Sunday
June 26, 2016

Posts by nevaeh

Total # Posts: 74

Chemistry/- Dr.Bob222
A voltaic cell consists of a Zn/Zn2+ half-cell and a Ni/Ni2+ half-cell at 25 C. The initial concentrations of Ni2+ and Zn2+ are 1.50 M and 0.10 M, respectively. a. What is the initial cell potential? My answer: 0.56 B b. What is the cell potential when the concentration of Ni2...
June 2, 2016

Chemistry - Dr.Bob
Predict the half-reactions occurring at the anode and the cathode for the electrolysis of aqueous Na2SO4.
June 1, 2016

Chemisty-Dr.Bob222
Determine the minimum concentration of the precipitating agent on the right to cause precipitation of the cation from the solutions to the left. a. 0.035 M BaNO3; NaF b. 0.085 M CaI2 ; K2SO4 c. 0.0018 M AgNO3 ; RbCl My work: Are my answers correct? a. BaNO3 + NaF --> BaF2...
May 21, 2016

Chemistry- Dr.Bob222
What is the solubility of AgCl in 10 M NH3? The Kf of Ag(NH3)2+ from AgCl(s) in aqueous NH3 is 0.0031, which is for the balanced reaction shown below. AgCl(s) + 2 NH3(aq) → Ag(NH3)2+(aq) + Cl-(aq) Work: Ksp = x^2 /(2x+10)^2 = 1.8 x 10^-10 Now I am confused....... At ...
May 8, 2016

Chemistry- Dr.Bob222
I do not quiet understand what you said. Could you show your work. What is the solubility of AgCl in 10 M NH3? The Kf of Ag(NH3)2+ from AgCl(s) in aqueous NH3 is 0.0031, which is for the balanced reaction shown below. AgCl(s) + 2 NH3(aq) → Ag(NH3)2+(aq) + Cl-(aq)
May 7, 2016

Chemistry- Dr.Bob222
Question 2 What is the solubility of AgCl in 10 M NH3? The Kf of Ag(NH3)2+ from AgCl(s) in aqueous NH3 is 0.0031, which is for the balanced reaction shown below. AgCl(s) + 2 NH3(aq) → Ag(NH3)2+(aq) + Cl-(aq) Is the answer 0.557 M?
May 7, 2016

Chemistry
I got pH = 5.3 A 1.00 L buffer solution is 0.250 M in HC2H3O2 and 0.250 M in NaC2H3O2. Calculate the pH of the solution after the addition of 0.150 mol of solid NaOH. Assume no volume change upon the Additon o f NaOH. The Ka value for HC2H3O2 at 25 C is 1.8 x 10^-5. Chemistry-...
April 29, 2016

Chemistry-Dr.Bob222
A 1.00 L buffer solution is 0.250 M in HC2H3O2 and 0.250 M in NaC2H3O2. Calculate the pH of the solution after the addition of 0.150 mol of solid NaOH. Assume no volume change upon the Additon o f NaOH. The Ka value for HC2H3O2 at 25 C is 1.8 x 10^-5.
April 29, 2016

Chemistry-Dr.Bob222
Calculate the molar solubility of calcium hydroxide in a solution buffered at each pH. a. pH=4 b. pH= 7 c. pH=9
April 27, 2016

Chemistry-Dr.Bob222
Consider the compounds with the generic formula listed and their corresponding molar solubilities in pure water. Which compound has the smallest value of Ksp? a. AC; molar solubility = 1.35 x 10^-4 M b. AX2; molar solubility = 2.25 x 10^-4 M c. A2X; molar solubility= 1.75 x 10...
April 27, 2016

Chemistry- Dr.Bob222
Is there an actual value for the buffer capacity of acetic acid? I need to know the actual value, so that I can calculate the percent error for my lab.
April 24, 2016

Chemistry
A 500 mL buffer solution is 0.1 M benzoic acid and 0.10 M in sodium benzoate and has an initial pH of 4.19. What is the pH of the buffer upon addition of 0.010 mol of NaOH?
April 21, 2016

Chemistry -Dr.Bob222
Arrange the solutions in order of increasing acidity. NaCl, NH4Cl, NaHCO3, NH4CLO2, NaOH
April 21, 2016

Grammar
Which is correct? The usefulness of learning is considered valuable. OR The learning usefulness is considered valuable.
April 21, 2016

