Saturday

October 25, 2014

October 25, 2014

Number of results: 49,745

**Chemistry**

Calculate the pOH of an aqueous solution of 146.6 ml of 0.000625 M HBr(aq) after dilution to 850 ml.
*March 21, 2013 by Mary Ann *

**Chemistry**

Calculate the pOH of an aqueous solution of 146.6 ml of 0.000625 M HBr(aq) after dilution to 850 ml.
*March 21, 2013 by Mary Ann *

**Chemistry**

Calculate the pOH of an aqueous solution of 146.6 ml of 0.000625 M HBr(aq) after dilution to 850 ml.
*March 21, 2013 by Mary Ann *

**Math**

Calculate the morality of a solution made by mixing 250ml of 0.75M H2SO4 with 400ml of 2.5MH2SO4
*March 26, 2013 by Alica*

**chemistry**

Calculate the concentrations of all species present C6H5N2, C6H5NH3+ OH^-, and H3O^+}) in a 0.14 M solution of aniline.
*April 5, 2013 by kim*

**chemistry**

calculate the enthalpy of mixing for the solution of 10% platinum and 90% gold .express your answer in units of kg/mole
*May 7, 2013 by himani.*

**Chemistry**

A solution contains 80.0 g of sodium chloride and 400.0 g of water. Calculate the NaCl as a mass percentage
*June 2, 2013 by Monica*

**chemistry**

Calculate the molarity (M) of a solution of the strong base RbOH if the hydroxide ion concentration is 0.000309 M.
*October 10, 2013 by HELP ASAP PLEASE*

**chemistry**

Calculate the molarity (M) of a solution of the strong acid H2SO4 if the hydrogen ion concentration is 0.000244 M.
*October 10, 2013 by HELP ASAP PLEASE*

**Chemistry**

Dr bob for this question :Calculate the molar solubility of manganese II hydroxide in ph 12.85 solution. The Ksp is 2.1 x 10^-13 but I can't solve for x thanks.
*May 26, 2014 by Anonymous *

**chemistry**

calculate the mass of Cuso4.5H2O required to prepare 500 cm3 of a 0.400 m/dm-3 solution
*June 8, 2014 by alice*

**science**

calculate the mass of Cuso4.5H2O required to prepare 500 cm3 of a 0.400 m/dm-3 solution
*June 8, 2014 by alice*

**chemistry, biology**

Calculate the pH of a solution obtained by adding 20 mL of .2M KOH to 480 mL to .02M isoelectric glycine
*July 6, 2014 by Laurel*

**chemistry**

calculate the molality, molarity, and mole fraction of NH3 in an 12.80 mass % aqueous solution (d=0.9651 g/ml)
*September 8, 2014 by maria*

**Chemistry**

Using the change in oxidation number method, balance the redox reaction shown below. (NO2^2)+ (MnO4^-)---> (NO3^-)+ Mn^2+ Divide into half reactions. I will show you how to do MnO4^- and you do the other one. MnO4^- ==> Mn^+2 Step 2. Determine the oxidation state of the ...
*June 17, 2007 by Aubrey*

**Math Quotations place value **

Good evening, I am not sure if Ross wrote the questions for homework correctly however, I am a little confused as to the difference in hundreds place value vs. hundreths place value is there such a place value as HUNDRETHS? Would HUNDRETHS APPLY TO DECIMAL PLACE VALUE? Thanks ...
*September 10, 2009 by Ross*

**chemistry**

Which solutions are acidic? (Assume all solutions are at 25C. Kw = 1.0 x 10-14 at 25C.) A. A solution with [H+] = 9.4 x 10-6 B. A solution with [H+] = 5.5 x 10-10 C. A solution with pH = 6.1 D. A solution with [OH-] = 6.4 x 10-7 E. A solution with [OH-] = 2.0 x 10-6
*October 8, 2010 by Ceci*

**Solving Rational Equations**

100mL of a solution contains 30 mL of acid; this is called a 30% acid solution because part 30 ---- = ---- = 0.30. whole 100 How many milliliters of acid x would need to be added to the solution to turn it into a 50% solution ? (HInt: Adding acid increases both the volume of ...
*October 23, 2013 by Stacey*

