Wednesday

February 22, 2017
Total # Posts: 1,236

**Chemistry**

Given the reaction 2HI (aq) + CaCO3(s) = CaI2(aq)+CO2(g)+H2O(l) What volume of of CO2 can be produced from 255mL of 3.0M HI and 75.2g of CaCO3 at STP? 75.2g CaCO3/100.09g/mol CaCO3 =.751mol CaCO3 (3M)(.255L)=.765 mol HI

*March 28, 2016*

**Chemistry**

Correction!! Cr2O7^2-(aq)+ 6F^-(aq)+14H+ = 2Cr^3+(aq)+3F2(aq)+7H2O(l) Is what I get, I put electrons on the wrong side for F to F2.

*March 15, 2016*

**Chemistry**

Well thank you very much for the site, it helps! I've worked out the problem myself, please tell me if this looks okay? Cr2O7{2-} +F-=Cr{3+}+F2 6e^- + Cr2O7^3- + 14H^+ = 2Cr^3+ + 7H2O 2F^- = F2 +4e^- Then I multiplied the top by 2 and the bottom by 3 to get a GCF for the ...

*March 15, 2016*

**Chemistry**

Use the method of half reactions to balance the oxidation half reaction in acid solution as well as provide the oxidized and reduced reactants. Cr2O7 {2-} (aq) + F{-} (aq) = Cr {3+} (aq) + F2(aq) Charges are in { }

*March 15, 2016*

**math**

deez nuts

*March 14, 2016*

**Physics**

Many people mistakenly believe that the astronauts that orbit the Earth are "above gravity". Calculate g for space-shuttle territory, 206 kilometers above the Earth's surface. Earth's mass is 6e24 kg, and its radius is 6.38e6 m (6380 km). Your answer is what ...

*March 9, 2016*

**Physics**

The mass of a certain neutron star is 3.4e+30 kg(around 1.5 solar masses) and its radius is 8400 m. What is the acceleration of gravity at the surface of this condensed, burned-out star? (Note on scientific notation: 3e+30 means 310^30.)

*March 9, 2016*

**Physics**

Find the change in the force of gravity between two planets when the distance between them is decreased by a factor of 4.7

*March 9, 2016*

**Chemistry**

Thanks Bob! Curious where .90 comes from? .0009molX1000mL? .5/6= .083M

*March 8, 2016*

**Chemistry**

Calculate the molarity of 3 drops (0.15mL) of a 0.5M Na3PO4 solution after adding 15 drops (.75mL) of water. (Presume drops are the same size, one drop = 0.05mL)((Presume volumes are additive)) So far I've figured .15g Na3PO4/163.94g/mol Na3PO4 = .0009moles .75g H20/18.015...

*March 8, 2016*

**AP Physics**

Two speakers, one directly behind the other, are each generating a 406-Hz sound wave. What is the smallest separation distance between the speakers that will produce destructive interference at a listener standing in front of them? Take the speed of sound to be 344 m/s.

*March 8, 2016*

**Biology**

I have a research article about the early advancement of laying times for Flycatchers, a bird species through Europe and Asia. My variables are: - Annual temperature recordings in each study site - The species, flycatcher - Clutch size of the flycatchers - The location of each...

*March 7, 2016*

**Finite**

Mike deposit $50 per week in account that pays 5% interest compounded weekly. how much will he have in the account at the end of 4years?

*March 7, 2016*

**Chemistry**

A solution is prepared by adding 45.0g of Na2SO4*6H2O to pure water to make 150mL of solution. What are molar concentrations of these ions in the resulting solution? Sodium Ion? Sulfate Ion? Phosphate Ion? I've determined the solution is 1.2M 45/250.16g/mol Na2SO4*6H2O = ....

*March 4, 2016*

**Math**

A rectangular park has an area of 6 square miles. The width of the property is 3/8 the length of the property. What is the width of the property? 6/1 x 3/8 = 18/8 = 2 and 2/8 = 2 and 1/4. 2 and 1/4 is my answer but in my test I got that wrong.

*March 3, 2016*

**physics**

A string under a tension of 43.0 N is used to whirl a rock in a horizontal circle of radius 2.25 m at a speed of 20.0 m/s on a frictionless surface as shown in the figure below. As the string is pulled in, the speed of the rock increases. When the string on the table is 1.00 m...

