4.6 x 100mm x 2.7um column, will the relative ...
*October 14, 2011*

**Pre-Calculus**

Could someone help me with this-we learned this today in school but I'm not getting it now that I'm home with my homework-I have lots of these to do can someone help with this one and then maybe it'll click-thank you Find (sqrt3/2 -1/2i)^4 by using DeMoivre's ...
*October 10, 2011*

**Algebra**

2 pumps can fill a water tank in 45 minutes when working together. Alone, the second pump takes 3 times longer than the first to fill the tank. How long does it take the first pump alone to fill the tank? Show all work
*October 9, 2011*

**Math**

Zachary saved x nickels and y dimes last month. Lily saved x nickels and 2y dimes. Lily saved $2 more than Zachary and the total number of her dimes is 4 times the total number of her nickels. (a) How much coins does Zachary have? (b) How much did Lily save? (c) How much did ...
*October 6, 2011*

**US government**

What is the freedom from prior restraint?
*October 2, 2011*

**Finance**

A state's lottery winner is promised $200,000 a year for 3 years(starting at the end of the first year). Interes rate is annually 7 percent on its fund. How much is the present value of this lottery?
*September 29, 2011*

**trig**

Cos(2x+30)-Sin(3x-20)
*September 28, 2011*

**math**

Zachary saved x nickels and y dimes last month. Lily saved x nickels and 2y dimes. Lily saved $2 more than Zachary and the total number of her dimes is 4 times the total number of her nickels. (a) How much coins does Zachary have? (b) How much did Lily save? (c) How much did ...
*September 22, 2011*

**physics**

A woman rides a carnival Ferris wheel at radius 16 m, completing 4.2 turns about its horizontal axis every minute. What are (a) the period of the motion, and the magnitude of her centripetal acceleration at (b) the highest point and (c) the lowest point?
*September 19, 2011*

**English**

with people
*September 12, 2011*

**English**

What are the ways of getting acquainted?
*September 12, 2011*

**french**

What would I use before etait in this statement ?"Nous avons beaucoup aime notre sejour en France . ..... etait splendide."
*September 11, 2011*

**environmental science**

what are the environmental parameters of intertidal zone?
*August 22, 2011*

**Chemistry**

I have 2 chemicals, A & B. Note: both do not contain buffer salts. Chemical A expires 1 week later. Chemical B expires next year. I prepare solution C (general laboratory reagent)containing Chemicals A & B. When assigning the expiry date of solution C, does this mean the ...
*July 23, 2011*

**CHEMISTRY**

Discuss in detail the healthcare applications of chemical reactions. Which chemical reactions would you consider to be of importance to healthcare professionals? Why? In which situations are these chemical reactions useful to healthcare professionals?
*July 21, 2011*

**Physics**

He meant 'Physics' as the subject instead of 'Tamucc', which stands for Texas A&M University - Corpus Christi. He must be taking the summer physics class at TAMUCC.
*July 7, 2011*

**maths**

1)Please check that you entered this answer correctly, as it is written now I'm not convinced it can be factored. 2)6x^2+5x-4=0 (3x+4)(2x-1) 3)x^2=3x x^2-3x=0 x(x-3) 4)x(x-3)=-2 x^2-3x=-2 x^2-3x+2 (x-2)(x-1) 5)4x^2+11x+6 (4x+3)(x+2)
*July 6, 2011*

**Calculus**

A car passes by a certain point at t = 0 hours heading east at 40 miles/hour. At t = 1 hour, another car passes by the same point heading north at 50 miles/hour. Which of the following functions equals the distance L (in miles) between the two cars as a function of t, for t is...
*June 14, 2011*

**algebra**

12(x-6)=2(x-9) x equals?
*June 11, 2011*

**math**

Sunae's group of close friends are going to fifth grade in September. All are going to Belleview Elementary and their homerooms will be rooms 12, 14, or 16. All of her friends but 4 are going to room 12, all but 4 are going to room 14, and all but 4 are going to room 16. ...
*May 28, 2011*

**Physics**

The helicopter view in the figure below shows two people pulling on a stubborn mule. Assume that F1 is 130 N, and F2 is 65 N. The forces are measured in units of newtons (N). (a) Find the single force that is equivalent to the two forces shown. In both magnitude and direction...
*May 18, 2011*

**Physics**

An astronaut takes a space trip to newly discovered palnet X. measurements from earth indicate that: Mx=3Me and Rx=2Re. What is the acceleration of gracity gx on this planet as a multiple of ge?
*May 18, 2011*

**Physics**

can u explain it in another way
*May 17, 2011*

**Physics**

Suppose the stone is thrown at an angle of 32.0° below the horizontal from the same building (h = 49.0 m) as in the example above. If it strikes the ground 69.3 m away, find the following. (Hint: For part (a), use the equation for the x-displacement to eliminate v0t from ...
*May 17, 2011*

