# Posts by Bob

Total # Posts: 3,279

**chemistry**

Using this data, 2 NO(g) + Cl2(g) == 2 NOCl(g) Kc = 3.20 X 10-3 NO2(g) == NO(g) + ½ O2(g) Kc = 3.93 calculate a value for Kc for the reaction, NOCl (g) + ½ O2 (g) == NO2 (g) + ½ Cl2 (g) A. 20.2 B. 2.06 X 10-4 C. 4.49 D. 4.84 X 10-3 E. 0.223 eliminated down...

*March 12, 2012*

**Math**

A bag has 4 red, 6 white, and 9 blue marbles. How many ways can 5 marbles be selected if 2 are one color, and 3 are another color?

*March 12, 2012*

**PHi103**

The truth table for a valid deductive argument will show

*March 11, 2012*

**math**

(4.35E-2 - x)(7.56E-2 -x ) ============================ (0.324 + 2x)2 Rearrange to get an expression of the form ax2 + bx + c = 0 and use the quadratic formula (solve for x. This gives: x = 1.05E-2, 0.143 basically i understand they use the quadratic equation but how did they...

*March 10, 2012*

**chemistry this is confusing to me please help**

Screw u

*March 9, 2012*

**chemistry this is confusing to me please help**

HAHA no

*March 9, 2012*

**english 11**

just took it. Joyce has the right answers.

*March 9, 2012*

**english 11**

a b c d

*March 9, 2012*

**physics**

a 25000000 gr rocket is propelled from rest by an engine that produces a 312500 kgm/s2 for 1.375s A) What is the sleds acceleration? B) What is the velocity after 1.375s?

*March 7, 2012*

**Math :(**

please answer......

*March 6, 2012*

**Math :(**

A rectangular pyramid with the base of 12 feet by 8 feet need to be filled with balloons. if the pyramid 16 feet tall, how much space is available for the balloons?

*March 6, 2012*

**math**

the outlier is 7 and the outlier is a number away from all the other ones,which in this case is 7.

*March 6, 2012*

**math**

Jean has 4 times as many marbles as Peter. If Jean gave 18 marbles to Peter, they would then have the same number of marbles. How many marbles does each have?

*March 6, 2012*

**Chemistry**

How many moles of nitric acid will be produced when .51 mole of dinitrogen pentoxide reacts

*March 5, 2012*

**7th grade math**

yes,Pi is an irrational number.

*March 5, 2012*

**math**

Determine the slope of a line passing through the points (2, 9) and (0.66, 9).

*March 5, 2012*

**physics**

Jabdbal

*March 5, 2012*

**6th grade science**

How do the surface proteins on a virus help it to invade a host cell?

*March 4, 2012*

**Math**

Parallel lines have the same slope so the slope of 3x-4y+5 =0 is y=(-3x-5)/-4 slope =3/4 therefore the y=(n-2)x+12 must have a slope of 3/4 so n-2=3/4 n=2.75 If the lines are perpendicular they have negative reciprocal slopes therefore n-2= -4/3 n=2-4/3 or 2/3

*March 3, 2012*

**algebra**

There are three important numbers coming from the factors, 0, -1, and 3 test using numbers around those numbers. Using -2 because it is less than -1 (-2)(-2+1)(-2-3) =-10 which is < 12 Using -.5 because it is between -1 and 0 (-.5)(-.5+1)(-.5-3)=.875 which is <12 Using 1...

*March 3, 2012*

**Physics help?**

A 170 -pF capacitor is connected in series with an unknown capacitance, and as a series combination they are connected to a battery with an emf of 25.0 V. If the 170 -pF capacitor stores 135 pC of charge on its plates, what is the unknown capacitance?

*March 3, 2012*

**maths**

Do the same thing you did before using -1/2 for x. (2x+1=0 and solve for x) Then you will have two equations and two unknowns and you can solve for p

*March 3, 2012*

**math**

x= total marbles x-(1/4)x what he had after 1st round (x-(1/4)x)-1/3(x-(1/4)x) what he had left after 2nd (x-(1/4)x)-1/3(x-(1/4)x)-1/2((x-(1/4)x)-1/3(x-(1/4)x)) what he had left after 3rd round which equals 2 (the one he gave to Shavana and the one he kept) (x-(1/4)x)-1/3(x-(1...

