Thursday

October 2, 2014

October 2, 2014

Total # Posts: 766

**Chemistry**

If the same volume (130-mL) of the buffer were 0.265 M in NH3 and 0.400 M in NH4Br, what mass of HCl could be handled before the pH fell below 9.00? I used the henderson-hasselbalch equation to solve this. i set it up as 9=9.24551+log((0.03445-x)/(0.052+x)) 0.03445= moles of ...
*March 28, 2010*

**Henderson-Hasselbalch**

If the same volume (130-mL) of the buffer were 0.265 M in NH3 and 0.400 M in NH4Br, what mass of HCl could be handled before the pH fell below 9.00? I used the henderson-hasselbalch equation to solve this. i set it up as 9=9.24551+log((0.03445-x)/(0.052+x)) 0.03445= moles of ...
*March 28, 2010*

**Buffer solution**

Solve an equilibrium problem (using an ICE table) to calculate the pH. a solution that is 0.205 M in CH3NH2 and 0.110 M in CH3NH3Br. i used th Ka of CH3NH2 and set up the problem as Ka=[H3O][CH3NH2]/[CH3NH3Br], but that was wrong. So i switched the equation to Ka=[H3O][...
*March 27, 2010*

**Pre-Calculus**

146.13 feet
*March 24, 2010*

**pH**

Determine the pH of each of the following solutions. 0.21 M KCHO2 0.19 M CH3NH3I 0.19 M KI I'm not sure how i should set up the ice chart, and what Ka I should be using for the solutions
*March 24, 2010*

**Physics**

(c22p46) A light ray of wavelength 589 nm is incident at an angle θ on the top surface of a block of polystyrene surrounded by air. PART 3: Find the maximum value of θ for which the refracted ray will undergo total internal reflection at the left vertical face of the...
*March 23, 2010*

**College Chemistry**

Amphetamine (C9H13N) is a weak base with a pKb of 4.2. Calculate the pH of a solution containing an amphetamine concentration of 215 mg/L. I calculated the molarity as 1.58*10^-3 and the Ka as 1.58*10^-10. I did ICE and i got the pH as 6.3, but it was wrong. Do you know what I...
*March 23, 2010*

**Chemistry**

Determine the pH of each of the following solution. a solution that is 5.8×10^−2 M in HClO4 and 2.6×10^−2 M in HCl
*March 21, 2010*

**pH levels**

The first one should read HC2H3O2. yes the second one is phenol
*March 21, 2010*

**pH levels**

Rank the following solutions in order of decreasing [H3O^+]. .10 M HC2H3C2 .10 M HC6H5O .10 M HF ,10 M HBr I think the correct order is: HBr>HF>HC2H3C2>HC6H5O am i right?
*March 21, 2010*

**college physics**

In a nuclear reactor, neutrons released by nuclear fission must be slowed down before they can trigger additional reactions in other nuclei. To see what sort of material is most effective in slowing (or moderating) a neutron, calculate the ratio of a neutron's final ...
*March 18, 2010*

**college physics**

A 0.580-kg bucket rests on a scale. Into this bucket you pour sand at the constant rate of 85.0 g/s. A)If the sand lands in the bucket with a speed of 4.30 m/s, what is the reading of the scale when there is 0.770 kg of sand in the bucket? B)What is the weight of the bucket ...
*March 18, 2010*

**physics (fixed) **

Two air-track carts move toward one another on an air track. Cart 1 has a mass of 0.34 kg and a speed of 1.1 m/s . Cart 2 has a mass of 0.68 kg and a speed of 0.55 m/s. Calculate the system's kinetic energy.
*March 17, 2010*

**physics**

Two air-track carts move toward one another on an air track. Cart 1 has a mass of 0.34 kg and a speed of 1.1 m/s . Cart 2 has a mass of 0.68 kg and a speed of 0.55 m/s .
*March 17, 2010*

