Saturday

August 27, 2016
Total # Posts: 3,219

**Chemistry**

If the standard state of sufur is S8 (s), which of the following equations represents the standard enthalpy of formation of H2SO4 (ℓ) ? A. 2H (g) + S (g) + 4 O (g) H2SO4 (ℓ) B. H2 (g) + S8 (g) + 2 O2 (g) H2SO4(ℓ) C. H2SO4 (ℓ) &#...
*October 2, 2011*

**Chemistry**

Calculate the enthalpy change, ΔrH, for the following reaction, 4 NH3 (g) + 5 O2(g) → 4 NO (g) + 6 H2O (g) given the thermochemical equations below. N2 (g) + O2 (g) → 2 NO (g) ΔrH° = +181 kJ N2 (g) + 3 H2 (g) → 2 NH3 (g) ΔrH° = ...
*October 2, 2011*

**Chemistry**

If H for the reaction I2 (s) 2I (g) is 153 kJ/mol. What is the longest wavelength of light that can break an I – I bond? In other words, what is the minimum energy, expressed in terms of wavelength, required to break one I – I bond? A. 246 nm B. 465...
*October 2, 2011*

**Chemistry(Please check)**

What is the oxidation number of chromium in K2Cr2O7 so k=+1 (2) = 2 O=-2(7) = -14 2x + 1 +(-14) = 0 2x-12=0 x=6 so Cr is 6 Is this correct?? Thank you!!
*October 1, 2011*

**math**

are we allowed to use calculators in sat 1 math?
*September 30, 2011*

**math**

A rectangle was constructed using 24 square tiles. If you add the length and width of her rectangle together, you would get 11. What is the length and width of this rectangle?
*September 29, 2011*

**Chemistry**

What is the oxidation number of chromium in K2Cr2O7? I know that K = 1 O=-2 so 7*-2=-14 I do not know what to do now. Thank you for your help!
*September 27, 2011*

**7th grade math**

it is a grid 0,5.10.15,20 thru 55 then it cost a camp;er 25.00 how does this work??
*September 26, 2011*

**7th grade math**

i need help with variables and patterns algebra
*September 26, 2011*

**Chemistry(Please help, thank you!!)**

Thank you. I understand how you got the numbers for Na and H and the -6 for O but why does S have to be +4?
*September 26, 2011*

**Chemistry(Please help, thank you!!)**

What is the oxidation number of sulfur (s) in NaHSO3? I know that Na is 1 but I do not know what else to do. Please explain, thank you for your help!!
*September 26, 2011*

**Chemistry**

When aqueous CuSO4 is added to aqueous Na2S2O3, why is there no reaction?
*September 25, 2011*

**Physics**

Can you explain how to figure this out? A helicoptor accelerates at a rate of 2m/s^2. If you drop a rock out of the helicoptor 3 seconds after takeoff how high is the helicoptor when the rock hits the ground. Thanks
*September 25, 2011*

**physics**

Two particles are at the same point at the same time, moving in the same direction. Par- ticle A has an initial velocity of 9 m/s and an acceleration of 2.7 m/s2. Particle B has an initial velocity of 2.9 m/s and an acceleration of 4.2 m/s2. At what time will B pass A? Answer ...
*September 25, 2011*

**Chemistry(Please help, thank you!!!)**

Write the balanced, complete, and net ionic equations for each precipitation reaction. 1) AgNO_3 + CoCl_2 ---> BE: AgNO_3(aq) + CoCl_2(aq) ---> AgCl_2 (aq) + Co(NO_3)(aq) CIE: Since the balanced equation is all (aq) there is no reaction so no complete or net equation. 2...
*September 24, 2011*

**Chemistry(Please check!!)**

Write the balanced, complete, and net ionic equations for each precipitation reaction. 1) AgNO_3 + CoCl_2 ---> BE: AgNO_3(aq) + CoCl_2(aq) ---> AgCl_2 (aq) + Co(NO_3)(aq) CIE: Since the balanced equation is all (aq) there is no reaction so no complete or net equation. 2...
*September 24, 2011*

**physics**

A student, starting from rest, slides down a water slide. On the way down, a kinetic frictional force (a nonconservative force) acts on her. The student has a mass of 75 kg, and the height of the water slide is 11.1 m. If the kinetic frictional force does -6.8 × 103 J of...
*September 21, 2011*