Chemistry
Like a equilibrium constants, the values of Kw depends on temperature. At body temperature (37 C), Kw= 2.4 x 10^-14. What are the [H3O+] and pH of pure water at body temperature?
April 20, 2016

math
Jay purchased a new leather jacket on sale at a 40% discount. The origanal list price was $320. What wad the amount of the discount. I just need to learn how to do this kind of question because my teacher did not teach me this.
April 20, 2016

Chemistry- Dr.Bob222
Determine [H30+], [OH-], and pH. A solution that is 0.655% HNO3 by mass (assume a density of 1.01 g/ mL for the solution).
April 20, 2016

Chemistry-Dr.Bob222
Like a equilibrium constants, the values of Kw depends on temperature. At body temperature (37 C), Kw= 2.4 x 10^-14. What are the [H3O+] and pH of pure water at body temperature?
April 20, 2016

Chemistry-Dr.Bob222
A 25.0 mL sample of 0.125 M pyridine is titrated with 0.100 M HCl. Calculate the pH at 0 mL of added acid.
April 19, 2016

Dr.Bob
A 100.0 mL sample of 0.05 M NH3 is titrated with 0.10 M HCl. Determine the pH of the solution after the addition of 50.0 mL HCl. Here is my work: NH3 + H3O+ --> NH4+ + H2O Before Addition: NH3= 0.005 mol H3O= 0 mol NH4+ = 0 mol Addition: NH3 = 0.005 mol H3O+ = 0.005 mol NH4...
April 16, 2016

Chemistry- Dr.Bob
A 40.0 mL sample of 0.100 M HNO2 is titrated with 0.200 M KOH. Calculate the pH at the equivalence point for the titration of HNO2 and KOH. When I did this problem again, I got pH= 8.08. Is this close to your answer? Dr.Bob: I estimated the pH and didn't come close to 11 ...
April 16, 2016

Chemistry-- Dr Bob, here is my work
Actually, when I did the problem again, I got 8.08. Is this correct?
April 16, 2016

Chemistry
A 40.0 mL sample of 0.100 M HNO2 is titrated with 0.200 M KOH. Calculate the pH at the equivalence point for the titration of HNO2 and KOH. I got pH= 11.74.
April 16, 2016

Chemistry
When titrating 50.0 mL of 0.10 M H2SO4 with 0.10 M NaOH, how many mL of NaOH will you have added to reach the 1st equivalence point? I am confused... What H2A problem? Chemistry-Dr.Bob222 - DrBob222, Tuesday, April 12, 2016 at 1:49am Refer to the H2A problem above BUT you only...
April 12, 2016

Chemistry
A student completes a titration of an unknown diprotic acid. In this experiment, 0.79 g of the acid is dissolved in 250.0 mL of water. It requires 13.48 mL of 1.0 M NaOH to reach the second equivalence point. What is the molar mass of the acid?
April 12, 2016

Chemistry-Dr.Bob222
A student completes a titration of an unknown diprotic acid. In this experiment, 0.79 g of the acid is dissolved in 250.0 mL of water. It requires 13.48 mL of 1.0 M NaOH to reach the second equivalence point. What is the molar mass of the acid?
April 11, 2016

Chemistry-Dr.Bob222
When titrating 50.0 mL of 0.10 M H2SO4 with 0.10 M NaOH, how many mL of NaOH will you have added to reach the 1st equivalence point?
April 11, 2016

Geometry
The outside diameter of a pipe is 5 cm. The inside diameter is 4 cm. The pipe is 4 meters long. What is the volume of the material used for this length of pipe?Round your answer to the nearest cubic centimeter. (Hint: be sure that all units are in centimeters when completing ...
April 11, 2016

Chemistry- Dr.Bob222
What is the pH of a solution that is 0.150 M in acetic solution and 0.300 M in sodium acetate? The Ka of acetic acid is 1.8 x 10^-5. My work: pH= pKa + log (base/acid) pH= -log (1.8 x 10^-5) + log (0.300/0.150) pH=5
April 11, 2016

Chemistry-Dr.Bob222
Determine [OH-] of a solution that is 0.135 M in CO3^2-. I got 0.00532.
April 4, 2016

