Friday

August 1, 2014

August 1, 2014

Total # Posts: 909

**Chemistry**

Using Hess’s Law with the following data: N2(g) + O2(g) = 2NO(g) Del(H) = 180.7kj 2NO(g) + O2(g) = 2NO2(g) Del(H)= -113.1kj 2N2O(g) = 2N2(g)+ O2(g) Del(H)=-163.2kj Calculate Del(H) for the reaction: N2O(g) + NO2(g) = 3NO(g)

**Chemistry**

Calculate the value of the standard enthalpy change for each of the following reactions (standard enthalpy for Na2SO4(s) is -1375.653 kj/mole): a)4HBr(g) + O2(g) = 2H2O(I) + 2Br(I) b)2Na(OH)(s) + SO3(g) = Na2SO4(s) + H2O(g) c)CH4(g) + 4CI2(g) = CCI4(I) + 4HCI(g) d)Fe2O3(s) + 6...

**Chemistry**

Using standard enthalpies information, calculate the standard enthalpy change for this reaction. a)(thermite reaction) 2Al(s) + Fe2O3(s) = Al2O3(s) + 2Fe(s) b)Mg(OH)2(s) = MgO(s) + H2O(I) c)N2O4(g) + 4H2(g) = N2(g) + 4H2O(g) d)SiCl4(I) + 2H2O(I) = SiO2(s) + 4HCI(g)

**Chemistry**

Given the Data: N2(g) + O2g) = 2NO(g) delta H = 180.7kj, 2NO(g) + O2(g) = 2NO2(g) delta H = 0113.1kj, 2N2O(g) = 1N2(g) + O2(g) delta H = -163.2kj. Using Hess’s Law calculate delta H for the reaction: N2O(g) + NO2(g) = 3NO(g)

**Chemistry**

A solution of hydrogen peroxide, H2O2, is titrated with potassium permanganate, KMnO4, according to the following equation: 5H2O2 + 2KMnO4 + 3H2SO4 = 5O2 + 2MnSO4 + 8H2O + K2SO4. It requires 46.0 mL of 0.145 Mol/L KMnO4 to titrate 50.0 mL of the solution of H2O2. What is the m...

**music**

I think your ideas are great,but you need to decide together. Why don't you talk to them and negotiate the correct song to fit with you. Find a time at school, after school, at a dance studio or all of them. It is great to practice and practice does make perfection. If thi...

**Math**

Please help, I don't understand.

**Math**

What is the degree of the monomial? 6x^5

**Physics**

1.How are alternating and direct current different? 2.Who invented direct current? 3.Who invented alternating current? 4.What are some of the advantages of alternating current? 5.Do all devices that plug into the wall run on alternating current? Why/why not? 6.What is the freq...

**chemistry**

20 mL of 0.125 M potassium iodide solution is mixed with 10 mL of 0.1 g L–1 sodium thiosulfate solution and 0.2 g of solid iodine indicator is added. To this solution is added 20 mL of 0.025 M peroxodisulfate solution. After 46 seconds a blue colour appears, indicating th...

**physics**

What is the right answer?

**physics **

A mercury barometer reads 760 mm of Hg on the ground. What will it read on the roof of the Empire State Building? (take the Ïair to be 1.29 kg/m3 and the ÏHg to be 13600 kg/m3.)(? mm of Hg)

**Physics**

A mercury barometer reads 760 mm of Hg on the ground. What will it read on the roof of the Empire State Building? (take the ρair to be 1.29 kg/m3 and the ρHg to be 13600 kg/m3.)(? mm of Hg)

**Physics**

If I attach a spring to the ceiling, then hang a weight on the spring, the spring extends by 1.56 meters, comes to rest for an instant, and then begins oscillating. The mass of the weight is 6 kg. What is the oscillation frequency of the block's oscillations.(? Hz)

**Physics**

If the amplitude of a harmonic oscillator decreases to 36.3 % of its maximum amplitude in 7 seconds, what is the time constant τ(Torque) of this system?(?s)

**Physics **

A mass on a spring has a period of 1.48 seconds. What will the period be if the mass is made 5 times heaver?(? s)

**PHYSICS HELP**

A long, ideal solenoid has a diameter d=12cm and n=1200turns/meter carrying current I=20A. If the current is lowered at 4.33amp/s to zero, what is the magnitude of the induced electric field in V/m at a position 8.2cm from the solenoid's axis

**Physics**

If an object has a work of 300J and a displacement of 20m, how would I determine the net force?

