# Katherine

Most popular questions and responses by Katherine-
## Chemistry

Using the following data calculate Delta Sfus and Delta Svap for K in J/mol-k Tm(K) = 336, Delta H Fus(kJ/mol) = 2.33, Tb (K) = 1033, Delta H vap (kJ/mol) = 77.1 For Delta S fus i'm supposed to use 336 K the Tm value and for Delta S vap i'm supposed to use

*asked on March 9, 2012* -
## SS

How is the number of Electoral College seats per state determined? (1 point) by the number of party delegates assigned to the state by the total number of House and Senate representatives by the traditional number assigned under the 12th Amendment by

*asked on October 5, 2016* -
## Chemistry

Under standard conditions (298 K and 1 atm), which statement is true? a] diamond converts to graphite spontaneously b] graphite converts to diamond spontaneously c] none of the above How can the spontaneity of the reaction be reversed? a] increase the

*asked on March 8, 2012* -
## chemistry

Indicate the number of equivalents in each of the following: 4mol Mg2+ 0.1mol H+ 2mol Cl- 3mol Fe3+

*asked on September 12, 2012* -
## Chemistry

For the reaction described by the chemical equation: 3C2H2(g) -> C6H6(l) .. Delta H rxn = -633.1 kJ/mol a) Calculate the value of Delta S rxn at 25.0 C... b) Calculate Delta G rxn... c) In which direction is the reaction, as written, spontaneous at 25 C

*asked on March 9, 2012* -
## Chemistry

Calculate the concentrations of all species in a 0.810 M Na2SO3 (sodium sulfite) solution. The ionization constants for sulfurous acid are Ka1 = 1.4 x 10^-2 and Ka2 = 6.3 x 10^-8 so I'm trying to find Na, SO3 2-, HSO3-, H2SO3, OH-, H+ and heres what I

*asked on April 20, 2012* -
## Chemistry

The Ksp of CaSO4 is 4.93× 10–5. Calculate the solubility (in g/L) of CaSO4(s) in 0.300 M Na2SO4(aq) at 25 °C

*asked on November 12, 2013* -
## Physics

A 4-kg sled sliding freely on an icy surface experiences a 2 _ N frictional force exerted by the ice and an air-resistive force of 0.5 N. a. What is the net force acting on the sled? b. What is the acceleration of the sled?

*asked on December 28, 2010* -
## Chemistry

A solution household bleach contains 5.25% NaClO, by mass. Assuming that the density of bleach is the same as water(1.0g/ml). Calculate the volume in mL of household bleach that should be diluted with water to make 500.0 ml of a pH= 9.80 solution. Here's

*asked on April 20, 2012* -
## Chemistry

The voltage generated by the zinc concentration cell described by, Zn(s)|Zn2+ (aq, 0.100 M)||Zn2+ (aq, ____ M)|Zn(s) is 24.0 mV at 25 °C. Calculate the concentration of the Zn2 (aq) ion at the cathode. Hi, I posted this question awhile back but I think it

*asked on June 7, 2012* -
## Chemistry

Consider two cells, the first with Al and Ag electrodes, and the second with Zn and Ni electrodes, each in appropriate 1.00M solutions of their ions. If 2.10g of metal is plated in the voltaic cell, how much metal is plated in the electrolytic cell?

*asked on June 3, 2012* -
## Chemistry

A 0.450-gram sample of impure CaCO3(s) is dissolved in 50.0 mL of 0.150 M HCl(aq). The equation for the reaction is: CaCO3(s)+2HCl(aq) -> CaCl2(aq) + H2O(l) + CO2(g) The excess HCl(aq) is titrated by 9.75 mL of 0.125 M NaOH(aq). Calculate the mass

*asked on April 10, 2012* -
## Chemistry

Silver chromate is sparingly soluble in aqueous solutions. The Ksp of Ag2CrO4 is 1.12× 10–12. What is the solubility (in mol/L) of silver chromate in 1.4 M potassium chromate aqueous solution? In 1.4 M silver nitrate aqueous solution? In pure water?

