Sunday
December 21, 2014

Posts by Ana


Total # Posts: 1,017

Chemistry - Science (Dr. Bob222)
the correct answer is 5.2 mmol; however, I get lost in the calculations. It seems easy to solve: I have pH, pKb, and HH eq, but then I get stuck to derive x correctly
May 6, 2014

Chemistry - Science (Dr. Bob222)
How many mmol ( millimoles) of HCl must be added to 130.0 mL of a 0.40M solution of methyl amine (pKb = 3.36) to give a buffer having a pH of 11.59? Thank you for your help!
May 6, 2014

Chemistry - Science (Dr. Bob222)
Posted by Ana on Saturday, May 3, 2014 at 11:23am. A zinc-copper battery is constructed as follows (standard reduction potentials given below): Zn | Zn2+ (0.10 M) || Cu2+ (2.50 M) | Cu Zn2+ + 2 e- → Zn(s) Eº = -0.76 V Cu2+ + 2 e- → Cu(s) Eº = 0.34 V The ...
May 5, 2014

Math
If a navigation error puts a plane 2 degrees off course, how far off course is the plane after flying 121 miles? Round to the nearest tenth of a mile. Just explain how to solve, please.
May 5, 2014

Math
A boat travels 74 miles on a course with direction 34 degrees and then changes its course to travel 58 miles at 53 degrees. How far north and how far east has the boat traveled on its 132-mile trip? A 87.7 miles east and 44.3 miles north B 35.7 miles east and 96.3 miles north ...
May 5, 2014

Math
An airplane, after 1 hour in the air, arrives at a point 350 miles south of its departure point. There was a steady wind of exactly 25 mph from the northwest during the entire flight. Which represents the airplane's average air speed?
May 5, 2014

Chemistry - Science (Dr. Bob222)
thank you!!
May 3, 2014

Chemistry - Science (Dr. Bob222)
Ammonium metavanadate reacts with sulfur dioxide in acidic solution as follows (hydrogen ions and H2O omitted): xVO3^–^ + ySO2 → xVO^2+^ + ySO4^2–^ What is the ratio of x : y? A. 1 : 1 B. 1 : 2 C. 2 : 1 D. 1 : 3 E. 3 : 1
May 3, 2014

Chemistry - Science (Dr. Bob222)
Thank you for such a great response! You are a legend!
May 3, 2014

Chemistry - Science (Dr. Bob222)
the correct answer is D, but i am confused on the rational here. Not sure what the professor wants me to understand here, the concept behind...
May 3, 2014

Chemistry - Science (Dr. Bob222)
Use the following information to answer this question: Cu+(aq) + e- → Cu(s) E° = 0.521V Cu2+ (aq) + e- → Cu+ (aq) E° = 0.153 V. Given these half cell reactions, an aqueous solution of Cu+ ion in the absence of O2(g) : A. will be thermodynamically stable B. ...
May 3, 2014

chemistry - Science
Disregard of 1M solution, it's a typo. The volume of 1.00L is relevant
May 3, 2014

chemistry - Science
A zinc-copper battery is constructed as follows (standard reduction potentials given below): Zn | Zn2+ (0.10 M) || Cu2+ (2.50 M) | Cu Zn2+ + 2 e- → Zn(s) Eº = -0.76 V Cu2+ + 2 e- → Cu(s) Eº = 0.34 V The mass of each electrode is 200 g. Each half-cell ...
May 3, 2014

chemistry - Science
A zinc-copper battery is constructed as follows (standard reduction potentials given below): Zn | Zn2+ (0.10 M) || Cu2+ (2.50 M) | Cu Zn2+ + 2 e- → Zn(s) Eº = -0.76 V Cu2+ + 2 e- → Cu(s) Eº = 0.34 V The mass of each electrode is 200 g. Each half-cell ...
May 3, 2014

Chemistry - Science
A fuel cell designed to react grain alcohol with oxygen has the following net reaction: C2H5OH(l) + 3O2(g) → 2CO2(g) + 3H2O(l) The maximum work that 1 mol of alcohol can yield by this process is 1320 kJ. What is the theoretical maximum voltage this cell can achieve?
May 3, 2014

chemistry - (Dr. Bob222)
Thank you so much! This makes much more sense now. Indeed a great tool to know
April 21, 2014

chemistry - (Dr. Bob222)
Thank you very much! The formula is very useful,but if it's no trouble for you could you please explain the concept?
April 21, 2014

chemistry - (Dr. Bob222)
A student attempted to synthesize malonic acid which has a molecular weight of 104 g/mol by the same method used to synthesize aspirin. A titration was performed to find the equivalent weight. 0.125 g of malonic acid product was used for a titration that required 24 mL of 0.10...
April 21, 2014