**chemistry**

Plan how you would make 100mL of a buffer solution with a pH of 10.80 to be made using only sodium carbonate, sodium hydrogen carbonate and water. You should specify the amount of sodium carbonate and sodium hydrogen carbonate that you would use. Below is what i got up to then...

**chemistry/science**

Not sure if i posted this but Need help with my pH calculations? 0.10 mol of solid sodium hydrogen carbonate and 0.20 mol of solid sodium carbonate are dissolved in the same beaker of water, transferred to a volumetric ﬂask and made to 250.0 mL. The Ka for HCO3 – i...

**chemistry**

Need help with my pH calculations? 1) 0.10 mol of solid sodium hydrogen carbonate and 0.20 mol of solid sodium carbonate are dissolved in the same beaker of water, transferred to a volumetric ﬂask and made to 250.0 mL. The Ka for HCO3 – is 4.7 x 10–11. a) Wha...

**Physics**

Wrong answer.

**Physics**

Here's a stationary bike. If you pedal such that the front wheel rotates at 6.7 rad/s, and that wheel's radius is half a meter, how far would you have gone in 44 minutes, if the bike where a non-stationary bike? (Assume a constant speed of rotation)

**Physics**

A star rotates twice in 24 hours. It then goes supernova, meaning it explodes and its radius gets a lot larger, about 4 times larger. Additionally, the explosion sends most of the mass to the edge of the sphere, making it resemble a spherical shell instead of a solid sphere. F...

**Physics**

A satellite is given a boost of 540 MJ of energy to move it from its initial orbit at an altitude of 150 km to a higher altitude orbit. If the satellite has a mass of 1.16 ✕ 10^3 kg, what is the new altitude it reaches? Take the mass of the Earth to be 5.97 x 10^24 kg a...

**Physics-Gravitational Potential Energy**

A satellite is given a boost of 540 MJ of energy to move it from its initial orbit at an altitude of 150 km to a higher altitude orbit. If the satellite has a mass of 1.16 ✕ 103 kg, what is the new altitude it reaches? Take the mass of the Earth to be 5.97 x 10^24 kg an...

**Physics**

A snowmobile, with a mass of 530 kg, applied a force of 410 N backwards on the snow. a) What force is responsible for the snowmobile’s resulting forward motion? (Hint: Think action–reaction force pairs.) b) If the force of friction on the snowmobile is 187 N backward...

**Physics( Explain and choose right answer) **

A ball on the end of a rope is moving in a vertical circle near the surface of the earth. Point A F T is at the top of the circle; C is at the bottom. Points B and D are exactly halfway between A and C. Which one of the following statements concerning the tension in the rope i...

**Physics( Explain and choose right answer) **

How long is a golf club in contact with a golf ball for? A. 0.5 seconds B. 0.1 seconds C. 0.01 seconds D. 0.001 seconds E. 0.0001 seconds F. Too short to measure

**Physics( Explain and choose right answer) **

A 3 kg cat sitting on a 1.5 kg piece of cardboard on a frozen lake wants to jump to shore without touching the ice. If there is no friction between the cardboard and the ice, when the cat jumps. the cardboard will move in the opposite direction with a velocity: A. half as grea...

**Physics**

Answer is wrong.

