Thursday

April 28, 2016
Total # Posts: 581

**Chemistry**

I need help ASAP! Colligative Properties- Ethylene glycol (C2H6O2) is the principal ingredient in antifreeze. How many grams of ethylene glycol will be needed to lower the freezing point of 2100 grams of water by 20 degrees celcius?
*April 10, 2012*

**math**

write an equation of an ellipse: Major axis 12 units long and parallel to the y-axis, Minor axis 8 units long, center at (-2,5)
*April 1, 2012*

**physics**

a person attaches a 25kg hay bale to one end of a rope passing over a frictionless pulley connected to a beam in the hay barn. another person then pulls down on the opposite end of the rope with a force of 277-N Ignoring the mass of the rope what will be the magnitude and ...
*March 25, 2012*

**DrBob222**

Everything is right except the system...i put -253.5 and it marked me wrong :(
*March 15, 2012*

**DrBob222**

also I checked this problem and I only got the deltaS(surr)=466.4 J/mol*K correct. Please help
*March 15, 2012*

**DrBob222**

chemistry - Kelsey, Thursday, March 15, 2012 at 1:16am My answer is: deltaS(sys)=654900J/mol*K deltaS(surr)=466.4 J/mol*K deltaS(univ)=655366J/mol*K Sorry I forgot to convert to J also I checked this problem and I only got thedeltaS(surr)=466.4 J/mol*K correct. Please help
*March 15, 2012*

**DrBob222**

I know I posted this but you didn't answer! Please help!!!! Consider the following reaction at 298 K: C(graphite) +2Cl2 (g) -----> CCl4(l) Calculate the following quantities. Delta H: -139 kJ/mol deltaS(sys)=? J/mol*K deltaS(surr)=? J/mol*K deltaS(univ)=? J/mol*K My ...
*March 15, 2012*

**Chemistry**

Yes it is correct! Thanks! :) I see my mistake!
*March 15, 2012*

**Chemistry**

Consider the decomposition of a metal oxide to its elements, where M represents a generic metal. M203(s)---> 2M(s) + 3/2 O2(g) info given for Gf(kJ/mol): M203= -10.60 M(s)=0 O2(g)= 0 1.) what is the standard change in Gibbs energy for rxn as written in forward direction? (...
*March 15, 2012*

**chemistry**

My answer is: deltaS(sys)=654900J/mol*K deltaS(surr)=466.4 J/mol*K deltaS(univ)=655366J/mol*K Sorry I forgot to convert to J also I checked this problem and I only got thedeltaS(surr)=466.4 J/mol*K correct. Please help
*March 14, 2012*

**chemistry**

DrBob222 could you please answer!!!!!!
*March 14, 2012*

**chemistry**

Also I don't know how you are working this problem out.
*March 14, 2012*

**chemistry**

So what are the answers for deltaS(sys)=? J/mol*K deltaS(surr)=? J/mol*K deltaS(univ)=? J/mol*K I need to verify the correct answers. Could you please tell me...Thanks!
*March 14, 2012*

**chemistry **

Consider the following reaction at 298 K: C(graphite) +2Cl2 (g) -----> CCl4(l) Calculate the following quantities. Delta H: -139 kJ/mol deltaS(sys)=? J/mol*K deltaS(surr)=? J/mol*K deltaS(univ)=? J/mol*K My answer is: deltaS(sys)=654.9J/mol*K deltaS(surr)=0.4664 J/mol*K ...
*March 14, 2012*

**Physics**

A 2.95 kg block on a horizontal floor is attached to a horizontal spring that is initially compressed 0.0330 m. The spring has force constant 900 N/m. The coefficient of kinetic friction between the floor and the block is 0.42 . The block and spring are released from rest and ...
*March 13, 2012*

**Physics**

A baseball is thrown from the roof of a 22.3 m tall building with an initial velocity of 13.1 m/s and is directed 50.9 degrees above the horizontal. A)What is the speed of the ball just before it strikes the ground? B)What is the answer for part A) if the initial velocity was ...
*March 13, 2012*

**math**

Express this ratio as a unit rate $2.40 per dozen
*March 7, 2012*

**math**

1 -1/6
*February 29, 2012*

**math**

A contactor is making preparations to re-tile the border around a swimming pool. The pool measures 60 feet by 30 feet. The border extends 1 foot from each side of the edge of the pool. The contractor is going to use that are 0.25 feet squared. A case of tiles contains 50 tiles...
*February 29, 2012*