College Chemistry (DrBob222)
Thank you! You are legendary!
April 16, 2014

College Chemistry (DrBob222)
The decomposition of HCO2H follows first-order kinetics. HCO2H(g) CO2(g) + H2(g) The half-life for the reaction at a certain temperature is 44 seconds. How many seconds are needed for the formic acid concentration to decrease by 73%?
April 16, 2014

chemistry - (Dr. Bob222)
No, they did not provide any reaction for this problem. If I'll find the solution, I'll post it here. Thank you for your help.
April 16, 2014

chemistry - (Dr. Bob222)
I did that and but I got 1.52 mol/L rather 0.97 (as the answer key provides it)
April 16, 2014

chemistry - (Dr. Bob222)
The rate constant for a second order reaction has the value of 2.5 x 10–3 L·mol–1·s–1. If the initial concentration of reactant is 3.5 mol·L-1, what will be the molar concentration of the reactant after 2.5 minutes?
April 16, 2014

Chemistry - Science (Dr. Bob222)
I have calculated K1 and K2 by dividing initial rate to initial concentration [A2], and I solved for Ea but for some reason I don't get the right answer, (which is 10.2KJ)
April 16, 2014

Chemistry - Science (Dr. Bob222)
Consider the kinetic data given in the table below for the first order reaction: What is the value of the activation energy? A_2_--> 2A Expt. Initial [A2] Temp. Initial Rate mol/L (°C) [A2]·s–1 1 0.10 100 1.2 x 10–3 2 0.20 200 4.8 x 10–3 3 0.15 ? 4...
April 16, 2014

Chemistry - Science (Dr. Bob222)
Consider the kinetic data given in the table below for the first order reaction: What is the value of the activation energy? A_2_--> 2A Expt. Initial [A2] Temp. Initial Rate mol/L (°C) [A2]·s–1 1 0.10 100 1.2 x 10–3 2 0.20 200 4.8 x 10–3 3 0.15 ? 4...
April 16, 2014

chemistry
a 0.0500 mol sample of a nutrient substance is burned in a bomb calorimeter containing 2.00 x 10^2g H2O. If the formula weight of this nutrient substance is 114g/mol, what is the fuel value (in nutrient Cal) if the temperature of the water increased 5.70C
April 15, 2014

Math
Use synthetic division to determine which pair of integers provide both a lower and an upper bound for the zeros of f(x)= x^5-2x^4-25x^3+50x^2+144x-290 PLEASE SHOW WORK!!!
April 9, 2014

Subtracting Fractions with like Denominators
If Lori's neighbor gave her sixths eighths cup of milk, would she then have enough milk to make her 2 pancakes?
April 8, 2014

french
Do this sentence is direct or indirect je vais voir mes cousins
March 26, 2014

Physics
if you throw a 0.2 kg ball straight up at 8 m/s how high will it go
March 23, 2014

physics
What are the principles behind seatbelts and air bags that make passengers safer in a collision?
March 23, 2014

physics
If a motorboat travels 25km/h towards the sea, down a river whose velocity is 4km/h what is the boats velocity related to the shore? A, 21 km/h B, 29km/h C, 25 km/h D, 4 km/h
March 21, 2014

physics
if an airplane is traveling at 550 km/h into a head wind with a velocity of 40km/h what is the airplanes velocity relative to the ground
March 21, 2014

Physics
If a motorboat travels 25km/h towards the sea, down a river whose velocity is 4km/h what is the boats velocity related to the shore?
March 21, 2014

Chemistry
How many copper atoms are in a pure copper statue with a mass of 139kg{\rm kg}
March 5, 2014

Chemistry
Iron ores have different amounts of iron per kilogram of ore. Calculate the mass percent composition of iron for each iron ore: Fe2O3{\rm Fe_2O_3} (hematite), Fe3O4{\rm Fe_3O_4} (magnetite), FeCO3{\rm FeCO_3} (siderite).
March 5, 2014