**Chemistry 12**

a) Use the standard reduction potentials table to balance the following redox equation: H2O2 + I + H = H2O + I2 b) Balance the following redox equation by the oxidation number method: Ag + HNO3 = AgNO3 + NO + H2O
*May 24, 2011 by Laura*

**ap chem**

an unknown gaseous hydrocarbon reacts with oxygen to form CO2 and H2O, DETERMINE HEAT OF FORMATION FOR THE HYDROCARBON. the density of the mixture of CO2 and H2O at 1 atm and 200 degree celsius is 0.751g /L and heat of reaction is equal to -2044.5 KJ /MOL hydrocarbon
*October 11, 2014 by Rita*

**college chemistry**

Use the thermochemical equations shown below to determine the enthalpy (kJ) for the reaction: H2SO3(l)=>H2S(g) + 3/2O2(g) H2SO3(l)=>H2O(l) +SO2(g) DH=62KJ SO2(g)=>S(s) + O2(g) DH=297KJ H2S(g) + 1/2O2(g)=>S(s) + H2O(l) DH=-155KJ
*October 24, 2010 by sara*

**chem**

balance the equation:(i can balance the equation but the problem i have is finding the formula for the last part HC2H3O2(aq) + Ca(OH)2(aq) -> H2O(l) + find the formula here the last part would be CaOC2H3O2? im a little confused. did the O fromt he H2O come from (OH)2?
*November 28, 2010 by hannah*

**math**

in the lab, tom has two solutions that contain alcohol and is mixing them with each other. he uses 300 millilters less of solution A than solution B. solution A is 10% alcohol and solution B is 13% alcohol. How many millilters of solution B does he use, if the resulting ...
*September 27, 2012 by Anonymous*

**chemistry**

1. a) 50ml of water at 46.9C were mixed with 50ml of water at 25.1C in a calorimeter also at 25.1C. The final temperature was 30.1C. Assuming that neither the density of water nor its specific heat capacity change with temperature, calculate the total heat capacity of the ...
*November 12, 2012 by Cicily*

**Chemistry**

Due to increased CO2 in the atmosphere, the pH of rainwater is more acidic than in the previous century. Use the following data to calculate the pH of unpolluted rainwater at 25C: vol% in air of CO2 = 0.033; solubility of CO2 in pure water at 25C and 1 atm = 88 mL CO2 per ...
*April 12, 2011 by Josh*

**chemistry **

Due to increased CO2 in the atmosphere, the pH of rainwater is more acidic than in the previous century. Use the following data to calculate the pH of unpolluted rainwater at 25C: vol% in air of CO2 = 0.033; solubility of CO2 in pure water at 25C and 1 atm = 88 mL CO2 per ...
*April 11, 2011 by jerry *

**chemistry**

a) Calculate the percent ionization of 0.125M lactic acid (Ka=1.4x10^-4) b) Calculate the percent ionization of 0.125M lactic acid in a solution containing 0.00075 M sodium lactate.
*July 31, 2014 by Nina*

**chemistry**

how in the world do you do this problem? Use the thermochemical equations shown below to determine the enthalpy (kJ) for the reaction: H2SO3(l)=>H2S(g) + 3/2O2(g) H2SO3(l)=>H2O(l) +SO2(g) DH=62KJ SO2(g)=>S(s) + O2(g) DH=297KJ H2S(g) +1/2O2(g)=>S(s) + H2O(l) DH=-...
*October 24, 2010 by anonymous*

**Chemistry**

Enough of a monoprotic acid is dissolved in water to produce a 0.0195 M solution. The pH of the resulting solution is 6.24. Calculate the Ka for the acid. Also, the answer is not 1.7 * 10 ^ -11 The response is: You treated the initial concentration as 0. In this case, the ...
*April 22, 2012 by chem1*

**physics**

For a damped harmonic oscillation, the equation of motion is 0, 2 2 + g + kx = dt dx dt d x m with m = 0.25 kg, g = 0.07 kgs−1 and k = 85 Nm−1. Calculate (i) the period of motion, (ii) number of oscillations in which its amplitude will become half of its initial ...
*March 9, 2012 by swapnali*

**Chemisty**

Calculate the % error of an experiement if a student obtained a destiny of 1.23g/ml(predicted) and the actual value was 1.30g/ml
*October 10, 2011 by Vic*

**math**

Calculate the future value of an annuity of $200 per month for 4 years at 12% interest compounded monthly
*April 1, 2012 by kurt*