**Physics**

A 49.5-g golf ball is driven from the tee with an initial speed of 41.9 m/s and rises to a height of 29.7 m. (a) Neglect air resistance and determine the kinetic energy of the ball at its highest point. (b) What is its speed when it is 5.66 m below its highest point?
*September 21, 2011*

**Physics**

A 27-kg girl is bouncing on a trampoline. During a certain interval after leaving the surface of the trampoline, her kinetic energy decreases to 150 J from 430 J. How high does she rise during this interval? Neglect air resistance.
*September 21, 2011*

**Physics**

Starting from rest, a 1.7x10-4 kg flea springs straight upward. While the flea is pushing off from the ground, the ground exerts an average upward force of 0.44 N on it. This force does 2.4x10-4 J of work on the flea. (a) What is the flea's speed when it leaves the ground...
*September 21, 2011*

**Physics**

A person pushes a 23.4-kg shopping cart at a constant velocity for a distance of 31.1 m on a flat horizontal surface. She pushes in a direction 34.8 ° below the horizontal. A 38.5-N frictional force opposes the motion of the cart. (a) What is the magnitude of the force ...
*September 21, 2011*

**Math(Please help, very confused!)**

A piece of copper contains 3.6 x 10^8 atoms. What is the volume of the sample in units of liters? i have no idea how to start this. Please help thank you!!!
*September 20, 2011*

**Calculus**

2sin(2theta) + sqrt(3) = 0 interval (0,2pi) How do I solve this? I thought about maybe subtracting the sqrt(3) from both sides, so that i would have 2sin(2theta) = -sqrt(3) Then maybe dividing by two? sin(2theta) = -sqrt(3)/2 Am I doing anything right here? It's been a ...
*September 20, 2011*

**chemistry**

If you dissolve 29.25 g of sodium chloride in 250 g of H2O. What would be the freezing point? Kfp- -1.86 degrees C/molal I know the formula is K times molality. I am taking -1.86(2.00) and getting -3.72 degrees Celsius, when the answer is -7.44 degrees. What am I doing wrong?
*September 19, 2011*

**Science**

Unscramble acnsrl spgei
*September 19, 2011*

**Math(Please help!!!)**

A piece of copper contains 3.6 x 10^8 atoms. What is the volume of the sample in units of liters? I know that first you have to get atoms to cancel out but them I do not know what to do!
*September 18, 2011*

**physics**

A 0.07 kg toy is made up of a spring of constant 375 N/m. When you place the toy on the floor, cock the spring 7 cm and release it, the toy jumps upwards. What is in Joules the mechanical energy of the toy when sitting on the floor with a cocked spring? Use 10 m/s2 for g.
*September 16, 2011*

**physics**

A 0.05 kg toy is made up of a spring of constant 466 N/m. When you place the toy on the floor, cock the spring 5 cm and release it, the toy jumps upwards. What is in Joules the spring potential energy stored in the toy when sitting on the floor with a cocked spring? Use 10 m/...
*September 16, 2011*

**physics**

A 0.05 kg toy is made up of a spring of constant 466 N/m. When you place the toy on the floor, cock the spring 5 cm and release it, the toy jumps upwards. What is in Joules the spring potential energy stored in the toy when sitting on the floor with a cocked spring? Use 10 m/...
*September 16, 2011*

**physics**

It takes 9.10 J of work to stretch a spring 5.10 cm from its unstressed length. What is the spring constant k in N/m?
*September 16, 2011*

**physics**

It takes 5.50 J of work to stretch a spring 5.90 cm from its unstressed length. What is the spring constant k in N/m?
*September 16, 2011*

**physics**

Amy threw a ball of mass m=0.79 kg horizontally with an initial velocity v=33.4 m/s from a height h=1.9 m. What is the kinetic energy of the ball just before it touches the ground? Express your answer in Joules and use 10 m/s2 for g.
*September 16, 2011*

**physics**

A 0.730 kg particle has a speed of 3.00 m/s at point A and kinetic energy of 7.40 J at B. What is its speed at B? Answer in units of m/s.
*September 16, 2011*

**physics**

A 4.62 x 10-5 kg raindrop falls vertically at constant speed under the influence of gravity and air resistance. After the drop has fallen 83.7 m, what is the work done by gravity? Answer in units of milliJoule (a thousandth of a Joule) and use 9.8 m/s2 for g
*September 16, 2011*

