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October 2, 2014

Posts by Chemistry


Total # Posts: 202

muah
using only words and no numbers how would i explain the steps necesarry to show how many kilograms are in a milligram? thanks :D
September 26, 2010

muah
With out using numbers just words what are the steps necesarry to show how many kilograms are in a milligram
September 26, 2010

muah
explain why the name of the insect millipede doesnt follow SI conventions? please help me i cant find this any where in my text. I would be very happy if you did help. :D
September 26, 2010

gen chem
What is the boiling point in K of Zn, if the entropy change for evaporation of .8564 mole at its boiling ponit is 95.067K? The heat of vaporization of Zn is 131jk/mole.
May 9, 2010

gen chem
im getting 1.54e-6
May 9, 2010

gen chem
thanks for the help but im still not getting the right answer
May 9, 2010

gen chem
The free energy change for dissolution of CaSO4 at 25C is 28.774kJ/mole. What is the solubility of this compound. i got ksp lnK = deltaG/RT lnK= 28774/(-8.31*298) Ksp = 2.39e-12 i dont know waht to do after this..
May 9, 2010

gen chem
suppose a compound could point in any of the three directions in the solid and still have the same energy. how many molecules would there be if the total entropy of a solid sample of this compound was 3.48x10^-9 j/k
May 9, 2010

gen chem
calculate [H+] if [OH] is 1.688x10^-3
May 9, 2010

ChEMISTRY (Help please)
discuss the kinetic theory of gases and proof that the equation pv =1/3 mv2
April 13, 2010

chemistry (quatatative analysis)
BARIUM IODATE CAN BE DISSOLVED IN WATER.
March 26, 2010

chemistry
CH3 CH3-C-CH3 CH3CH2CH2-C-CH2CH2CH2CH3 CH3 give the IUPAc name for this compound? is it 4-methyl-4-tert-methyloctane?
March 5, 2010

Im organic chemistry
What hapens you moving from left to right in a periodc table?
December 16, 2009

To bobpursley
Thank you once again for helping me!!!!
November 3, 2009

To bobpursley
two more questions.... 1. so when you use the superscript ^- that is the same as saying ^-1 ? 2. what are OH^-1 and H^+1 in the equations? (liquid , or gas)
November 3, 2009

To bobpursley
okay..... K^+1 + OH^-1 + H^+1 + Br(not sure which ionization number to put here)-> K^+1 + Br + H20 (l) also, i am not sure what the other ions are.... (aq)? is my guess Then the net ionic equation is... OH^-1 + H^+1 -> H2O (l)
November 3, 2009

To bobpursley
Thank you so much for giving me a step-by-step! I am homeschooled so i have no one to ask. I have had trouble with this and you are the only thing that has clearly told me how to do this. I only asked bob pursley b/c he gave me the answer last time and i was fustrated and ...
November 3, 2009

To bobpursley
i do not know how to break down the ions when i know that they are soluble. for example...Ca(HO)2 is soluable but i dont know what to do with the two or what superscripts to use...
November 3, 2009

To bobpursley
Is the answer you gave the ionic and net ionic equation....
November 3, 2009

To bobpursley
You helped me earlier today whith one of these problems... and i have two more...... What is the ionic and net ionic equation? 1. Ca(HO)2(aq)+ Na2CO3(aq)-> CaCO3 -> (s)+ 2NaOH (aq) I dont understand why there are two arrows? This is what i have so far... Ca+2OH+Na2(aq)+...
November 3, 2009

ChemChem
Hi, please help! Question: Farmers added Calcium hydroxide to soil one morning. They then planned to add Ammonium chloride fertilisers to the soil immediately. However, the instruction label on the packet of fertilisers read: "Do not add fertiliser immediately after ...
November 2, 2009

Chemistry Octane Combustion
Write the balanced equation for the combustion of octane (C8H18). Assuming that gasoline is 100% octane, with a density of 0.692 g/mL, what mass of CO2 is produced by combustion of 1.7 1010 gal of gasoline? Need help on how to get started, I have the balanced equation...
September 15, 2009

Chemistry
Got it now, thanks a ton.
September 15, 2009

Chemistry
Please elaborate on step 3. The balanced chemical equation is: Fe2O3(s) + 2 Al(s) -> 2 Fe(l) + Al2O3(s) After step 2 I have .32 moles Fe.
September 15, 2009

Chemistry
Fe2O3(s) + 2 Al(s) 2 Fe(l) + Al2O3(s) Suppose we want to make 18.0 grams of iron. We must figure out how much starting material we need. This is a three-step calculation. Let's go through these steps one-by-one to calculate the mass of Fe2O3 that we must start with. ...
September 15, 2009