**math**

How many people would it take to produce a human pyramid 12m tall? Give various methods
*February 29, 2012*

**new american gov't 2**

Over time, _____ has gained power at the expense of
*February 10, 2012*

**Geometry**

the angle of depression from D to F measures 40 degrees. If EF= 14 yd, find DE. round answer to nearest 10th
*February 8, 2012*

**math**

John wants to put a lace edge around a square piece of cloth. If the cloth is 4 inches wide on one side, how long of a piece of lace should Melina cut?
*February 5, 2012*

**Chemistry**

Use your value for the heat of neutralization, ∆H, -9490, to determine the amount of heat evolved when 10.00mL of 0.4091 M HCL reacts with 10.00mL of 0.4037 M NaOH.
*January 9, 2012*

**Chemistry**

yes, Al3+ sorry. so the moles=.01380. Could you help with the equation?
*January 9, 2012*

**Chemistry**

0.3724 g x 26.98MW = 10.05 mol -538.4kJ x 10.05 mol = -5410 kJ/mol 5410 kJ/mol of heat is evolved?????
*January 9, 2012*

**Chemistry**

The standard enthalpy of formation of Al3-(aq) is -538.4kJ/mol. How much heat is evolved when 0.3724 g of Al(s) reacts with excess hydrochloric acid?
*January 9, 2012*

**physical science**

Brad rides his bike 20 km. He covers the distance in 45 minutes (0.75 hours). What is his speed in kilometers per hour? A.44 km/hr B.15 km/hr C.9.0 km/hr D.27 km/hr
*December 18, 2011*

**Calculus**

find the second derivative of f(x)=3/(x^2+12)
*December 15, 2011*

**pre-algebra**

when rounding to the nearest cent does it have to be to right or left or does it matter?
*December 12, 2011*

**math**

Ryan takes 12 minutes to rake up and bag a pile of leaves. His sister Kareesa takes twice as long. How many minutes would it take both of them working together to complete 10 bags of leaves
*December 12, 2011*

**math**

What does a boy who likes to play with switches do?
*November 30, 2011*

**math**

12 tablespoons cause 16/4=4 so, 4x3=12!
*November 30, 2011*

**math **

sqrt(75)=sqrt(25)sqrt(3) which simplifies to 5 times sqrt(3) so 6x5xsqrt(3)= 30 sqrt(3)
*November 28, 2011*

**Calculus**

Given f"(x)=-25sin(5x)and f'(0)=0 and f(0)=4. Find f(pi/2)
*November 28, 2011*

**math**

30/40=.75 .75x100= 75 percent
*November 28, 2011*

**Physics**

A solid cylindrical disk has a radius of 0.18 m. It is mounted to an axle that is perpendicular to the circular end of the disk at its center. When a 40-N force is applied tangentially to the disk, perpendicular to the radius, the disk acquires an angular acceleration of 90 ...
*November 22, 2011*

**Geometry**

draw a picture, hint its more then 10 but less then 16
*November 16, 2011*

**Physics**

planet orbits a star once every 2.84 10^7 s in a nearly circular orbit of radius 1.42 10^11 m. (a) With respect to the star, determine the angular speed of the planet. (b) With respect to the star, determine the tangential speed of the planet. (c) With respect to the star, ...
*November 16, 2011*

**math**

3 feet in a yard 12 inches in a foot. 12x3x10=360 360/10=36 tiles
*November 16, 2011*

**geometry**

3 feet in a yard 12 inches in a foot. 12x3x10=360 360/10=36 tiles
*November 16, 2011*

**Algebra **

-9+3x=??? if you still need help let me know
*November 16, 2011*

**Algebra **

4-12x=??
*November 16, 2011*

**algebra**

-21+3x
*November 16, 2011*

**algebra **

27-2x
*November 16, 2011*

**algerbra**

ride=.40+.15x
*November 16, 2011*

**Physics**

Two children hang by their hands from the same tree branch. The branch is straight, and grows out from the tree trunk at an angle of 27.3° above the horizontal. One child, with a mass of 40.8 kg, is hanging 1.24 m along the branch from the tree trunk. The other child, with...
*November 16, 2011*

**SOCIAL STUDIES**

Harvard?
*November 16, 2011*

**Science**

A is wrong because they could have more or less children. C is wrong because it is impossible to have an aa child with the genotypes of the parents. And D is wrong because A is wrong. If you draw out the punett square you would see that B is correct
*November 16, 2011*