**physics**

You are holding a shopping basket at the grocery store with two 0.69-kg cartons of cereal at the left end of the basket. The basket is 0.90 m long. Where should you place a 1.8-kg half gallon of milk, relative to the left end of the basket, so that the center of mass of your ...
*March 17, 2010*

**physics**

Two 72.0-kg hockey players skating at 7.00 m/s collide and stick together. If the angle between their initial directions was 130 degrees , what is their speed after the collision?
*March 17, 2010*

**College Physics**

You are holding a shopping basket at the grocery store with two 0.69-kg cartons of cereal at the left end of the basket. The basket is 0.90 m long. Where should you place a 1.8-kg half gallon of milk, relative to the left end of the basket, so that the center of mass of your ...
*March 16, 2010*

**College Physics**

Two 72.0-kg hockey players skating at 7.00 m/s collide and stick together. If the angle between their initial directions was 130 degrees , what is their speed after the collision?
*March 16, 2010*

**College Physics**

During a rescue operation, a 5600-kg helicopter hovers above a fixed point. The helicopter blades send air downward with a speed of 69 m/s. What mass of air must pass through the blades every second to produce enough thrust for the helicopter to hover?
*March 16, 2010*

**Calculus 2**

i need to find the amount of gallons of different water heights on a Horizontal tank with Elliptical Cross-Sections minor axis height is 4 minor axis length is 6 tank length is 16
*March 16, 2010*

**Calculus 2**

i need to find the amount of gallons of different water heights on a Horizontal tank with Elliptical Cross-Sections minor axis height is 4 minor axis length is 6 tank length is 16
*March 16, 2010*

**Math**

how do I solve; two parallelograms have the same base length. The height of the first is half the height of the second. What is the ratio of the area of the smaller parallelogram to the area of the larger one?
*March 9, 2010*

**Math **

how do I solve; two parallelograms have the same base length. The height of the first is half the height of the second. What is the ratio of the area of the smaller parallelogram to the area of the larger one?
*March 9, 2010*

**Math**

would you use centimeter or millimeter for width of your finger
*March 4, 2010*

**College Physics**

Part A) A 2.2 kg rock is released from rest at the surface of a pond 1.8 m deep. As the rock falls, a constant upward force of 5.0 N is exerted on it by water resistance. Let y=0 be at the bottom of the pond. Calculate the nonconservative work, Wnc , done by water resistance ...
*March 3, 2010*

**College Physics**

There are 3 portions. The next one is at 0.50 m and the last one is when the rock is at 1.0 m.
*March 3, 2010*

**College Physics**

A 2.2 kg rock is released from rest at the surface of a pond 1.8 m deep. As the rock falls, a constant upward force of 5.0 N is exerted on it by water resistance. Let y=0 be at the bottom of the pond. Calculate the nonconservative work, Wnc , done by water resistance on the ...
*March 3, 2010*

**physics**

Thank you sir. I appreciate it.
*March 2, 2010*

**physics**

In order to keep a leaking ship from sinking, it is necessary to pump 11.0 lb of water each second from below deck up a height of 2.50 m and over the side. What is the minimum horsepower motor that can be used to save the ship?
*March 2, 2010*

**World History**

How did colonies with large European populations differ from other colonies?
*February 22, 2010*

**Rate Laws**

If the initial concentration of AB is 0.210 M, and the reaction mixture initially contains no products, what are the concentrations of A and B after 75 s? The reaction is in the second order: rate=k[AB]^2 The rate constant is k=5.4*10^2 M*s I don't understand how to find A...
*February 20, 2010*

**Math**

There is a list of triominoes: 0,5,5... 0,1,1... 1,1,3... you get the picture. There are 10 triangles. How am I suppose find the measure of the largest angle? How many sides are congruent? I think 2 but are the talking about the entire triomino?
*February 18, 2010*

**Math**

how to clasify by angles... x, 60 degress, 61 degrees = so I add 60 to 61 and it equals 121 so does that mean its a obtuse angle? I have one moe question, I'll post it.
*February 18, 2010*