*asked on November 12, 2013* -
## Chemistry

A generic solid, X, has a molar mass of 77.7 g/mol. In a constant-pressure calorimeter, 31.2 g of X is dissolved in 289 g of water at 23.00 °C. The temperature of the resulting solution rises to 24.40 °C. Assume the solution has the same specific heat as

*asked on November 2, 2014* -
## Chemistry

Calculate delta G of the reaction at 25 degrees C: 2Au^3+ (aq) + 3Ni(s) 2Au(s) + 3Ni^2+(aq) Au3+ + 3e- ==> Au Eo = +1.50V Ni2+ + 2e- ==> Ni Eo = -0.23 V 2Au3+ + 3Ni ==> 3Ni2+ + 2Au The answer is -1.00 x 10^3 kJ but i'm not getting that answer!!!!!!! please

*asked on June 3, 2012* -
## Chemistry

A current of 5.18 A is pass through a Cr(NO3)2 solution for 1.20 hours. How much chromium is plated out of the solution? __g I have no idea how to approach this. Here's what I tried to do logically but I'm not sure if it works out: I know that the

*asked on June 3, 2012* -
## Math

Tiffany bought 2/5 kg of cherries. Linda bought 1/10 kg of cherries less than Tiffany. How many kg of cherries did they buy altogether?

*asked on January 22, 2014* -
## Math

Shelly compared the number of oak trees to the number of maple trees as part of a study about hardwood trees in a woodlot. She counted 9 maple trees to every 5 oak trees. Later in the year there was a bug problem and many trees died. New trees were planted

*asked on September 19, 2013* -
## chemistry

Calculate the cell potential for the following reaction as written at 51 degrees C, given that [Zn2+] = 0.837 M and [Sn2+] = 0.0180 M. Zn(s) + Sn^2+(aq) = Zn^2+(aq)+Sn(s) E = __ V Reduction Half-Reaction Standard Potential Ered° (V) Zn2+(aq) + 2e– →

*asked on June 7, 2012* -
## Language Arts

Which of the following sentences contains a dependent clause? a) my mother, who never wastes anything, rinsed and saved the take-out boxes b) we were running late and, we had to skip stopping by the post office. c) I had never been to New York before this

*asked on March 10, 2016* -
## Chemistry

Assume equal concentrations, rank these solutions by pH HBrO, Ca(OH)2, HCl, KOH, NH3 Here's how I ranked it: highest: Ca(OH)2 > HCl > KOH > NH3 > HBrO lowest is this correct? if not please tell me why!

*asked on April 16, 2012* -
## Chemistry

Phosphorus pentachloride decomposes according to the chemical equation PCl5(g) -----> PCl3 (g)+ Cl2(g) Kc= 1.80 at 250 degrees C A 0.206 mol sample of PCl5(g) is injected into an empty 3.30 L reaction vessel held at 250 °C. Calculate the concentrations of

*asked on September 30, 2013* -
## English

Why does Yoni think the Arab he finds is perfect for his film? It was in Bethlehem, actually, that Yonatan found his Arab, a handsome man who used his first wish for peace. His name was Munir; he was fat with a big white mustache. Superphotogenic. It was

*asked on September 9, 2017* -
## Chemistry

I keep getting the last part of this question wrong. Strong base is dissolved in 765 mL of 0.200 M weak acid (Ka = 4.63 x 10^-5) to make a buffer with a pH of 4.18. Assume that the volume remains constant when the base is added. HA(aq) + OH-(aq) -. H2O(l)

*asked on May 13, 2012* -
## Chemistry

I'm a bit iffy on oxidation numbers... can someone please tell me if this is correct? Assign oxidation states to each element on both sides of the equation : KClO2--->KCl+O2 Reactants K = +1 Cl = +1 O = -2 Products K = +1 Cl = -1 O = 0 the element being

*asked on May 20, 2012* -
## Math Statistics

"In the United Kingdom's Lotto game, a player picks six numbers from 1 to 49 fir each ticket. Rosemary brought one ticket for herself and one for each of her four adult children. She had the lottery ticket. When the sic winning numbers were drawn, Rosemary

*asked on February 7, 2017* -
## Physics

Take two Styrofoam cups, partially fill them with equal amounts of cold water, and drop equal amounts of ice into each cup to obtain a mixture of ice and water. a. Stir the water and ice mixture in one of the cups vigorously with a nonmetallic stirrer

*asked on December 28, 2010* -
## Chemistry

What NaCl concentration results when 209 mL of an 0.660 M NaCl solution is mixed with 492 mL of a 0.270 M NaCl solution? __ mol/.209 L = 0.660 M __ mol/.492 L = 0.270 M .. I have no idea how to solve this. I have no idea why I even set up the equation

*asked on April 9, 2012* -
## Chemistry

At 25 degrees Celsius all of these are true for a neutral solution : pH = 7.00, pOH = 7.00, and [H+] = [OH-] is that correct? For a neutral, aqueous solution regardless of temperature.. would the only correct statement be [H+] = [OH-]? pH = 7.00 and pOH =