**Physics**

Disregard. I figured it out
*November 16, 2011*

**Physics**

The shaft of a pump starts from rest and has an angular acceleration of 3.40 rad/s2 for 11.0 s. (a) At the end of this interval, what is the shaft's angular speed? rad/s (b) What is the angle through which the shaft has turned
*November 16, 2011*

**physics**

A 220 N crate is pushed along the ground with a horizontal force. The coefficient of kinetic friction is 0.21 and the coefficient of static friction is 0.31. The crate moves at a constant speed of 4.1 m/s. a) Draw a free-body diagram for the crate. b) What is the size of the ...
*November 15, 2011*

**Algebra**

a^2+b^2=C^2 x^2+(x+1)^2=5^2 the other legs are 3ft and 4ft
*November 9, 2011*

**Algebra 1 (HELP PLEASE!!)**

5/3 x 3= 15/3 or 5 cups
*November 9, 2011*

**8th grade math**

it takes 5 minutes to make 2 cuts to give you 3 pieces. so if you continue at a rate of two cuts per 5 minute and in order to get 9 pieces you need 8 cuts. so I think 20 minutes
*November 9, 2011*

**Algebra 1**

Kim weighed 6.5lbs which is the same as 2/3t+3. so 6.5=3+2/3t 3.5=2/3t t=5.25
*November 9, 2011*

**science**

chloride is a form of chlorine
*November 9, 2011*

**science**

both
*November 9, 2011*

**physics**

I figured it out. the velocity of the recoil is in the negative direction.
*November 9, 2011*

**physics**

no that is not a problem. I just have to put in the number. the label is provided.
*November 9, 2011*

**physics**

The lead female character in the movie Diamonds Are Forever is standing at the edge of an offshore oil rig. As she fires a gun, she is driven back over the edge and into the sea. Suppose the mass of a bullet is 0.012 kg, and its velocity is +715 m/s. Her mass (including the ...
*November 9, 2011*

**physics**

Thanks. I was messing up the change in velocity part
*November 9, 2011*

**physics**

a baseball (m = 153 g) approaches a bat horizontally at a speed of 41.0 m/s (92 mi/h) and is hit straight back at a speed of 45.8 m/s (102 mi/h). If the ball is in contact with the bat for a time of 1.05 ms, what is the average force exerted on the ball by the bat? Neglect the...
*November 9, 2011*

**math**

bayside=5 lincoln x+1 hendricks=x band 20=5+x+x+1 20=2x+6 14=2x 7=x so hendricks has 7 and lincoln has 8
*November 9, 2011*

**Health, Safety, and Nutrition**

There are 9 calories in a gram of fat. 9x9=81 calories. 81/115=70.4%. C is the correct answer
*November 9, 2011*

**math algerba**

½(y-2)+2 =3/8(3y-4) Is 4 a solution?
*November 8, 2011*

**algebra 2**

49=x+(x+9)+(x+4) 49=3x+13 36=3x 12+x so one side is 12cm, on is 16cm and one is 21cm
*November 3, 2011*

**physics**

force=G(m1m2/r^2) G=6.673x10^-11
*November 3, 2011*

**Science**

work=force*distance work=800N*100m
*November 3, 2011*

**Math**

draw out the picture of the trapezoid. Since it is a regular trapezoid the bottom angles on both sides are the same. If you draw imaginary lines from the top to the bottom you can form a figure composed of two triangles and 1 square in the middle. You can then use some right ...
*November 3, 2011*

**Math**

a=P(1+(r/n))^nt
*November 3, 2011*

**Math**

semiannual means twice a year. so 2*5=10
*November 3, 2011*

**Algebra 1**

yes
*November 3, 2011*

**Basic math**

median is the middle number. so put the numbers in descending or ascending order and find the middle number. It would be 1,700
*November 3, 2011*

**SCIENCE**

They are "renewable" resources, and less polluting
*November 3, 2011*

**physics**

disregard. I figured it out
*November 3, 2011*

**physics**

A projectile of mass 0.550 kg is shot straight up with an initial speed of 22.0 m/s. (a) How high would it go if there were no air friction? I get 24.7m for this. (b)If the projectile rises to a maximum height of only 13.6 m, determine the magnitude of the average force due to...
*November 3, 2011*

