Wednesday

October 1, 2014

October 1, 2014

Total # Posts: 2,203

**Chemistry**

Given 2Al(s) + 3/2O2(g) → Al2O3(s), ΔH°f = -1,670 kJ/mol for Al2O3 (s). Determine ΔH° for the reaction 2Al2O3(s) → 4Al(s) + 3O2(g).
*May 5, 2014*

**Chemistry**

A piece of copper metal is initially at 100.0°C. It is dropped into a coffee cup calorimeter containing 50.0 g of water at a temperature of 20.0°C. After stirring, the final temperature of both copper and water is 25.0°C. Assuming no heat losses, and that the ...
*May 5, 2014*

**Chemistry**

A system initially has an internal energy U of 493 J. It undergoes a process during which it releases 107 J of heat energy to the surroundings, and does work of 225 J. What is the final energy of the system, in J?
*May 5, 2014*

**Chemistry**

Calculate the enthalpy change for the reactions NO(g) + O(g) → NO2(g) from the following data: NO(g) + O3(g) → NO2(g) + O2(g) ΔH = -198.9 kJ O3(g) → 1.5O2(g) ΔH = -142.3 kJ O2(g) → 2O(g) ΔH = 495.0 kJ Put the answer in kJ.
*May 5, 2014*

**Chem Check Please!!!**

1) Calculate the cell potential, at 25 C, based upon the overall reaction Zn2+(aq) + 2 Fe2+(aq) -> Zn(s) + 2 Fe3+(aq) if [Zn2+] = 1.50 x 10^-4 M, [Fe3+] = 0.0200 M, and [Fe2+] = 0.0100 M. The standard reduction potentials are as follows: Zn2+(aq) + 2 e– -> ...
*May 3, 2014*

**Chem Check Please!!!**

1) Assuming the following reaction proceeds in the forward direction, 3 Sn4+(aq) + 2 Cr(s) ---> 3 Sn2+(aq) + 2 Cr3+(aq) a.Sn4+(aq) is the reducing agent and Cr(s) is the oxidizing agent. b.Cr(s) is the reducing agent and Sn2+(aq) is the oxidizing agent. c.Sn4+(aq) is the ...
*May 2, 2014*

**math**

find the bank discount and proceeds on the following loans RM4215 FROM 10 june to 5 august of the same year at 10 percent
*May 2, 2014*

**Calculus Help and Check**

find the derivative of the function integral from cosx to sinx (ln(8+3v)dv) y'(x)= (sin(8+3((sin(x)))+x)+sin(8+3sin(x)-x))/2 Is this the right answer?????
*May 1, 2014*

**calculus help**

y'(x)= (sin(8+3((sin(x)))+x)+sin(8+3sin(x)-x))/2 Is this the right answer?????
*May 1, 2014*

**calculus help**

find the derivative of the function integral from cosx to sinx (ln(8+3v)dv)
*May 1, 2014*

**math**

A regular hexagon is drawn inside of a circle so that each of its vertices touches the circle. The diameter of the circle is 4 centimeters and the perimeter of the hexagon is 12 centimeters. How much longer is the circumference of the circle than the perimeter of the hexagon...
*April 30, 2014*

**Math**

Two dice are rolled what are the odds of getting a smaller number on the second roll? P ( same number or sum greater than 8)
*April 29, 2014*

**Chemistry **

A system which undergoes an adiabatic change (i.e., q = 0) and has work done on it by the surroundings has a. w < 0, ΔU = 0 b. w < 0, ΔU < 0 c. w > 0, ΔU < 0 d. w > 0, ΔU > 0 e. w < 0, ΔU > 0
*April 28, 2014*

**calculus help**

Farmer Brown wants to fence in a rectangular plot in a large field, using a straight rock wall that is already there as the north boundary. The fencing for the east and west sides of the plot will cost $3 a yard, but she needs to use special fencing, which costs $5 a yard, on ...
*April 25, 2014*

**Calculus Help **

Farmer Brown wants to fence in a rectangular plot in a large field, using a straight rock wall that is already there as the north boundary. The fencing for the east and west sides of the plot will cost $3 a yard, but she needs to use special fencing, which will minimize the ...
*April 24, 2014*