Chemistry
1355.37
September 13, 2009

Chemistry
Vitamin B12, cyanocobalamin, is essential for human nutrition. It is concentrated in animal tissue but not in higher plants. Although nutritional requirements for the vitamin are quite low, people who abstain completely from animal products may develop a deficiency anemia. ...
September 13, 2009

Sara
okie thank you =)
August 9, 2009

Sara
Neither Ka nor Pka was given
August 9, 2009

Sara
how did you calculate pKa because this is a practise question for my test and we won't be given the value. so how would you calculate it?
August 9, 2009

Sara
I'm making a mistake in using that equation: n (CH3COO-)= .0132*.2 = .oo264 ..does that mean that CH3COOH also has the same n? ph= pKa +log(Conjugate Base/ Weak Acid) 4.2= pKa + log (.00264/ .00264) since i have n the same it doesn't work. How do you calculate n?
August 9, 2009

Sara
How many mL of .200M acetic acid are mixed with 13.2mL of.200M sodium acetqte to give a buffer with pH=4.2
August 9, 2009

Chemistry
me again 8. You are given two beakers, A and B, with colorless liquids in htem. What two tests would you perform to determine which one is a strong acid and which one is a weak acid? Be specific with the test and the results as well as how you would determiine which is which. ...
April 7, 2009

Chemistry
so i got a test and like usual my teacher didn't teach me half of the stuff that's going to be on it so he gave us a pretest of what is going to be on it and an answer key and i got several questions 13.) what is the pH of a formic acid if the concentration is .00055 M...
April 7, 2009

Math
radius increasses by 25000 solve for dimater then solve for circumference i think
April 7, 2009

chemistry
The reaction converting glycerol to glycerol-3-phosphate is energetically unfavorable by 9.2kJ. The reaction of ATP with water to yield ADP, hydrogen phosphate ion, and hydrogen ion is energetically favorable by 30.5kJ. These reactions are coupled so that the overall process ...
March 19, 2009

chemistry
thanx alot =)
March 16, 2009

chemistry
i tried dat..n got: AlPO4(s)+H3O^+(aq)<=>Al^3+(aq)+HPO4^2-(aq) buh for sum reason its not accepting the answer
March 16, 2009

chemistry
AlPO4(s)<=>Al^3+(aq)+PO4^3-(aq) PO4^3-(aq)+H3O^+(aq)<=>HPO4^2-(aq)+H2O(l) What is the net ionic equation for AlPO4(s) dissolving in H3O^+(aq)?
March 16, 2009

chemistry
thanx alot =)
March 16, 2009

chemistry
Consider a system consisting of a cylinder with a movable piston containing 10^6 gas molecules at 298K at a volume of 1L. Consider the following descriptions of this system: 1. Initial system 2. Starting from the initial system, the volume of the container is changed to 2L and...
March 16, 2009

chemistry
A solution of Na2CO3 is added dropwise to a solution that contains 1.34×10−2M Fe^2+ and 1.33×10−2M Cd^2+ . What CO3^2- concentration of is need to initiate precipitation? Neglect any volume changes during the addition.
March 14, 2009

Chemistry
correction: initially 1.22*10^-4 mols of Fe(II) were present
March 14, 2009

Chemistry
I converted CN^- to moles iron(II)which is 2.75*10^-5, and initially 1022*10^-4 mols of Fe(II) were present. now i dont get the next step ..
March 14, 2009

Chemistry
The average human body contains 5.30L of blood with a Fe2+ concentration of 2.30×10−5M . If a person ingests 11.0mL of 15.0mM NaCN , what percentage of iron(II) in the blood would be sequestered by the cyanide ion?
March 14, 2009

CHEMISTRY
PartA: Ammonia,is a weak base with a Ka value of 1.8x10^-5 .What is the pH of a 0.22M ammonia solution? PartB: What is the percent ionization of ammonia at this concentration? I got the answer for PartA which is pH=11.3. but i cant slove PartB..HELP!!!
March 2, 2009

Chemistry
Do you think you know how to figure out this one: Sorry about that The chemical 5-amino-2,3-dihydro-1,4-phthalazinedione, better known as luminol, is used by forensic scientists in analyzing crime scenes for the presence of washed-away blood. Luminol is so sensitive that it ...
February 11, 2009

Chemistry
Nevermind I figured it out with your help. The answer was 2.94. Thank you so much!
February 11, 2009

Chemistry
Are you saying that the molar concentration is .005
February 11, 2009

Chemistry
Ammonia has the formula NH3. Household ammonia is a dilute aqueous solution of NH3 . Aqueous ammonia is a base that can neutralize acids. If 18.4mL of 0.800 M HCl solution are needed to neutralize 5.00 mL of a household ammonia solution, what is the molar concentration of the ...
February 11, 2009

Chemistry
Sorry about that The chemical 5-amino-2,3-dihydro-1,4-phthalazinedione, better known as luminol, is used by forensic scientists in analyzing crime scenes for the presence of washed-away blood. Luminol is so sensitive that it can detect blood that has been diluted 10,000 times...
February 11, 2009

