Saturday
August 29, 2015

Posts by K


Total # Posts: 799

History Quote
“Man is not made better by being degraded; he is seldom restrained from crime by harsh measures, except the principle of fear predominates in his character; and then he is never made radically better for its influence.” - Dorothea Dix What exactly does this quote mean?
November 17, 2013

Algebra
Remove the parentheses from the following expression, and combine like terms: 3(ax + b2 – c) + 2 22 A. –3(ax – b2 + 3c – 6 B. 3ax +3b2 – 3c + 2 C. 3(ax + 3b2 – 3c + 6 D. (ax + b2 – c + 5
November 15, 2013

Math
What is a 2 step equation that equals 8 ?
November 7, 2013

Chemistry (Dr.Bob222)
Ok thanks, yes that answer was right, thanks so much for explaining the equation to me, it makes total sense now!
November 7, 2013

Chemistry (Dr.Bob222)
Just Kidding I got 46.51, but that is not one of the answer choices, so which would I pick? or did I do it wrong?
November 7, 2013

Chemistry (Dr.Bob222)
ok, so I got 3.32, so would I just multiply that by the half-life? Because the answer choices are 28 days, 14 days, 42 days, 56 days, and 70 days
November 7, 2013

Chemistry (Dr.Bob222)
The half-life of P-32 is 14 days. How long after a sample is delivered can a laboratory wait to use a sample in an experiment if they need at least 10 percent of the original radioactivity? I need help on how to set up this problem. What is the general equation to use for a ...
November 7, 2013

Chemistry (Dr.Bob222)
How can you tell if a salt is neutral? Like the examples you gave: NaCl, KCl and KNO3, how do you know their anions or cations won't hydrolyze
November 2, 2013

Chemistry (Dr.Bob222)
The generic equation: Base− + H2O -> HBase+ OH− can be used to account for the pH of which salt? 1)CaI2 2)NH3 3)KCN 4)Al(NO3)3 5)NaCl Ok, so I know NH3, won't work because it is not a salt. The answer is KCN, but I don't understand why, could you explain...
November 2, 2013

Chemistry (Dr. Bob222)
How can you tell if something is highly concentrated or lowly concentrated? For example: H2CO3, H+, HCO3-, CO3(2- charge), is in order of highest concentration to lowest concentration, can you explain why it is that order? Thanks for your help :)
November 2, 2013

physics
A flower pot is thrown out of a window with a horizontal velocity of 8 m/s. If the window is 1.5 m off the ground, how far from the window does it land?
October 28, 2013

Personal finance
c
October 24, 2013

Chemistry
Hello Dr. Bob, I'm also having issues with a similar problem. I was able to calculate the XAr, but am unable to find the correct answers for H2 and N2, can you please help this Blake kid and I out? My book shows no problems of this sort, in order for me to work out and i&#...
October 16, 2013

Chemistry help (DrBob222)
ok will do, I just honestly had no idea how to do this. Can you explain how you got "2012 kJ/5*32 g oxygen. Therefore, for 320 g (10*32 g O2) you will get (2012 kJ/160) x 320 = ? " this part? thanks :)I don't understand where the grams came from, like I know it ...
October 15, 2013

Chemistry help (DrBob222)
propane (c3h8) is burned in oxygen to produce carbon dioxide and water. The heat of combustion of propane is -2012 kJ/mole. How much heat is given off when 3.0 mol C3H8 are react with 10.0 mol O2? Thanks, and please if possible show all steps!
October 15, 2013

algebra
-48x^3 + 32x^2 -8x
October 12, 2013

chemistry (DrBob222)
A student fails to fill the cuvette 2/3 full with the reaction mixture ( CV+ and OH-). What effect does this error have on the measured absorbance values? Thank you :)
October 9, 2013

chemistry (Dr.Bob222)
In a reaction, if the concentration decreases faster, that means the reaction has a larger rate constant, and a faster reaction, and a shorter half-life. Is that a correct statement? If not, please correct me, thanks for your help :)
October 2, 2013

Physics Changing Acceleration
Derive position, velocity, and acceleration kinematics equations for an object undergoing a changing acceleration? I understand that somehow we need to get (∆a/∆t) as the change in acceleration into the kinematic equations but I really don't know where to start.
September 28, 2013

