Friday

September 30, 2016
Total # Posts: 889

**chemistry**

Thank you very much Dr. Bob for your help. I didn't post the original question, but was working on a similar problem. It probably would have taken me an hour to figure this out without your help. Thanks again!

*July 7, 2012*

**Math help please**

(This homework question was removed due to a copyright claim submitted by k12.com.)

*May 21, 2012*

**Chemistry**

Amino acid solution was made by taking 3.58 g of the dry amino acid and making it up to 1.00L in water. A 25.0 mL sample was taken and titrated with NaOH of concentration of 0.0493M, with the first equivalence point at 18.15 mL and the second equivalence point at 32.05 mL. ...

*May 20, 2012*

**combine functions.. please help.**

Given: f(x)=2x^2-x+1 g(x)=2 sin x h(x)=3^x Determine: a) f(g(x)) b) (h^-1 o f)(x) c) g(f(h(x)))) Please show steps, thank you very much.

*May 17, 2012*

**World Civilizations **

A Hindu society in Southeast Asia that resisted both Buddhism and Islam was

*May 4, 2012*

**5th grade math**

She either scored 196 or 327 points Explaination: Range is difference between greatest and smallest numbers. We know the answer of range that is 129. If we consider 325 as greatest number than we can subtract 129 from 325 and get smallest number - 196. If we consider 198 as ...

*April 19, 2012*

**chemistry**

The rate constant for this first-order reaction is 0.0570 s–1 at 400 °C. A-->Products After how many seconds will 14.0% of the reactant remain?

*March 23, 2012*

**geom/trig**

The base of a right rectanglar prism is 12 cm by 8 cm. The height is 5 cm. Find its surface area.

*March 5, 2012*

**algebra 2**

evaluate f(x) = x^-2/3 + x^-3 for each value of x. f(-8)

*March 5, 2012*

**math**

name two different numbers that are greater than .66 and less than .9

*February 22, 2012*

**calculus**

f(x)= 3x^7 +2x -9 If g(x)= f inverse of x and g(-4)= 1, what is g'(-4)? I know that f inverse is the same as 1/f'(x) but I'm not sure where to go from there.

*February 21, 2012*

**math**

Seven thousand raffle tickets are to be sold at $10 each to benefit a local community group. The prizes, the number of each prize to be given away, and the dollar value of winnings for each prize are as follows: Prize Number to Be Given Away Dollar Value Automobile 2 $21,730 ...

*February 11, 2012*

**math**

Suppose that an automobile parts wholesaler claims that .5 percent of the car batteries in a shipment are defective. A random sample of 200 batteries is taken, and four are found to be defective. (a) Use the Poisson approximation to find the probability that four or more car ...

*February 11, 2012*

**math**

A telephone company's goal is to have no more than 4 monthly line failures on any 100 miles of line. The company currently experiences an average of 5 monthly line failures per 50 miles of line. Let x denote the number of monthly line failures per 100 miles of line. ...

*February 11, 2012*

**math**

A telephone company's goal is to have no more than 4 monthly line failures on any 100 miles of line. The company currently experiences an average of 5 monthly line failures per 50 miles of line. Let x denote the number of monthly line failures per 100 miles of line. ...

*February 11, 2012*

**calculus**

Find the limit. lim h → 0 square root (49 + h) − 7 / h Note: Only 49 +h are under square root.

*February 2, 2012*

**chemistry**

A patient has 0.050 L of blood drawn and this volume of blood has a mass of 55.0 g. What is the density of the blood? Answer with the correct number of sig figs

*January 31, 2012*

**chemistry**

(3.84 x 103 x 0.764) + 1.59 answer with the correct sig figs

*January 31, 2012*

**Chemistry - Naming Compounds**

Name the following compound. Ba3Pb2 I don't really understand since both the elements are metals and usually these bonds occur with a metal and nonmetal or two nonmetals.

*January 30, 2012*

**chemistry**

Chloroquine is used to treat malaria. Studies have shown that an effective dose for children is 3.5 mg per kilogram (3.5 mg/kg) of body weight, every 6 hours. If a child weighs 21 kg, how many milligrams of this drug should be given in a 66 hour period?