*March 2, 2016*

**Chemistry**

Show the calculation for the limiting reagent when 0.853g of sodium sulfate (95% pure) react with 1.707g of barium hydroxide octahydrate (87% pure) to produce a precipitate of barium sulfate. I've determined the equation is Na2SO4+Ba(OH)2*8H2O=BaSO4+2NaOH However, that is ...

*March 1, 2016*

**Chemistry**

what is the oxidation number of Chlorine in KCIO4???

*February 26, 2016*

**Physics**

A small object with a mass of m = 615 g is whirled at the end of a rope in a vertical circle with a radius of r = 123 cm. When it is at the location shown, (mid-height), its speed is v = 5.60 m/s. Determine the tension in the rope. Calculate the magnitude of the total force ...

*February 26, 2016*

**Physics**

A test tube in a centrifuge is pivoted so that it swings out horizontally as the machine builds up speed. If the bottom of the tube is 160.0 mm from the central spin axis, and if the machine hits 40500 rev/min, what would be the centripetal force exerted on a giant amoeba of ...

*February 26, 2016*

**Chemistry**

Consider the following reaction: CO2 (g) + H2 (g) CO (g) + H2O (g) Calculate the value of the equilibrium constant, Kc, for the above system, if 0.1908 moles of CO2, 0.0908 moles of H2, 0.0092 moles of CO, and 0.0092 moles of H2O vapour were present in a 2.00 L reaction vessel...

*February 25, 2016*

**Chemistry**

5. Consider the following reaction: CO2 (g) + H2 (g) CO (g) + H2O (g) Calculate the value of the equilibrium constant, Kc, for the above system, if 0.1908 moles of CO2, 0.0908 moles of H2, 0.0092 moles of CO, and 0.0092 moles of H2O vapour were present in a 2.00 L reaction ...

*February 25, 2016*

**Chemistry**

Calculate the pH of a NaOH solution of concentration 0.5M (Kw = 1.0 x 10-14 mol2dm-6 at 25oC)

*February 25, 2016*

**Chemistry**

2. Does a precipitate of silver chloride form when 200.0 mL of 1.0 x 10-4 M AgNO3 (aq) and 900.0 mL of 1.0 x 10-6 M KCl (aq) are mixed at 25oC?[ Ksp AgCl @ 25oC = 1.6 x 10-10]

*February 25, 2016*

**Math**

the sum of two numbers is 27. one number is 3 more than the other number. write and solve a system of equations to find the two numbers. i understand the first equation but i don't know the other one.

*February 18, 2016*

**Math**

Jackie makes patterns. She makes each pattern with 5 counters. she makes 13 patterns. How many counters does she need? Show your working.

*February 18, 2016*

**Cal 2**

Find the volume of the solid obtained by rotating the region bounded by the given curves about the specified axis. y=1/x^3,y=0,x=4,x=7. About the y-axis. Volume =

*February 12, 2016*

**Social Studies**

Why do we celebrate black history month?

*February 11, 2016*

**math**

Thanks!

*February 9, 2016*

**math**

Problem: Lexington, and Elizabethtown, Kentucky are 79 miles apart. If the distance on the map is 2 1/2 inches, find the scale of the map. do i make a ratio for inches to miles? is it 2.5x inches = 79 miles?

*February 9, 2016*

**pre-calculus**

State the amplitude, period, phase shift, and vertical shift of the function y= -3 (1/2x- 2/3 pi)-4

*February 7, 2016*

**Chemistry**

The molarity of concentrated HCl purchased for laboratory use is approximately 12.1 M. How many milliliters of this reagent should be diluted to 1.000 L to make 0.100 M HCl?

*January 19, 2016*

**dynamics**

(a) A rocket is travelling out of the earth’s atmosphere. During flight it burns fuel at a rate of 80kg/s producing a constant thrust of 500kN which drives the rocket in a vertical trajectory. It has a mass of 3500Kg when it reaches a speed of 1220m/s. At this point in ...

*December 29, 2015*

**Statistics**

ln a box of 200 computer chips 30 of them are defective. lf 3 chips are chosen at random with replacement, what is the probability that at least one of them is defective?

*December 15, 2015*

**chemistry**

the number of moles in 12.04x10^23 molecules of Oxygen

*December 12, 2015*

**Walk two moons**

What is the meaning of the fourth message in your own words?

*December 9, 2015*

**health**

What are the ten building blocks for total health

*December 8, 2015*

**chemistry**

Stoichiometrics: a 36 grams sample of calcium hydroxide is allowed to react with 40.5 grams of phosphoric acid according to the following reaction. 3Ca(OH)2 + 2H3PO4 = Ca3(PO4)2 + 6H2O how many grams of calcium phosphate are produced? how many moles of Calcium phosphate are ...