Physics (pls help mr.bobpursley or drbob222)
A block is resting on top of a rough incline with coefficients of kinetic and static friction of 0.25 and 0.45 respectively. The angle of the incline is gradually increased until the block just begins to slip. How long will it take the block to slide to the bottom of the ...
September 16, 2013

chemistry
We have to mixed 2 hydrated compounds each in a separate beaker filled with water, and then dump one of the solutions into the other and mix that, then filter the 1 solution out, so that the precipitate is caught in a filter paper, and the water is caught in an erlynmeyer ...
September 15, 2013

chemistry
So I did an experiment at school in which we had to form 2.00 grams of precipitate by mixing 2 hydrated compounds. So for the products, obviously one of it is water, and the other 2 products are compounds, one of which, is insoluble. So when I measured the amount of ...
September 15, 2013

chemistry
Oh! That makes much more sense, so the chemical factor is used to keep the atom of interest equal, which in this case was the Fe, and when we look at the atom of interest we don't need to worry about the rest of the formula being balanced, meaning in the example, as long ...
September 5, 2013

chemistry
So the bottom line is, that the chemical factor is used to make the amount of atoms equal?
September 5, 2013

chemistry
So when you wrote the balanced equation, how did you know that you had to add O2 in the equation? Thanks, sorry for the trouble
September 5, 2013

chemistry
Why is the molar mass of Fe3O4 being multiplied by 2? and why is the molar mass for Fe2O3 being multiplied by 3? Thanks
September 5, 2013

chemistry
An ore contains Fe3O4 and no other iron. The iron in a 38.9-gram sample of the ore is all converted by a series of chemical reactions to Fe2O3. The mass of Fe2O3 is measured to be 12.5 g. What was the mass of Fe3O4 in the sample of ore? Please show all work, not just the ...
September 5, 2013

chemistry
Haha ok, thanks :)
September 5, 2013

chemistry
Isn't it 2 moles of KCL, from the balanced equation? for the 2nd step (mole ratio)
September 5, 2013

chemistry
A 1.24 gram sample of potassium chlorate was heated with manganese dioxide until no addition reaction was visible. THe potassium chloride residue was found to be .72 grams. What was the mass of the oxygen evolved in the experiment? If there is a balanced equation, if you could...
September 5, 2013

chemistry
Those are not the right answers
September 2, 2013

chemistry
A solution is 40% acetic acid by mass. The density of this solution is 1.049 g/mL. Calculate the mass of pure acetic acid in 170 mL of this solution at 20 C. Answer in units of g The density of a solution of sulfuric acid is 1.29 g/cm3 and it is 38.1% acid by mass. What volume...
September 2, 2013

US History
What is the Puritan concept of "calling" and how does it relate to the Puritan beliefs? Thanks for you help :)
September 1, 2013

Physics
A car travels in a straight line with an average velocity of 80 km/hr for 2.5 hours and then with an average velocity of 40 km/hr for 1.5 hours. a. Calculate the largest displacement for the 4-hour trip. b. Calculate the largest average velocity for the total trip in ...
August 28, 2013

Health
d is wrong
August 22, 2013

Chemistry
A volume of 150mL of 0.35M HCl is to be prepared from 80% HCl stock solution. (Density of HCl = 1.191g/mL). Calculate the molarity of 80% HCl stock solution.
August 9, 2013

Physics
A 1.0 x 10^3 kg elevator carries a maximum load of 800.0 kg. A constant frictional force of 4.0 x 10^3 N retards the elevator's motion upward. What minimum power, in kilowatts, must the motor deliver to lift the fully loaded elevator at a constant speed of 3.0 m/s? Please ...
July 7, 2013

reproduction
why doesn't a women body reject the sperms since it is an external organism , instantly i.e, it should have produced the antibodies against it right?
June 28, 2013

Physics
thank you a lot
June 25, 2013

Physics
A small coin is inside a bowl. The bowl is a surface of revolution of the curve y=100x4 m−3. This coin slides around the inside of the bowl at a constant height of y=0.01 m above the bottom of the bowl. What is its angular velocity in rad/s? please just say the method , ...
June 25, 2013

Physics
how do we calculate speed ? time i know
June 24, 2013

maths
A ship is sailing due east at 18 knots runs into a 3 knot current moving 40 East of North. The resultant speed an direction of the ship are:
June 20, 2013

math
Explain, please?
June 7, 2013

chemistry
Thank you Dr. Bob
June 4, 2013

chemistry
Ok, so using Le Chatelier's Principle If you add heat to an exothermic reaction, the equilibrium will shift to the left. If you remove heat to an exothermic reaction, the equilibrium will shift to the right. What is it for an ENDOTHERMIC reaction? If you add a substance, ...
June 4, 2013

