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September 16, 2014

Homework Help: Science: Chemistry

Recent Homework Questions About Chemistry

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Chemistry
Vitamin K is involved in normal blood clotting. When 1.05 g of vitamin K is dissolved in 25.0 g of camphor, the freezing point of the solution is lowered by 3.53 °C. The freezing point and Kf constant for camphor can be found here. Calculate the molar mass of ...
Wednesday, March 26, 2014 at 8:51pm

Chemistry
Given that the vapor pressure of water is 17.54 Torr at 20 °C, calculate the vapor-pressure lowering of aqueous solutions that are 1.90 m in (a) sucrose, C12H22O11, and (b) aluminum chloride. Assume 100% dissociation for electrolytes. I got .5799 Torr for sucrose, ...
Wednesday, March 26, 2014 at 8:49pm

Chemistry
Which of the following substances could be heated from 20°C to 100°C most quickly? Assume identical heat sources are used on all substances. Specific Heat (J/g degrees C) Gold: 0.1291 Platinum: 0.1326 Silver: 0.2350 Tin: 0.2274 Can you please explain how you figured it...
Wednesday, March 26, 2014 at 7:36pm

Chemistry
The principal quantum number, n, describes the energy level of a particular orbital as a function of the distance from the center of the nucleus. Additional quantum numbers exist to quantify the other characteristics of the electron. The angular momentum quantum number (ℓ...
Wednesday, March 26, 2014 at 6:35pm

english essay
* I need help writing research essay. The topic is to write about an issue or problem that you want to change. Well, I am mostly interested in Science, particularly Chemistry and Nature.
Wednesday, March 26, 2014 at 6:09pm

Chemistry
"Determine the volume of a 0.925M K2Cr2O7 solution required to completely react with 5.28g of Cu." My attempted method for solving was to convert the 5.28g of Cu to moles, find moles of K2Cr2O7 using the mole to mole ratio, and then use M=mol/L to solve for volume. ...
Wednesday, March 26, 2014 at 4:54pm

Chemistry
"Determine the volume of a 0.925M K2Cr2O7 solution required to completely react with 5.28g of Cu." My attempted method for solving was to convert the 5.28g of Cu to moles, find moles of K2Cr2O7 using the mole to mole ratio, and then use M=mol/L to solve for volume. ...
Wednesday, March 26, 2014 at 4:54pm

Chemistry
Complete ionic equation and net ionic equation for 2 K3PO4 + 3 Fe(NO3)2 --> 6 KNO3 + Fe3(PO4)2
Wednesday, March 26, 2014 at 4:09pm

Chemistry
CIE and NIE for 2 K3PO4 + 3 Fe(NO3)2 --> 6 KNO3 + Fe3(PO4)2
Wednesday, March 26, 2014 at 2:43pm

chemistry
a piece of metallic iron (10 moles) was dissolved in concentrated hydrochloric acid. the reaction formed iron (II) chloride and hydrogen gas. how many moles of iron (II) chloride were formed?
Wednesday, March 26, 2014 at 1:50pm

chemistry
URGENT!!! How many grams of sodium benzoate (NaC6H5CO2) must be added to 500 mL of 0.15 M benzoic acid (HC6H5CO2) to make a buffer solution with pH of 5.0? Assume no volume change upon sodium benzoate dissolution. Ka = 6.46 x 10-5 How would I go about this question?
Wednesday, March 26, 2014 at 1:29pm

Chemistry
Write the reactions that occur for the benzoic acid/sodium benzoate buffer when you react it with HNO3 and KOH. How would I go about writing it? Thanks.
Wednesday, March 26, 2014 at 1:20pm

Chemistry
How many milliliters of 0.242 M NaOH are required to exactly titrate 18.0 grams of H2C2O4?
Wednesday, March 26, 2014 at 1:06pm

CHemistry
SO2(g) + H2O(l)= H2SO(l) What mass of sulfur dioxide is needed to prepare 36.86 g of H2SO3(l)
Wednesday, March 26, 2014 at 11:54am