*January 30, 2012*

**chemistry**

Which of the following is a situation where an object’s potential energy varies as a result of changes due to its chemical composition? The melting of ice. The burning of wood. A ball rolling down a hill. A parachute slowing a skydiver's fall.

*January 29, 2012*

**chemistry**

Which of the following is an example of a chemical change (change in chemical composition) that involves starting with a liquid and ending up with a gas? Burning gasoline (combustion). Boiling acetone. A pond evaporating. Condensation of steam.

*January 29, 2012*

**Calculus**

what is the inverse function of f(x)=-[sqrt(25-x^2]

*January 24, 2012*

**calculus (limits)**

Use limits to explain why f(x)= (7-3X)/(X+9) has a vertical asymptote.

*January 21, 2012*

**chemistry**

A solar heating specialist is considering paraffin as a possible solar heat collector. How many kilograms of paraffin would be needed to collect as much energy as 4.73 x 10^3 kg of water? The specific heat of paraffin is 2.90J/gxC. Hint: Assume the same temperature change.

*January 15, 2012*

**chemistry**

A solar heating specialist is considering paraffin as a possible solar heat collector. How many kilograms of paraffin would be needed to collect as much energy as 4.73 x 10^3 kg of water? The specific heat of paraffin is 2.90J/gxC. Hint: Assume the same temperature change.

*January 15, 2012*

**trig**

find the exact value of sin(u+v) given that sin u=3/5 and sin v= 15/17

*December 18, 2011*

**physical science**

27 KM/Hr

*December 18, 2011*

**Physics**

A race driver has made a pit stop to refuel. After refueling, he starts from rest and leaves the pit area with an acceleration whose magnitude is 5.4 m/s2; after 3.7 s he enters the main speedway. At the same instant, another car on the speedway and traveling at a constant ...

*December 13, 2011*

**Physics**

A jetliner, traveling northward, is landing with a speed of 66.5 m/s. Once the jet touches down, it has 766 m of runway in which to reduce its speed to 13.1 m/s. Compute the average acceleration (magnitude and direction) of the plane during landing (take the direction of the ...

*December 13, 2011*

**Physics**

In getting ready to slam-dunk the ball, a basketball player starts from rest and sprints to a speed of 11.1 m/s in 2.30 s. Assuming that the player accelerates uniformly, determine the distance he runs.

*December 13, 2011*

**Physics**

A race driver has made a pit stop to refuel. After refueling, he starts from rest and leaves the pit area with an acceleration whose magnitude is 5.4 m/s2; after 3.7 s he enters the main speedway. At the same instant, another car on the speedway and traveling at a constant ...

*December 13, 2011*

**math**

did you get the answer to this?

*November 23, 2011*

**physics **

a 1.29 kg ball is connected by means of two massless strings to a vertical, rotating rod. The strings are tied to the rod and are taut. The tension in the upper string is 38 N. The length of both strings is 1.70m and the distance between the strings on the rod is 1.7.

*November 20, 2011*

**Math**

In this problem, x cubed = 12y...how do you solve to determine if this is direction variation or not?

*November 15, 2011*

**algebra **

Katydid population is modeled by N(t) = 50 / 1+9e^ -.33t where t is number ofyears and N(t) is population is thousands at time t. when will katydid population reach 40,000? I somehow got a negative log, producing an error so i can't go any farther. Please help.

*November 8, 2011*

**7th Math**

what would you do than with 5/8 ??

*October 27, 2011*

**7th Math**

A plumber must bend a piece of tubing twice, allowing 5/8 inch for each bend. use the total of 12 1/2, 16 3/4, and 18 3/4. To find the total length of tubing needed?

*October 27, 2011*

**Physics Honors**

8.7s,56.55m

*October 23, 2011*

**Finance**

Tuttle Buildings Inc. has decided to go public by selling $5,000,000 of new common stock. Its investment bankers agreed to take a smaller fee now (6% of gross proceeds versus their normal 10%) in exchange for a 1-year option to purchase an additional 200,000 shares at $5.00 ...

