Thursday

February 23, 2017
Total # Posts: 4,433

**chemistry**

how would that help trying a new solvent? i don't understand why the recovery would be so poor, do you know?

*February 11, 2013*

**chemistry**

a student dissolves 80 mg of a crude product in 4.5 mL( the minimum required) of methanol at 25 deg C . She cools the solution in an ice bath and obtains crystals. The crystals are recovered by filtration and rinsed with 0.5 mL of ice-cold methanol. After drying, the weight of...

*February 11, 2013*

**calculus**

Find the integral of (tan x)^2 sec(x)dx

*February 11, 2013*

**calculus**

Find the integral of: dx/(x^2-4x)

*February 11, 2013*

**math**

I don't know

*February 11, 2013*

**statistics**

Jsns

*February 10, 2013*

**chemistry**

I got x= 8.88 g the second extraction you mean the same solve, that means I should do 8.88+8.88= total of z?

*February 9, 2013*

**chemistry**

Suppose a compound Z had a partition coefficient of 8.0 in ether-water. If 10.0 g of Z was dissolved in 100 mL of water, and if the water solution was extracted with two 100 mL portions of ether, answer the following questions. show your calculation. a) What is the total ...

*February 9, 2013*

**Chemistry**

what conditions are shared by cities that suffer from photochemical smog?

*February 6, 2013*

**PLEASE CHECK THESE ANSWERS AMERICAN GOV**

1. Question : The purpose of the War Powers Act is to Student Answer: INCORRECT allow the Commander in Chief to issue informal declarations of war. to grant the President unlimited military powers. grant Congress equal military power with the President. CORRECT ensure ...

*February 3, 2013*

**Chemistry**

54.0 mL of a 1.50 M solution is diluted to a total volume of 258 mL. A 129-mL portion of that solution is diluted by adding 165 mL of water. What is the final concentration?

*February 2, 2013*

**PHYSICS**

Because Earth's rotation is gradually slowing, the length of each day increases: The day at the end of 1.0 century is 1.0 ms longer than the day at the start of the century. In 93 centuries, what is the total (in hours) of the daily increases in time (that is, the sum of ...

*February 1, 2013*

**PHYSICS**

Grains of fine California beach sand are approximately spheres with an average radius of 50 μm and are made of silicon dioxide, which has a density of 2.4 × 103 kg/m3. What mass of sand grains would have a total surface area (the total area of all the individual ...

*February 1, 2013*

**PHYSICS**

During heavy rain, a section of a mountainside measuring 5.4 km horizontally (perpendicular to the slope) 0.80 km up along the slope, and 2.1 m deep slips into a valley in a mud slide. Assume that the mud ends up uniformly distributed over a surface area of the valley ...

*February 1, 2013*

**math**

what is formula to show how much time it took car to travel 7km is .4hrs

*January 30, 2013*

**medical transcription 2**

I need help finding an answer in the Diagnostic imaging/interventional radiology TE #13, which is MRI brain for Edgar jorda. The part where it says: "The ________ appears minimally changed from the study..."

*January 24, 2013*

**Physics**

Q1 and Q2 are charged objects of the same sign separated by a distance 29.9 m. If you place another charged object (Q3) a distance 8.0 m from Q2 along a direct line between Q1 and Q2, it experiences no net electric field. So, if the magnitude of Q2 = 9.3 C, what is the ...

*January 23, 2013*

**physics**

In Rutherford's famous scattering experiments that led to the planetary model of the atom, alpha particles (having charges of +2e and masses of 6.64 × 10−27 kg) were fired toward a gold nucleus with charge +79e. An alpha particle, initially very far from the ...

*January 23, 2013*

**Math**

This table gives the number of AIDS cases reported in men in Los Angeles from 1983-1989: Month and Year of Diagnosis AIDS cases reported in period Jan-June 83 116 July-Dec 83 154 Jan-June 84 197 July Dec 84 269 Jan-June 85 415 July-Dec 85 503 Jan-June 86 668 July-Dec 86 773 ...

*January 23, 2013*

**math**

What are the basic elements of an effective medical office financial policy?