Chemistry
CIE and NIE for 2 K3PO4 + 3 Fe(NO3)2 = 6 KNO3 + Fe3(PO4)2
Wednesday, March 26, 2014 at 11:50am

chemistry
in an experiment, a 4.000grams sample of aluminum metal is added to a solution containing 5.000grams of dissolved iron chloride. the reaction results in the formation of aluminum chloride and metallic iron. when the reaction is complete, unreacted aluminum remains, and this ...
Wednesday, March 26, 2014 at 11:46am

Chemistry
Which nucleophile, when reacted with 1-bromopropane (CH3CH2CH2Br), would produce a thiol? OH- SH- I- -OCH3
Wednesday, March 26, 2014 at 11:15am

chemistry
Which nucleophile, when reacted with 1-bromopropane (CH3CH2CH2Br), would produce an ether? I- OH- -OCH3 SH-
Wednesday, March 26, 2014 at 11:14am

Chemistry
So my chem professor had a slide with a question that follows: If you combine 100 ml of 0.10 M HCl and 100 ml of 0.10 M NaOH, and find that the temperature goes up 0.67 degrees K  What is ΔH° for the reac/on: OH(aq)- + H+(aq)->H2O(l)(c H2O= 4.18 J/°C sg, ...
Wednesday, March 26, 2014 at 10:27am

Chemistry
Calcium can also be precipitated out of the solution by adding sodium phosphate (Na3PO4) to form solid calcium phosphate. A.) write a net ionic equation for this process B.)calculate the mass of this precipitate you would generate from treating 1.000 L of your unknown sample ...
Tuesday, March 25, 2014 at 11:45pm

chemistry
Based on your titration of the 150ppm standard solution of Ca2+ calculate the molarity of the EDTA solution we used, which is Ca2+ + EDTA4- ----> [CA(EDTA)]2-
Tuesday, March 25, 2014 at 11:41pm

chemistry
The rate constant of a first-order reaction is 4.25 x 10^-4 s^-1 at 350 Celsius. If the activation energy is 103 kJ/mol, calculate the temperature at which its rate constant is 8.75 x 10^-4 s^-1.
Tuesday, March 25, 2014 at 11:21pm

chemistry
please help! how do i find the molecular mass of C3H5O2 molecular mass of 292 g.
Tuesday, March 25, 2014 at 10:46pm

Chemistry
The degradation of CF3CH2F (an HFC) by OH radicals in the troposphere is first order in each reactant and has a rate constant of k=1.6×108M−1s−1 at 4∘C. If the tropospheric concentrations of OH and CF3CH2F are 8.1×105 and 6.3×108 molecules ...
Tuesday, March 25, 2014 at 10:03pm

Chemistry
The concentration of Ca2+ in a particular water supply is 5.7×10−3M. The concentration of bicarbonate ion, HCO−3, in the same water is 1.7×10−3M. What masses of Ca(OH)2 and Na2CO3 must be added to 5.6×107L of this water to reduce the level ...
Tuesday, March 25, 2014 at 10:00pm

chemistry
Question Part Points Submissions Used A swimming pool, 20.0 m ✕ 12.5 m, is filled with water to a depth of 3.85 m. If the initial temperature of the water is 18.9°C, how much heat must be added to the water to raise its temperature to 28.7°C? Assume that the ...
Tuesday, March 25, 2014 at 9:51pm

chemistry
enzoic acid is a weak monoprotic acid with Ka = 6.5×10-5 M. NaOH(s) was gradually added to 1.00 L of 8.66×10-2 M benzoic acid. 1. Calculate the pH of the solution before the addition of the base. 2. Calculate the pH of the solution after the addition of 5.20×...
Tuesday, March 25, 2014 at 9:14pm

chemistry
how many moles of H2O are produced when 5.00 mols of oxygen gas are used
Tuesday, March 25, 2014 at 8:02pm

chemistry
Consider a buffer solution consisting of CH3NH3Cl and CH3NH2. Which of the following statements are true concerning this solution? (Ka for CH3NH3+ = 2.3 x 10 -11). 1. A solution consisting of 0.1 M CH3NH3Cl and 0.1 M CH3NH2 would be a more effective buffer than one containing ...
Tuesday, March 25, 2014 at 7:30pm

chemistry help
what is lead (II) acetate + hydrogen sulphide --> Pb(C2H3O2)2 + H2S --> how do i figure it out?
Tuesday, March 25, 2014 at 7:13pm