Chemistry- Dr.Bob222
Ammonium hydroxide is commonly advertised as an ingredient in some window cleaners. Rank the following in order of decreasing concentrations in these solutions: NH4OH, NH4+, OH-, NH3. Explain your reasoning. (Note that kb for ammonia = 1.8 x 10^-5. So does an unionized ion ...
April 3, 2016

Chemistry - Dr.Bob 222
The pH scale ranges from 0 to 14. What is the range of the hydronium ion concentration covered by this scale?
April 3, 2016

Chemistry- Dr.Bob222
Which if the folowin species is not amphoteric? a) H2SO4 b) H2PO4- c) HPO4 2- d) HSO4- e) H2O
March 28, 2016

Math
9+4=13 13/2=6.5 So the answer is 6.5
March 16, 2016

Chemistry-DrBob222
I got an answer of -1.34 x 10^3 KJ/mol. A 10.00 mL aliquot of 0.100 M NaOH is added to 15.00 mL of 0.100M HCl in a coffee cup calorimeter. The initial temperature of the two dilute liquids were both 25.0 degrees C and the final temperature of the mixture was found to be 37.8 ...
March 14, 2016

Chemistry-DrBob222
Is the answer for part c 0.91? A 1.0 L ball containing Ar at 5 atm is connected to a 10.0 L ball containing N2 at 2atm. A)Calculate the partial pressures and mole fractions of Ar and N2 after the valve is opened and the gases are allowed to mix (they fill the balls on both ...
March 14, 2016

Chemistry-DrBob222
Where did you get 5E-5. Is this how you set it up? 0.01 x 0.05 = 5E-4 If so, is it supposed to be 5E-4 instead of 5E-5? What is the equilibrium constant for a weak acid HA that dissociates 1% at an initial concentration of 0.05 M according to the following balanced chemical ...
March 14, 2016

Chemistry- DrBob222
What is the equilibrium constant for a weak acid HA that dissociates 1% at an initial concentration of 0.05 M according to the following balanced chemical equation? HA <----> H+ + A-
March 12, 2016

Chemistry
A 10.00 mL aliquot of 0.100 M NaOH is added to 15.00 mL of 0.100M HCl in a coffee cup calorimeter. The initial temperature of the two dilute liquids were both 25.0 degrees C and the final temperature of the mixture was found to be 37.8 degrees C. What is the (molar) heat of ...
March 12, 2016

Chemistry-DrBob222
I got 62.9 mL. Is this correct? I think HCl is the LR. A piece of solid magnesium is reacted with hydrochloric acid to form hydrogen gas: Mg (s) + 2HCl (aq) ---> MgCl2 (aq) + H2 (g) What volume of hydrogen gas (in mL) is collected over water at 25 degrees Celsius by ...
March 12, 2016

Chemistry -DrBob222
How many gallons of ethylene glycol, molar mass 62.07 g/mol, density = 1.1 g/mol do you need to add to each gallon of water ( 1 gallon = 4 liters and kf = 1.85 C/m) in your radiator to get the water to freeze at -15 C? Is it 0.458 gallon?
March 12, 2016

Chemistry-DrBob222
What is the final temperature and physical state if water when 47.50 kJ of energy is added to 15.0 g of ice at -10.0 C? Helpful information: Cs (ice) = 2.1 J/g C Heat of fusion (water) = 6.02 kJ/mol Cs (water) = 4.184 J/g C Heat of vaporization (water) = 40.7 kJ/mol Cs (steam...
March 12, 2016

Chemistry
A 1.0 L ball containing Ar at 5 atm is connected to a 10.0 L ball containing N2 at 2atm. A)Calculate the partial pressures and mole fractions of Ar and N2 after the valve is opened and the gases are allowed to mix (they fill the balls on both sides). My answers: P argon = 0....
March 12, 2016

Chemistry-DrBob222
A 1.0 L ball containing Ar at 5 atm is connected to a 10.0 L ball containing N2 at 2atm. A)Calculate the partial pressures and mole fractions of Ar and N2 after the valve is opened and the gases are allowed to mix (they fill the balls on both sides). My answers: P argon = 0....
March 11, 2016