*January 23, 2013*

**chem**

for 2Al2O3----> 4Al(s) + 3O2 the question is what is the heat change for the formation of 1 mol of aluminum oxide from its elements? Al2O3:-1676.0 O2:0.0 Can someone please explain how to complete this problem step by step please??

*January 22, 2013*

**Math**

Write an equation: x varies directly as y and inversly directly to the cube of Z

*January 21, 2013*

**Health**

Thank you so very much. These websites are a great help to me.

*January 19, 2013*

**Health**

I have to create a nursing case study. I have everything I need, but am not sure how to present it. Details: 67 year old causcasain male diagnosed with emphysema returns with shortness of breath, etc. supposedly associated with CHF. Have to have everything including ABCD ...

*January 19, 2013*

**Chemistry**

A steel tank at 300 K contains 0.285 L of gas at 1.92 atm pressure. The tank is capable of withstanding a maximum pressure of 5.76 atm. Assuming that doubling the kelvin temperature causes the internal pressure to double, a. at what temperature will the tank burst? b. will it ...

*January 16, 2013*

**Chemistry**

A steel tank at 300 K contains 0.285 L of gas at 1.92 atm pressure. The tank is capable of withstanding a maximum pressure of 5.76 atm. Assuming that doubling the kelvin temperature causes the internal pressure to double, a. at what temperature will the tank burst? b. will it ...

*January 16, 2013*

**Chemistry**

I'm supposed to compare the percent composition of gases in the atmosphere at sea level to the percent composition at high altitude.. Would the percents decrease? I don't really understand

*January 16, 2013*

**Chemistry**

explain why a sealed bag of potato chips "puffs out" (increases in volume) if taken from sea level to a high mountain pass. I know this has to do with pressure.. so is it because the higher up you go, the less pressure there is? Thanks!

*January 16, 2013*

**bio**

The most common protein secondary structures (the alpha helix and beta conformation) are stabilized primarily by A. ionic bonds B. hydrogen bonds C. disulfide bonds D. van der Waals interactions E. hydrophobic interactions

*January 16, 2013*

**integrated math**

Suppose a laboratory has a 26 g sample of polonium-210. The half-life of polonium-210 is about 138 days.?

*January 15, 2013*

**Chemistry**

Just having some trouble with this chemistry problem.. Thanks for help! Toxic carbon monoxide (CO) gas is produced when fossil fuels such as petroleum burn without enough oxygen. The CO can eventually be converted to CO2 in the atmosphere. Automobile catalytic converters are ...

*January 15, 2013*

**Chemistry**

What volume would be occupied at 0°C and 1 atm by 3 mol CO₂(g)? I just might need someone to help me work this out, I would greatly appreciate it! I don't understand this chemistry problem.

*January 15, 2013*

**Physics**

i think d

*January 15, 2013*

**math**

a ball is dropped from a height of 10 ft. if the ball's height after t sec is modeled by the following equation h(t)=-16t^2+10. when does the ball hit the ground?

*January 15, 2013*

**math**

Roses were planted 100 cm apart around a rectangular garden. There were no roses at the corners. They started 1 m from each corner. The garden was 5 m by 3 m. How many roses were planted?

*January 15, 2013*

**Chemistry**

Assume that the LHMP is enclosed in a transparent polymer stucture. a. How will the gases inside LHMP be affected by hot days and cool nights? b. What design features might be incorporated in the LHMP to reduce those heating and cooling effects? I know that gases expand in ...

*January 13, 2013*

**Chemistry**

In planning to administer a gaseous anesthetic to a patient, a. Why must the anesthesiologist take into account the fact that during surgery the gaseous anesthetic is used both at room (18 degrees C) and the patient's body temperature (37 degrees C)? The warmer the ...

*January 13, 2013*

**Chemistry**

If a sample of gas is cooled at a constant pressure until it shrinks to one-fourth its initial volume, what change in its kelvin temperature must have occurred?

*January 13, 2013*

**Algebra**

Nadia has 32 coins made up of nickles, dimes, and quarters. The sum of the number of nickels and the number of quarters is three times the number of dimes. If the total value of the coins is $4.60, how many of each kind does she have? I can't figure out how to make this ...