*October 20, 2011*

**Finance**

Rainier Bros. has 12.0% semiannual coupon bonds outstanding that mature in 10 years. Each bond is now eligible to be called at a call price of $1,060. If the bonds are called, the company must replace them with new 10-year bonds. The flotation cost of issuing new bonds is ...

*October 20, 2011*

**Finance**

Thompson Enterprises has $5,000,000 of bonds outstanding. Each bond has a maturity value of $1,000, an annual coupon of 12.0%, and 15 years left to maturity. The bonds can be called at any time with a premium of $50 per bond. If the bonds are called, the company must pay ...

*October 20, 2011*

**statistics**

Scatterplot

*September 26, 2011*

**physics**

In a large hotel, a fast elevator takes you from the ground floor to the 21st floor. The elevator takes 17 s for this trip: 5 s at constant acceleration, 7 s at constant velocity, and 5 s at constant deceleration. Each floor in the hotel has a height of 2.5 m. Calculate the ...

*September 26, 2011*

**7th grade Science**

dmf

*September 24, 2011*

**Math**

Show how the Commutative Property of Addition works using the numbers 2, 3, and 5.

*September 20, 2011*

**Math**

Minnie has 6 country CDs and 5 rock CDs. Amanda has 5 rock CDs and 6 country CDs. Who has more CDs? Explain.

*September 20, 2011*

**physics**

the

*September 13, 2011*

**mkt 421**

Marketing strategy planners should recognize that

*August 14, 2011*

**mkt 421**

Dell, Inc. wants to offer customers televisions in addition to computers. This is a change in their _____________________

*August 14, 2011*

**mkt 421 **

For Tesla, a new firm that makes an electric sports car, estimating how many competitors will make electric vehicles and what kinds they will make, is:

*August 14, 2011*

**equilibrium constant (Kp)**

What is the equilibrium constant "Kp" at 200 C for the reaction below: P4(s) + 6 Cl2(g) --><-- 4 PCL3(l) Given the following at 200 C P4(s)+ 10 Cl2(g) --><-- 4 PCl5(s) Kc=8.12 PCl3(l)+ Cl2(g) --><-- PCl5(s) Kc=0.771 Answer: 6.7*[10^(-9)] not sure ...

*July 20, 2011*

**Statistics**

foofy computes the correlation between an individual's physical strength and his or her college grade poing average. Using a computer, the correlation for a sample of 2000 people is r(1998)=+.08, p=<.0001. she claims this is a useful tool for predicting which college ...

*July 10, 2011*

**Chemistry**

The following standard free energies are given for 25 degrees celcius. 1) N2(g) + 3H2(g)-> 2NH3(g) delta g = -33.0 kJ 2) 4NH3(g) + 5O2(g)-> 4NO(g) + 6H20() delta g = -1010.5 kJ 3) N2(g) + o2(g)-> 2NO(g) delta g = 173.1kJ 4) N2(g) + 2O2(g) -> 2NO2(g) delta g = 102.6...

*July 6, 2011*

**statistics**

Heights of fences are normally distributed with a mean of 52 inches and a standard deviation of 4 inches. Find the probability that one randomly selected fence is under 54 inches.

*July 5, 2011*

**us history **

((AN ERA OF LIMITS 1969-1980)) How were the relations between the United States and the Soviet Union different during this era? How were the relations the same?

*June 22, 2011*

**us history**

what nonmilitary measures did president kennedy take to counter Soviet influence and to spead democracy around the world? (clashes in the cold war)

*June 20, 2011*

**us history**

Yes i do mean we should NOT have been... && sorry i will proofread my posts.

*June 18, 2011*

**us history**

No wait i meant to put "helped" i wrote the question wrong! sorry HOW DID THE ANTI-WAR PROTEST HELP THE UNITED STATES DURING THE VIETNAM WAR? && one thing i know is that the United States started to believe that we should have been fighting in the first place.

*June 18, 2011*

**us history**

why did the anti-war protest hurt the united states during the Vietnam war?