Chemistry- Dr.Bob222
Predict the effect of decreasing the temperature on the position of the following equilibria. (a) H2(g) + Cl2(g) ↔ 2HCl(g) + 49.7 kJ My answer: shifts to the right (b) 2NH3(g) ↔ N2(g) + 3H2(g) ∆ H = 37.2 kJ My answer: shifts to the left (c) CO(g) + H2O(g) &#...
March 10, 2016

chem
never mind.. I got 0.10..
March 6, 2016

chem- to DrBob222
I got 0.08, but the answer is wrong!
March 6, 2016

chem
Exercise 14.55 Consider the reaction: NiO(s)+CO(g)⇌Ni(s)+CO2(g) Kc=4000.0 at 1500 K When calculating the answer, do not round to the appropriate number of significant figures until the last calculation step. If a mixture of solid nickel(II) oxide and 0.10000 M carbon ...
March 6, 2016

Chemistry
Exercise 14.55 Consider the reaction: NiO(s)+CO(g)⇌Ni(s)+CO2(g) Kc=4000.0 at 1500 K When calculating the answer, do not round to the appropriate number of significant figures until the last calculation step. If a mixture of solid nickel(II) oxide and 0.10000 M carbon ...
March 6, 2016

Chemistry
Exercise 14.55 Consider the reaction: NiO(s)+CO(g)⇌Ni(s)+CO2(g) Kc=4000.0 at 1500 K When calculating the answer, do not round to the appropriate number of significant figures until the last calculation step..
March 6, 2016

Science/Math
Give an analogy to illistrate how air pressure works
November 5, 2015

7th grade English
ugghh
May 18, 2015

math
COULD 35 ever be the product of 10 and another number?Explain
May 12, 2015

counting cents
Dara has 5 coins in her purse. The coins total 40 cents
March 23, 2015

math
541,641,741.what is the next number.
March 18, 2015

time
when the hour hand is pointing at ten and the minute hand is pointing at the five. what time is it
February 10, 2015

math
Draw a cookie that is divided into 2 equal parts.Write the fraction to go with your drawing.
February 3, 2015

Math
The answer is more than and 275 more because if u divide 13,750 by 50 you will get 275and if you divide 13,750 by 25 you will get 550 and is more than 275 Your welcome and sorry im so late but at least you know the answer now
October 7, 2014

math
an eight sided number cube has the numbers 1,2,3,4,5,6,7 and 8 on it. the number cube is thrown once. What is the probability of 2?
June 2, 2014

math
3,375
March 11, 2014

Science
ii am michelle
March 4, 2014

Math
i don't know how to do these questions it so hard for me I don't get it at all so I need help I mean a ot of help really please help me please thanks al al ot bncvdfen'[sdw xcw rwohsd'[dwe2 s dwbnde;pwch ew[ddwe] e cknsdf[erjhe'fdsfer snnd[s'dsdwb;p ...
February 10, 2014

Science
shut the hell up nicole
January 5, 2014

Math
655
April 17, 2013

Math
Evan told his class that the people in his family have 14 legs in all. Quinton said that there must be 7 people in Evan's family. Is Quinton correct?Explain.
February 5, 2013

english/check
"About Russell" 28. Russell’s family encourages him to seek help for his problems. true false 29. Russell ends up a)working with his father as a real estate agent. b)collecting and redeeming soda bottles. c)begging on the street. d)teaching math in high school. ...
May 2, 2012

Social Studies
correct!
May 2, 2012

math
If there is an square 8 by 8, how many 4 sq ft tiles would i need?
February 23, 2012

MATH
$41
November 15, 2010

Chemistry
It's still not giving me the right answer. I'm pulling in the numbers, and doing the equation right. But, it keeps telling me, I am wrong.
October 22, 2010

Chemistry
(30.5)(X)(10.8)+(?)(10.8)=0 What number goes in the calorimeter constant ?
October 22, 2010

Chemistry
A 30.5 g sample of an alloy at 94.0°C is placed into 48.7 g water at 20.3°C in an insulated coffee cup. The heat capacity of the coffee cup (without the water) is 9.2 J/K. If the final temperature of the system is 31.1°C, what is the specific heat capacity of the ...
October 22, 2010

Chemistry
What is the change in internal energy (in J) of a system that absorbs 0.677 kJ of heat from its surroundings and has 0.438 kcal of work done on it?
October 22, 2010

College Chemistry
1. What is the change in internal energy (in J) of a system that absorbs 0.677 kJ of heat from its surroundings and has 0.438 kcal of work done on it? 2. A 30.5 g sample of an alloy at 94.0°C is placed into 48.7 g water at 20.3°C in an insulated coffee cup. The heat ...
October 20, 2010

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