Finance
What does "loan amortization requirements" mean?
May 31, 2013

Chemistry
Yes, so in other terms, you are saying that exothermic reactions usually generate more, but endothermic reactions store more?
May 31, 2013

Chemistry
Ah ok, makes sense, thank you :) Also one more question if you don't mind, which produces more energy, exo or endo? Or does it depend on the delta H it gives you in the equation?
May 31, 2013

Chemistry
Ok, so in an when an endothermic reaction occurs, is it hot or cold? and why? Also what is it for an exothermic reaction? Thank you
May 31, 2013

Chemistry
Ok, so in an when an endothermic reaction occurs, is it hot or cold? and why? Also what is it for an exothermic reaction? Thank you
May 31, 2013

Eng
A is wrong because it should be its
May 27, 2013

Trigonometry
wrong man
May 27, 2013

MATHS
explain, please?
May 23, 2013

math
Why?
May 23, 2013

chemistry
Ok, so the shape of the metal affects the reaction rate, correct? And any shape, will increase the rate, right?
May 22, 2013

chemistry
If you add a metal piece to excess acid, what of listed factors below will increase, decrease, or have no impact on how fast a reaction happens? a) lower molarity (concentration) of a solution b) higher molarity (concentration)of a solution c) increase volume of a solution (...
May 22, 2013

Chemistry
Ok, so you just do .333/.333 =1 (NO) and .625/.333= 1.87 (O2) So, then you go back to your equation, and you see how 1 < 2(# of moles of NO in the equation), that means it is the limiting reactant Then you do the same thing with 1.87, and 1.87> 1( # of mole of O2), so ...
May 22, 2013

Chemistry
In order to find the limiting and/ or excess reactant, you have to first convert grams to moles, then once you have that you did the #s by the smallest mole #. Once you have that, you compare that to the coefficients of the balanced equation.
May 22, 2013

chemistry
Explain how dispersion forces, dipole-dipole forces, and hydrogen bonds (intermolecular forces) affect the 2 states of matter using phase changes and heating curves. What is the effect on vapor pressure with dispersion forces, dipole-dipole forces, and hydrogen bonds?
May 20, 2013

Chemistry
Thanks for all your help!
May 19, 2013

Chemistry
How many oxygen atoms are in a) 3.21 x 10^22 molecules CH3OH b) .250 mol C6H12O6 Is it a) 3.21 x 10^22 atoms b) 9.03 x 10^23 atoms
May 19, 2013

Chemistry
A bracelet containing .200 mol of metal atoms is 75% gold. How many particles of gold atoms are in the bracelet?
May 19, 2013

Chemistry
What are the Oxidation and Reducation reactions for these equations : BaCl2 + NaHCO3 -> BaCO3 + NaCl + HCl (carbon is the reduction reaction, but I don't know what the oxidation reaction is) CaCO3 + HCl -> CaCl2 + CO2 + H2O
May 19, 2013

chemistry
Surface tension is a contractive tendency of the surface of a liquid that allows it to resist an external force. It is revealed, for example, in the floating of some objects on the surface of water, even though they are denser than water, and in the ability of some insects (e....
May 9, 2013

math
What if it is something like 0 = 5?
May 7, 2013

math
Ok, so when you are solving an equation, and you have an answer such as 5x=0 , does that mean that it is no solution or all real #s? And, when the answer is 4=4 , does that mean it is no solution or all real #s? And when the answer is 2x=2x, does that mean it is no solution or...
May 7, 2013

chemistry
Use the formula (V1*P1) / T1 = (V2*P2)/ T2
May 7, 2013

Math
anyone can explain?
May 5, 2013

Math
Why the possible sets are 2^5?
May 5, 2013

Geometry
Explain, please?
May 5, 2013

chemistry
Pipette 3 drops of oil into a test tube of water and shake. Describe what takes place and why? - Would it be the oil settles at the top of the water, because the oil is less dense, and its a non-polar substance, so it doesn't mix with a polar substance (water). Add 1 scoop...
April 30, 2013

chemistry
Ok, well it gives us the equation: CH4 + 2O2 --> CO2 + 2H20 ( I balanced it) And then it asks us to calculate: deltaHf (#of mol) I think we have to do that using the mole ratio and the balanced equation? Sorry if it's confusing :/
April 29, 2013

chemistry
How do you calculate deltaHf using the # of moles from a balanced equation? How do you connect the Law of Conservation of Energy to a Thermochemical Equation? Thanks so much!
April 29, 2013

