Saturday
April 19, 2014

Posts by Chemistry


Total # Posts: 199

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.

gen chem
im getting 1.54e-6

gen chem
thanks for the help but im still not getting the right answer

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..

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

gen chem
calculate [H+] if [OH] is 1.688x10^-3

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

chemistry (quatatative analysis)
BARIUM IODATE CAN BE DISSOLVED IN WATER.

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

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

To bobpursley
Thank you once again for helping me!!!!

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)

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)

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 look...

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...

To bobpursley
Is the answer you gave the ionic and net ionic equation....

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)+C...

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 addin...

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...

Chemistry
Got it now, thanks a ton.

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.

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. Expla...

Chemistry
1355.37

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. Cya...

Sara
okie thank you =)

Sara
Neither Ka nor Pka was given

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?

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?

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

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. ...

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...

Math
radius increasses by 25000 solve for dimater then solve for circumference i think

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 i...

chemistry
thanx alot =)

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

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)?

chemistry
thanx alot =)

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...

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.

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

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 ..

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?

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!!!

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 ca...

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

Chemistry
Are you saying that the molar concentration is .005

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 ...

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....

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

chem
how can you fill a flask with pure oxygen without mixing it with air

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 ...

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

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

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 H...

Jack
how does cross linking alter the properties of a polymer?

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?

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...

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 appre...

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 10...

Lauren
-6783.72 J

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

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

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....

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...

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...

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...

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...

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.

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 volumet...

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 volumet...

Suzy
did you get all of it there is more than the introduction

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 a...

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

Lauren
Fe(s) is an element right

Lauren
So I need to find the Hf of each of those equations

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

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.

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

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

Lauren
correct thank you for the help

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

Lauren
Which has the larger radius N^3- or P^3-? Please Explain

Lauren
so which is the correct way of increasing radius and what is a Te=

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-

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

Lauren
Write the electron configuration of Sn and Sn2+ Give the electron configuration of Cu+ and Cu2+

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

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

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...

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 bet...

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 pu...

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 ...

CHEMISTRY
Thank you DrBob222! I got it now!

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

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 chal...

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 ...

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 ...

Chemistry
Which of the following does form a Group II cation? lead iron cobalt nickel How do you figure this one out? You must know what is in group II. Fe, Co, and Ni are in group III. Pb is in both group I and group II. Pb ppts as the chloride in group I and as the sulfide in group II.

Chemistry
Al3+ and Pb2+ act as acids or bases in acidic or alkaline environment. True or False? I think this is true because they are amphoteric, but I am not sure. yes. They are amphoteric.

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