**Math**

9x-(-6x-4)=-5
*February 9, 2010*

**calc**

Suppose the total cost, C(q), of producing a quantity q of a product is given by the equation C(q) = 5000 + 5q The average cost per unit quantity, A(q), equals the total cost, C(q), divided by the quantity produced, q. Find the limiting value of the average cost per unit as q ...
*February 8, 2010*

**math**

how do I solve and state if it is an overestimate or an underestimate? 1.2% of 490 Do I .012 x 490 or Do I round 1.2% to 1
*February 4, 2010*

**math**

I need help finding the answer In the US about 46% of the population wear glasses or contact lenses. A sample of 85 people is taken. About how many people would you ecpect to wear glasses or contact lenses? Do I multiply .46 to 85?
*February 3, 2010*

**mole fraction**

A solution contains a mixture of pentane and hexane at room temperature. The solution has a vapor pressure of 241 torr. Pure pentane and hexane have vapor pressures of 425 torr and 151 torr, respectively, at room temperature. What is the mole fraction of hexane? (Assume ideal ...
*January 30, 2010*

**Molality**

An aqueous solution contains 8.7% NaCl by mass. 1. Calculate the molality of the solution. 2. Calculate the mole fraction of the solution.
*January 30, 2010*

**Math**

I get it now! Thanks everyone!!!
*January 29, 2010*

**Math**

I'm still needing some help knowing how to work this proportion. A glacier moves about 12 inches every 36 hours. About how far does the glacier move in 1 week? Is it 12 in / 36 hrs = x/week (in hours)
*January 29, 2010*

**Math**

Can you explain how you work the problem? I know its a proportion but I don't get it?
*January 29, 2010*

**Math**

A glacier moves about 12 inches every 36 hours. About how far does the glacier move in 1 week?
*January 29, 2010*

**math**

How do I solve: write 45.6 as a percent and a fraction in simplest form.
*January 27, 2010*

**math**

unit rate in fraction form:2.40 per dozen
*January 26, 2010*

**algebra**

who do i solve this equation 49x-y=558
*January 25, 2010*

**algebra**

I am not sure how to solve this equation 49x-y=558
*January 25, 2010*

**math 7th**

+2 -10
*January 21, 2010*

**history**

hi i need a lot of sources about the history of throwing coins into fountains
*January 18, 2010*

**Physics**

A student wants to run an experiment to determine how the distribution of mass (location of mass) affects an object`s rotational velocity. For this experiment the student picks 3 rings. One is a wood ring (like a hula-hoop) with all of its mass at the outer edge (A). The next ...
*January 17, 2010*

**Calculating Vapor Pressure**

The vapor pressure of nitrogen at several different temperatures is shown below. Temperature (K) Pressure (Torr) 65 130.5 70 289.5 75 570.8 80 1028 85 1718 1. Use the data to determine the heat of vaporization of nitrogen in kJ/mol. 2.Determine the normal boiling point of ...
*January 17, 2010*

**heat of vaporization**

Suppose that 1.00 g of rubbing alcohol (C3H8O) evaporates from a 54.0 g aluminum block. If the aluminum block is initially at 25 C, what is the final temperature of the block after the evaporation of the alcohol? Assume that the heat required for the vaporization of the ...
*January 16, 2010*

**physics**

5. K =5 J since the only force acting on it is gravity, it's a conservative force. That means the energy is only transferred from U to KE and never lost. We use the formula: E= U + KE At its max displacement, KE=0 and E must equal U. It says that at its max displacement U=...
*January 5, 2010*

**S.S.**

What is an Assyrian Library?
*December 13, 2009*

**math**

write an equation in point-slope form for the line through the given point with the given slope (4, -6); m = 3 over 5
*December 13, 2009*

**Earth Science**

Broad areas of folded rock layers that resemble a bowl turned right-side up are called
*December 10, 2009*