**Math**

Yes you would multiply this. And assuming the tank is empty that is the correct answer
*November 3, 2011*

**physical science**

mechanical energy is the sum of kinetic and potential energy. there fore the one who says that there is mechanical energy is correct. Because there is potential energy present
*November 3, 2011*

**math**

a=Pe^rt a=25000e^(.0575)(7.5)
*November 2, 2011*

**math (calculus)**

A rectangular sheet of paper of width a and length b, where 0<a<b, is folded by taking one corner of the sheet and placing it at point P on the opposite long side of the sheet. The fold is flatened to form a crease across the sheet. Assuming that the fold is made that ...
*October 29, 2011*

**PHYSICS**

An object is originally moving at 13 m/s at the top of a frictionless, quarter-circular ramp with a radius of R = 13 meters. It then travels on a frictionless horizontal surface, around a frictionless loop of radius r = 2 meters, across another horizontal, frictionless surface...
*October 27, 2011*

**PHYSICS**

An object is thrown straight upwards from the ground at 28 m/s. Due to air resistance (a non-conservative force), the object loses 31.4 percent of its initial energy during its trip to reach maximum height. How much higher does the object travel if there was no air resistance...
*October 27, 2011*

**Physics**

A bicyclist is coasting straight down a hill at a constant speed. The mass of the rider and bicycle is 55.0 kg, and the hill is inclined at 16.0° with respect to the horizontal. Air resistance opposes the motion of the cyclist. Later, the bicyclist climbs the same hill at ...
*October 25, 2011*

**Probability**

0.062
*October 25, 2011*

**Spelling Skills**

Use the spelling words in the boxes below to complete the story. Then use proofreading marks to correct mistakes in the use of capital letters and periods.
*October 17, 2011*

**calculus**

A trough is 12 feet long and 3 feet across at the top. It ends are isosceles triangles with a height of 3 feet. If water is being pumped into the trough at 2.5 cubic feet per minute, how fast is the water level rising when the water is 1 foot deep?
*October 15, 2011*

**Chemistry**

How many grams of formaldehyde, H2CO, are in 500 ml of a 40% solution of formaldehyde in water? (Assume for this problem that the density of the formalin solution is 0.98 g/ml)
*September 19, 2011*

**chemistry**

How many grams of sodium were isolated from the decomposition of 0.0292 moles of Na2O, if the reaction occurred with a 44.9% percent yeild? 2 Na2O(s) --> 4 Na(s) + O2(g)
*September 13, 2011*

**chemistry**

How many molecules of NH3 could be generated from 64 molecules of N2 and 210 molecules of H2? How many molecules of N2 and H2 would be left over after the reaction?
*September 13, 2011*

**chemistry**

How many molecules of NH3 could be generated from 64 molecules of N2 and 210 molecules of H2? How many molecules of N2 and H2 would be left over after the reaction?
*September 13, 2011*

**Physics**

An object is in free fall. At one instant, it is traveling at 41 m/s. Exactly 3.2 s later, what is its speed? The acceleration of gravity is 9.8 m/s2 . Answer in units of m/s
*September 7, 2011*

**Science**

Hi, I am needing help with the following question. How long would it take to produce 150 kW with 780 J of energy? (make sure you have the corerct units)
*August 9, 2011*

**programming**

How do i read in a vector of integers with a space inbetween (i.e. 0 1 2 3) and make it an integer array? in java
*July 16, 2011*

**Physics**

A small ferryboat is 4.00 m wide and 6.00 m long. When a loaded truck pulls onto it, the boat sinks an additional 4.80 cm into the water. What is the weight of the truck?
*June 25, 2011*

**Spanish-8th gradePlease check**

1.¿Tienes que hacer mucha tarea hoy? Sí, tengo que hacer mucha tarea hoy. 2.¿Cómo vas al parque? Voy a pie. 3.¿Dónde está la cocina en tu casa? En mi casa, la cocina está abajo. 4.¿Prefieres lavar la ropa o quitar ...
*May 19, 2011*

**Physics**

Kathy is changing the tire of her car on a steep hill 20 m high. She trips and drops the 10 kg spare tire which rolls down the hill. What is the speed of the tire at the top of the next hill if the height of the hill is 5 m high?
*May 17, 2011*

**Physics**

A player kicks a footbal with a velocity of 27 m/s at an angle of 31° with the ground. How high does the ball travel?
*May 17, 2011*