**Math(Please help)**

A piece of copper contains 3.6 x 10^8 atoms. What is the volume of the sample in units of liters? I know that first you have to get atoms to cancel out but them I do not know what to do.
*September 13, 2011*

**Math(Please help! Thank you!!)**

A piece of copper contains 3.6 x 10^8 atoms. What is the volume of the sample in units of liters? I know that first you have to get atoms to cancel out but them I do not know what to do.
*September 13, 2011*

**scientific method and measurement 8th Hons science**

You see i already know its not replicable or such 13 letters long and it ends with an N.
*September 12, 2011*

**scientific method and measurement 8th Hons science**

Can Anyone Please Help Me?
*September 12, 2011*

**scientific method and measurement 8th Hons science**

what allows results to be verified to maintain credibility?
*September 12, 2011*

**Math(Please help)**

The radius of a niobium atom is 131 pm. How many niobium atoms would have to be laid side by side to span a distance of 1.4 mm?? I know that 10^9 is pm or is it -9??
*September 11, 2011*

**Math**

4.47 x 10^1 g How wouldI convert this to nanmograms? would I use 1mg / 10^-9 g? I do not understand how to do this
*September 11, 2011*

**math**

8 decimeters
*September 11, 2011*

**Math(Please check! Thank you!!)**

metric system conversions 1)3.68kg = ? g (3.68 kg) (10^-3 / 1kg) = 3.68 x 10^-2 g 2) 568cm = ? m (568cm) (1 m /100cm) = 5.68 m Are these correct?
*September 11, 2011*

**PHYSICS**

A student of weight 830 N was sent to another planet called Nerdland. If Nerdland has a mass that is three times the mass of the earth and a radius that is half the radius of the earth, what would be the mass in kg of the student when on Nerdland?
*September 8, 2011*

**Calculus**

find f(3) and f'(3), assuming that the tangent line to y=f(x) at a=3 has the equation y=5x+2.
*September 7, 2011*

**Physics**

At the heighest point on earth, the distance to the center of the earth is approximately equal to 1.0014 times the radius of the earth. What would be in N/kg the magnitude of the gravitational field (g) due to the earth at that position? Assume 9.8 N/kg for g at the surface of...
*September 6, 2011*

**pre cal**

A movie theater seats 400 people. For any particular show, the amount of money the theater makes is a function m(n) of the number of people, n, in attendance. If a ticket costs 2 dollars, find the domain and range of this function
*September 4, 2011*

**Math**

An auditorium has 1600 seats. At a ticket price of $6, the owners can sell 1200 tickets. For each 25 cent increase in price the tickets sold reduces by 25. What price should the owners set to maximize the income?
*August 29, 2011*

**Math**

What is another name for odd numbers?
*August 29, 2011*

**Biology(Please help)**

Why are cyanobacteria not bacteria? Is it because they can be nitrogen fixers?
*August 28, 2011*

**Math**

The expression 9a + 6s is theh cost for a adults and s students to see a musical performance.
*August 26, 2011*

**physics**

A body moving with uniform acceleration has a velocity of 9.9 cm/s when its x coordinate is 1.28 cm. If its x coordinate 1.3 s later is -9.1 cm, what is the magnitude of its acceleration? Answer in units of cm/s2.
*August 25, 2011*

**physics**

An electron has an initial speed of 178000 m/s. If it undergoes an acceleration of 4.8 x 1014 m/s2, how far has it traveled before reaching a speed of 789000 m/s? Answer in units of m.
*August 24, 2011*

**physics**

An electron has an initial speed of 178000 m/s. If it undergoes an acceleration of 4.8 x 1014 m/s2, how far has it traveled before reaching a speed of 789000 m/s? Answer in units of m.
*August 24, 2011*

**Speech**

I have to give a speech soon about my different " sides" of my life. Like my school life and what I do at school compared to how I act as a sibling etc. But I'm stumped on what my visual should be. My teacher wants originality no power point or posters with just ...
*August 22, 2011*

**Pre-Algebra**

5 and 17/20 - 3 and 1/4
*August 18, 2011*

**Pre-Algebra**

5 and 17/20 - 3 and 1/4
*August 18, 2011*

**math**

Suppose f is a 1-1 function with domain A and range B. What is the range of f^-1? Would it be A?
*August 14, 2011*