**Chemistry**

sorry. Determine the molar mass of the unknown acid. Determine the molecular formula of this acid.
*December 6, 2009*

**Chemistry**

Determine the molar mass of the unknown acid.? A 0.167-g sample of an unknown acid requires 27.8 mL of 0.100 M NaOH to titrate to the equivalence point. Elemental analysis of the acid gives the following percentages by mass: 40.00% C; 6.71% H; 53.29% O.
*December 6, 2009*

**Chemistry**

Determine the molar mass of the unknown acid.? A 0.167-g sample of an unknown acid requires 27.8 mL of 0.100 M NaOH to titrate to the equivalence point. Elemental analysis of the acid gives the following percentages by mass: 40.00% C; 6.71% H; 53.29% O.
*December 5, 2009*

**Physics**

bobpursley forgot to put the second mass in the equation. whenever there is a v^2/r , remember to multiply it by mass. tension[low] = mg + (v^2/r * m) tension[high] = (v^2/r * m) - mg
*December 5, 2009*

**Lattice Energy**

Arrange the following substances in order of decreasing magnitude of lattice energy. KCl NaF SrO BaO
*December 5, 2009*

**physics**

A box is given a push so that it slides across the floor. How far will it go, given that the coefficient of kinetic friction is 0.17 and the push imparts an initial speed of 4.3 m/s?
*December 3, 2009*

**physics**

A box is given a push so that it slides across the floor. How far will it go, given that the coefficient of kinetic friction is 0.17 and the push imparts an initial speed of 4.3 m/s?
*December 3, 2009*

**biology**

how are babies made?
*November 26, 2009*

**math**

Use two points on any horizontal line to illustrate why a horizontal line has a slope of 0...I'm really confused. Can anyone answer with an explanation?
*November 25, 2009*

**de Broglie Wavelength**

The presence of oxygen atoms on the surface results in auger electrons with a kinetic energy of approximately 505 eV. What is the de Broglie wavelength of this electron? [KE= (1/2)mv^2; 1 electron volt (eV) = 1.602*10^-19 J]
*November 13, 2009*

**Chemistry**

Water is exposed to infrared radiation of wavelength 3.0×10^−4 cm. Assume that all the radiation is absorbed and converted to heat. How many photons will be required to raise the temperature of 1.7 g of water by 2.2 K?
*November 9, 2009*

**Heat of Formation**

0.04319 moles F3O4 Specific Heat Constant: 4.18 J/mol*C
*November 6, 2009*

**Heat of Formation**

I got 1518 kJ/mol using that equation, but I still got it wrong. Did I do something wrong?
*November 6, 2009*

**Heat of Formation**

When 10.00 g of iron is burned in O2(g)to form Fe3O4 (s) , enough heat is generated to raise the temperature of 784 g of water from 18.0 C to 38.0 C. Calculate the heat of formation of Fe3O4 (s) under these conditions in kJ/mol.
*November 6, 2009*

**Chemistry Equations**

What's the equation for the formation of NO2(g) from its elements in its standard states? What's the equation for the formation of BF3(g) from its elements in its standard states? What's the equation for the formation of C2H5OH(l) from its elements in its standard ...
*November 5, 2009*

**12th grade Physics**

Hi, actually Bob, your answer is not 30 degrees, but 60 degrees. 30 degrees does not refer to the angle inside the triangle formed by the x and y components.
*November 4, 2009*

**Thermochemistry**

w is work
*October 30, 2009*

**Thermochemistry**

Suppose a 0.17-kg billiard ball is rolling down a pool table with an initial speed of 4.5 m/s. As it travels, it loses some of its energy as heat. The ball slows down to 3.5 m/s and then collides straight-on with a second billiard ball of equal mass. The first billiard ball ...
*October 30, 2009*

**chemistry**

Predict the mass of gold formed when a gold (III) nitrate solution reacts completely with 125 mL of 0.352 mol/L sulfurous acid (aqueous hydrogen sulfite)
*October 27, 2009*