**Math**

Question is misleading. Group A ate 1 pizza. Group B ate 1 pizza + 2 slices. Group B ate more pizza. Group C would have ate 4/6 if they ate the rest of the pizza. This we can only assume because they did not provide enough information.
*April 24, 2014*

**Math ~ Check Answers ~**

You go to CCA! Cheater
*April 23, 2014*

**Math**

It's B! ;)
*April 17, 2014*

**Math**

Simplify 15C3 A. 182 B. 455 C. 2,730 D. 910
*April 17, 2014*

**Math**

13. A true or false test has 8 questions. What is the probability of guessing the correct answers to all the questions? A. 1/10 B. 1/16 C. 1/64 D. 1/256
*April 17, 2014*

**Math**

Each of two urns contains green balls and red balls. Urn one contains 10 green balls and 8 red balls. Urn two contains 3 green balls and 10 red balls. If a ball is drawn from each urn, what is P(red and red)? A. 23/18 B. 10/27 C. 40/117 D. 18/31
*April 17, 2014*

**Math**

Thanks!
*April 17, 2014*

**Math**

Food Express is running a special promotion in which customers can win a free gallon of milk which their food purchase if there is a star on their receipt. So far, 147 of the first 156 customers have not received a star on their receipts. What is experimental probability of ...
*April 17, 2014*

**Steve please help!**

Thank you :)
*April 17, 2014*

**Steve please help!**

3. A number cube is rolled 160 times. The number 2 comes up 39 times. What is the experimental probability of rolling a 2? What is the theoretical probability of rolling a 2? A. 39/160; 1/80 B. 1/6; 39/160 C. 39/160; 1/6 D. 121/160; 1/6
*April 17, 2014*

**Probability**

1. You roll a number cube numbered one to six 12 times. P(5)=2/3. What type of probability is illustrated and why? A. Experimental; the result is based on the number of possible outcomes. B. Experimental; the result is found by repeating an experiment. C. Theoretical; the ...
*April 17, 2014*

**Educational Technology**

Got 'em all right ;)
*April 16, 2014*

**Educational Technology**

1. Which of the following choices is a strategy that could help with time management? A. Spending most of the day on leisure activities. B. Doing homework in every spare moment. C. Cutting back on sleep. D. Creating a list of tasks to be completed daily.* 2. What is a planner...
*April 16, 2014*

**Chemistry**

I did that but got 5.346 g as my answer. Is that correct?
*April 14, 2014*

**Chemistry**

What mass of lithium phosphate is needed to prepare 500.0 mL of a solution having a lithium ion concentration of 0.1385 M?
*April 14, 2014*

**Chemistry**

Vinegar is a solution of acetic acid, CH3COOH, dissolved in water. A 4.69 g sample of vinegar was neutralized by 32.97 mL of 0.100 M NaOH. What is the percent by weight of acetic acid in the vinegar?
*April 14, 2014*

**Chemistry**

What mass of hydrogen gas is produced when a 7.43 g chunk of zinc dissolves in 500.0 mL of 1.200M HCl?
*April 14, 2014*

**Chemistry**

A 4.379 g sample of MgCl2 is dissolved in enough water to give 750.0 mL of solution. What is the chloride ion concentration in this solution?
*April 14, 2014*

**Math**

A number cube with numbers 1 through 6 is rolled. Find the given probability. P(complement of 4) A. 1/6* B. 5/6 C. 2/6 D. 4/6
*April 8, 2014*

**Math**

A number cube with numbers 1 through 6 is rolled. Find the given probability. P(number¡Ý3) A. 4/6 B. 1/6 C. 2/6 D. 5/6*
*April 8, 2014*

**Math**

A number cube with numbers 1 through 6 is rolled. Find the given probability. P(number<2) A. 1/6* B. 2/6 C. 4/6 D. 3/6
*April 8, 2014*

**physics**

A lightning bolt may carry a current of 1.00 ✕ 104 A for a short time interval. What is the resulting magnetic field 134 m from the bolt? Assume that the bolt extends far above and below the point of observation.
*April 6, 2014*

**science(check answers)**

60 kg cheetah reaches a speed of 30 m/s when chasing its prey
*April 3, 2014*

**language arts **

6.Which of the following places events in chronological order? A.formation of Negro Leagues, invention of baseball, Civil War B.invention of baseball, Civil War, formation of Negro Leagues C.invention of baseball, formation of Negro Leagues, Civil War D.Civil War, invention of...
*March 28, 2014*