*March 3, 2012*

**Math**

When raising to a power multiply the exponents. 8.8*10^25

*March 2, 2012*

**math**

I do

*March 1, 2012*

**math 2nd grade**

francisco (:

*February 29, 2012*

**3 grade math**

You body consist of 7/10 water. Is more than 1/2 your body water? Explain

*February 29, 2012*

**5th grade Math**

-3+5*(2(-6))=37

*February 29, 2012*

**Trig**

A pilot is flying over a straight highway. He determines the angles of depression to two mileposts, 6.7 mi apart, to be 36° and 41°, as shown in the figure

*February 29, 2012*

**One Trigonometry Question Please Help!**

8 1/2 inches long into 1/2 inches long will be how many short pecies

*February 28, 2012*

**physical science**

kkk

*February 28, 2012*

**Math**

Words

*February 27, 2012*

**Mathematics**

What percentage is 2/27?

*February 27, 2012*

**Physics**

A 73kg sprinter, starting from rest, reaches a speed of 7.0 m/s in 1.8s, with a negliable effect due to air resistance. The sprinter then runs with the remained of the race at a steady speed of 7.0 m/s under the influence of a 35-N force due to air resistance. What is the ...

*February 27, 2012*

**Math**

It equauls 2sinx

*February 25, 2012*

**Math**

How do I solve: sqrt(3)tanx= I need to use the identity tanx=sinx/cosx Thanks

*February 25, 2012*

**chemistry**

If the reaction Cl2 (g) + O3 (g) = Cl2O (g) + O2 (g) occurred in just two steps, what would be the overall order of the reaction be? a. 1 b. 2 c. 3 d. 4 e. not possible to determine from the information given help

*February 25, 2012*

**chemistry**

The equation A + 2 B = C + D describes an elementary reaction, which takes place in a single step. Thus, the rate law must be a. rate = k(A]2 b. rate = k(B]2 c. rate = k(A][B] d. rate = k(A][B]2 e. none of the above represents the rate law for this elementary reaction. help

*February 25, 2012*

**chemistry**

The decomposition of hydrogen peroxide in solution and in the presence of iodide ion was studied in laboratory, and the following mechanism proposed based on the experimental data. H2O2 + I - = H2O + IO - (slow) H2O2 + IO - = H2O + O2 + I - (fast) Which one of the following ...

*February 25, 2012*

**chemistry**

A particular reaction has an activation energy of 51.6 kJ/mol-rxn. How much faster is the reaction at 50 degrees C versus 25 degrees C? a. 2 times b. 5 times c. 3 times d. half as fast d. 20% as fast help No one has answered this question yet.

*February 25, 2012*

**chemistry**

For a one step reaction, the activation energy for the forward reaction is 40.0 kJ/mol and the enthalpy of reaction is -20.0 kJ /mol. Which statement below is true? a. The activation energy of the forward reaction would be affected to a greater extent than the activation ...

*February 25, 2012*

**chemistry**

If the reaction Cl2 (g) + O3 (g) = Cl2O (g) + O2 (g) occurred in just two steps, what would be the overall order of the reaction be? a. 1 b. 2 c. 3 d. 4 e. not possible to determine from the information given

*February 24, 2012*

**chemistry**

A catalyst alters the rate of a reaction by a. changing the products in the reaction. b. increasing the activation for the reaction. c. always providing a surface on which the molecules react. d. providing an alternate pathway for the reaction. e. increasing the concentrations...

*February 24, 2012*

**chemistry**

The equation A + 2 B = C + D describes an elementary reaction, which takes place in a single step. Thus, the rate law must be a. rate = k(A]2 b. rate = k(B]2 c. rate = k(A][B] d. rate = k(A][B]2 e. none of the above represents the rate law for this elementary reaction.

*February 24, 2012*

**chemistry**

The decomposition of hydrogen peroxide in solution and in the presence of iodide ion was studied in laboratory, and the following mechanism proposed based on the experimental data. H2O2 + I - = H2O + IO - (slow) H2O2 + IO - = H2O + O2 + I - (fast) Which one of the following ...

*February 24, 2012*

**chemistry**

The reaction: A + 3 B = D + F was studied and the following mechanism was finally determined A + B = C (fast) C + B = D + E (slow) E + B = F (very fast) The step with largest activation energy is a. the first step b. the second step c. the third step d. none of the steps has ...