*January 13, 2013*

**Algebra**

Nadia has 32 coins made up of nickles, dimes, and quarters. The sum of the number of nickels and the number of quarters is three times the number of dimes. If the total value of the coins is $4.60, how many of each kind does she have? I can't figure out how to make this ...

*January 13, 2013*

**Algebra**

Nadia has 32 coins made up of nickles, dimes, and quarters. The sum of the number of nickels and the number of quarters is three times the number of dimes. If the total value of the coins is $4.60, how many of each kind does she have? I can't figure out how to make this ...

*January 13, 2013*

**Algebra**

Nadia has 32 coins made up of nickles, dimes, and quarters. The sum of the number of nickels and the number of quarters is three times the number of dimes. If the total value of the coins is $4.60, how many of each kind does she have? I can't figure out how to make this ...

*January 13, 2013*

**Math**

Name the lengths of the sides of three rectangles with a perimeter of 12 units. Use only whole numbers

*January 9, 2013*

**Physical science**

Compute the gravitational force between two 1.00 kg lead spheres whose centers are 1.00 m apart?

*January 6, 2013*

**physics**

Ceres is a dwarf planet located in the asteroid belt between the orbits of mars and Jupiter. the radius of Ceres is 4.76 x 10^5 m. suppose an astronauts stands on the surface of Ceres and drops a 0.85 kg hammer from a height of 1.25 m. the hammer takes 3.0 to reach the ground...

*January 5, 2013*

**Algebra**

8s+ 12 = 16, 6s+ 9t = 12 solve by substitution

*December 8, 2012*

**French**

1. J'utilise un ventilateur quand il fait chaud. 2. Je n'utilise pas le congélateur si j'ai froid. 3. Il ya une couverture sur mon lit. 4. Mes livres sont sur l'étagère. 5. Je mets mes vêtements dans l'armoire. 6. ...

*December 4, 2012*

**French**

1. J'utilise un ventilateur quand il fait chaud. 2. Je n'utilise pas le congélateur si j'ai froid. 3. Il ya une couverture sur mon lit. 4. Mes livres sont sur l'étagère. 5. Je mets mes vêtements dans l'armoire. 6. ...

*December 4, 2012*

**science**

Fast help Please Hurry!!!!!!!!!!!!!!!!!!!!!! A bicyclist is in a 50-km race. He says he had an average velocity of 35. What is missing in the cyclist’s velocity? A. units only B. units and distance C. direction only D. units and direction

*December 3, 2012*

**science**

Thanks so much!

*December 3, 2012*

**science**

im blank today please help thanks!!!!!!!!!!! It takes a car 1.75 h to go from mile marker 10 to mile marker 115. What is the average speed of the car? A. 1.6 mph B. 60 mph C. 65 mph D. 183 mph

*December 3, 2012*

**Algebra2**

Check? Give the slope and y-intercept of the given line. 1. 2x-3y=6 = 3y = 2x-6 y = 2/3 x - 2 2. y=-2x = 2/1x + 1 3. y=3 = y=3/1x + 3 3y = 2x-6 y = 2/3 x - 2

*November 29, 2012*

**Algebra2**

Check? Give the slope and y-intercept of the given line. 1. 2x-3y=6 = 3y = 2x-6 y = 2/3 x - 2 2. y=-2x = 2/1x + 1 3. y=3 = y=3/1x + 3 3y = 2x-6 y = 2/3 x - 2

*November 29, 2012*

**Algebra2**

Graph the given function using the given values of x. 1. f(x) = 5 ; x = -3, -2, -1, 0, 1, 2, 3 2. g(x) = x^3 + 2 ; x = -2, -1, 0, 1, 2

*November 29, 2012*

**math**

What's the inequality ? the crowd that heard the President speak was estimated to be 10000 people.The actual crowd could be 750 people more or less than this. what are the possible values for the actual crowd size?