Chemistry - Science (Dr. Bob222)
A student wanted to determine the amount of copper in a sample of copper ore. The student dissolved a 2.500 ± 0.001 g piece of copper ore in about 75 mL of nitric acid; then, a complexing agent was added. The student transferred this solution to a volumetric flask and ...
Tuesday, March 25, 2014 at 6:38pm

Chemistry - Science
A 6.70 g sample of a binary mixture of silver (I) nitrate and sodium nitrate is completely dissolved in water to make a solution. Aqueous barium chloride is then added to this solution in excess to form 3.60 g of silver chloride solid. What is the percent by mass of silver ...
Tuesday, March 25, 2014 at 6:28pm

chemistry
what is the chemical & word equation of sulfur dioxide + water i don't understand this, can someone please explain to me how to do this!!?
Tuesday, March 25, 2014 at 5:58pm

College Chemistry (DrBob222)
A solution of an unknown weak acid, HA, is titrated with 0.100 M NaOH solution. The equivalence point is achieved when 36.12 mL of NaOH have been added. After the equivalence point is reached, 18.06 mL of 0.100 M HCl are added to the solution and the pH at that point is found ...
Tuesday, March 25, 2014 at 5:31pm

College Gen.Chemistry
A student wanted to determine the amount of copper in a sample of copper ore. The student dissolved a 2.500 ± 0.001 g piece of copper ore in about 75 mL of nitric acid; then, a complexing agent was added. The student transferred this solution to a volumetric flask and ...
Tuesday, March 25, 2014 at 5:29pm

Chemistry
The equilibrium constant for the reaction of the weak base aniline is Kb = 4.3e-10. C6H5NH2 (aq) + H2O (l) --> C6H5NH3+ (aq) + OH- (aq). Calculate ΔG at 298 K when [C6H5NH2] = 0.250 M, [C6H5NH3+] = 1.0E-5 M, [OH-] = 0.000480 M i used the equations dG=dG^o - RTlnQ and ...
Tuesday, March 25, 2014 at 5:21pm

Chemistry
What volume in liters will be required to dissolve 60.9 grams of Mg(OH)2? Ksp = 1.8×10-11 After doing the math, i got 1.58e-4, but its not right, so i have no idea what to do now.
Tuesday, March 25, 2014 at 5:07pm

College Chemistry (DrBob222)
You have 120.0 mL of a 0.245 M solution of NaCl in an open beaker. After several days, you test the solution and find that it now has a concentration of 0.348 M. How much water must have evaporated from the beaker given the new concentration?
Tuesday, March 25, 2014 at 4:52pm

College Gen. Chemistry - Science
You have 120.0 mL of a 0.245 M solution of NaCl in an open beaker. After several days, you test the solution and find that it now has a concentration of 0.348 M. How much water must have evaporated from the beaker given the new concentration?
Tuesday, March 25, 2014 at 4:47pm

chemistry
How ml silver nitrate solution (0.05 mol / l) K = 1.0000 consumed for titration of sodium chloride, 0.0500 g. MW Sodium chloride 58.44.
Tuesday, March 25, 2014 at 2:37pm

chemistry
How do I determine how many moles of KMnO4 it takes to neutralize C2O4-?
Tuesday, March 25, 2014 at 2:17pm

Chemistry
10.1g of potassium nitrate were dissolved in 50cm^3 of water. the temperature fell by 16 degrees celsius. Determine (a) the number of moles of potassium nitrate dissolve in 50cm^3 of water. (b) heat change that would be produced if one mole of potassium Nitrate dissolve ...
Tuesday, March 25, 2014 at 11:51am

Chemistry
What can be said about the presence of each of these groups of cations in the orginial solution
Tuesday, March 25, 2014 at 10:48am