**Physics**

In a physics lab experiment, a spring clamped to the table shoots a 18 g ball horizontally. When the spring is compressed 20 cm, the ball travels horizontally 4.9 m and lands on the floor 1.3 m below the point at which it left the spring. What is the spring constant?
*May 17, 2011*

**Physics**

A 18 kg child slides down a 4.0 m-high playground slide. She starts from rest, and her speed at the bottom is 2.8 m/s. What is the change in the thermal energy of the slide and the seat of her pants?
*May 14, 2011*

**physics**

A ball is thrown vertically upward with a speed of +12.0 m/s. How long does the ball take to hit the ground after it reaches its highest point? What is its velocity when it returns to the level from which it started?
*May 14, 2011*

**biology**

can alcohol go through a visking tubing?
*May 12, 2011*

**math**

At Andrews sweet shop almond fudge costs $5.23 per pound, and vanilla fudge costs $4.17 per pound. Allison buys 0.75 pound of almond fudge and 1.25 pounds of vanilla fudge. About how much will Allison pay altogether (excluding tax)?
*April 19, 2011*

**Chemistry-atoms**

A. How many protons are in one atom of fluorine - 19? B. How many neutrons are in one atom of potassium - 39? C. How many electrons are in one neutral atom of V - 51? D. What is the symbol for the element that has 78 protons? E. What is the symbol for the neutral atom that has...
*April 14, 2011*

**Physics**

How do I find Period T(s) and Period^2 T^2 (s^2), given mass(kg) = 0.1 and Average time for ten vibrations (s) = 5.05?
*April 12, 2011*

**physics**

At what distance (in m) from a 3.8 mC charge is the electric potential equal to 32 V? (k = 9 x 109 Nm2/C2)
*March 22, 2011*

**Psycology**

Psychology and Health Problems Paper
*March 17, 2011*

**statistics**

A population is normally distributed with a mean of 40 and a standard deviation of 6. For samples of size 10, what is the probability that the sample mean will be more than 42?
*March 17, 2011*

**medical coding**

What OB/GYN subspecialties specializes in the use of a hysteroscopy?
*March 14, 2011*

**computer science**

Opera Mobile is an example of: a smartphone. a wireless ISP. SmartMedia. a microbrowser.
*March 1, 2011*

**Physics**

2 trains with 132Hz horns approach one another. The slower train has a speed of 25m/s. what is the speed of the fast train if an observer standing near the tracks between the trains hears a beat frequency of 5.2 Hz?
*February 28, 2011*

**math**

give exact and approximate solutions to three decimal places y^2-12y+36=4
*February 27, 2011*

**Organic Chemistry **

Starch
*February 20, 2011*

**Organic Chemistry **

What is the substrate of the enzyme amylase?
*February 20, 2011*

**Chemistry **

Write the reversible equation for the esterification and hydrolysis of glyceryl ethanoate
*February 7, 2011*

**Math**

I need to find the inverse function of f(x)=sqrt(x^2+2x), where x>o This is as far as I got: x=sqrt(y^2+2y) How in the world am I going to isolate for y? Should I complete the square underneath the square root symbol, and then use the quadratic equation? Does that work? :/
*January 25, 2011*

**math**

4 25cent of 20
*January 18, 2011*

**History **

thankkkyouuu :D
*January 18, 2011*

**History **

Any info about Liberals and conservatives? (mexico history)
*January 18, 2011*

**chemistry**

If an alcohol solution has a pH of 5 would it be a primary, secondary or tertiary alcohol or a phenol?
*January 18, 2011*

**Math**

Use a ruler to create a 6" x 8" rectangle. Cut rectangle on a diagonal. Use the two triangles to create four new shapes. List the most specific shape and its perimeter
*January 13, 2011*

**math**

49<squareroot of 52<64 true or false
*January 10, 2011*

**math**

49<squareroot of 52<64 true or false
*January 10, 2011*

**business math**

A store buys 30 gallons of milk at $1.58 per gallon. To achieve a 20% markup based on cost, what should be the selling price per gallon rounded to the nearest cent?
*January 6, 2011*

**Physics**

A 11 kg object and a 19 kg object are connected by a massless compressed spring and rest on a frictionless table. After the spring is released, the object with the smaller mass has a velocity of 12 m/s to the left. What is the velocity of the object with the larger mass?
*January 4, 2011*

**11th grade**

4. The use of technology such as telephones and computers means that money exchanges and other financial transactions can be a. based on the U.S. dollar all over the world. b. converted to prices in any currency. c. made instantaneously. d.sensitive to variations in any ...
*December 21, 2010*

**Math**

Find the slope of the secant line on f joining the points at x = e and x = 2e.
*December 18, 2010*