*November 27, 2012*

**Math .-.**

All eighth grade students can choose to take one of the following elective courses: art, chorus, band, or woodworking. There are 2o more students enrolled in chorus than art. Band has 3/4 the enrollment as chorus. woodworking has 5 fewer students than band. Which expressions ...

*November 26, 2012*

**Chemistry**

.006

*November 21, 2012*

**Chemistry**

Calculate pH of NH4OH which is 1%ionized

*November 20, 2012*

**Grammar**

which one should be capitalized? (the Rocky Mountains)

*November 19, 2012*

**7th grade math Ms. Sue please**

(1 pt) Max’s percent increase was about 1.1% more than Sara’s.

*November 19, 2012*

**physics**

Calculate the net charge on a substance consisting of a combination of 8.9 × 10 13 protons and 2.6×10 13 electrons. The elemental charge is 1.6 × 10 −19 C. Answer in units of C

*November 18, 2012*

**Science**

How can knowing about the chemical properties of different elements help a society become more sustainable?

*November 14, 2012*

**Statistics**

$50.50+-11.08$

*November 14, 2012*

**chemistry**

assuming the reaction goes to completion, determine the final concentration of NH4Cl in the calorimeter. NH4Cl(s)+ H2O(l)-> NH4Cl(aq) concentration of NH4Cl is 1.00M its specific heat is 3.93 and density is g/ml. note: the exact same question was asked for a previous ...

*November 13, 2012*

**physics**

A ball is thrown horizontally off the top of a 65 m tall building at a velocity of 7.8 m/s. How far did the ball land from the base of the building? Round your answer to 2 decimal places.

*November 11, 2012*

**physics**

A ball is thrown horizontally off the top of a 65 m tall building at a velocity of 7.8 m/s. How far did the ball land from the base of the building? Round your answer to 2 decimal places.

*November 11, 2012*

**physics**

A rifle allowed a bullet fired with an initial horizontal velocity to travel 76.0 m while only falling a distance of 0.40 m. What was the initial x-velocity of the bullet? Round your answer to 2 decimal places.

*November 11, 2012*

**math**

sally made 12 dozen cookies .she sold 3 1/3 and gave away 2 3/4 how many are left

*November 7, 2012*

**Statistics**

A random sample of 14 evenings at the O'Sullivan house hold showed that the family received an average of 2.4 solicitation calls each evening. The sample standard deviation was s= 0.9. Find a 99% confidence interval for the population mean number of solicitation calls this...

*November 7, 2012*

**Chemistry**

1.63E-27 photon/sec

*November 5, 2012*

**Chemistry**

Calculate the mass of CO2 emitted (in lbs) when 1 gallon of octane is burned

*November 4, 2012*

**algebra**

If $1000 is invested in an account that earns 11.75%, compounded annually, what will the account balance be after 12 years?

*November 4, 2012*

**physics**

its includes 1. about any diameter 2. about a tangent in its plane 3. about a tangent perpendicular to its plane

*November 1, 2012*

**physics**

moment of inertia of a ring perpendicular to tangent and its plane

*November 1, 2012*

**Physics**

a refree throws a basketball vertically upward with an inital speed of 5.0m/s determine the maxium height above the floor reached by the basketball if it starts from a height of 1.50m

*October 28, 2012*

**Physics**

a refree throws a basketball vertically upward with an inital speed of 5.0m/s determine the maxium height above the floor reached by the basketball if it starts from a height of 1.50m

*October 28, 2012*

**Physics**

Thanks!!

*October 27, 2012*

**Physics**

A car of mass 1100 kg starts from rest at sea level and climbs a hill of altitude 50 m. At the top of the hill the car has a speed of 25 m/s. From the top of the hill the driver turns off the engine and coasts down to an altitude of 15 m. Assume the friction and the air ...

*October 27, 2012*

**Physics**

A car of mass 1100 kg starts from rest at sea level and climbs a hill of altitude 50 m. At the top of the hill the car has a speed of 25 m/s. From the top of the hill the driver turns off the engine and coasts down to an altitude of 15 m. Assume the friction and the air ...