*February 24, 2012*

**chemistry**

For a particular chemical reaction, the rate constant at 30.0 °C is 1.38 X 10-4 L mol-1 s-1, while the value at 49.0 °C is 1.21 X 10-3 L mol-1 s-1 . What is the activation energy for this reaction? a. 92.8 kJ b. 200 kJ c. 40.4 kJ d. 343 kJ e. 56.4 kJ ln 1.38x 10 -4 / 1...

*February 24, 2012*

**chemistry**

For a certain chemical reaction, the rate constant at 250.0 °C is 0.00383 s-1 and the activation energy is 22.40 kilojoules. Calculate the value of the rate constant at 335.0 °C. a. 0.00513 s-1 b. 0.00946 s-1 c. 0.00787 s-1 d. 0.0224 s-1 e. 0.000640 s-1 b or c

*February 24, 2012*

**chemistry**

For a one step reaction, the activation energy for the forward reaction is 40.0 kJ/mol and the enthalpy of reaction is -20.0 kJ /mol. Which statement below is true? a. The activation energy of the forward reaction would be affected to a greater extent than the activation ...

*February 24, 2012*

**chemistry**

A particular reaction has an activation energy of 51.6 kJ/mol-rxn. How much faster is the reaction at 50 degrees C versus 25 degrees C? a. 2 times b. 5 times c. 3 times d. half as fast d. 20% as fast help

*February 24, 2012*

**Math/Calculus.**

Suppose (x^2)*(e^(-2y))= ln(xy) Find dy/dx by implicit differentiation.

*February 22, 2012*

**chemistry**

how does the electrolyte paste in a battery work

*February 22, 2012*

**math**

I have a rectangle w/ 20 boxes in it what would 1/5 of the boxes be?

*February 22, 2012*

**calculus**

The voltage signal from a standard European wall socket can be described by the equation V(t)=325sin100 pi x , where t is time, in seconds and V is the voltage at time, t. determine the period frequency and amplitude

*February 21, 2012*

**English**

Tree

*February 21, 2012*

**physics/chemistry**

so it is a physics project

*February 21, 2012*

**physics/chemistry**

if i'm testing conductivity of different salts?

*February 21, 2012*

**physics/chemistry**

is conductivity a physical or chemical property

*February 21, 2012*

**math**

a data set of size 19 has correlation coefficient of r= 0.432. Test the significance of r at the 5% level and at the 1% level

*February 19, 2012*

**geometry**

In the figure below, the measure of arc AC is 88 degrees if angle ABC is equal to 88 degrees.

*February 19, 2012*

**math**

Write as a single log of a single argument: log3 24 + log3 17 - log3 51

*February 17, 2012*

**Math**

For a class play, student tickets cost $2 and adult tickets cost $5. A total os 30 tickets were sold. If the total sales must exceed $90, what is the miniuim number of adult tickets that must be sold?

*February 17, 2012*

**chemistry**

How many molecules of hydrogen gas are produced by the reaction of tin with 20.0 L hydrogen mono fluoride at STP

*February 16, 2012*

**algebra**

In 16 years, Ben will be 3 times as old as he is right now. How old is he right now?

*February 15, 2012*

**PHYICS HELP**

While a person is walking, his arms swing through approximately a 45° angle in .530s. As a reasonable approximation, we can assume that the arm moves with constant speed during each swing. A typical arm is 70.0 cm long, measured from the shoulder joint. 1) What is the ...

*February 15, 2012*

**Rydberg equation**

42

*February 13, 2012*

**Math**

What's the answer to "230 is increased to 250?"

*February 13, 2012*

**math**

8/year

*February 12, 2012*

**Math**

25 times 4 is the man with purple eyes

*February 12, 2012*

**Physics**

Henrietta is going off to her physics class, jogging down the sidewalk at a speed of 2.05 m/s. Her husband Bruce suddenly realizes that she left in such a hurry that she forgot her lunch of bagels, so he runs to the window of their apartment, which is a height 43.9 m above the...

*February 8, 2012*

**chemistry**

Consider the reaction below: Cgraphite(s) + F2(g) +1/2O2(g) → CF2O(g) Which of the following is a correct rate expression? 1. rate = −2∆[O2]/∆t 2. rate = −∆[CF2O]/∆t 3. rate =∆[F2]/∆t 4. rate = −∆[Cgraphite]/&#...