**Chemistry**

I'm working on this same problem I'm right there with you until the last step where you have Mass Water x 2257.56 = 34752.8 Can you explain to me where the 2257.56 comes from? THANKS!
*December 11, 2010*

**math**

latoya has 3/4 of a bag of popcorn. If she eats half of the popcorn at the movie, how much does she have left?
*December 9, 2010*

**Math question**

I don't understand how to find the aproximate area of a shaded region This problem has a big cirlce with 1/4 shadded with a radius of 20 cm. the answer chocies are A. 90 cm squared B. 270 cm squared C. 314 cm squared D. 1.256 cm squared how do I find the answer?
*December 7, 2010*

**chemistry**

A compound,KBrOx, is analyzed and found to contain 52.92% Br by mass. What is the value of x?
*December 6, 2010*

**Science**

If India had a population of 1.05 billion in 2002 with a steady growth rate of .9%, when would its population reach 4.2 billion?
*December 5, 2010*

**Finance**

A non-profit hospital's asset definition is >$1500, but they want to buy 10 chairs at $200 each - for a total purchase price of $2000. The useful life of the chairs would be 15 yrs, per AHA guidelines. Can this purchase be capitalized & depreciated over the life or must...
*December 3, 2010*

**Chemistry **

If you add acid or base to a buffer, how will the pH change.
*December 1, 2010*

**math**

a cold front moves in at noon and in 5 hours, the temperature had dropped 23%. the temperature at 5:00 p.m. was 14%. let x be the temperature at noon. write an equation to find x.
*November 30, 2010*

**chemistry**

This question has three paarts: 1. Determine the mass of water formed when 14.5L NH3 (at 298K and 1.5 atm) is reacted with 19.3 L of O2 (at 321K and 1.2 atm) 4NH3+O2-->4NO+6H2O I got the answer of 19 g H2O 2.What are the partial pressures for all gases that remain at the ...
*November 20, 2010*

**chemistry**

What are the partial pressures for all gases in 4NH3+O2-->4NO+6H2O that remained at the end, if the reaction took place in a sealed 50.0L tank and the final temperature is 345K?
*November 20, 2010*

**URGENT! Temperature Conversion problem help!**

never mind problem resolved
*November 15, 2010*

**Physics**

the only force acting on the rocket in the time its in the air is gravity. so the force acting against it (the force that propels it) is the force coming out of the rocket's exhaust which is greater than gravity.
*November 14, 2010*

**Chemistry**

Consider the combustion of propane (C3H8) in the presence of oxygen: C3H8+5O2 => 3CO2+4H2O How many grams of O2 are required to react completely with 3 moles of propane?
*November 11, 2010*

**Physics**

I mean it's horizontal velocity.
*November 10, 2010*

**Physics**

Since it's Okm/h, if the pencil is relased on the road will it still be Okm/h? Thanks
*November 10, 2010*

**Physics**

Suppose you are standing in the aisle of a bus traveling along a straight road at 100km/h, and you hold a pencil still above your head. Then relative to the bus, the velocity of the pencil is 0km/h, and relative to the road, the pencil has a horizontal velocity of? a. less ...
*November 10, 2010*

**Physics**

As you approach the I-90 exit in your uncle's little red sports car convertible, you happen to notice a cat crossing the road. Not that you have any particular love of cats (especially this one, whose snooty disposition seems to beckon for a game of chicken), but you ...
*November 1, 2010*

**Chemistry**

find the reaction quotient: partial pressures are: p of N2=.903, P of H2=.888, P of NH3=.025
*October 31, 2010*

**Chemistry**

find the reaction quotient: partial pressures are: p of N2=.903, P of H2=.888, P of NH3=.025
*October 31, 2010*

**physics.**

Sound with a frequency of 261.6Hz travels through water at a speed of 1435m/s.
*October 25, 2010*

**geography**

how thick is the bedrock in the inetrior plains and why is it so thick
*October 24, 2010*

**college**

When I was considering what to do with my $10,000 Lottery winnings, my broker suggested I invest half of it in gold, the value of which was growing by 12% per year, and the other half in CDs, which were yielding 5% per year, compounded every 6 months. Assuming that these rates...
*October 20, 2010*

**Math 1320**

When I was considering what to do with my $10,000 Lottery winnings, my broker suggested I invest half of it in gold, the value of which was growing by 12% per year, and the other half in CDs, which were yielding 5% per year, compounded every 6 months. Assuming that these rates...
*October 20, 2010*

**physics**

My answer for this question A 11.0 kg box is released on a 37 degreesincline and accelerates down the incline at 0.25 m/s^2. What is the coefficient of kinetic friction? My answer was 68.2 and it was incorrect.
*October 15, 2010*

**physics**

For the question about friction force impeding motion. I'm sorry I tried what you wrote and did not get the correct answer. Its' not your fault. I am doing university phys and have never taken it before. I am little confused about what to do. Could you put it in steps...
*October 15, 2010*