Chemistry
Citric acid, the compound responsible for the sour taste of lemons, has the following elemental composition: C{\rm C}, 37.51%\%; H{\rm H}, 4.20%\%; O{\rm O}, 58.29%\%.Calculate the empirical formula of citric acid
March 5, 2014

statistics
Suppose a manufacturer claims that each family-size bag of pretzels sold weighs 12 ounces on average with a standard deviation of 0.8 ounces. A consumer's group decides to test this claim. If a simple random sample of 49 bags of pretzels gives a sample mean of 11.8 ounces...
February 25, 2014

chemistryyyy
(a) What is the pH of a 6.1 ✕ 10-5 M Ca(OH)2 solution? (b) What is the H3O+ concentration of the solution? I already know the answer to part A, I just don't understand how you could use that information to find the concentration of H30+ when its not in the ionic ...
February 23, 2014

chemistryyyy
Thanks! I got part A but how are you supposed to know the concentration of H30+ if its not in the equation?
February 23, 2014

chemistryyyy
a. What is the pH of a 6.1 ✕ 10-5 M Ca(OH)2 solution? b. What is the H3O+ concentration of the solution? I just cant figure out the ionic equation.
February 23, 2014

Physics
Canadian geese migrate essentially along a north-south direction for well over a thousand kilometers in some cases, traveling at speeds up to about 100 km/h. If one such bird is flying at 100 km/h relative to the air, but there is a 38.0km/h wind blowing from west to east. a) ...
February 19, 2014

Physics
A canoe has a velocity of 0.410m/s southeast relative to the earth. The canoe is on a river that is flowing at 0.510m/s east relative to the earth. Find the magnitude of the velocity v⃗ c/r of the canoe relative to the river
February 19, 2014

Algebra 2
A ball is dropped from 400 ft what is the height of the ball on the 6th bounce? 1 bounce =280 ft 2 bounce= 196 ft 3 bounce = 137.2 How do I figure this out?
February 6, 2014

Biology
what is independent variable definition?
February 5, 2014

english
Please HELP Type the word that the underlined phrase modifies or renames. Store the records OF PAYMENTS in the file cabinet. Question 24.. Type the word that the underlined phrase modifies or renames. The house, AN OLD FASHIONED COTTAGE SURROUNDED BY CREPE MYRTLESs, was charming.
January 8, 2014

chemistry
Acetic acid (CH3CO2H) is a weak acid. As a result, a solution of sodium acetate (NaCH3CO2) will be _____.
January 6, 2014

Math
(1) 8/1 divided (-3 2/5) My answer is 68/1 (2) 3 2/3 divided by -8 6/7 answer 682/21 3) 41/5 x -8/5 =32/25 Please I need help i'm so confused please show work so I can understand these other 27 problems that i have to complete. Thank you Ms. Sue
December 10, 2013

Compters
The major reason for the predominance of the PCI bus in the latest models of PCs is that A. the size and form factor make it easy to package. B. it's exclusively manufactured in the USA. C. the technology was released as open source. D. it uses ASSEMBLER language commands.
December 9, 2013

Math
If x over three minus y over two= negative three. Which statement best explains the value of y changes each time x is increased by one unit? A. The value of y increase by three over two units. B. The value of y increase by two over three units. C. The value of y decrease by ...
November 21, 2013

algebra
200<d<260
November 1, 2013

Science
How is Earth like a system?
October 25, 2013

french
Tu viens d'ou? Comment est CE que le Prof skie? Ou est-CE que tu vas? les crêpe coutent combines? Vous allez a l' Ecole, n'est CE pas?Avec qui est- CE que tu joues au foot? Tu es le professeur match the question question with the letter appropriate answer....
October 22, 2013

french
Match the question with the letter of the appropriate answer pourquoi est - CE que tu e' tudies le francais
October 22, 2013

math
powers and exponents
September 7, 2013

math
can***
August 28, 2013

math
i dont understand, csn you explain it to me
August 28, 2013

psychology
In the brain, most excitatory communication in synapses occurs by way of glutamate and most inhibitory communication occurs by way of gamma-aminobutyric acid. In general terms, describe what the other neurotransmitters do.
July 30, 2013

calculus
A cooling tower for a nuclear reactor is to be constructed in the shape of a hyperboloid of one sheet. The diameter at the base is 260 m and the minimum diameter, 500 m above the base, is 200 m. Find an equation for the tower. (Assume the center is at the origin with axis the ...
July 8, 2013

calculus
A cooling tower for a nuclear reactor is to be constructed in the shape of a hyperboloid of one sheet. The diameter at the base is 260 m and the minimum diameter, 500 m above the base, is 200 m. Find an equation for the tower. (Assume the center is at the origin with axis the ...
July 8, 2013

algebra
(3x^2-2x-1) - (5x^2+4x+2)
June 3, 2013

algebra
I think your wrong A=lxW w=x l=2x+1 So it should be something like A=( ) ( ) and that's the part I dont understand
June 3, 2013

chemistry
18.5g Al is submerged in 20.2g of water with a total temperature of 27°C. How much energy in joules is absorbed by the Al if the temperature changes to 32°C ?
May 28, 2013