**Physics**

During a tennis serve, the ball goes from rest to approximately 32.1 m/s. The average power generated during the serve is equal to 2614 Watts. If the acceleration is constant during the serve, what is the magnitude of the force acting on the ball?(? N)

**Physics**

During a tennis serve, the ball goes from rest to approximately 32.1 m/s. The average power generated during the serve is equal to 2614 Watts. If the acceleration is constant during the serve, what is the magnitude of the force acting on the ball?(? N)

**Physics**

During a tennis serve, the ball goes from rest to approximately 32.1 m/s. The average power generated during the serve is equal to 2614 Watts. If the acceleration is constant during the serve, what is the magnitude of the force acting on the ball?(? N)

**Physics**

A 3.9 kg cat falls out a window. Just before landing, the cat's momentum is equal to 55.8 kg m/s. How high was the window where the cat fell from?(?m)

**Physics**

Two lovebirds are held together by a stange force called love. Physicists recently discovered the functional form of love (a conservative force) as a function of distance, for lovebirds. Flove(x)=2x^2+3x^3. (units in meters) Assuming they start off next to each other, how much...

**Chem**

The density of ethanoic anhydride is 1.092 g/mL. Use this value, and the amount that you used in the laboratory to show that ethanoic anhydride is in excess for your preparation of ASA?, 2.5ml of ethanoic anhydride was used.

**Physics**

A 97 kg person slides down a pole, just for fun. The pole has a frictional force of 810 N and the speed of the person at the bottom of the pole is 3.7 meters per second. How long was the pole?(? m)

**Physics**

If I stop my 1000 kg car by applying a force with my brakes equal to 3000 N in a distance of 719 meters, how much work is done. (Pay attention to the direction of the force and the displacement)(? J)

**Physics**

How fast can a car be going around a turn with radius 42.3 m if the road is covered with ice? (The μs for rubber on ice is 0.10)? Give your answer in miles per hour.

**Physics**

1. A standard LP record has a diameter of 30 centimeters. A record on a standard turntable rotates 33.3 times a minute. What is the centripetal acceleration of a point on the edge of the record? 2.If a 7.3 gram coin is placed at the very edge of the record described in the abo...

**Physics**

A solar sail is a possble means of interplanetary travel. It uses the pressure from the sun's light to provided a force on the sail (like a regular sailboat does with wind). If the force from the sun's light on the sail is equal to 4.1 Newtons, how fast will the 's...

**Physics**

How fast can a car be going around a turn with radius 42.3 m if the road is covered with ice? (The μs for rubber on ice is 0.10)? Give your answer in miles per hour.

**Physics**

1. A standard LP record has a diameter of 30 centimeters. A record on a standard turntable rotates 33.3 times a minute. What is the centripetal acceleration of a point on the edge of the record?(? m/s2) 2. If a 7.3 gram coin is placed at the very edge of the record described i...

**English**

A?

**English**

Which implicit element of the analogy in these lines is analogous to "family worship"? Breakfast over, Aunt Polly had family worship: it began with a prayer built from the ground up of solid courses of Scriptural quotations, welded together with a thin mortar of orig...

**Please help with Chemistry?????**

5.00 mL of 2.00x10^-3M Fe(NO3)3 is mixed with 4.03 mL of 2.00x10^-3M NaSCN and 1.08 mL of 0.1M HNO3, for a total volume of 10.11 mL. a) What is the initial concentration of the Fe(NO3)3 in the mixed solution? b) What is the initial concentration of the NaSCN in the mixed solut...

**Please help with Chemistry?????**

A standard solution with a FeSCN2+ concentration of 1.55x10^-4M has a percent transmittance (%T) of 18.8%. Another solution of unknown FeSCN2+ concentration has a percent transmittance of 44.8%. A) Calculate the absorbance (A) of each solution. B) Using the absorbances calcula...

**Chemistry**

A standard solution with a FeSCN2+ concentration of 1.55x10^-4M has a percent transmittance (%T) of 18.8%. Another solution of unknown FeSCN2+ concentration has a percent transmittance of 44.8%. A) Calculate the absorbance (A) of each solution. B) Using the absorbances calcula...

**Chemistry**

5.00 mL of 2.00x10^-3M Fe(NO3)3 is mixed with 4.03 mL of 2.00x10^-3M NaSCN and 1.08 mL of 0.1M HNO3, for a total volume of 10.11 mL. a) What is the initial concentration of the Fe(NO3)3 in the mixed solution? b) What is the initial concentration of the NaSCN in the moxed solut...