**Math 11**

Calculate the final value after 10 years if you invest 5000.0 at 2.5% per annum compunded annually?
*April 9, 2012 by krystal*

**Grade 12 AP calculus**

You are using Newton's method to solve x3-5x-2=0. If your first guess is x1=2, what value will you calculate for the next approximation x2?
*December 2, 2012 by Alannah*

**physics **

Calculate the effective value of g, the acceleration of gravity (in meters/second^2), at 5100 km above the earth's surface.
*March 14, 2013 by Nicole *

**math**

Calculate the final value after 10 years if you invest $5000.00 at 2.5% per annum, compounded annually.
*April 16, 2014 by Eeyore*

**math**

Calculate the final value after 10 years if you invest $5000.00 at 2.5% per annum, compounded annually.
*May 8, 2014 by Rafiki*

**chemistry**

Calculation of )Hf0 for Mg2+(aq.) 1. Assume the heat capacity of the final solution is 3.92 J K-1 g-1. Using the mass of the HCl solution, calculate qcontents from equation (4.6). Calculate qsystem from equation (4.5). 2. Calculate the moles of Mg2+ produced, nrxn. Be sure to ...
*March 25, 2011 by Narash*

**Chemistry**

A compound of carbon, hydrogen, and oxygen was burned in oxygen, and 2.00g of the compound produced 2.868 g CO2 and 1.567 g H2O. In another experiment, 0.1107 g of the compound was dissolved in 25.0 g of water. This solution had a freezing point of -0.0894 degrees C. what is ...
*August 6, 2013 by Desz*

**Finance**

Benson Incorporated has bonds with the following features: Par value of 1,000, maturity of 12 years, and a coupon rate of 8%.The yield to maturity is 10%. Pleases determine if the bond sells for for a premium, par, or discount and explain your answer. Calculate the value of ...
*August 20, 2011 by Mybenz*

**Chemistry**

If a solution of sodium hydroxide is mixed from a 3M solution of sodium hydroxide, such that the volume of the original solution is 50ml and the volume of the final solution is 150ml, determine each of the following: a. The volume of water added to the solution b. The new ...
*December 28, 2012 by Ece*

**chem**

The mass of the CuSO4 x 5H2O sample is 1.664 g. The mass of the recovered copper is 1.198 g. 1. Compute the experimental percent by mass of copper in the sample: 1.1664/1.998x 100=71.81% 2. Calculate the percent copper in pure copper sulfate pentahydrate(this is the ...
*April 13, 2009 by Lou*

**Algebra II**

1) find n of the arithmetic sequence A1 = -5, An = 63, d = 2 2) Find the common ratio in the geometric sequence:7, -28, 112 ... 3) the vertex of the graph of y = -99(x-7)^2 - 2 is a minimum value ? a) True b) False 4) There is a solution to y = 7 and x^2 = -y^2 + 9. a) true b...
*May 1, 2011 by anonymous*

**Chemistry**

Calculate the initial molarity of KNH2 and the molarities of K+, NH3, OH-, and H3O+ in an aqueous solution that contains 0.75 g of KNH2 in 0.255 L of solution. You may ignore the reaction of NH3 with water. I already found the initial molarity, but I am not sure how to find ...
*February 22, 2010 by Trixie *

**Chemistry**

A calorimeter contains 22.0 mL of water at 14.0 C. When 2.50 g of X (a substance with a molar mass of 66.0 g/mol) is added, it dissolves via the reaction X(s)+H_2O(l)--------> X(aq) and the temperature of the solution increases to 25.5 C. Calculate the enthalpy change, ...
*April 2, 2012 by Amanda*

**Chemistry**

Predict the standard cell potential and calculate the standard reaction Gibbs free energy for galvanic cells having the following cell reactions: a.)3Zn + 2Bi3+ = 3Zn2+ + 2Bi b.)2H2 + O2 = 2H20 in acidic solution c.)2H2 + O2 = 2H20 in basic solution d.)3Au+ = 2Au + Au3+ I ...
*February 27, 2014 by Anonymous*

**CHM1045**

NH4NO3(s) right arrow NH4+(aq) + NO3−(aq) In order to measure the enthalpy change for this reaction, 1.21 g of NH4NO3 is dissolved in enough water to make 25.0 mL of solution. The initial temperature is 25.8C and the final temperature (after the solid dissolves) is 22....
*March 30, 2013 by Philip Golden*