Statistics
X Y 0 23 2 27 2.3 29 4.1 32 5 35 What is the correlation for this data set? 10) Find the regression line for this data set.
May 25, 2013

math
what is a data
May 9, 2013

math
finding the average
May 9, 2013

math
finding the mean
May 9, 2013

Algebra
Evaluate the determinant of the matrix. [-4 5 6 0 4 4 -2 -5 4]
April 19, 2013

Algebra 2 variables
Find the values of the variables. [-12 -w^2] = [2k -81] [2f 3] [-4 3] Show your work?
April 19, 2013

Algebra 2
Find the sum [1 4] [0 0] [0 3] + [0 0] A - [1 4] [0 3] B - undefined C - [0 0] [0 0] D - [1 0] [4 3]
April 19, 2013

math
evaluate the expressions below and leave them in radical form. 1. sin(pie symbol/6)csc(pie symbol/6) 2. sec(pie symbol/3)cos(pie symbol/3)+tan(pie symbol/3)cot(pie symbol/3)
March 30, 2013

science
thank you.
March 27, 2013

science
plz delete after 20 minutes of answering
March 27, 2013

algebra
A store mixes kenyan coffee worht $12 per kilogram and turkish coffee worth $16 per kilogram the mixture is to sell for $14 per kilogram how much of each should be used to make a 348-kilogram mixture?
March 18, 2013

Spanish
how old am I
February 17, 2013

Science
How do you find the hours of daylight ?
January 30, 2013

Algebra 2
The Formula s= sqrt 30fd can be estimated the speed of s, in miles per hour that a car is traveling when it goes into a skid, where f is the coefficient of friction and d is the length of the skid marks in feet. Kody skids to a stop on a street with a speed limit of 35 mi/h. ...
January 21, 2013

4th grade math
you find a common denominator, which is 4 in your case, and because you multiply 2 by 2 you have to multiply 41 by 2 as well, so you get 82/4-1/4, ok or do you need more help?
January 20, 2013

math
In the xy-coordinate plane, the distznce between point B(15,7) and point A(x,15) is 17. What is one possible value of x?
January 19, 2013

science project
I'm trying to find information on does lung capacity depend on height
January 18, 2013

Reading/Language Arts
Did i rewrite my paragraph right.Also thank you for your help
January 12, 2013

Reading/Language Arts
the energy we get to heat up the house and run our appliances is a energy solar panel.And it has an adverse affect on it do to the heavy snow fall.The apparatus does not generate enough energy do to lack of sunlight. And we need that energy to power our house for heat hot ...
January 12, 2013

Reading/Language Arts
The energy we get to heat up our house and run our appliances. Is a solar panel and is a necessity to live an everyday life. Do to a adverse affect on the solar panel caused by to much snow. The apparatus does not get enough sunlight to generate electricity. That the house ...
January 12, 2013

Reading/Language Arts
I,m writing a paragraph about using resources responsibly.And I have to use three vocabulary words adverse,generate,apparatus. And this is what I wrote. The energy to the house I live in has had a adverse affect.Do to the apparatus not getting enough sunlight to generate all ...
January 12, 2013

reading/language arts
write a paragraph about using resources responsibly using these three words:renewable,nonrenewable,generate.
January 11, 2013

greenhouse biology
what organism is a porkaryotic cell?
January 11, 2013

Math
700 eggs will be needed
January 9, 2013

Government
I don't know.
January 8, 2013

Government
What are the duties of congressional committees?
January 8, 2013

Government
They are in the system of goverment letting each branch keep each other in balance so none of the branches gets too powerful
January 8, 2013

Government
Identify checks and balances.
January 8, 2013

Government
thank you.
January 8, 2013

Government
A progressive tax is a tax whose rate increases as the payers income increases? if individuals who earn high incomes have a greater proportion of their incomes taken to pay the tax? A regressive tax is one whose rate increases as the payers income decreases?
January 8, 2013

Government
Explain progressive and regressive taxes.
January 8, 2013

Government
Explain the social contract theory.
January 8, 2013

Government
Who works on the federal budget?
January 8, 2013

Government
List one of the unalienable rights.
January 8, 2013

government
Describe the different types of primaries.
January 8, 2013

government
How do the duties of the Lieutenant Governor compare to those of the vice president?
January 8, 2013

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