*February 7, 2012*

**Chemistry**

Carbon dioxide gas has a solubility of 0.0972 g/100 g H2O at 40 degrees celsius. Expressed in parts per million, this concentration is closest to... (1)0.972 ppm (2)9.72 ppm (3)97.2 ppm (4)972 ppm

*February 7, 2012*

**geometry**

A regular hexagon has side lengths 15 in. The perimeter of the hexagon is 90 in. A second hexagon has side lengths 18.75 in. Find the perimeter of the second hexagon. Round to the nearest tenth.

*February 7, 2012*

**algebra**

A box of animal crackers measures 12 inches by 8 inches by 2 inches. What is the volume of the box?

*February 7, 2012*

**algebra**

The sum of three consecutive integers is -96. What is the largest integer?

*February 7, 2012*

**algebra**

The sum of three consecutive integers is . What is the largest integer?

*February 7, 2012*

**algebra**

Ky has 3 times more books than Grant, and Grant has 6 fewer books than Jaime. If the total combined number of books is 176, how many books does Jaime have?

*February 7, 2012*

**math - integers**

68 kms

*February 7, 2012*

**Mathg**

8*2=16. Answer is 8.

*February 6, 2012*

**math**

Side of Square is 25 feet. One side of rectangle is 30 feet and other is 20 feet.

*February 6, 2012*

**math**

512

*February 6, 2012*

**math**

35*6 is 210 not 200.

*February 6, 2012*

**physics**

in 1989 michel menin of france walked on a tightrope suspended under a balloon nearly at an altitude of 3150 m above the ground . suppose a coin falls from menin's pocket during his walk . how high above the ground is the coin when its speed is 60 m/s ?

*February 6, 2012*

**physics**

the largest watermelon ever grown had a mass of 118 kg. suppose this watermelon were exhibited on a platform 5 m above the ground . after the exhibition, the watermelon is allowed to slide along to the ground along a smooth ramp, How high above the ground is the watermelon at ...

*February 6, 2012*

**physics**

A Physics book , mass unknown , is dropped from a table . its velocity just before hitting the ground is 9.39 m/s . what is the height of the table ?

*February 6, 2012*

**physics**

a 20 kg rock is on the edge of a 100 m cliff . the rock falls from the cliff , what is its kinetic energy just before it hits the ground ?

*February 6, 2012*

**physics**

gtfo fag^

*February 6, 2012*

**materials science**

A bar of pure nickel is coupled with a bar of pure iron (interfaced). The diffusion couple is then heated to a temperature of 1000°C. (a) How long will it take for the concentration of nickel to reach 0.1 wt%, 1.0 μm below the interface? (b) How long will it take for ...

*February 6, 2012*

**chemistry**

6.8 grams

*February 4, 2012*

**geometry**

ABCD is a trapezoid with DC parallel to AB, AB=4, AD=4, angle A=60, angle C=45. Find DC and BC

*February 3, 2012*

**chemistry**

In a nickel bath with a total volume of 1000 gallons, titration of a 50 milliliter sample with 0.1 N silver nitrate used up 10.5 milliliters to the end point. What is the concentration in ounces per gallon of the nickel chloride (NiCl2 ) in the bath?

*February 3, 2012*

**chemistry**

A 10 milliliter sample of HCl pickle is titrated with 0.2 N NaOH to a phenol-phthalein end point and it is found that 6.5 milliliters are used. What is the concentration of HCl in the Pickle in grams per liter? In weight Percent?

*February 3, 2012*

**math**

Bob and Jack play a shooting game. In this game, they have a net at a distance. The net is made up of 1 mm thick wires. The wires run vertically and horizontally to form a mesh that has 5 mm square openings between them. A bullet 2 mm in diameter must be shot in such a way ...

*February 1, 2012*

**calculus**

actually an ODE question(but there's no diff. eq. subforum) (y^2)(dy/dx)+y^3/x =2/x^2 using substitution u(x)=y^3 so I've been doing a few of these and getting them all wrong and this problem... I don't know where to start. I tried (1/u)(du/dx)+u/x(du/dx)=2/x^2 but...

*January 30, 2012*

**materials science**

Consider a copper lattice with an excessive average of one vacancy in every 100 unit cells. What will be its density? Compare this to the theoretical density of copper.

*January 30, 2012*