**5th Grade Math**

8 games
*March 27, 2014*

**5th Grade Math**

Keith played some games of chess at a tournament. He recorded the results of the games on the table shown. Game Results: Number of Games TIES 4 WINS 12 Losses 4 If Keith plays 10 more games, how many of the 10 games is he likely to win? A. 6 games B. 8 games C. 4 games D. 2 games
*March 27, 2014*

**Math**

-7x + 9y = -29 8x + 5y = -28
*March 22, 2014*

**Math **

solving applied problems two equations (Coles two student loans totaled $31,000. One of his loans was at 2.8% simple interest and the other at 4.5%. After one year, Cole owed $1024.40 in interest. What was the amount of each loan?)
*March 22, 2014*

**us history**

X( WHY DOESN'T ANYBODY FIX THE WRONG ANSWERS?!?!
*March 19, 2014*

**Math**

Sam spent half his money on a shirt. At another store he spent half the money he had left. Then he bought a cd for $6.75. He had $2.50 left. How much money did Sam have in the beginning?
*March 12, 2014*

**English**

Compare and contrast the elements of the Kelly-Frye and Daubert decisions. What do you think about each decision and how it pertains to the rules of evidence?
*March 9, 2014*

**physics**

A block of mass m = 2.7 kg is released from rest at a height of H = 0.49 m on a curved frictionless ramp. At the foot of the ramp is a spring whose spring constant is k = 515.0 N/m. What is the maximum compression of the spring, x? B)After the spring reaches its maximum ...
*March 5, 2014*

**Physics**

At the top of an inclined track, a spring is attached to a rod at one end and a dynamics cart at the other such that the spring stretches parallel to the track. The cart has a mass of .850kg and there is negligible friction between the cart and the track. The spring has a ...
*March 3, 2014*

**Physics**

A spring of unknown force constant is attached to a rod so that it hangs vertically. With no mass attached, the spring has a length of 12.0 cm. When a student attaches a mass of 50 grams, the spring stretches to a length of 18.0cm. Determine the force constant for this spring.
*March 3, 2014*

**physics**

A 25.5- kg block (m1) is on a horizontal surface, connected to a 5.7- kg block (m2) by a massless string as shown in the Figure. The pulley is massless and frictionless. A force of 239.3 acts on m1 at an angle of 32.1 . The coefficient of kinetic friction between m1 and the ...
*March 3, 2014*

**Algebra**

Sorry I submitted before finishing my input. Arrange the terms of the polynomial in ascending powers of b. 25db^5-7dm+3b^10-6db^6 Am I correct? Please help? My answer is: 25b^5d-7dm+3b^10-6b^6d=3b^10-6b^6d+25b^5d-7dm
*March 2, 2014*

**Algebra**

Arrange the terms of the polynomial in ascending powers of b. 25db^5-7dm+3b^10-6db^6 Please tell me if I am correct on my answer? I got: 25b
*March 2, 2014*

**math**

The Mills Lunch Shop prepares fresh take-out entrees each day. On Tuesday, 40 baked chicken dinners were prepared at a cost of $3.20 each. A 20% spoilage rate is anticipated. Mills Lunch Shop sells the dinners at an 80% markup based on cost. They decided to offer a $1.00-off ...
*March 2, 2014*

**Science**

Why do you think the human brain has more convolutions than a pig brain?
*March 1, 2014*

**Chemistry**

The value of KC for the interconversion of butane and isobutane is 2.5 at 25°C. If you place 0.067 mol of butane in a 0.250-L flask at 25°C and allow equilibrium to be established, what will be the concentrations of the two forms of butane? A)[butane] B)[isobutane]
*March 1, 2014*

**political science**

what civil liberties are protected by the Georgia Constitution?
*February 27, 2014*

**physics**

The oxygen taken in by the body reacts with fats, carbohydrates, and protein, liberating energy internally at a rate of about 2.12×104 J /liter. If a 85.4 kg man requires 73.0 W of power even while sleeping, what is his rate of oxygen consumption?
*February 25, 2014*