**math Steve for your solution**

0.224g sample that contained only bacl2 and kbr required 19.7ml of 0.1M ango3 to reach the end point. Calculate the percentage of each compound present in the sample. The right answer bacl2 32.4% KBR 67.7% You need to use 3 solution of drug H containing respectively 50%, 20% ...
*December 28, 2013 by Fai*

**Chemistry**

When 1.5 grams of magnesium burns, how many grams of magnesium oxide will be formed? a) Write a balanced chemical equation for the above reaction. b) Show by unit conversion (show conversion factors, ie. 2 g H20 x 1 mole H2O/18 g H2O x ...... x ...... = answer
*June 15, 2012 by Ashley *

**Chemistry**

Magnesium sulfate is often used it first aid hot-packs giving off heat when dissolved in water. When 2.00 g of MgSO4 dissolves in 15.0 mL of water (d= 1.00g/mL) at 25.0C, 1.51 kJ of heat is evolved. A) Write the balanced equation for this reaction. I have: MgSO4 + H2O --> ...
*January 28, 2007 by Chris*

**Chemistry**

Mg + 2HCl -> MgCl2 +H2 delta H = ? MgO + 2HCl (aq) -> MgCl2+ H2O delta H = ? H2+ 1/2O2 -> H2O delta H = -285.8 kJ Using Hess' Law find both the missing delta H values.
*March 28, 2012 by Hunter*

**Chemistry**

Consider the reaction, CH4(g) + 2 O2(g) => CO2(g) + 2 H2O(g). How many grams of H2O(g) will be made by the reaction of 17 moles of CH4(g) with 7 moles of O2(g)?
*November 29, 2010 by Alle*

**visual basic**

Im trying to get this program to average three number having a problem the sample nmubers im using are 6 6 2 average supposed to be 4.6667 but im just geting .6667 I think it has something to do with my s=value(i) not sure what i need to do now can anybody help? Dim no As ...
*October 8, 2009 by vsu1*

**AP chem**

A 0.345g sample of anhydrous BeC2O4, which contains an inert impurity, was dissolved in a sufficient water to produce 100ml of solution. A 20.0ml portion of the solution was titrated w/ KMnO4(aq). The balanced equation for the reaction that occurred is as follows: 16H^+(aq) + ...
*January 4, 2007 by michelle*

**Algebra!**

Can someone help me with these problems so i can do the rest of my textbook work on my own plz? What is the value of n so that the expression x^2+11x+n is a perfect square trinomial? (1 point) What is a solution of x^2+6x=-5? (1 point) What is the solution of x^2+14x+112=0? If...
*March 24, 2014 by Gabby*

**chemistry**

What is the freezing point of each solution? a)1.40mol Na2SO4 in 1750 g H2O Are these the right steps? 1.40mol Na2SO4 / 1.75kg = .8m 3 * 1.86 degrees C * .8m = 4.46 degrees C 4.46 degrees C - 1.86 degrees C = 2.6 degrees C
*April 29, 2010 by Jack*

**Chemistry**

What is the molarity of a solution with 3.5mol of CaCl2 in 1.89L of solution What is the molarity of a solution with 16g of CH3OH in 487mL of solution
*March 4, 2009 by Ali*

**Chemistry**

A 2% solution of Hydrochloric acid is required for a procedure. A 5% solution is availabe. How much of the 5% solution will be required to make 1 L of solution?
*April 14, 2009 by Jessi*

**chemistry**

A solution contains 4.46 g KCl in 178 mL of solution. The density of the KCl solution is 1.11 g/ml. What is the percent (m/m) for the potassium chloride solution?
*October 9, 2010 by Samantha*

**Math**

If a mixture of a 6% acid solution with an 11% solution is to be made, how much of each solution is needed to make 10 liters of an 8% acid solution?
*September 2, 2012 by DAD*

**College Chemistry II**

What is the solubility of ZnCO3 at 25C in a buffer solution with a pH of 10.21? ZnCO3 <----> Zn++ + CO3 - CO3-- + H2O ----> HCO3- + OH- pOH = 14 10.21 = 3.79 [OH-] = 1.62x10^-4 M = [CO3--] = [Zn++] Ksp = [Zn++][CO3-] = (1.62x10^-4)( 1.62x10^-4) = 2.63x10^-8 when i...
*August 10, 2014 by Monica *