Precipitates
If i used NaCl to try to precipitate Ag+ from a solution, will it be as effective as HCl?
November 16, 2008

chem
how can you fill a flask with pure oxygen without mixing it with air
November 1, 2008

REETA
A 2.10 mol sample of oxygen gas is confined to a 5.10 L vessel at a pressure of 7.99 atm. Find the average translational kinetic energy of an oxygen molecule under these conditions in (j/mol) When i was working this out i tried using pv=nrt to find the temperature which i got ...
October 21, 2008

chemistry
What is the difference between Keq and the term of [prod]pr / [react]pr?
September 1, 2008

scsu
What is the weight per volume percent (i.e. % density) of 0.5522 g acetic acid in the 10.00 mL sample?
April 21, 2008

kim
a gaseous hydrocarbon reacts completely with oxygen gas to form carbon dioxide and water vapor. given the following data, determine (delta)HoF for hydrocarbon: (delta)Horxn=-2044.5kj/mol hydrocarbon (delta)HoF CO2= -393.5kj/mol (delta)HoF H2O = -242kj/mol denstity of CO2 and ...
April 20, 2008

Jack
how does cross linking alter the properties of a polymer?
February 28, 2008

Jason
I understand that polymers are long chain 500-20,000 repeating units, but I don't know: what car components are made of polymers?
February 28, 2008

Brad
My problem is calculate the molarity of HCl and NaOH (molarity of acid)x(volume of acid)=(molarity of base)+(volume of added base) HCl=acid NaOH=base HCl volume = 25mL=0.025L NaOH=67.05mL=0.06705 molarity = moles of solute Liters of a solution M=0.015000 moles of NaOH 0.06705L...
February 19, 2008

Chem
Directions: Use the principles of atomic structure and/or chemical bonding to explain each of the following. In each part, your answer must include references to both substances. Problem: The carbon-to-carbon bond energy in c2h4 is greater than it is in c2h6. Any help is ...
November 19, 2007

Mike
N2 + 3H2 --> 2NH3 At 25°C (delta)Ho = -92.22 kJ and (delta)So = -198.53 J/K. Using this information, calculate the equilibrium constant for the reaction at 2.43x10^2°C. (R = 8.314 J/K) Apparently the way I'm doing it is wrong: I divide 198.53 by ...
November 17, 2007

Lauren
-6783.72 J
November 16, 2007

Lauren
wouldnt it be 4.184J/g * degrees C so 4.184 J/ 162 g H2O * 10 degrees C = ?
November 16, 2007

Lauren
The specific heat of water is at 4.184J/g * degree C. How much heat is evolved, or absorbed, when the temperature of 9.00 mol of liquid water cools from 38 degrees C to 28 degrees C? How do I start this problem
November 16, 2007

Suzy
it is a linear regression of a graph I have that deals with the absorbance by the concentration I couldnt paste it on here for you to see....
November 16, 2007

Suzy
ALSO PART OF THE DISCUSSION In Figure B the line of y=0.0052x-6E-05, R^2 .9989 the .9989 is really close to 1, the closer to one the better, to go over one seems to make the lab a failure. Less than one must mean that the lab went well and was done correctly. COULD YOU HELP ME...
November 16, 2007

Suzy
Discussion: This experiment was conducted to identify the iron content in a breakfast cereal. The results indicate that there was iron in the chosen breakfast cereal of Kix, the spectrometer shows that the absorbance or color was around .39 so about 39% as seen in Figure A the...
November 16, 2007

Suzy
Discussion: This experiment was conducted to identify the iron content in a breakfast cereal. The results indicate that there was iron in the chosen breakfast cereal of Kix, the spectrometer shows that the absorbance or color was around .39 so about 39% as seen in Figure A the...
November 16, 2007

Suzy
Discussion: This experiment was conducted to identify the iron content in a breakfast cereal. The results indicate that there was iron in the chosen breakfast cereal of Kix, the spectrometer shows that the absorbance or color was around .39 so about 39% as seen in Figure A the...
November 16, 2007

Suzy
Results: The combination of the solutions: sodium acetate, hydroxylamine hydrochloride and phenanthroline solutions mixed together with the colorless iron solution made the iron phenanthroline solution turn into an orange tint.
November 16, 2007

Suzy
Methods and Materials: The 100 mL volumetric flask with the colorless iron solution was fitted with a rubber stopper. First, transfer the colorless iron solution into a 250 mL volumetric flask, since the substance in the 100 mL volumetric flask was too much. The 250 mL ...
November 16, 2007

Suzy
Methods and Materials: The 100 mL volumetric flask with the colorless iron solution was fitted with a rubber stopper. First, transfer the colorless iron solution into a 250 mL volumetric flask, since the substance in the 100 mL volumetric flask was too much. The 250 mL ...
November 16, 2007