**physics**

Part C Piles of snow on slippery roofs can become dangerous projectiles as they melt. Consider a chunk of snow at the ridge of a roof with a pitch of 21 degrees. If the edge of the roof is 11.0 above ground, what is the speed of the snow when it hits the ground?
*October 15, 2010*

**physics**

Part B Piles of snow on slippery roofs can become dangerous projectiles as they melt. Consider a chunk of snow at the ridge of a roof with a pitch of 21. As the snow begins to melt, the coefficient of static friction decreases and the snow eventually slips. Assuming that the ...
*October 15, 2010*

**physics**

Piles of snow on slippery roofs can become dangerous projectiles as they melt. Consider a chunk of snow at the ridge of a roof with a pitch of 21. What is the minimum value of the coefficient of static friction that will keep the snow from sliding down in units uK?
*October 15, 2010*

**physics**

A 11.0 box is released on a 37 incline and accelerates down the incline at 0.25 .What is the coefficient of kinetic friction in units uk? What is the friction force impeding its motion in N?
*October 15, 2010*

**physics**

I worked it through and checked it didn't make sense to me. But I have to finish the assignment soon so I put the answer in anyway. Thanks for you patience.
*October 15, 2010*

**physics**

For my question about the carton's speed must I do each step you laid out or just the last one? I got the wrong answer. Thanks for your help.
*October 15, 2010*

**physics**

A carton lies on a plane tilted at an angle theta 29 degrees to the horizontal, with a friction of uk .12.If the carton starts from rest 7.90 up the plane from its base, what will be the carton's speed when it reaches the bottom of the incline?
*October 15, 2010*

**physics**

A flatbed truck is carrying a heavy crate. The coefficient of static friction between the crate and the bed of the truck is 0.66.What is the maximum rate at which the driver can decelerate and still avoid having the crate slide against the cab of the truck?
*October 15, 2010*

**physics**

A 11.0 box is released on a 37 incline and accelerates down the incline at 0.25 .What is the coefficient of kinetic friction?
*October 15, 2010*

**science**

i need to define variable, independent variable, control and control group. HELP!
*October 7, 2010*

**geometry**

The perimeter of a quadrilateral is 56. The lengths of three consecutive sides are 9, 13, and 16. What is the length of the fourth side?
*October 1, 2010*

**math**

The perimeter of a quadrilateral is 56. The lengths of three consecutive sides are 9, 13, and 16. What is the length of the fourth side?
*October 1, 2010*

**Math-New Geometry**

Choose the correct property illustrated by the following statement: If 3m¡ÐZ = 90¨¬, then m¡ÐZ = 30¨¬ Please help know its either division property or reflexive property...im not sure wich though..if any one knoes its very appreciated thxx
*September 29, 2010*

**2nd grade**

How would you explain this to a teacher that says the first one is correct?
*September 28, 2010*

**2nd grade**

Please tell me which sentence is correct. Adrian chose him and I for the job. *Adrian chose him and me for the job.
*September 28, 2010*

**Chemistry -help**

To determine the sodium carbonate content & total alkali in NaOH, the following steps were performed:- 1) 2.0g of NaOH was dissolved in 80ml of CO2 free water. 2) 3 drops of phenolphthalein indicator were added and the solution was titrated with 1M HCl. Colour changed from ...
*September 18, 2010*

**Chemistry- Dr Bob please help **

Thanks Dr Bob,the purpose of this experiment is to test for the clarity of my sodium hydroxide sample. I intend to boil deionized water to get CO2 free water, cool the water and add it to a 100mL volumetric flask containing 10g of solid NaOH. Would that be alright? Also, can ...
*September 18, 2010*

**Chemistry- please help**

Thanks, can you then explain the exact steps (including the apparatus to use) so that the procedure can be followed? Thanks a lot:)
*September 18, 2010*

**Chemistry- please help**

I have test procedure to evaluate the clarity of a sodium hydroxide (NaOH) sample that goes like this: Dissolve 10g of NaOH in carbon dioxide free water and dilute to 100ml with the same solvent. Please explain how to perform this test. Do I boil 100ml of deionized water and ...
*September 18, 2010*

**Chemistry**

I have test procedure to evaluate the clarity of a sodium hydroxide (NaOH) sample that goes like this: Dissolve 10g of NaOH in carbon dioxide free water and dilute to 100ml with the same solvent. Please explain how to perform this test. Do I boil 100ml of deionized water and ...
*September 18, 2010*

**college**

A thirteen-year-old girl, who is underdeveloped and thin, has a blood disorder. She frequently experiences chest and abdominal pain, fever, and coughing, and has trouble breathing. Her teachers often spend additional time with her, explaining concepts that the rest of the ...
*August 25, 2010*