*asked on April 16, 2012* -
## AP Stats

Bolivian adult females are much shorter than US females although the standard deviation of their heights is about the same at 2.3 inches. Only 4.1% of Bolivian females are at least five feet tall. What is the mean height of adult Bolivian women assuming

*asked on September 25, 2017* -
## Chemistry

What mass of precipitate will form if 1.50L of concentrated Pb(ClO3)2 is mixed with 0.200L of 0.280M of NaI? Assume the reaction is complete

*asked on April 17, 2013* -
## Chemistry

Calculate the concentrations of all species in a 0.810 M Na2SO3 (sodium sulfite) solution. The ionization constants for sulfurous acid are Ka1 = 1.4 x 10^-2 and Ka2 = 6.3 x 10^-8 I calculated SO32- = 0.8096 M, HSO3- = 3.58E-4, H2SO3 = 7.1E-13, OH- =

*asked on April 21, 2012* -
## math

a true or false test has 5 questions. what is the probability of guessing exactly four out of the five answers correstly.

*asked on November 6, 2009* -
## Math

In Wilbur's math class, his grade is based on the average score of six tests, each worth 100 points. Wilbur always worries about his grade. He knows that his average on the four first tests is 88.5. What is the lowest average he could get on his next two

*asked on September 22, 2010* -
## Chemistry

Delta H is 20.1 kJ/mol and Delta S is 45.9 J/(mol-k). Assuming these values change very little with temperature, over what temperature range is the reaction spontaneous in the forward direction? Is the reaction spontaneous for temperatures less than or

*asked on March 9, 2012* -
## math

A store sells two types of nut mixtures. The standard mix contains 100 grams of cashews and 200 grams of peanuts and sells for $2. The deluxe mix contains 120 grams of cashews and 40 grams of peanuts and sells for $2.50. The store has 15kilograms of

*asked on April 20, 2018* -
## Language Arts

What is the pattern of stressed and unstressed syllables in this line: The sun should drop its greatest gold

*asked on March 2, 2016* -
## Chemistry

The kinetic energy of a rolling billiard ball is given by {\rm{KE}} = 1/2\,mv^2 . Suppose a 0.17-{\rm kg} billiard ball is rolling down a pool table with an initial speed of 4.5 m/s. As it travels, it loses some of its energy as heat. The ball slows down

*asked on October 9, 2009* -
## Chemistry

There is a current being applied to an aqueous solution fo sodium bromide. What is produced at the cathode and anode? I said that Na(s) being produced at the cathode and Br2(l) being produced at the anode. The other options are H2 and O2 for either but

*asked on May 20, 2012* -
## math

an empty rectangle tank with a base area of 2400 cm^2 is filed with water from 2 taps. one tap can fill the tank with 12L of water per minute, while the other tap can do it at 3l less perminute. (A) what will be the depth of water in the tank after both

*asked on November 30, 2010* -
## Math

A company paid $110,000 for a new 18-wheeler. When it is 9 years old it will be worth $20,000. Using straight-line depreciation, the value of the trick in dollars, V, is a linear function of its age in years, n. Find the function and the value when the

*asked on August 22, 2018* -
## chemistry

In the following experiment, a coffee-cup calorimeter containing 100 mL of H2O is used. The initial temperature of the calorimeter is 23 degrees Celsius. If 4.00 g of CaCl2 is added to the calorimeter, what will be the final temperature of the solution in

*asked on October 19, 2009* -
## College Chem.

If 20.0 mL of glacial acetic acid (pure HC2H3O2) is diluted to 1.30 L with water, what is the pH of the resulting solution? The density of glacial acetic acid is 1.05 g/mL.

*asked on March 8, 2010* -
## Chemistry

Calculate the final concentration for the standardization of KMnO4 given this information: 2MnO4- + 5C2O4^-2 + 16H+ -> 2Mn^2+ + 10CO2 + 8H2O [final redox equation] Volume of KMnO4 titrated with H2SO4 + Na2C2O4 = 293 mL Volume KMnO4 titrated with H2SO4

*asked on May 2, 2012* -
## Chemistry

60cm3 of hydrogen diffused through a porous membrane in 10minutes.The same volume of gas G diffused through the same membrane in 37.4 minutes .Determine the relative molecular mass of G.(H=1)

*asked on January 4, 2019* -
## Need Help with Math?