**physics**

A 0.13 kg ball of dough is thrown straight up into the air with an initial speed of 18 m/s. The acceleration of gravity is 9.81 m/s2 .What is its momentum halfway to its max- imum height on the way up?
*February 24, 2014*

**math**

Triangle abc and triangle xyz are similar. If ab,bc, and ac are 10, 13, and 14 inches respectively, and xy is 11 inches, find xz to the nearest tenth of an inch.
*February 24, 2014*

**PHYSICS**

A large stone block has been loaded in the bed of a dump truck. The bed is slowly raised until it makes an angle of 30 degrees with the horizontal; at this point, the block starts to slide downward. What is the coefficient of static friction between the block and the truck bed...
*February 23, 2014*

**PHYSICS**

2.352 m/s^2
*February 23, 2014*

**Finite Math and Applied Calculus **

Betty Sue sets up a retirement account. For the first 35 years, she deposits $500 at the end of each month into an account with an annual interest rate of 3.6%, compounded monthly. Then, she stops making monthly payments and transfers the money into a different account ...
*February 19, 2014*

**statistic**

I a 3 team league the teams play each other once per year. Team A won 3 over a 2 year period. Team B won 4 and Team C won 5 What is the probability of Team wining all two games next season
*February 19, 2014*

**Science**

Why is the thymus gland so large in the fetal pig?
*February 19, 2014*

**economics**

The government could pass new laws that force you to use environmentally friendly cleaning products which may cost more and ultimately increase your overhead.
*February 15, 2014*

**Physics**

Ball A is thrown straight down off the top of a tall building with an initial velocity of 20m/s. Ball b is thrown straight up from the top of the same building with initial velocity of 20 m/s. Which ball, if either, experiences the greater acceleration after leaving the ...
*February 7, 2014*

**physics**

A proton, initially traveling in the +x-direction with a speed of 6.00×105m/s , enters a uniform electric field directed vertically upward. After traveling in this field for 4.38×10−7s , the proton’s velocity is directed 45 ∘ above the +x-axis.
*February 6, 2014*

**Math**

.50x+.20y=3.60 x+y=9
*February 5, 2014*

**Help!!!**

Thanks Emily! Got a 100!
*February 3, 2014*

**science(check answers)**

im the one who needs help not give help
*January 29, 2014*

**Physics**

A car experiences a constant acceleration of 2.3 m/s2. How long does it take (in s) for the car's speed to increase from 6.6 m/s to 17.9 m/s?
*January 29, 2014*

**PHYSICS**

Suppose that the electric potential outside a living cell is higher than that inside the cell by 0.0928 V. How much work is done by the electric force when a sodium ion (charge = +e) moves from the outside to the inside? no idea how to do this can i just have the step by step ...
*January 28, 2014*

**physics**

The coeﬃcient of linear expansion for a silver strip is 1.9 × 10−5 / ◦C. What is its length on a hot day when the temperature is 32◦C if the strip is 1.4 m long when it is −15◦C? Answer in units of m Your answer must be within ±...
*January 24, 2014*

**Math**

Kyle is training for a bike race. He rides 5 miles one day, 10 miles the next day, and 15 miles the third day. If Kyle repeats this schedule, what is the total distance he will have ridden after 5 days?
*January 16, 2014*

**5th grade math**

Tia collected $10 for a walk-a-thon and $ 5 from each friend. What is the total amount of donations she collected from 4 friends? Is my answer below correct? Friend - 1,2,3,4 Donations - $5, $5, $5, $5 = $20 Answer is $20 from 4 friends.
*January 14, 2014*

**Geometry**

Suppose point J has coordinate of -2 and JK=4. Then what is the possible coordinate(s) for K?
*January 10, 2014*

**Math **

Let f(x)=ln(3x^(2)-2x-4). Find the domain.
*January 8, 2014*

**social studies**

A) Thomas Jefferson Because He Was In That Time Frame and was actually president when the Louisiana purchase Happened. :)
*December 30, 2013*

**Chemistry **

What is the effect of Independent Variable on Dependent Variable ?
*December 30, 2013*

**Chemistry **

What is the effect of Independent Variable on Dependent Variable ?
*December 30, 2013*

**Calculus**

what is the limit n to infinite of cos1*cos(1/2)*cos(1/4)*cos(1/8)*cos(1/16)*...*cos(1/2^n)
*December 19, 2013*