*June 18, 2011*

**precal**

Given an initial value of 17 g, which is halving once each 32 hours, an exponential function in term of hour t which models this situation is ...?

*June 12, 2011*

**Chemistry**

Alright thanks so much.

*June 7, 2011*

**Chemistry**

How many mL of concentrated HCl(aq) (36% HCL by mass, d=1.18g/mL_ are required to produce 12.5 L of a solution with ph = 2.10? First I started with finding out the concentration of [H30+] and for that I got 7.94 x 10^-3 but I don't know how to continue.

*June 7, 2011*

**Chemistry**

Thanks so much. I did that and I used 751 for P, .205L for V, 0.08206 for R and 296 K for T and I got 6.34 moles. When I substituted that into the formula for M = moles/L I got 30.9 but the actual answer that is written in my textbook is 1.96 x 10^-3 M.

*June 7, 2011*

**Chemistry**

What is [H30+] in a solution obtained by dissolving 205mL HCl(g), measured at 23 C and 751mmHg, in 4.25L of aqueous solution?

*June 7, 2011*

**math**

You receive an invoice for $565.00 with terms 3/10, net 30. If you pay it immediately, how much will you pay? A. $548.05 B. $551.25 C. $558.05 D. $559.95

*June 3, 2011*

**Chemistry**

Okay I think I figured out how to do it all. Thanks for explaining.

*May 28, 2011*

**Chemistry**

No I wasn't, but can I just use the pressure formula of P() = nRT/V and then just add all of them together?

*May 28, 2011*

**Chemistry**

Sorry my ICE table came out wrong. It is actually suppose to be 2SO3 <-> 2SO + 02 I 0 .100 .100 C 0 .1- 0.0916 .1-.0458 E 0.0916 .0084 .0542

*May 28, 2011*

**Chemistry**

0.100 mol of SO2 and 0.100 mol of O2 are introduced in a flask of 1.52 L. When in equilibrium, 203 is found to be 0.0916 mol. Determine kp. 2S03(g) <-> 2SO(g) + O2(g) In order to solve this question 1st I made an ICE table and I got the values 2SO3 <-> 2SO + 02 I ....

*May 28, 2011*

**math**

How many real number solutions exist for 2x2 8x 8 = 0?

*May 28, 2011*

**Chemistry**

Thanks so much for your help.

*May 28, 2011*

**Chemistry**

Hi. Thanks for your help. So this is how I solved the equation. 2NO2(g) <-> 2NO(g) + O2(g) Since the 2NO2 is reversed from the 1st equation, I got (1/7.5x10^2) and then since the 2NO(g) and the O2(g) are doubled from the 1st equation I got (7.5x10^2)^2 for 2NO(g) and the...

*May 28, 2011*

**Chemistry**

Given the equation NO(g) + 1/2)O^2(g) <-> NO(g) at 457 Kelvin with a K = 7.5 x 10^2 Find the K value for the equation 2NO^2(g) <-> 2NO(g) + O(g)

*May 28, 2011*

**Chemistry**

Oh okay, thank you so much for your whole explanation. I finally understand the whole concept behind it and what we are suppose to do. Thanks so much again :)

*May 28, 2011*

**Chemistry**

Yeah I did all the previous things to find Kc and I got kc = 0.012. But you know how for to get the other kc you said I would have to do 1/sqrt Kc, I know that I would do that because the product is H2S and I would do the inverse because it is reversed and I would sqrt because...

*May 28, 2011*

**Chemistry**

So instead of looking at each compound in the equation you would only look at the product side of it and compare it to the other equation and only either square,square root etc. that value?

*May 28, 2011*

**Chemistry**

Given the equation 2H^2S(g) <-> 2H^2(g) + S^2(g) With a Kp = 1.2x10^-2 at 1338 Kelvin Find the value of Kc for the reaction H^2(g) + 1/2S^2(g) <-> H^2S(g) at 1338 Kelvin

*May 28, 2011*

**Chemistry**

Ok this helps so much. Thanks a lot I appreciate it.