**introductory technology**

A boat is tied to a stake on a fast flowing river. What energy does the boat gain when the rope is cut.
*August 10, 2011*

**reading**

the setting where does the story take place, time period (present, future etc.), the main character(s), the plot-what happens to the main character
*August 8, 2011*

**reading**

I need help on writing a book report on anastasia absolutely
*August 8, 2011*

**Statistics(Please help)**

t-test for independent means: n=8 t=-1.33 df= 8 C.V. = plus or minus 2.306 My question is how do you get 2.306 for the cv??? Why wouldnt the cv be 2.31?
*August 2, 2011*

**statistics**

t-test for independent means: n=8 t=-1.33 df= 8 C.V. = plus or minus 2.306 My question is how do you get 2.306 for the cv???
*August 2, 2011*

**Chemisty**

How would you classify a solution of NaCl at 35.9 g/100 g of water at 20° C?
*August 1, 2011*

**Chemisty**

that's all the information i have, this is my only worksheet on the subject so i'm honestly only looking for an answer
*August 1, 2011*

**Chemisty**

How much KNO3 will you have to add to 100 g of water at 40° C to make a saturated solution?
*August 1, 2011*

**Chemisty**

In terms of saturation, how would you classify a KBr solution with a concentration of 78 g/100 g of water at 47°C?
*August 1, 2011*

**Chemisty**

In terms of saturation, how would you classify a KBr solution with a concentration of 78 g/100 g of water at 47°C?
*August 1, 2011*

**Prob ans stat**

Let x be a random variable that represents the length of time it takes a student to complete a take-home exam in Dr. Larson's psychology class. After interviewing many students, it was found that x has an approximately normal distribution with mean of 5.2 hours and ...
*July 29, 2011*

**Statistics(Please check)**

calculate the probability of the following: A four, three, or spade from a single draw from a 52 card deck. there are 4 4's so 4/52, 4 3's so 4/52 and then 13/52 spades so 21/52 but and one 4 and one 3 are from spades so minus 2 = 19/52 Is this correct?
*July 23, 2011*

**Statistics(Ugent Please help!!)**

Nevermind I figured it out
*July 23, 2011*

**Statistics(Ugent Please help!!)**

Assume that 100 subjects received one of four treatment combinations and produced the data reported below. Conduct a two-factor ANOVA and complete an ANOVA table reporting the relevant SS, df, MS, F's. N=100 n=25 the table shows A1 and A2 at the top and B1 and B2 on the ...
*July 23, 2011*

**Statistics(Please help)**

Assume that 100 subjects received one of four treatment combinations and produced the data reported below. Conduct a two-factor ANOVA and complete an ANOVA table reporting the relevant SS, df, MS, F's. N=100 n=25 the table shows A1 and A2 at the top and B1 and B2 on the ...
*July 23, 2011*

**chemistry**

A sample of metallic element X, weighing 4.315 g, combines with 0.4810 L of Cl2 gas (at normal pressure and 20.0¢ªC) to form the metal chloride with the formula XCl. If the density of Cl2 gas under these conditions is 2.948 g/L, what is the mass of the chlorine? The ...
*July 22, 2011*

**chemistry**

A sample of metallic element X, weighing 4.315 g, combines with 0.4810 L of Cl2 gas (at normal pressure and 20.0¢ªC) to form the metal chloride with the formula XCl. If the density of Cl2 gas under these conditions is 2.948 g/L, what is the mass of the chlorine? The ...
*July 22, 2011*

**Statistics(Please help)**

thank you
*July 21, 2011*

**Statistics(Please help)**

the problem asks to complete an ANOVA table and report the relevant SS, df, MS, and F values, and find the critical value for the F-values. I found my F values: they were 3 and 16. I do not understand how to find the critical value.
*July 21, 2011*

**Math/Algebra**

The length of Karen's living room is 2ft longer than the width. The perimeter is 80ft. Find the length and the width. Can someone please explain to me how you find the answers? Thanks a ton!
*July 17, 2011*

**chemistry**

After you preform your experiment, you determine that the Kf value for naphthalene is 6.9 . You are using 10g of naphthalene and added 1.0 g of your unknown. The the freezing point of the solvent decreased by 4.42 when the unknown was added. Knowing this information, determine...
*July 17, 2011*