Chemistry 2
CALCULATE THE SOLUBILITY OF CuBr in 0.69 M NH3
Tuesday, March 25, 2014 at 10:24am

Chemistry 2
What is the solubility of silver chromate in pure water
Tuesday, March 25, 2014 at 10:10am

Chemistry
The Ksp of manganese (II) hydroxide, Mn(OH)2 is 2.00x10^-13. Calculate the solubility of this compound in g/L?
Tuesday, March 25, 2014 at 9:59am

Chemistry
if the pressure read by the barometer is 0.882atm, what is the height of the column of mercury in cm?
Tuesday, March 25, 2014 at 3:26am

Chemistry
I don't really understand how to do this problem, or where to start exactly. Can someone explain to me where to start and how I can solve the problem in a step by step process? Thank you in advance! 1. An acetic acid / sodium acetate buffer solution is also 0.020 M AlCl3. ...
Tuesday, March 25, 2014 at 12:37am

Chemistry
Can someone show and explain to me step by step how to do the problems? I feel like I am doing it incorrectly. a) The solubility of PbI2 is 3.67 mg per mL. What is the Ksp? b) Three drops of 0.20 M potassium iodide are added to 100.0 mL of 0.010 M lead nitrate. Will a ...
Tuesday, March 25, 2014 at 12:33am

Chemistry
Mohr's indicator is 5g/100ml of K2CrO4 in water. What is the concentration of CrO4^2- in the indicator? (in mol/L)
Tuesday, March 25, 2014 at 12:20am

chemistry
Quinine is a natural product extracted from the bark of the cinchona tree, which is native to South America. Quinine is used as an antimalarial agent. When 2.50 g of quinine is dissolved in 25.0 g of cyclohexane, the freezing point of the solution is lowered by 6.43 °C. ...
Tuesday, March 25, 2014 at 12:14am

Chemistry
A 3.0g sample of NaCl is added to a Styrofoam cup of water, and the change in water temperature is 6.5∘C . The heat of solution of NaCl is 3.76 kJ/mol. What is the mass (in g) of water in the Styrofoam cup?
Monday, March 24, 2014 at 10:50pm

Chemistry
Acetylene(C2H2) torches are used in welding. How much heat (in kJ) evolves when 2.0L of C2H2 (d=1.0967kg/m3) is mixed with a stoichiometric amount of oxygen gas? The combustion reaction is C2H2(g)+52O2(g)→2CO2(g)+H2O(l), ΔH∘=−1299.5kJ
Monday, March 24, 2014 at 10:49pm

Chemistry
3.25g of zinc was added to 50cm^3 of a 4.0 molar dm^-3 HCl. When the reaction was completed the temperature rose by 28 degrees celcius. (a) Is the reaction exothermic or endothermic? (b)All the zinc dissolve in this reaction. How many moles of zinc reacted? (c) How many moles ...
Monday, March 24, 2014 at 9:20pm

chemistry
how much heat is required when 6.00g of water is melted at its melting point
Monday, March 24, 2014 at 5:15pm

chemistry
Calculate the resulting pressure if 4.50 liters of nitrogen at 35 degrees Celsius and 790 torr and 3.7 liters of oxygen at 15 degrees Celsius and 750 torr are pumped into a 1.00 liters container at 25 degrees celsius. Assume ideal gas behavior.
Monday, March 24, 2014 at 4:27pm

Chemistry: Check my answers?
Write “yes” or “no” below if the chemical equation is balanced or not. 1. 2H2 + O2 ---> 2H2O 2. S8 + 12O2 ---> 8SO3 3. HgO ---> Hg + O2 4. Zn + HCl ---> ZnCl2 + H2 5. 2Na + 2H2O ---> 2NaOH + H2 6. 2Al + 3FeO ---> Al2O3 + 3Fe 7. 4Si2H3 + ...
Monday, March 24, 2014 at 1:55pm

chemistry
Distilled water normally contains dissolved CO2. When preparing NaOH standard solutions, it is important to use CO2 free distilled water. How does dissolved CO2 in distilled water affect the accuracy of the determination of a NaOH solution’s concentration?
Monday, March 24, 2014 at 1:36pm