**Chemistry**

The following three step mechanism has been proposed for the oxidation of iodide ion by peroxide: H2o2 + I^- ----> HOI + OH^- Slow OH^- + H^+ ----> H2O Fast HOI + H^+ + I^+ ---> I2 + H2O Fast A. What is the overall reaction described by this mechanism? B. What is the ...
*November 20, 2012 by Krissy *

**math**

50gm of a sample of ca(oh)s is dissolved in 50ml of 0.5N hcl solution. The excess of hcl was titrated with 0.3N -naoh. The volume of naoh used was 20cc. Calculate of naoh used was 20cc. Calculate % purity ca(oh)2 Who help me step by step
*December 22, 2013 by Fai*

**Chemistry(Please check answers)**

1) The standard molar entropy value of N2 (g) is 191.5 J/K-mol, of O2 (g) is 205.0 J/K-mol and of NO2 (g) is 240.0 J/K-mol. From these values we can calculate the Delta So for the reaction N2 (g) + 2 O2 (g)-> 2 NO2 (g) to be? I did products - reactants (240 X 2) - [191.5...
*April 23, 2012 by Hannah*

**math**

The table shows the closing value of a stock index for one week in March, 2004. a. Using the day as the x-value and the closing value as the y-value, write equations in slope-intercept form for the lines that represent each value change. b. What would indicate that the rate of...
*July 23, 2009 by ashlin*

**AP Chem - to Dr. Bob**

I don't understand how to even start this problem: A mixture of H2(g), O2(g), and 2 mL of H2O is present in a 0.5 L rigid container at 25 degrees Celsius. The number of moles of H2 and the number of moles of O2 are equal. The total pressure is 1146 mmHg. Vapor pressure of ...
*January 23, 2007 by Belinda*

**chem**

A solution contains 4.60 g KCl in 179 mL of solution. The density of the KCl solution is 1.11 g/mL What is the percent (m/m) for the potassium chloride solution? What is the molarity, M, for the potassium chloride solution? need help pls
*November 8, 2012 by byke*

**Linear Algebra**

I previously posted this question under the wrong topic. Which of the following choices is a solution for: (-3-i)x1 + (1-2i)x2 = 0 (-7-9i)x1 + (7-4i)x2 = 0 for any value of the variable t [x1] = ? [x2] A: [5] [1+7i] * t B: [5] [1-7i] * t C: [5] [-1-7i] * t D: [5] [-1+7i] * t
*December 4, 2009 by Michael*

**calculus**

solve the logarithmic equation. Be sure to reject any value of x that is not in the domain. In square root x+7=1 x= ? What is the decimal approximation to the solution? x= ?
*January 1, 2013 by NayNay*

**Math**

Let p and q be the roots of the polynomial mx^2 + x(2 - m) + 3. Let m1 and m2 be two values of m satisfying p/q + q/p = 2/3. Determine numerical value of m1/(m2)^2 + m2/(m1)^2. Please work the complete solution.
*April 23, 2013 by Watson*

**Math**

Let p and q be the roots of the polynomial mx^2 + x(2 - m) + 3. Let m1 and m2 be two values of m satisfying p/q + q/p = 2/3. Determine numerical value of m1/ (m2)^2 + m2/(m1)^2. Please work the complete solution.
*April 23, 2013 by Watson*

**Algebra 1**

23.what is the slope of a line parallel to a line represented by the equation x=2y-3? 19.what is the solution to the following system of equation? Y=4x-8 Y=2x 16.which graph below shows the function f(x)=-3x-1? 12.what is the solution to the following system of equations? Y=2x...
*January 21, 2012 by Elyon*

**chemistry**

1. calculate the volume of concentrated HNO_3 (68%)that is needed to prepare stock solution 0.25M in 1000mL volumetric flask. (density HNO_3 = 1.513 g/cm^3) 2. from above stock solution, determine volume needed to dilute to 500mL volumetric flask that contained 10 times dilution.
*July 10, 2013 by khadijah*

