# drbob222

Most popular questions
1. ## DrBob222

I know I posted this but you didn't answer! Please help!!!! Consider the following reaction at 298 K: C(graphite) +2Cl2 (g) -----> CCl4(l) Calculate the following quantities. Delta H: -139 kJ/mol deltaS(sys)=? J/mol*K deltaS(surr)=? J/mol*K deltaS(univ)=?

asked by Kelsey on March 15, 2012
2. ## DrBob222

How fast should a car move toward you for the car's horn to sound 2.88% higher in frequency than when the car is stationary? The speed of sound is 343 m/s. I don't know what equation to use. I think I'm suppose to use this: fs(v-vd/v-vs) I know I got it

asked by Jon on April 5, 2008
3. ## DrBob222

A car moving at 16.0 m/s, passes an observer while its horn is pressed. Find the difference between the frequencies of sound heard when the car approaches and when it recedes from the stationary observer. The velocity of sound is 343 m/s and the frequency

asked by Jon on April 5, 2008
4. ## DrBob222

A boy is blowing a whistle of frequency 536 Hz and walking toward a wall with a speed of 1.64 m/s. What frequency of the reflected sound will the boy hear if the speed of sound is 343 m/s? 532 Hz

asked by Jon on April 5, 2008
5. ## DrBob222

2N2O(g) → 2N2(g) + O2(g) d[N2O]/dt = -5.8×10-4 M/s at a particular temperature and set of concentrations. What are d[O2]/dt and d[N2]/dt? d[O2]/dt = d[N2]/dt = What is the rate of the reaction? my answer for the first one im getting -.00016 and the

asked by Jane on September 29, 2010
6. ## DrBob222

These are the other equations I've balanced. I need help with one. AgNO3 + K2Cr2O7 --> double replacement AgNO3 + K2Cr2O7 --> AgCr2O7 + K2NO3 Please tell me if I've balanced these right. Br2 + NiI3 --> single replacement, element is a non-metal Br2 + NiI3

asked by Derrick on July 15, 2010
7. ## DrBob222

You just answered my previous half-life question, and I was curious how to find the value of k. You said that k = 0.693/t1/2 , but how do you evaluate t sub1/2?

asked by Sarah on April 12, 2011
8. ## DrBob222

Im in the 10th grade in Chemistry 1 Honors. Im learning to write a chemical equation. Im confuse on that statement i was given for my homework. The products and reactants are just magnesium Sulfide and magnesium and sulfur? Then why are they talking about

asked by Christy on April 29, 2008
9. ## DrBob222

On Monday you helped me to understand and answer the one question, but I am not too sure if they want all the calculations that you answered... regretably, I am still a bit lost with these! Below is the question as it is printed: The isotope caesium-137,

asked by Mary on February 7, 2007
10. ## DrBob222

The unique rate for the combustion of ethane is 0.44 M/s (a) what is the rate that oxygen reacts? (b) what is the rate of formation of water molecules?

asked by tevon on May 2, 2015
11. ## DrBob222

I really want to know what this symbol means ^. I haven't learned about it at all. Does it mean squared or something?

asked by Sara on April 20, 2010
12. ## DrBob222

True/False The medium determines the speed through which most mechanical waves will travel. True

asked by Jon on April 5, 2008
13. ## DrBob222

Thank you very much. I appreciate it a lot.

asked by Leigh on March 28, 2008
14. ## DrBob222

If you don't mind me asking, How are you so smart, and how old are you?

asked by Courtney on April 7, 2010
15. ## Drbob222

Are you done helping me? Sorry, to bugg you i just reall need the help.

asked by Courtney on April 6, 2010
16. ## DrBob222

You are creating a transverse wave in a rope by shaking your hand from side to side. Without changing the distance that your hand moves, you begin to shake it slower and slower. What happens to the wavelength? it decreases

asked by Jon on April 5, 2008
17. ## drbob222

Thank You!