Chemistry
What is the molarity of a 5.00 x 102 ml solution containing 2490 g of KI? How many moles of LiF would be required to produce a 2.5 M solution with a volume of 10.5 L? How many grams of NaI would be used to produce a 2.0 M solution with a volume of 10.00 L? Very confused on ...
Monday, March 24, 2014 at 12:19pm

Chemistry
Arsenic acid (H3AsO4) is a triprotic acid with Ka1 = 5 ✕ 10-3, Ka2 = 8 ✕ 10-8, and Ka3 = 6 ✕ 10-10. Calculate [H+], [OH ‾ ], [H3AsO4], [H2AsO4‾ ], [HAsO42 ‾ ], and [AsO43 ‾ ] in a 0.16 M arsenic acid solution.
Monday, March 24, 2014 at 10:42am

Chemistry
Your muscles are switched on by releasing calcium ion from the sarcoplasmic reticulum that surrounds your muscle bundles. The Ca2+ binds to a muscle fiber, and that triggers the contraction. To relax the muscle again, Ca2+ must be pumped out, so that the concentration in...
Monday, March 24, 2014 at 8:24am

chemistry
Distilled water normally contains dissolved CO2. When preparing NaOH standard solutions, it is important to use CO2 free distilled water. How does dissolved CO2 in distilled water affect the accuracy of the determination of a NaOH solution’s concentration? would it be too...
Monday, March 24, 2014 at 7:51am

chemistry
2. When preparing a NaOH solution, a student did not allow the NaOH pellets to completely dissolve before standardizing the solution with KHP. However, by the time the student refilled the buret with NaOH to titrate the acetic acid, the remaining NaOH pellets had ...
Monday, March 24, 2014 at 7:50am

Chemistry
How many moles of hydrochloric acid are required to react with 2.57 moles of calcium hydroxide in a neutralization reaction?
Monday, March 24, 2014 at 6:10am

chemistry
In an experiment of hydrogen reacts with 110.0 g nitrogen gas, producing 100.1 g ammonia. a) How many grams of nitrogen will be left over?
Sunday, March 23, 2014 at 11:56pm

College Chemistry
A solution is saturated in both nitrogen gas and sodium iodide at 50 degrees C . When the solution is cooled to 25 degrees C what is most likely to occur?
Sunday, March 23, 2014 at 11:42pm

Chemistry
What factors control the bond length in a covalent bond
Sunday, March 23, 2014 at 10:21pm

chemistry
Consider the titration of 50.0 mL of 0.200 M HOCl by 0.200 M KOH for the next five questions (Ka for HOCl = 3.5 x 10-8). Calculate the pH after 150.0 mL of KOH has been added.
Sunday, March 23, 2014 at 9:50pm

chemistry
Calculate the concentration in % (m/m) of a solution containing 20.5 g of LiF dissolved in 340.0 g of H2O. a.1.14% (m/m) b.5.69% (m/m) c.6.03% (m/m) d.6.42% (m/m)
Sunday, March 23, 2014 at 8:58pm

chemistry
In which of the following pairs of ionic compounds are both members of the pair soluble in water? a.AgNO3 and AgCl b.LiOH and Li2SO4 c.PbSO4 and BaCO3 d.NH4I and Sn3(PO4)2
Sunday, March 23, 2014 at 8:53pm

AP Chemistry
What is the entropy change for the vapor- ization of 2.2 mol H2O(ℓ) at 100◦C and 1 atm? H = 40700 J/mol.
Sunday, March 23, 2014 at 7:43pm

Chemistry
if a glass of ice water is at equilibrium, what is its temperature?
Sunday, March 23, 2014 at 7:27pm

Chemistry
explain equilibrium in terms of the collision theory
Sunday, March 23, 2014 at 7:02pm

Chemistry
For a gaseous reaction, standard conditions are 298 K and a partial pressure of 1 atm for all species. For the reaction 2NO(g) + O2(g) --> 2NO2(g) the standard change in Gibbs free energy is ΔG° = -69.0 kJ/mol. What is ΔG for this reaction at 298 K when the ...
Sunday, March 23, 2014 at 5:43pm