*May 25, 2011*

**Chemistry**

Ok thanks so much. So when I solve for X I got 4.48(0.086 - x) = x^2 0.385 - 4.48x - x^2 = 0 Now i'd substitute that into the quadratic formula? Or is there an easier way to solve for X?

*May 25, 2011*

**Chemistry**

Okay thanks so much.

*May 25, 2011*

**Chemistry**

When I am solving for X my formula comes out to be 4.84 = X^2/ (.186-X) Can I assume that x << .05 and eliminate it from the denominator and just solve for the equation 4.84 = X^2/.186?

*May 25, 2011*

**Chemistry**

HCONH2(g) <-> NH3(g) + CO2(g) Kc= 4.84 at 400 K2(g) If 0.186 mol of HCONH2(g) dissciates in 2.16L at 400K, what will be the total pressure at equilibrium?

*May 25, 2011*

**Chemistry**

OK thanks so much, I appreciate it.

*May 25, 2011*

**Chemistry**

When I converted everything I got 1.2x10^3 = (0.02 + x) / (0.12 - x)(x) = (0.02 + x) / (0.12x - x^2) 1.2x10^3(0.12x - x^2) = 0.02 + x 144x - 1.2x10^3x^2 = 0.02 + x Then I brought x to the other side and I got 145x - 1.2x10^3x^2 = 0.02 Then I get confused with the x's and ...

*May 25, 2011*

**Chemistry**

Starting with 0.3500mol Co(g) and 0.05500mol COCL2(g) in a 3.050 L flask at 668K, how many moles of Cl2 are present at equilibrium? Co(g) = Cl2(g) <-> COCL2(g) Kc = 1.2x10^3

*May 25, 2011*

**Chemistry**

Thank you so much. I got 9.7 x 10^-16. The answer is correct. I was just confused because why did we only substitute the k values for 2 compounds in the equation rather then all 4?

*May 25, 2011*

**Chemistry**

Determine Kc for the following reaction: 1/2N2(g) + 1/2O2(g)+ 1/2Br(g) <-> NOBr(g) from the following information (at 298K) 2No(g) <-> N2(g) + O2(g) Kc = 2.1x10^30 NO(g) + 1/2Br2(g) <-> NOBr(g) Kc = 1.4

*May 25, 2011*

**math**

how do you use the numbers 4, 5, 9, 7, and 21 to get the number 23 (using it in a number sentence) i cannot get it and its driving me crazy! please help

*May 17, 2011*

**Chemistry**

The Hydrolysis Reactions - Write net-ionic equations for the reaction of each salt with water below. If there is no reaction, write N.R. 1. NH4C2H3O2 2. NH4Cl 3. NaCl 4. Na2CO3 5. NaC2H3O2 6. NaHSO4 7. FeCl3 8. NaH2PO4 9. NaHCO3

*April 30, 2011*

**math**

yeah in some cases if you really truley need it,like maybe if your dealing with decimals

*April 28, 2011*

**algebra**

explain why a solution of a word problem should be checked using the original wording of the problem and not the equation written from the wording

*April 12, 2011*

**math**

8x+16÷x^(2)-1 . x+1÷4x+8

*March 30, 2011*

**physics**

It takes 15 seconds for a wave to pass a buoy 25 meters from shore. If its wavelength is 30 meters, what is its speed.

*March 30, 2011*

**Chemistry**

Titration of an Unknown Acid... What effect on the molar mass of the unknown acid would each of the following have... Would it make the calculated molar mass high, low, or would it have no effect? 1. Adding 5 drops of phenolphthalein instead of 1 drop... Answer: No effect. 2. ...

*March 26, 2011*

**Chemistry**

Would it be better to use an unknown acid sample of a size that should require 10.00 milliliters or one that would require 15.00 milliliters of titrant? Explain. I have been thinking about this question... And I don't believe it matters what measurement of milliliters is ...

*March 26, 2011*

**Chemistry**

Thank you.

*March 26, 2011*

**Chemistry**

Why is it important to swirl the NaOH solution each time before using it during a titration?

*March 26, 2011*