1. Translate P(4,0) right 3 units and up 5 units. Give the coordinates of the image point. (-5,1) (1,-5) (5,7) (7,5) 2. Point A(6, -2) is reflected over the x-axis. Write the coordinates of A'. 6,2 6,-2 -6,2 -6,-2

*asked on October 11, 2013* -
## Chemistry

When 1 mol of a gas burns at constant pressure, it produces 2424 J of heat and does 6 kJ of work. How do i calculate delta E for this problem? I tried q+w but that didn't work for me. I got the answer wrong.

*asked on October 9, 2009* -
## math

kyle had 36 books in hislocker. some were library books, some were textbooks, and the rest were telophone books. the number of library books and textbooks combined equal twice the number of textbooks. the number of textbooks and telephone books combined

*asked on November 10, 2010* -
## math !!!! :O

The ratio of the number of postcards john had to the number of postcards Zachary ha d was 4:9. Zachary had 45 more postcards than John. After giving some postcards to John, Zachary had 6/7 as many postcards as John. (A) How many postcards did Zachary have

*asked on April 4, 2011* -
## Chemistry 11

So I did a lab determining the chemical formula of a hydrate. We had to find the molecular formula of a hydrate of copper (2) sulphate, CuSO4 .xH2O. My observation table looks like this: Mass of clean, dry test tube: 21.6g Mass of test tube + hydrated

*asked on November 18, 2014* -
## Chemistry

A reaction: A(aq) + B(aq) C(aq) has a standard free-energy change of –4.65 kJ/mol at 25 °C. What are the concentrations of A, B, and C at equilibrium if, at the beginning of the reaction, their concentrations are 0.30 M, 0.40 M, and 0 M, respectively?

*asked on November 24, 2013* -
## science

why are plastic handles on frying pans safer to than metal handles

*asked on May 22, 2012* -
## Chemistry

C6H5COOH(aq) + NO2-(aq) C6H5COO-(aq) + HNO2(aq) A table of ionizations is given to calculate the equilibrium constant for this overall reaction.. but when i looked onto the table the only thing given was the Ka for C6H5COOH [6.3×10^–5] and HNO2

*asked on April 20, 2012* -
## Chemistry

Calculate the equilibrium constant for the following reaction at 100°C. 2 TiCl3(g)+2 HCl (g) = 2 TiCl4(g)+H2(g) ∆G°rxn = + 47.0 kJ mol-1 cant i just use K = e^ -Delta G/RT? --> K = e ^ -47.0 kJ mol-1 /(8.314)(273+100)? what is the point of having the

*asked on March 15, 2012* -
## math

Daniel gave 4/5 of his stickers to Javier. Javier’s collection of stickers increased to 64. If Javier had 28 stickers in the beginning, how many stickers did Daniel have in the beinging? can u please show the work and explain how u got it...so i could

*asked on March 31, 2011* -
## Chem 11

So I did a lab determining the chemical formula of a hydrate. I really just need somebody to check this over for me. We had to find the molecular formula of a hydrate of copper (2) sulphate, CuSO4 .xH2O. My observation table looks like this: Mass of clean,

*asked on November 18, 2014* -
## Physics

The electric field at the point x=5.00 cm and y=0 points in the positive x direction with a magnitude of 10.0 N/C. At the point x=10.0 cm and y=0, the electric field points in the positive x direction with a magnitude of 15.0 N/C. Assuming the field is

*asked on February 7, 2010* -
## chemistry

The Rydberg equation (1/lambda=R/ni^2–R/nf^2) can be treated as a line equation. What is the value of nf as a function of the slope (m) and y-intercept(b)?

*asked on January 10, 2010* -
## Chemistry

What is the significance of the distance between two metals in the activity series?

*asked on March 4, 2013* -
## math

Hitomi has a total of 30 red and blue bowling balls at her bowling alley. Each red ball weighs 8 lb. Each blue ball weighs 9 lb. If the total mass of the blue balls is 49 lb. heavier than the total mass of the red balls, how many red balls does she have?

*asked on March 3, 2011* -
## Language Arts

Which of the following sentences contains a dependent clause? a) my mother, who never wastes anything, rinsed and saved the take-out boxes b) we were running late and, we had to skip stopping by the post office. c) I had never been to New York before this

*asked on March 10, 2016* -
## SS

Which factors led to the downfall of Ghana? Select all that apply. A. Ghana was engaged in conflict with people to the north. B. Ghana lacked nearby water resources. ******* C. Ghana was unwilling to participate in trade. D. Ghana's large population began

*asked on April 1, 2019* -
## social studies

How are petitions and Demonstrations similar?