*December 5, 2015*

**chemistry**

a 36 grams sample of calcium hydroxide is allowed to react with 40.5 grams of phosphoric acid according to the following reaction. how many grams of calcium phosphate are produced? how many moles of calcium phosphate are produced? how many moles of excess reagent remain? if 43...

*December 5, 2015*

**chemistry**

a 36 grams sample of calcium hydroxide is allowed to react with 40.5 grams of phosphoric acid according to the following reaction.

*December 5, 2015*

**Chemistry**

Calculate the final temperature in degrees Fahrenheit of 1.25 liters of gas X at 85 degrees Celsius and 2700 mm/Hg, if the pressure is changed to 2.35 atmospheres and the volume is increased to 2500ml

*December 4, 2015*

**Chemistry**

if 16.5 liters of gas X is at 398 torr and -90.5 degrees celsius, what would be the volume of this same gas if the pressure is changed to 3.1 atmospheres and the temperature is changed to 399K

*December 4, 2015*

**Physics**

A stone is aimed at a cliff of height h with an initial speed of v = 36.0 m/s directed 75.0° above the horizontal, as shown in the Figure below by the arrow. The stone strikes at A, 6.25 s after launching. What is the height of the cliff?

*December 3, 2015*

**Chemistry**

50g*1mol/26.04g*2molh20/1molC2H2*18.02g/1molh20 69.20g H20 needed to make 50g c2h2

*December 1, 2015*

**physics**

So in projectile problems horizontal a=0 so the velocity is constant. So finding x and y components for initial velocity X: 172.5m/s*cos30=149.4m/s Y: 172.5m/s*sin30=86.25m/s The max height is at the apex of the projectile, so use vertical velocity in Vfy =Viy+at---> -vi/a=...

*December 1, 2015*

**physics**

A projectile is fired at 30.0° above the horizontal. Its initial speed is equal to 172.5 m/s. Assume that the free-fall acceleration is constant throughout and that the effects of the air can be ignored. What is the maximum height reached by the projectile? At what time ...

*December 1, 2015*

**Physics**

A person who is 1.1 m tall throws a ball with a speed of 5.2 m/s at an angle of 56 degrees above the horizontal. What are the x and y components of the velocity (in m/s) of the ball the instant before it strikes the ground? The acceleration due to gravity is 10 m/s2

*December 1, 2015*

**Physics**

The launching speed of a certain projectile is 6.8 times the speed it has at its maximum height. Calculate the elevation angle at launching.

*December 1, 2015*

**Physics**

A catapult on a cliff launches a large round rock towards a ship on the ocean below. The rock leaves the catapult from a height H = 32.0 m above sea level, directed at an angle theta = 46.9° above the horizontal, and with a speed v = 29.6 m/s. Assuming that air friction ...

*December 1, 2015*

**Science**

Well I'm not sure if you need it in MKS system or not but here is the conversion 66km/hr*1hr/60min*1min/60sec*1000m/1km =18.06m/s or .01806km/s Since the car is stopping its final velocity =0 Use the equation Vf=Vi+a*t (Where vf is final velocity vi is initial velocity a ...

*December 1, 2015*

**physics**

Hmm, I may be overlooking something here, unless the mass is irrelevant, but I drew Y0=0 V0=8.1m/s VF=0m/s( because the jumper reached Yf stops and comes back down toward earth) and a=9.8m/s^2 so you're looking for Y final position I used Vf^2=V0^2+2a(Yf-Y0) since vf=0 and...

*December 1, 2015*

**PHYSICS**

So this gives you the mass and force of m1, use Newton's second law (F=m*a) to get the acceleration.... 33.0/4.5kg=7.33 m/s^2 I drew this situation as [m1]----[m2] since the applied force was to the right the --- tension force becomes limp and should =0 [m1]>~~_[m2] it...

*December 1, 2015*

**math**

A: FUNCTION Q1. (a) The function C (x) = 25x + 80,000 express the total cost C (x) (in K£) of manufacturing x units of a product. If the maximum number of units which can be produced equals 20,000, state the restricted domain and range for this function. (b) An analysis ...

*December 1, 2015*

**math**

Well50k-27k=23k So since 8.5%interest is on Corp bonds 27000*.085=2,295 23,000*.068=1,564 3,859$ is the most he makes from interest Since it says maximum income look at the maximum amount he count spend on the higher interest rate then subtract from the total he wants to spend...