**Batteries - Engineering**

Here we consider instead dissolving guns (which we will assume are pure iron) with sulfuric acid. Fe+H2SO4->FeSO4+H2 It is apparent that they must use an outside source of electrical power to drive the dissolution of the iron. They use a small current so that the ...
*December 18, 2013*

**Solar Energy - Engineering**

In the process of electrolysis, electrical power is used to separate water into oxygen and hydrogen molecules via the reaction: H2O --> H2 + ½O2 This is very much like running a hydrogen fuel cell in reverse. We assume that only the activation potential for the ...
*December 18, 2013*

**Engineering**

What is the answer for b and c? Please Help.
*December 15, 2013*

**Math 5th grade**

Mrs. Rodriguez mixed water and plant food in a container and filled the container until it measured 6/8 gallon. She poured 4/8 gallon of the mixture on her geraniums and 1/8 gallon on her petunias. How much of the mixture did she have left after pouring ot on her plants?
*December 9, 2013*

**Chemistry**

What are the formulas of the salts that precipitate when the reaction mixture (n-butyl alcohol, sodium bromide, water, and sulfuric acid) is cooled?
*December 2, 2013*

**chemistry**

From the periodic table, you get the atomic mass of Mg, which is 24.31. Atomic mass is grams/mole, by dimensional analysis: (2.5g)/(24.31g/mol)=0.1028 moles of Magnesium as the grams units cancel out. *This answer does not have proper significant figures.
*December 2, 2013*

**Chemistry**

Balancing Complete Redox Reactions I need help on the half reduction part for both reduction and oxidation of Cl2(g) --> cl^1- (aq) + OCl^1- (aq). I got both of the half reactions started. Cl2 --> Cl^- (Reduction) .... Cl^1- (aq) + OCl^1- (aq) (Oxidation). I need know ...
*November 23, 2013*

**Chemistry**

Balancing Complete Redox Reactions I need help on the half reduction part for both reduction and oxidation of Cl2(g) --> cl^1- (aq) + OCl^1- (aq). I got both of the half reactions started. Cl2 --> Cl^- (Reduction) .... Cl^1- (aq) + OCl^1- (aq) (Oxidation)
*November 23, 2013*

**science**

what is matter
*November 21, 2013*

**Chemistry**

A solution is made by adding 0.100 mole of ethyl ether to 0.500 mole of ethyl alcohol. If the vapor pressures of ethyl ether and ethyl alcohol at 20 oC are 375 torr and 20.0 torr, respectively, the vapor pressure of the solution at 20 oC (assuming ideal behavior) is:
*November 14, 2013*

**Chemistry**

Benzene (C6H6) and toluene (C5H5CH3) form nearly ideal solutions. At 20°C the vapor pressure of benzene is 74.7 Torr and that of toluene is 22.3 Torr. a) Find the equilibrium partial pressures above a solution of 100.0 g benzene and 100.0 g toluene. b) Find the mole ...
*November 14, 2013*

**math**

explain how you could show five less than a number using an expression
*November 14, 2013*

**Maths**

An operation produces (A-1)/A from a fraction A=m/n, where m is not equal with n and m is not zero. If the initial value of A is 22/47 and the operation is repeated 2012 times, the final output is a/b. What is a and b?
*November 9, 2013*

**Math**

Find the common factors of each set of numbers. 1. 1,4,8,32_____
*November 3, 2013*

**civics**

I have searched for a case study done on women being paid less in the workforce and cannot come up with anything. Would any of you know of any real-life examples of women being paid less?
*November 3, 2013*

**physics**

An iron rod(a=11.8x10-6 C-1) has a length of 1000 meters (or 1 km) at 0 degrees Celsius. If the rod must expand 10 cm to bridge a gap, to what temperature must the rod be heated?
*November 1, 2013*

**physics**

An iron rod has a length of 1000 meters (or 1 km) at 0 degrees Celsius. If the rod must expand 10 cm to bridge a gap, to what temperature must the rod be heated?
*November 1, 2013*

**Physics **

A container of volume 19.4 cm3 is initially filled with air. The container is then evacuated at 0oC to a pressure of 6.0 mPa. How many molecules are in the container after evacuation if we assume that air is an ideal gas?
*October 29, 2013*

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