**chemistry**

Strontium has density of 2.64 and crystallizes with the face-centered cubic unit cell. Find the radius of the strontium atom
*July 10, 2011*

** chemistry**

How much heat (in ) is evolved in converting 1.00 of steam at 150.0 to ice at -55.0? The heat capacity of steam is 2.01 and of ice is 2.09 .
*July 10, 2011*

** chemistry**

How much heat (in ) is evolved in converting 1.00 of steam at 150.0 to ice at -55.0? The heat capacity of steam is 2.01 and of ice is 2.09 .
*July 10, 2011*

**chemistry**

Benzene has a heat of vaporization of 30.72kJ/mol and a normal boiling point of 80.1 C. At what temperature does benzene boil when the external pressure is 490 ? I think I have the equation setup, but I can't figure out how to solve for T2..please help
*July 10, 2011*

**statistics**

thank you!!!
*July 6, 2011*

**statistics**

calculate the correlation for data set A. Data Set A: xi = 65, 55, 50, 45, 35 yi= 44, 52, 68, 20, 36 I know how to find the mean, variance, standard deviation, and z-score. The part I am having trouble finding is the ZxiZyi. In the chart that I have to fill in it says Zxi in ...
*July 6, 2011*

**economics**

What is the role of economic theory in the way economies are run today? I need some concrete examples.
*July 6, 2011*

**Statistics(Please help)**

I have a chart that has 4 columns across the top and 33 going down. The colunms on the top read: predicted number, selected number, (col 1 - col2)^2, and the mean of x. Their are 32 predicted numbers and 33 selected numbers. I need to fill in the column that says the mean of x...
*July 2, 2011*

**Statistics(Urgent!Please help)**

I have a chart that has 4 columns across the top and 33 going down. The colunms on the top read: predicted number, selected number, (col 1 - col2)^2, and the mean of x. Their are 32 predicted numbers and 33 selected numbers. I need to fill in the column that says the mean of ...
*July 1, 2011*

**Statistics**

I have a chart that has 4 columns across the top and 33 going down. The colunms on the top read: predicted number, selected number, (col 1 - col2)^2, and the mean of x. Their are 32 predicted numbers and 33 selected numbers. I need to fill in the column that says the mean of ...
*June 30, 2011*

**Statistics**

I have a chart that has 4 columns across the top and 33 going down. The colunms on the top read: predicted number, selected number, (col 1 - col2)^2, and the mean of x. Their are 32 predicted numbers and 33 selected numbers. I need to fill in the column that says the mean of x...
*June 30, 2011*

**Chemistry**

yep its right
*June 5, 2011*

**maths**

5x10^2 divide by 7x10^4 what is the answer in standard form
*June 5, 2011*

**maths**

expand 5(3w^2+4)
*June 5, 2011*

**Calculus**

Find the definite integral that represents the arc length of the curve y=sqrt(x) over the interval [0, 3]
*May 26, 2011*

**Calculus**

Find the volume of the solid formed by revolving the region bounded by y=x^3, x=2 and y=1 about the y-axis. Please help =(
*May 26, 2011*

**Spanish**

How do you say she was looking at the tv in Spanish. I know this is in the imperfect progressive but ver ( to look) is irregular in the imperfect . Does that matter? Would it be esta viendo a la tele?
*May 25, 2011*

**chemistry**

Calculate the E° for each of the following reaction. Decide whether each is product-favored in the direction written 2 Cl-(aq) + Cu2+(aq) --> Cu(s) + Cl2(g) i got -1.020 but its wrong and i do not know why.
*May 12, 2011*

**chemistry**

From the indicated voltages for the voltaic cell pictured, determine the standard electrode potential, E°M3+/M, if the metal, M, is each of the following. description on the image: in the left beaker there is one Cr3+ and one Cr2+ on the right beaker there is 'M'3...
*May 12, 2011*

**Probability NEED HELP**

1. When two fair dice are tossed, what is the probability of a sum of 4 or a sum of 8? 2. When two fair dice are tossed, what is the probability of doubles or a sum over 9? 3. Evaluate 1025! / 1022! Please help
*May 11, 2011*

**Probability**

1. When two fair dice are tossed, what is the probability of a sum of 4 or a sum of 8? 2. When two fair dice are tossed, what is the probability of doubles or a sum over 9? 3. Evaluate 1025! / 1022! Please help
*May 11, 2011*