*October 26, 2012*

**Physics**

A car of mass 1100 kg starts from rest at sea level and climbs a hill of altitude 50 m. At the top of the hill the car has a speed of 25 m/s. From the top of the hill the driver turns off the engine and coasts down to an altitude of 15 m. Assume the friction and the air ...

*October 25, 2012*

**calculus**

A street light is mounted at the top of a 6-meter-tall pole. A man 2 m tall walks away from the pole with a speed of 1.4 m/s along a straight path. How fast is the tip of his shadow moving when he is 16 m from the pole?

*October 16, 2012*

**college orgo**

calculate how to make 10 mL of 15:85 ethyl acetate:hexane solution from 2 mL of 5:95 ethyl acetate:hexane, using pure hexane and pure ethyl acetate.

*October 15, 2012*

**Physics**

Never mind, figured it out.

*October 14, 2012*

**Physics**

A wagon is rolling forward on level ground. Friction is negligible. The person sitting in the wagon is holding a rock. The total mass of the wagon, rider, and rock is 97.0 kg. The mass of the rock is 0.320 kg. Initially the wagon is rolling forward at a speed of 0.540 m/s. ...

*October 14, 2012*

**Physics**

87 09 7

*October 9, 2012*

**science**

I dissolved two different white solids into water. One solid dissolved and gave off heat and the other became cold. Reading various texts online, I was not sure if these were physical or chemical changes. Some texts say if these solids are salts then these are physical changes...

*October 8, 2012*

**physics**

A jogger runs down the street at a rate of 1.1 m/s. She sees the finish line, and speeds up to a velocity of 3.6 m/s over 1.1 s. What is the acceleration of the jogger?

*October 3, 2012*

**physics**

A ball is dropped from a height of 18.6 m. What is the velocity of the ball the instant it hits the ground?

*October 3, 2012*

**Math does anyone know this?**

I have to state whether these equations are parallel or perpendicular y=4x+6 y-4x=-1

*October 3, 2012*

**physics**

Sarah shoots a toy dart vertically downward at 11.7 m/s at Mark standing on the ground below. Calculate the dart's velocity after 0.8 seconds.

*September 30, 2012*

**physics**

Sarah shoots a toy dart vertically downward at 11.7 m/s at Mark standing on the ground below. Calculate the dart's velocity after 0.8 seconds.

*September 30, 2012*

**bridge to terabitha**

Hello i read the book bridge to terabitha and i have an assignment i need some help on. i need to pick 5 characters and describe six events or circumstances that caused the character to change or evolve. i have picked the characters Jesse Oliver Aarons Leslie Burke Mrs. Aarons...

*September 30, 2012*

**math**

how do u multiply a positive number and a negitave number

*September 26, 2012*

**science**

Draw the condensed structures of the esters formed from the following reactants. Name the compound in each case. (a) butanoic acid and methanol

*September 25, 2012*

**math**

There are 5 purple, 3 yellow, and 4 pink rocks in a jar. What is the chance of getting a purple rock if it was pulled out of the jar without looking?

*September 25, 2012*

**chem**

Using condensed structural formulas, write a balanced chemical equation for each of the following reactions a)addition of H2O to trans-2-pentene using H2SO4 as a catalyst (two products) i got 2-pentanol and 3-pentanol but it is counting it wrong!

*September 25, 2012*

**Chemistry**

A 2.914 gram sample of gypsum, a hydrated salt of calcium sulfat, CaSO4, is heated at a temperature greater than 170 degrees Celcius in a crucible until a constant mass is reached. The mass of the anhydrous CaSO4 salt is 2.304 grams. Calculate the percent by mass of water in ...

*September 24, 2012*

**math help?**

2x+4 (2x+6) I did this and ended up with a decimal number. I distributed then combined like terms.

*September 21, 2012*

**chemistry**

The atomic mass of chlorine is listed as 35.454 amu on the periodic table. It has two naturally occurring isotopes, CI-35 and CI-37. What are the approximate percentage of each?

*September 20, 2012*

**PHYSICS**

Suppose a moose jumps straight up with an initial upward velocity of 95 m/s. How long until the ungulate lands back on the ground, where it belongs?

*September 17, 2012*