asked by alan on February 5, 2008
18. ## drbob222

Are you available to help for a few more min. I am back. Been gone about two hours. What is it you don't understand about the former problem? Honestly I don't know what am I doing wrong or what should i be doing with the previous problem the one about

asked by Jasmine20 on December 11, 2006
19. ## DrBob222

DrBob222 I am kind of stuck with the balancing stuff, and I already had send the post, did you not read it?

asked by Derrick on July 15, 2010

21. ## DRBOB222

THANKS so much for all of your quick and useful help!

asked by paul on July 16, 2009
22. ## DrBob222

As a sound source moves away from a stationary observer, the number of waves will. decrease

asked by Jon on April 5, 2008
23. ## DrBob222

A wave created when two different waves meet will have an amplitude greater than the individual waves because of. constructive interference

asked by Jon on April 5, 2008
24. ## DrBob222

For incomplete cancellation to occur, opposite pulses must have. equal displacements

asked by Jon on April 5, 2008
25. ## DrBob222

Moth crystals. Those round moth balls are not foam, they are napthalene, a form of benzene. were could i find moth balls because the only one's i have at home are foam balls, or is there something else with an aromatic compound in it?

asked by bobpursley on February 5, 2007
26. ## Drbob222

asked by Mandy on November 27, 2010
27. ## DrBob222

I reponded back to you on my science helpers post.

asked by Sara on April 6, 2010
28. ## drbob222

thankyou for your help its helped alot.you are a star!

asked by dominique on October 6, 2009
29. ## DrBob222

The Doppler effect is a change in the ______of a sound. pitch

asked by Jon on April 5, 2008
30. ## DrBob222

If a wave has a period of .02 seconds and a speed of 4 m/s, what is its wavelength? .08 m

asked by Jon on April 5, 2008
31. ## DrBob222

For the medium to remain undisturbed as two pulses pass the same point, they must have. different amplitudes

asked by Jon on April 5, 2008
32. ## DrBob222

What happens when a wave reaches the boundary of a new media? it would reflect back.

asked by Jon on April 5, 2008
33. ## DrBob222

You are creating a transverse wave in a rope by shaking your hand from side to side. Without changing the distance that your hand moves, you begin to shake it slower and slower. What happens to the frequency? it decreases

asked by Jon on April 5, 2008
34. ## DrBob222

You are creating a transverse wave in a rope by shaking your hand from side to side. Without changing the distance that your hand moves, you begin to shake it slower and slower. What happens to the amplitude? it decreases

asked by Jon on April 5, 2008
35. ## DrBob222

Shaking a towel up and down would create what type of wave in the towel? surface

asked by Jon on April 5, 2008
36. ## DrBob222

BTW I just want a yes, no, and/or hint for these questions to save some time. True/False Doubling the amplitude of a wave will double the amount of energy the wave can transfer. True

asked by Jon on April 5, 2008
37. ## DrBob222

Everyone's help is greatly appreciated. I have put alot of thought into all of my answers, I may have used the incorrect formula or what have you but it happens. Now that I got that out of the way here goes the questions: True/False A wave's amplitude

asked by Jon on April 5, 2008
38. ## Drbob222

I so need help please tell me some obscure facts about spain

asked by Lauren F on December 7, 2007
39. ## DrBob222

are snow foam ball the same as moth balls? no. Styrofoam? Styrene is a aromatic, made from benzene. http://en.wikipedia.org/wiki/Polystyrene

asked by claudia on February 5, 2007
40. ## drbob222

Can you check this one for me i want to make sure. The simple interest I on a principal of P dollars at Interest rate r for time t, in years, is given by I=PrT.Find the simple interest on aprincipal of \$6000 at 3% for 2years. I got the following: I= 6000 x

asked by jasmine20 on December 12, 2006
41. ## drbob222

Can you check my previous postage I'd reply already. Thank you done below What are about the other messages are they okay too. I think I just finished with all of them.

asked by Jasmine20 on December 11, 2006