Suzy
did you get all of it there is more than the introduction
November 16, 2007

Suzy
Introduction: This report discusses an experiment to study the percent mass of iron determined by the concentration of a colored iron solution from the absorbance of the spectrometer. This lab is designed to tell the content of iron in cereal, usually food products list iron ...
November 16, 2007

Suzy
Can some one read my lab report for me... I have it almost finished.. I just need help on the discussion part Please
November 16, 2007

Lauren
Fe(s) is an element right
November 16, 2007

Lauren
So I need to find the Hf of each of those equations
November 16, 2007

Lauren
Which of the following has a standard enthalpy of formation value of zero at 25 degrees C and 1.0 atm A. Fe(s) B. Fe2O3(s) C. FeSO4(s) D. FeSO4(aq) E. FeS3(s) and what is enthalpy or how do you find it
November 16, 2007

Lauren
The amount of heat required to raise temperature of 55.85 g of iron 1 degrees C is called its A. Change of energy B. Enthalpy C. Molar heat capacity D. Specific heat capacity E. Specific Heat.
November 16, 2007

Lauren
Use Lewis symbols to represent the electron transfer between the following atoms to give ions with noble gas configuations: A. Mg and S B. Ba and I
November 14, 2007

Lauren
Arrange the following in order of increasing ionic radius: I^-, Cs+, and Te^2-. Explain this order
November 14, 2007

Lauren
correct thank you for the help
November 14, 2007

Lauren
so in my book there is a chart but there is not a number for it so I can see which has a larger radius what is another way to tell which is larger they both have a 3- charge
November 14, 2007

Lauren
Which has the larger radius N^3- or P^3-? Please Explain
November 14, 2007

Lauren
so which is the correct way of increasing radius and what is a Te=
November 14, 2007

Lauren
Arrange the members of each of the following pairs in order of increasing radius and explain the order: A. Te, Te2- B. Al, Al3-
November 14, 2007

Lauren
What I dont understand is where I get the number of dots from and what is the electron configuration
November 14, 2007

Lauren
Write the electron configuration of Sn and Sn2+ Give the electron configuration of Cu+ and Cu2+
November 14, 2007

Lauren
For each of the following, write the electron configuration and Lewis symbol: A. In B. In- C. K+ D. I-
November 14, 2007

Lauren
How do I figure out how to write the lewis symbol for the following A. Br B. Br- C. Sr D. Sr2+
November 14, 2007

question for Dr.Bob22
i get how you get X = 2.077*Y, but i dont understand how if you plug in 0.481X in for Y to solve for x. x = 2.077(0.481x) x = 0.999x then what??? i know this is probably a simple stupid math question, but i need to do another problem like this and i'm stuck at this part...
November 11, 2007

question for Dr.Bob22
The mole fraction of acetic acid (CH3COOH) in an aqueous solution is 0.675. Calculate the molarity of the acetic acid, if the density of the solution is 1.0266 g mL-1. To give a different take on this, here is another way of approaching the problem. I don't claim it is ...
November 11, 2007

Jake
A combustion bomb containing 5.417 g of aluminum metal and 15.974 g of iron III oxide is placed in an ice calorimeter that initially contained 7.746 kg of ice (at o degrees C) and 7.894 kg of liquid water (at o degrees C). The reaction, once ignited by remote control, forms ...
October 16, 2007

Jake
If 142.38 g of l water at 21.7 degrees C is placed into a syrofoam cup with 174.36 g of ice at -27.5 degrees C what would be the final temperature of the entire contents at equilibrium? If it is partially frozen, how many g of the ice has melted? given values cp water = 4.184 ...
October 16, 2007

CHEMISTRY
Thank you DrBob222! I got it now!
September 27, 2007

chemistry
what does an atom of lead look like? what are the parts that compose of the atom? help me pls
September 3, 2007

Chemistry
A certain mine produces 2.5 108 kg of copper from chalcopyrite (CuFeS2) each year. The ore contains only 0.80% Cu by mass. (a) If the density of the ore is 2.0 g/cm3, calculate the volume of ore removed each year. (b) Calculate the mass of SO2 produced by roasting (assume ...
April 13, 2007

Jennifer
I asked this question yesterday and it was answered, but I still have a question on it. Standard entropies for substances are defined at a pressure of exactly 1 bar in some books or exactly 1 atm(760 torr) in different books. For gases, this correction factor would be..... in ...
April 4, 2007

Jim
I need some help with calculating percent yield and percent purity of aspirin. Here's my data (questions follow): SYNTHESIS Mass of salicylic acid.., 2.0 g Volume of acetic anhydride.., 5 mL Mass of watch glass.., 22.10 g Mass of aspirin and watch glass.., 28.01 g Mass of ...
March 24, 2007

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