*asked on February 18, 2013* -
## math !!!! :O

Amanda is 12 years old. She is 2/7 times as old as her father. How many years ago was her father 4 times as old as Amanda.

*asked on March 21, 2011* -
## math

a student playing a computer chess game gets 5 points every time he wins a round.the computer gets 3 points every time it wins a round.they play 64 rounds and end with a tied score.how many rounds did the computer win. please help me .. i think the answer

*asked on April 22, 2010* -
## sewing2

Mrs. Shotto was once one of your regular customers, but she hasn't asked to have any garments made in approximately one year. You note she has lost weight. She would like you to make her a special silk blouse to replace a favorite blouse that has worn out.

*asked on April 20, 2010* -
## Physics

A car is backing up at a rate of 10km/hr. If the driver looks through his rear-view mirror, how fast does a tree, which is behind him, appear to approach him?

*asked on October 27, 2016* -
## math !!!! :O

Tierra, Nico, and Alex had $865 altogether. Tierra spent 2/5 of her money. Nico spent $40 , and Alex spent twice as much as Tierra. If the three friends had the same amount of money left, how much money did Alex have in the beginning.

*asked on February 24, 2011* -
## math

jake spent 3/8 of his money on a book and 1/2 of what was left on a magazine.he now has $6.25. how much money did he start with? please help me i am confused... thank you :)

*asked on April 20, 2010* -
## Chemistry

Given the following equations: 2 H2 (g) + O2 (g)--> 2 H2O (l) deltaH = -571.6 kJ N2 (g) + O2 (g)-->2 NO (g) deltaH = +180.5 kJ N2 (g) + 3 H2 (g) --->2 NH3 (g) deltaH = -92.22 kJ Determine the enthalpy change (deltaH) for the following reaction: 2 NO (g) +

*asked on October 8, 2009* -
## math

What is the base 7 representation of the number 275? 21201 is the base 3 representation of what number? I'm having trouble with both questions. Can someone help me out? I tried using the internet but I was still confused.

*asked on January 31, 2018* -
## physics 1

Two isolated masses, M1 = 2.20 kg and M2 = 589 kg are initially rest, a distance d= 161 cm apart. Their gravitational attraction is the only force acting. Calculate the time it takes for M1 to move from that distance to 159 cm from M2. Assume that M2 does

*asked on December 12, 2014* -
## physics

If each of the three rotor helicopter blades is L = 3.69m long and has a mass of m = 159kg, calculate the moment of inertia of the three rotor blades about the axis of rotation.

*asked on November 11, 2014* -
## Chemistry

Hydrazine, N2H4 can be made (on paper) by reaction of molecular nitrogen and molecular hydrogen, 2 H 2 ( g ) + N 2 ( g ) --> N 2 H 4 ( g ) and suppose that the equilibrium constant Kp has the value 1×10^–3. (a) A stoicheometric mixture of H2 and N2 is

*asked on August 13, 2011* -
## math

At Irv's Cycle Rental Shop, Irv renst all knids of cycles: unicyles, tandem bikes, regualr bikes, and even tricycles for little kids. He parks all the cycles in front of the shop with a helmet for each rider strapped to the cycles. This morninf Irv counted

*asked on October 20, 2010* -
## Chem

The hydrolysis of sucrose into glucose and fructose in acidic water has a rate constant of at 25 degrees C. Assuming the reaction is first order in sucrose, determine the mass of sucrose that is hydrolyzed when 2.60 L of a 0.150 M sucrose solution is

*asked on February 28, 2010* -
## math

37.52 rounded to the nerast whole

*asked on December 5, 2018* -
## math !!!! :O

Luisa and Connor had $360 altogether. After Connor gave Luisa 2/5 oh his money, she had the same amount of money as he did. How much money did Connor have in the beginning?

*asked on April 12, 2011* -
## Accounting

How do I calculate the future value of the following? $5,000 compounded annually at 12% for 2 years $5,000 compounded semiannually at 12% for 2 years $5,000 compounded quarterly at 12% for 2 years $5,000 compounded monthly at 12% for 2 years

*asked on November 16, 2010* -
## math

still don't get it.....Our class planned a holiday party for disadvantaged kids.Some of us baked cookies for the party.On the day of the party,we found we could divide the cookies into packets of two, three, four, five, or six and have just one cookie left

*asked on November 30, 2009* -
## Math

Express fraction 9/4 as the sum of two or three equal parts. Rewrite the problem as a multiplication equation.