**Reaction Stiochiometry Involving Gases**

Ozone is depleted in the stratosphere by chlorine from CF3Cl according to the following set of equations: CF3Cl + UV Light ---> CF3 + Cl Cl + O3 ---> ClO + O2 O3 + UV Light ---> O2 + O ClO + O ----> Cl + O2 What total volume of ozone measured at a pressure of 25.0 ...
*October 25, 2009*

**Kinetic Molecular Theory**

A sample of N2O effuses from a container in 48 seconds. How long would it take the same amount of gaseous I2 to effuse from the same container under identical conditions?
*October 25, 2009*

**Chemistry**

You wish to make a 0.200 M solution of NiSO4 (aq). How many grams of NiSO4 * 6H2O should you put in a 0.500 L volumetric flask? The answer is 26.3 g NiSO4 * 6H20 but I am not sure how to get there.
*October 20, 2009*

**9th grade**

I need an answer to my question in spanish Que vas a hacer despues de las clases hoy?
*October 15, 2009*

**Spanish**

Need an answer in Spanish to a spanish question! Que vas a hacer despues de las clases hoy?
*October 15, 2009*

**Chemistry**

A solution contains Cr+3 ion and Mg+2 ion. The addition of 1.00 L of 1.55 M NaF solution is required to cause the complete precipitation of these ions as CrF3(s) and MgF2(s). The total mass of the precipitate is 49.8 g. Find the mass of Cr+3 in the original solution.
*October 12, 2009*

**Organic Chemistry**

ahh I got it the C5 and O need to be double bonded
*September 18, 2009*

**Organic Chemistry**

oh thank you but when I tried it seems there is another structure in which all atoms have their octet
*September 18, 2009*

**Organic Chemistry**

like this? img198.imageshack .us/img198/7855/trialt.jpg
*September 18, 2009*

**Organic Chemistry**

img17.imageshack .us/img17/6517/cycloo.jpg
*September 18, 2009*

**Organic Chemistry**

I do have a picture but I can't show the url well I believe its a cyclopentdiene the number is going from the right the 1 is a oxygen and the 3 is CH+ and the double bond is located between 4 and 5
*September 18, 2009*

**Organic Chemistry**

ahh it didn't show o / \ \\ / -CH+
*September 18, 2009*

**Organic Chemistry**

ahh it didn't show
*September 18, 2009*

**Organic Chemistry**

Draw the most important resonance contributor of the following structure? I'm confused on this one o / \ double bond -> \\ / - CH+
*September 18, 2009*

**Physics**

Atomic physicists ignore the effect of gravity within an atom. To see why, Calculate and compare the gravitational and electrical forces between an electron and a proton separated by 10^-10 m.
*September 9, 2009*

**science**

how it is
*August 25, 2009*

**History**

What do think I'll learn by interviewing a teacher about their school? Here are the questions I asked the teacher: Kearsney is the name of the school Where and when were you born? How would you describe your childhood? What was your ambition growing up? What did you study ...
*August 9, 2009*

**History**

What questions could you ask a person about there life story if you had to interview them?
*July 20, 2009*

**History**

Can someone please help me make a biography of a person about there old high school? Ok I'm interviewing a person about his life at his old high school. I've split it into 4 steps. Introduction Transcript Conclusion Introduction: It should be a life story of the ...
*July 20, 2009*

**social studies**

after the 1800's what type of manufacturing was chicago know for?
*June 2, 2009*

**capitalization**

New Year's day occurs on January the first. Numbers under 100 need to be written out.
*June 1, 2009*

**capitalization**

Yes this is right.
*June 1, 2009*

**capitalization**

John Grisam is the author of "The Street Lawyer."
*June 1, 2009*

**Algebra**

How do you do this? Which binomial is a fctor of 3x^2+2^x-5? A: 3x-1 B: x-1 C: 3x-5 D: x-5 I know you tried to help but it wasn't right but thanks.
*June 1, 2009*

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