Chemistry
How to use the octet rule to predict the formula of the simplest compound formed from hydrogen and selenium, (Write the formula with hydrogens)?
Sunday, March 23, 2014 at 3:39pm

Chemistry
What factors control the bond length in a covalent bond? Select all that apply. -It involves the attraction between the two nuclei involved in the bond. -It involves the attraction between the electrons in the bond and the nuclei of the atoms. -It involves the repulsion ...
Sunday, March 23, 2014 at 3:37pm

Chemistry
When the oxide of generic metal M is heated at 25.0 °C, only a negligible amount of M is produced. O2M(s) ----> M(s) +O2(g) Delta G^o = 290.3 kJ/mol When this reaction is coupled to the conversion of graphite to carbon dioxide, it becomes spontaneous. What is the ...
Sunday, March 23, 2014 at 3:10pm

chemistry
1. When performing this experiment, a student mistakenly used impure KHP to standardize the NaOH solution. If the impurity is neither acidic nor basic, will the percent by mass of acetic acid in the vinegar solution determined by the student be too high or too low? Justify ...
Sunday, March 23, 2014 at 3:05pm

Chemistry for health science
Considering the neutralization reaction when nitric acid reacts with solid iron(II)carbonate. What is the minimum volume of 2.00 M HNO3 necessary to react completely with 1.06 kg of solid iron(II) carbonate, FeCO3 ?
Sunday, March 23, 2014 at 1:33pm

chemistry
A piece of magnesium weighing 48 grams is burned in air n 80 gram of magnesium oxide is formed. what mass of oxygen combined with the magnesium is in the reaction?
Sunday, March 23, 2014 at 10:26am

Chemistry
I need to balance the equation of the reactants NaHCO3->CuCl2 please help me.
Sunday, March 23, 2014 at 9:32am

Chemistry
What is the total heat evolved when a saturated solution of boric acid (H3BO3) in water is cooled from 100C to 20C? Note the specific heat capacity of the saturated solution is approximately that of water in that temperature range (4.20 J/g.K) and the specific heat capacity of...
Sunday, March 23, 2014 at 5:45am

Chemistry
When 24g of Magnesium reacts with oxygen gas the only product is magnesium oxide. If 40g magnesuim is produced how much oxygen was consumed?
Saturday, March 22, 2014 at 9:33pm

Chemistry - check answers
1) Which element has the largest first ionization energy? A) Rb, B) Fr, C) K, D) Na, E) Mg Answer: E 2) Which has the highest electronegativity? A) Na, B) Cs, C) Si, D) Te, E) Cl Answer: E 3) In which of the following are the bonds arranged in order of increasing polarity? A) ...
Saturday, March 22, 2014 at 8:22pm

Chemistry
The decomposition of hydrogen iodide on a gold surface at 150 oC HI(g) ½ H2(g) + ½ I2(g) is zero order in HI. In one experiment, when the initial concentration of HI was 0.206 M, the concentration of HI dropped to 3.71E-2 M after 898 seconds had passed. Based on ...
Saturday, March 22, 2014 at 7:45pm

Chemistry
The decomposition of hydrogen iodide on a gold surface at 150 oC HI(g) ½ H2(g) + ½ I2(g) is zero order in HI with a rate constant of 1.20E-4 Ms-1. If the initial concentration of HI is 0.575 M, the concentration of HI will be 0.116 M after how many seconds have ...
Saturday, March 22, 2014 at 7:03pm

Chemistry
The decomposition of hydrogen iodide on a gold surface at 150 oC HI(g) ½ H2(g) + ½ I2(g) is zero order in HI with a rate constant of 1.20E-4 Ms-1. If the initial concentration of HI is 0.575 M, the concentration of HI will be 0.116 M after seconds have passed.
Saturday, March 22, 2014 at 7:02pm