*asked on January 9, 2014* -
## chemistry

1.which of the following is the most polar bond? explain n-f c-f h-f o-f 2. in the trigonal bipyramidal geometry, which position - axial or equatorial - do nonbonding electrons prefer? why? 3.under what circumstances is the molecular geometry around a

*asked on April 23, 2010* -
## science

How many seconds does it take for mercury to go from 0 degrees celsius to 300 degrees celsius?

*asked on January 29, 2013* -
## Chemistry

Suppose we have a solution of lead nitrate, Pb(NO3). A solution of NaCl(aq) is added slowly until no further precipitation occurs. The precipitate is collected by filtration, dried and weighed. A total of 10.27g of PbCl2(s) is obtained from 200.0mL of the

*asked on April 17, 2013* -
## physics

A diver springs upward from a board that is 2.98 meters above the water. At the instant she contacts the water her speed is 9.39 m/s and her body makes an angle of 70.4° with respect to the horizontal surface of the water. Determine her initial velocity.

*asked on September 11, 2012* -
## physics

What is the longest wavelength that can be heard by a normal ear?

*asked on April 22, 2012* -
## math

Our class planned a holiday party for disadvantaged kids.Some of us baked cookies for the party.On the day of the party,we found we could divide the cookies into packets of two, three, four, five, or six and have just one cookie left over in each case.If

*asked on November 30, 2009* -
## objective and eyepiece lens

What is the approximate magnification of a compound microscope with objective and eyepiece focal lengths of 0.3 cm and 3.6 cm, respectively, and a separation between lenses of 20 cm? The answer is 460. I tried finding the magnification for the eyepiece

*asked on May 22, 2009* -
## Chemistry

How much solid ammonium chloride would be needed to make 100 mL of a 0.5M solution?

*asked on May 18, 2016* -
## Physics

A copper calorimeter can with mass .100 kg contains .160 kg of water and .018 kg of ice in thermal equilibrium at atmospheric pressure. If .750 kg of lead at a temperature of 255 degrees Celsius is dropped into the can what is the final temperature of the

*asked on October 18, 2010* -
## physics

A block is projected up a frictionless inclined plane with initial speed v0 = 8.42 m/s. The angle of incline is è = 58.4°. (a) How far up the plane does it go? (b) How long does it take to get there? (c) What is its speed when it gets back to the bottom?

*asked on October 9, 2010* -
## US History

The question is "How might Juan Cabrillo's explorations affect later settlements in CA?" In the book there's only a little sentence talking about him.. "Cabrillo sailed 1,200 miles along the coast of what is now California. Cabrillo failed to find wealth,

*asked on October 6, 2010* -
## reading

thank u mrs sue

*asked on November 23, 2009* -
## Chemistry

how much silver nitrate must be measured to yield 1.00g silver?

*asked on October 18, 2009* -
## Physics

Show that the average speed of a rabbit that runs a distance of 30 m in a time of 2 s is 15 m/s. I have a whole bunch of problems such as these and i'm not sure what math formula to use to figure problem.I know its Acceleration ! change of velocity time

*asked on October 10, 2012* -
## Chemistry

If a buffer solution is 0.190 M in a weak acid (Ka = 5.8 x 10^-5) and 0.550 M in its conjugate base, what is the pH? What if it said "if a buffer solution is ___ M in a weak base (Kb = ____) and ___ M in its conjugate acid, what is the pH? Would the steps

*asked on April 22, 2012* -
## math

The ratio of the number of postcards john had to the number of postcards Zachary ha d was 4:9. Zachary had 45 more postcards than John. After giving some postcards to John, Zachary had 6/7 as many postcards as John. (A) How many postcards did Zachary have

*asked on April 6, 2011* -
## math

a student has $8 to spent on a phone call.the cost of the call is $0.34 for the first minute and $0.24 for each additional minute. how long can the student talk on the phone? i think the answer is... $8-$0.34=$7.66 $7.66/$0.24=31.9 so i guess its about 31

*asked on April 22, 2010* -
## chemistry

The thermal decomposition of calcium carbonate produces 2 by-products, c02 and calcium oxide. calculate the volume of the co2 produced at STP from the decomposition of 231 grams of caco3. i know the equation i need to use is V=nrt/p but am i supposed to

*asked on February 18, 2010* -
## math

you have one penny one nickel one dime and one quarter. how many different amounts of money can you make using one or more of these coins ... please help..me..:(

*asked on December 9, 2009*