**Math**

Interest is a concept familiar to most people: every credit card in existence has a term called annual percentage rate (APR), which is an interest rate. Suppose you charged $1,000 to a credit card that has a minimum payment each month equal to the interest owed. Can you figure...

**Math**

The formula for simple interest is where I is the amount you will pay in interest, r is the rate at which interest will accrue, P is the principal (amount borrowed), and m is the number of times the interest is applied. To solve for the interest rate of your credit card, you n...

**Math**

B?

**Math**

Gabe is the human resource manager for the Advanced Scientific Research Lab. He has to record the heights (in centimeters) and weights (in pounds) for each of the scientists in the lab. Height distribution (cm): 178, 163, 174, 186, 154, 167, 167, 181, 159, 165, 177, 191, 158 W...

**AP chem**

Mostly just setting up my reaction to use for each problem

**AP chem**

Mostly just setting up my reaction to use for each problem

**AP chem**

Consider the titration of 50.00 ml .250 M HBr with .100 M Ba(OH)2. What is the pH after the following additions of Ba(OH)2 to the 50 ml of hydrobromic acid? 0 ml. 15 ml. 25 ml. 50ml. 51ml.

**programming**

using pseudocode debug the following 3 programs // A high school is holding a recycling competition // This program allows a user to enter a student's // year in school (1 through 4) // and number of cans collected // Data is entered continuously until the user wants to qu...

**Physics**

I got it!!! Thank you!!!

**Physics**

I dont understand it, can you please explain it to me?.. Thanks

**Physics**

I think it is. and it's not one person, we study in a group. Thank You.

**Physics**

A pilot, whose mass is 91.0 kg, makes a loop-the-loop in a fast jet. Assume that the jet maintains a constant speed of 125 m/s and that the radius of the loop-the-loop is 0.478 km. What is the apparent weight that the pilot feels (i.e., the force with which the pilot presses a...

**Physics**

Thank you so much Elena!!

**Pre-Calc**

Using the difference for formula, find the tan 255. Step by step would be appreciated

**Math Quiz**

Math Quiz please help fast Write the following ratio in simplest form: 32 min:36 min (1 point) 8:9 8:36 32:9 128:144 2. Marie saved $51. On Wednesday, she spent $8 of her savings. What ratio represents the portion of her total savings that she still has left? (1 point) 43:8 8:...

**Maths**

Will it be 16x^2-40x+25

**Maths**

(4x-5)^2

**Maths**

(5x+4)(5x-4)=

**physics**

You apply a potential difference of 5.00 V between the ends of a wire that is 2.65 m in length and 0.654 mm in radius. The resulting current through the wire is 17.6 A. What is the resistivity of the wire?

**Math**

Carla and Candice left from the same place at the same time and rode their bikes in the same direction along a straight road . Candice biked at an average speed that was three-quarters of Carla's average speed. After 2 hours they were 28 miles apart. What was the average s...

**Math**

The area of each trapezoid is 3 times the area of one triangle. The area of one triangle is six square units. What is the total area of the figure in square units?

**Algebra word prob**

If you graph the table of values and draw a line through the coordinates, the graph will look like a parabola. Thus the equation is quadratic. Since you don't have a graphing calculator, I will give you the resulting a/b/c values that it comes up with, but the rest is for ...

**Math**

2. True or false. Suppose the slope of a straight line L is -3/4 and P is a given point on L. If Q is a point on L lying 2 units to the right of P, then Q is situated 3/2 units below P. Prove why.

**physics **

The Hyperloop is a hypothetical new fast transport system between cities, which works by launching pods that carry people through a very low air pressure tunnel. The Hyperloop reduces friction between the pods and the tunnel by supporting the pod on a cushion of air. This air ...

**Statistics**

Hola ¿Cuál es el P - value en este problema que escribiste?

**Math**

A circle of radius 1 is drawn in the plane. Four non-overlapping circles each of radius 1, are drawn (externally) tangential to the original circle. An angle γ is chosen uniformly at random in the interval [0,2π). The probability that a half ray drawn from the centre...