Chemistry
an extremely soluable salt is added to water, and all of it dissolves. is it at equilibrium? explin.
Saturday, March 22, 2014 at 6:47pm

chemistry
calculate the freezing point of an aqueous solution of 15.5 grams of glucose dissolved in 150 grams of water
Saturday, March 22, 2014 at 5:32pm

chemistry
Calculate the molar conc. Of ethanoate acid needed to prepare ethonoic buffer of ph 6.8 using 0.5 molar solution of sodium ethanoic.pka of acid 0..127
Saturday, March 22, 2014 at 1:16pm

Chemistry
Complete and balance the equation for this reaction in basic solution? Redox reaction Cr is oxidized to CrO42– and Fe3 is reduced to Fe2...? For a particular redox reaction Cr is oxidized to CrO42– and Fe3 is reduced to Fe2 . Complete and balance the equation for ...
Saturday, March 22, 2014 at 9:45am

Chemistry
1.350g of insoluble carbonate, MCO3 was dissolved in 250cm^3 of a 0.203 mol/dm^3 HCL solution. The resulting solution was boiled off to remove all carbon dioxide produced. 25.0 cm^3 of the solution required 24.10cm^3 of 0.100 mol/dm^3 sodium hydroxide solution. Determine the ...
Saturday, March 22, 2014 at 9:39am

Urgent Chemistry
The Heisenberg Uncertainty Principle: A student is examining a bacterium under the microscope. The E. coli bacterial cell has a mass of mm = 0.100fg\rm fg (where a femtogram, fg\rm fg, is 10−15g\rm 10^{-15}\; g) and is swimming at a velocity of vv = 7.00ìm/s\mu m/...
Saturday, March 22, 2014 at 6:42am

chemistry
Given these standard reduction potentials at 25oC: Cr3+ + e- -> Cr2+ (E1^o = -0.407V) Cr2+ + 2e- -> Cr(s) (E2^o = -0.913V) Determine the standard reduction potential at 25oC for the half-reaction equation: Cr3+ + 3e- -> Cr(s) This seems like a really simple problem (...
Friday, March 21, 2014 at 11:46pm

Chemistry
carbon dioxide dissolves in water to form carbonic acid. Estimate the thermodynamic equilibrium constanst (K) for this reaction (delta Gf values: H2CO3= - 616.1, H2O= - 237.1, CO2= - 394.4) . Carbonic acid then ionizes in water (Ka1= 4.5 x 10^-7). Ignoring Ka2, estimate (K) ...
Friday, March 21, 2014 at 4:47pm

Chemistry-Repost for DrBob222
500 ml of a buffer solution with ph=2.10 must be prepared using .4 M HNO2 and solid KNO2. The ka value of HNO2 is 4e-3. a.) What mass of KNO2 should be added to 3 L of the HNO2 to make the buffer? b.) What is the buffer's pH after 150 ml of .5 M HNO3 is added? Your answer ...
Friday, March 21, 2014 at 2:34pm

Chemistry
Given that 20 ml of a weak acid (HA) was titrated with NaOH and the titration curve of pH vs titrant volume in ml is given, find the initial concentration of the acid? The problem gives the full titration curve starting at pH=2.2 at 0 ml added and with the equivalance pt at pH...
Friday, March 21, 2014 at 2:11pm

Chemistry-Repost for DrBob222
A sample of C60O3 decomposes with an activation energy of 50 kg/mol, an Arrehnius pre-factor of 2e10 s-1 and a k value of .04 s-1. How long does it take for a 25 mg sample at 25 degrees C to produce 10 mg. Your response was is that C60O<suh>3 or what? And I thought ...
Friday, March 21, 2014 at 2:06pm

Chemistry
What is the pH of a solution prepared by mixing 24.6 g sodium acetate and 50 mL of 2.5 M acetic acid in a 500 mL flask and filling to volume
Friday, March 21, 2014 at 12:58pm

Chemistry-Repost for DrBob222
The reaction OH- + NH4+ = H20 + NH3 is kinetically first order in both reactants' concentrations. The rate constant is 2e10 1/M s. If 50 ml of .01 M NaOH is mixed with 50 ml of .01 M NH4CL, find the time required for the OH- concentration to reach 1e-4 M. Your answer: It ...
Friday, March 21, 2014 at 10:39am

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