government
What exactly is the war going on between the U.S. and Pakistan? Is it because the U.S. though Bin Laden was in Pakistan? Also is that war and the Afghanistan war still going on? From what I researched, they still are.
April 23, 2013

government
Is fiscal policy the same thing as a fiscal cliff? If not, then how do they differ? Also what are some important policies in foreign countries that affected citizens their citizens?
April 22, 2013

organic chemisty
acid based reaction takes place.
April 21, 2013

World History
Thank you :)
April 20, 2013

World History
Sorry, I meant the decade of 2000-2010
April 20, 2013

World History
What policies affected the citizens during the 21st century? For example: In the U.S. we had the Homeland Security Policy
April 20, 2013

math 4th grade
All you have to do is add 16/24 and 15/24
April 16, 2013

Chemistry
Thanks for your help! Makes lots of sense :)
April 14, 2013

Chemistry
Ah, ok, so another question I have is how would you determine which elements are oxidized and reduced?
April 14, 2013

Chemistry
I'm having a little trouble determining oxidation numbers for elements in a redox reaction KMnO4+HCl--> MnCl2+Cl2+H2O+KCl So far what I have for the reactants side is: K= +1 Mn= +7 O4= -2 H= +1 Cl= -1 And for the products side I have: Mn= +2 Cl2= -1 Cl2(diatomic)= 0 H2...
April 14, 2013

physics
The figure below shows two current carrying wires and the directions of the currents they carry. The wires carry the following currents: I1 = 12.5 A and I2 = 9.8 A. Wire 1 is at (0, 4.0) mm; wire 2 is at (13.3, 0) mm; point P is at (13.3, 4.0) mm. webassign. net/userimages/...
April 10, 2013

chemistry
If 8.72 grams of oxalic acid, H2C2O4, a diprotic acid, is neutralized when 23.4 mL of a solution of KOH is added, what is the molarity of KOH? the topic is acid-base triation, and i have already converted the mass to moles,but I am having trouble finding the volume for the ...
April 9, 2013

chemistry
ha :) thanks so much, that helps lots, i don't know why i was over thinking it! you're awesome!
April 8, 2013

chemistry
how do i predict a conjugate a base? Ex: HBr. The conjugate base is Br- a. NH4+ b. H2O c. H2PO4
April 8, 2013

Chemistry
use the formula (V1*P1)/T1 = (V2*P2)/T2 and make sure all the units are converted correctly, so i believe you just convert 325ml to .325 L, and then convert -125oC to Kelvin, and once you plug in all yours #s solve, and then convert it back to oC since you will have your ...
April 8, 2013

English
What do stage directions tell the reader? Do they tell about characterization or about the setting?
April 3, 2013

statistics
ER promises you will be seen in 10 minutes. the standard deviation is 2 minutes. chance someone will wait more than 13 minutes. i dont know what to do without a population size or sample size
April 3, 2013

Stastics
average for all football teams was an 86 with variance of 16. the buckeyes program over the last 16 year was a 93. is there sufficient proof at the .05 level of significance to say buckeyes were higher than everyone else.
April 3, 2013

Geometry
What is the surface area and lateral area of a regular triangular pyramid if the slant is 7 and the altitude is 5?
April 1, 2013

chemistry
Pure water has a density of 1.00 g/ml at 297 . Calculate the molar concentration of pure water at this temperature. Would i just convert grams to moles, and ml to liters?
March 28, 2013

chemistry
left?
March 27, 2013

chemistry
H2 + CO2 <--> H2O + CO if there were something that were added to this system to absorb the CO2, where would the equilibrium shift? Please don't just give the answer, explain as well, thanks :)
March 27, 2013

chemistry
that makes sense, thanks for your help
March 25, 2013

chemistry
I think the question was asking for the Cl (aq) ions
March 25, 2013

chemistry
NaCl(s) + H2O(l) <--> Na(aq) + Cl(aq) If you added chloride ions to the above equilibrium, what would happen to the concentration of the products, and the concentration of the reactants? I know the equilibrium would shift to the left, and I am guessing the concentration ...
March 25, 2013

Math
30?
March 25, 2013

chemistry
For the reaction CO2 + H2 <--> CO + H20 + heat, indicate how the change in condition will shift the equilibrium (ie right or left) a. Removal of CO2 b. Addition of H2 molecules c. Increase volume of reaction vessel d. Addition of catalyst e. Refrigerate reaction vessel
March 25, 2013

  1. Pages:
  2. <<Prev
  3. 1
  4. 2
  5. 3
  6. 4
  7. 5
  8. 6
  9. 7
  10. 8
  11. Next>>

Members