**Math**

There are 100 runners, each given a distinct bib labeled 1 to 100. What is the most number of runners that we could arrange in a circle, such that the product of the numbers on the bibs of any 2 neighboring runners, is less than 1000?

**Math**

γ is a permutation on eight elements, though you are not told which permutation it is. If γ is applied to an 8-element set, what is the minimum number of additional times we must apply γ to the resulting set in order to guarantee the set is back in its original ...

**Physics 1**

A body of mass 6kg moving at 8m/s collides with a stationary body of mass 10kg and sticks to it. Find the speed of the composite body immediately after the impact.

**Math (Algebra)**

Thanks Steve!

**Math (Algebra)**

f(x) is a cubic polynomial that satisfies f(1)=f(2)=f(3)=4 and f(0)=0. What is the value of f(7)?

**Math (Probability)**

Please tell the answer. I'm not able to get it. Thanks.

**Math (Probability)**

Bret and Shawn are playing a game where each turn the players roll a 20-sided die fair and then add the number they get to their score. The winner is the player with the highest score at the end of the game (there may be a tie). Before the last turn, Shawn is winning by 10 poi...

**Math (Algebra)**

A number is called algebraic if there is a polynomial with rational coefficients for which the number is a root. For example,√2 is algebraic because it is a root of the polynomial x^2−2. The number √2+√3+√5 is also algebraic because it is a root o...

**Physics**

A 15 kg, 1m wide door which has frictionless hinges is closed but unlocked. A 400 g ball hits the exact middle of the door at a velocity of 35 m/s and bounces off elastically, thereby causing the door to slowly swing open. How long in seconds does it take for the door to fully...

**Math (Combinatorics)**

Six boxes labeled 1,2,…,6 are arranged in a line. Seven identical balls are to be placed into the boxes such that for any 1 ≤ k ≤ 6, there are at least k total balls amongst boxes 1,2,…k. How many different placements of the balls into the boxes are possi...

**math**

or 9√970/500.

**math**

It's 0.5606068140863.

**Physics**

A 15 kg, 1m wide door which has frictionless hinges is closed but unlocked. A 400 g ball hits the exact middle of the door at a velocity of 35 m/s and bounces off elastically, thereby causing the door to slowly swing open. How long in seconds does it take for the door to fully...

**Geometry**

Perimeter of Rectangle = 2L + 2W where: L = length, and W = width Perimeter = 2(8) + 2 (6)= 28 inches Area of Rectangle = L x W Area = (6in)(8in) = 48 inches squared.

**heeelp MATH**

Yes please Reiny. It would help me a lot. Thanks! :)

**Math (Geometry)**

ABC is a triangle with a right angle at A. M and N are points on BC such that AM is the altitude, and AN is the angle bisector of ∠BAC. If CN/NB=21, what is CM/MB?

**Math (Geometry)**

ABC is a triangle with a right angle at A. M and N are points on BC such that AM is the altitude, and AN is the angle bisector of ∠BAC. If CN/NB=21, what is CM/MB?

**Math (Geometry)**

Thanks hans!

**Math (Geometry)**

A point P is given outside of a circle Γ. A tangent from P to Γ touches Γ at T with PT=45. A line from P cuts Γ at the 2 points A,B. If PA=25, what is the length of PB?

**Math (Geometry)**

ABCD is a parallelogram with side lengths AB=15,BC=10 and ∠ADC=75∘. A point P in the interior of the parallelogram is chosen such that ∠APD+∠CPB=180∘. What is the measure (in degrees) of ∠PAD+∠PCB?

**Math (Probability)**

When Lino submitted an essay for his English class, it was 9 pages long. Lino's essay had errors on pages 2 and 7. If the teacher chose 3 pages uniformly at random to read, then the probability that she didn't read any of the pages with errors can be expressed as a/b w...

**Math - Maximizing Logarithm**

x and y are positive values satisfying x + y = 1/4. When ln(y^2+4xy+7) attains its maximum (subject to the given constraint), what is the value of 1/xy?

**algebra**

12(3+y)=5(2y+8)

**math**

the class room had 100 students.in 200, there were 6 few men than there were woman.how man women were in the classroom in 2010?

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