*December 1, 2015*

**Chemistry**

pH=Pka+log[A-]/[HA] Pka=-log 1.8x10-5 +log (.025/.053) Divide the concentrations out and take the log of it and add it to the negative log of 1.8x10-5 You can tell HC2H3O2 is the acid because Ka is the constant for the acid, while Kb would be constant for the base. I don't...

*December 1, 2015*

**biology**

Which of the following organelles is common to both prokaryotic and eukaryotic cells? Cytoskeleton Nucleus Nucleolus

*November 30, 2015*

**algebra**

A wire is 264 ft in length is to be cut into two pieces, one to form a rectangle whose length is four less than twice the width, and the other to form a square whose side is equal to the sum of the width and the length of the rectangle. how long is the shorter piece of wire

*November 29, 2015*

**c programming**

Write a program to read from a file called "input.txt" information about 5 workers. Each line would contain two values respectively, an employee ID and the employee's monthly salary. Assume that the data from the input file is stored in a format as shows in this ...

*November 26, 2015*

**Calculus**

Let f(x)=5x^(9/5)−45x^(4/5). Find the largest open interval(s) where f(x) increases.

*November 23, 2015*

**Math**

Let f(x) be a function such that f′(x)=x(ln|x|)^2. Find the open interval(s) in which f(x) is concave down . In interval notation, f(x) is concave down in ___________

*November 23, 2015*

**Algebra**

James walked 212 miles in 23 of an hour. What was his average speed, in miles per hour?

*November 21, 2015*

**conversions**

How to calculate the square meters of a roll that is 30500 LF x 117" x 75 gauge

*November 20, 2015*

**Physics**

A thin spherical shell of silver has an inner radius of 8.74 x 10-2 m when the temperature is 29.4 °C. The shell is heated to 145 °C. Find the change in the interior volume of the shell.

*November 15, 2015*

**Physics**

A copper (shear modulus 4.2 x 1010 N/m2) cube, 0.324 m on a side, is subjected to two shearing forces, each of magnitude F = 6.93 x 10 5 N (see the drawing). Find the angle (in degrees), which is one measure of how the shape of the block has been altered by shear deformation.

*November 14, 2015*

**Grammar check**

Hello, can you please check my answer. Which of the following sentences is written in the subjunctive mood? A. If the sun is shining, then I will wear sandals. B. It was the weekend, so she slept until noon. C. My health teacher recommends that I eat five servings of ...

*November 11, 2015*

**Math**

A marketing research firm wishes to determine if the residents of Caldwell, Idaho, would be interested in a new downtown restaurant. The firm selects a simple random sample of 120 phone numbers from the Caldwell phone book and calls each household. Only 62 of those called are ...

*November 9, 2015*

**Statistics**

A marketing research firm wishes to determine if the residents of Caldwell, Idaho, would be interested in a new downtown restaurant. The firm selects a simple random sample of 120 phone numbers from the Caldwell phone book and calls each household. Only 62 of those called are ...

*November 9, 2015*

**Statistics**

Researchers wish to determine if a new experimental medication will reduce the symptoms of allergy sufferers without the side-effect of drowsiness. To investigate this question, the researchers give the new medication to 50 adult volunteers who suffer from allergies. Forty-...

*November 9, 2015*

**physics**

Two blocks with masses M1 = 8.0 kg and M2 = 5.4 kg are connected with a massless string over two massless and frictionless pulleys, as shown in the Figure. One end of the string is connected to M1 while the other end is fixed. What is the acceleration of mass M2?

*November 4, 2015*

**Sixth grade math**

The sum is 1.7 and the product is 6.3. What are the numbers?

*November 3, 2015*

**LA check work**

ok thank you for the second question I believe it would be A then

*November 3, 2015*

**LA check work**

Hello could you check my work on these two questions? Question one: How do you form the perfect tense of a verb? A. use the helping verb will and the base form of the verb B. use a form of the verb have and the present particle of the verb C. use a form of the verb have and ...

*November 3, 2015*

**algebra**

With an 80 km/h head wind a plane can fly a certain distance in 4 h. Flying in the opposite direction, with the same wind blowing, it can fly that distance in one hour less. What is the plane’s speed?

*November 2, 2015*

**Calculus III**

What is the velocity vector of a particle traveling to the right along the hyperbola y=x−1 with constant speed 1 when the particle's location is (4, 14). (Use symbolic notation and fractions where needed. Give your answer in the form of comma separated list of i, j ...

*October 22, 2015*

**math homework**

Find the all the possible values for x if there are any so that the graph of the function has a horizontal tangent. y(x)=x^4-4x+4

*October 18, 2015*

**English**

What's the correct capitalizations for, the henderson family moved to chicago from the east coast.

*October 5, 2015*

**English**

thank you very much.

*September 24, 2015*

**English**

Hello which sentence is correct? I'm not sure. as I had learned much from garfield high school. or I have learned much from Garfield high school. Should I use had or have? thank you

*September 24, 2015*

**Math.**

A jet is travelling at 600 miles per hour. Determine the velocity of the jet in meters per second

*September 21, 2015*

**Physics**

An aerialist on a high platform holds onto a trapeze attached to a support by an 9.8-m cord. (See the drawing.) Just before he jumps off the platform, the cord makes an angle of 37° with the vertical. He jumps, swings down, then back up, releasing the trapeze at the ...

*September 17, 2015*

**math**

The track is 1/8 a mile

*September 15, 2015*

**math**

Jacob is jogging around a track. Th track is a mile. How many laps will he have to jog to make 3 miles? Is it 24 laps

*September 15, 2015*

**Statistics/probability**

Not sure

*September 13, 2015*

**english 9**

Who was Mary Elizabeth Lease?

*September 8, 2015*

**math**

x-54

*September 8, 2015*

**english 9**

What was the goal of the Americanization movement?

*September 8, 2015*

**World Geography**

1.5

*September 2, 2015*

**algebra**

Price # of pizzas 1.50 1 3.00 2 4.50 3 6.00 4 each pizza costs 1.50 so you add on 1.50 to each slice of pizza you buy

*September 1, 2015*

**math**

Find x 1) 6log(down)10 x=1.6 2) e^-4x=1.943 3) 1.3x10^-4 x=4.7/x -6.3x10^-3 4) 6lnx=1.6 5) x^2¡Ñ23y^2 = 1.78x10^32¡Ñz please help I really can't solve this problem.

*August 30, 2015*

**Science**

It's essential to remember acceleration as a vector ( having magnitude/size and direction) So the plane taking off is the easy one to mark off, a cheetah running 27m/s east could be assumed it's speed is constant and not accelerating, a car stopping at a stop sign has ...

*August 27, 2015*

**Science**

Which of the following is not an example of acceleration. A a person jogging atn3 m/s along a winding path B a car stopping at a stop sign. C a cheetah running 27m/s east D a plane taking off

*August 27, 2015*

**math**

Sandra wants to buy some chocolates as a gift to her friend . Each bar of chocolate is worth Php. 75.00 Question : a.Write the equation . b.What is the constant of variation ? c.How much did she pay if she buy 7 bar of chocolates ?

*August 25, 2015*

**physics**

A cyclist is at rest at a traffic light. When the light turns green, he begins accelerating at 2.13 m/s2. How many seconds after the light turns green does he reach a cruising speed of 5.05 m/s?

*August 22, 2015*

**math sqrt root**

1) x¡Ô2x + 2¡Ô2x^3 + 2x^2/¡Ô2x Ans 4x¡Ô2x 2) (1/2)^1/3 Ans 3¡Ô1/2 = 3¡Ô4 /2 3) ¡Ô2/3 Ans ¡Ô6/3 4) 3¡Ô2/3 Ans 3¡Ô18/3 5) ¡Ô2 + 1/¡Ô2 ...

*August 18, 2015*

**math**

2/9 divided 15/4 divided 4/12

*August 14, 2015*

**physics**

The mass of meter stick= 151.77g but with 3 sig figs it's roughly 152grams (47.7g)*(38.5cm-10.5cm)=(47.3cm-38.5cm)*(Mass of meter stick) Simple algebra given the information, hope this helps!

*July 29, 2015*

**sociology**

Studies show that people from higher socioeconomic backgrounds tend to live longer and report feeling healthier than people from the lower classes. What are some explanations for this phenomenon? please help

*July 28, 2015*

**sociology**

How does one¡¦s place in the socioeconomic system affect their ability to achieve the American Dream?

*July 28, 2015*

**psychology**

<11{1[4(23)23]}> People have claimed that Jamie’s paintings have given them the blues. Clearly this cannot be entirely correct, since many of Jamie’s paintings contain no blue at all. The argument above is flawed because the author:

*July 9, 2015*

**sociology**

can you copy and paste some information for me please? I couldn't get access to sing up for that website.

*July 7, 2015*