**Chemistry**

1. calculate the volume of concentrated HNO3 (68%)that is needed to prepare stock solution 0.25M in 1000mL volumetric flask. (density HNO3 = 1.513 g/cm^3) 2. from above stock solution, determine volume needed to dilute to 500mL volumetric flask that contained 10 times dilution.
*July 10, 2013 by Susan*

**Chemistry**

In a silphuric acid (H2SO4)-Sodium Hydroxide (NaOH) acid-base titration, 17.3mL of 0.126M NaOH is needed to neutralize 25mL of H2SO4 of unknown concentration. What is the morality of the H2SO4 solution? H2SO4 (aq)+ NaOH (aq) = Na2SO4 (aq) + H2O (l)
*July 1, 2014 by Dawn*

**General Chemestry**

A galvanic (voltaic) cell consists of an electrode composed of chromium in a 1.0 M chromium(II) ion solution and another electrode composed of gold in a 1.0 M gold(III) ion solution, connected by a salt bridge. Calculate the standard potential for this cell at 25 C.
*January 26, 2013 by Anonymous*

**chemistry**

A is a solution of HCL containing 7.30g/dm3.B is a solution ofX2CO3 containing 10.6g/dm3.assume that average volume of acid is 2.81cm3 and the volume of base is 25.00cm3.from your result and information .calculate (I)concentration of A in mol/dm3(ii)concentration of B in mol/...
*May 26, 2014 by john kelechi*

**Chemistry**

Prepare a theoretical titration curve for titration of 25.0 mL of 0.1037 formic acid (HCOOH; pKa = 3.75) solution (diluted to 100 mL volume with deionized water) by 0.0964 M solution of KOH. I have to determine volume of KOH needed to reach equivalence point, the pH of ...
*March 5, 2012 by Clint*

**Chemistry**

I posted this question on Thursday April 12 and received some help..but need more.. thanks Use the following information to identify element A and come pound B, then answer questions a and b. An empty glass container has a mass of 658.572 g. It has a mass of 659.452 g after it...
*April 16, 2007 by Julia*

**Chemistry**

In an experiment liquid hexane, C6H14 (l) is combusted completely to produce CO2(g) and H2O (l) according to the equation: 2 C6H14 (l) + 19 O2(g) -> 12 CO2(g) + 14H2O (l) The change in H degrees for the reaction is -8.39 x 10^3 KJ. Calculate change in H degrees for C6H14 (l).
*November 29, 2010 by vvvvvv*

**Chemistry**

1.9 mol HCl and 3.8 mol NaOH react according to the equation HCl + NaOH −→ NaCl + H2O . Calculate the amount in moles of NaCl formed. Answer in units of mol
*February 9, 2012 by Mary*

**Calculating DHrxn?**

What is DHrxn for the following reaction, CH4(g) + 2 O2(g) ---> CO2(g) + 2 H2O(l), given DHf[CH4(g)] = -74.8 kJ; ...DHf[CO2(g)] = -393.5 kJ; ...DHf[H2O(l)] = -285.5 kJ. a. ) -604.2 kJ b. ) 869.7 kJ c. ) -997.7 kJ d. ) -889.7 kJ e. ) 997.7
*June 12, 2009 by AnthoniiEllis*

**math**

A lab needs a 20 liters of a 15% acid solution. The lab only has a 10% acid solution and a 30% acid solution. How much of the 10% acid solution will they need to mix with the 30% solution to obtain 20 liters of a 15% solution?
*April 2, 2013 by Anonymous*

**chemistry**

1. the solubility of AgCl in water is 3.97x10^-6 at 0*C and 1.91X10^-4 at 100*C. calculate Ksp for AgCl at each temp. 2. using the data from #1 and the clausius- Clapeyron equation, calculate deltaH* and deltaS* for the formation of a saturated solution of AgCl. I just need ...
*March 28, 2011 by anonymous*

**Chemistry**

Ethanol, C2H5OH or C2H6O, is mixed with gasoline and sold as gasohol. Given the following thermo-chemical reaction, calculate the kilograms (kg) of CO2 produced when enough ethanol is combusted to provide (or give off) 369 kJ of heat: C2H5OH (l) + 3 O2 (g) --> 2 CO2 (g) +3 ...
*July 12, 2011 by Robert*

**chemistry**

Given the thermochemical equation below, calculate the amount of energy released when 250. g of NaOH (molar mass = 40.0 g/mol) reacts with an excess of HCl. Report answer to the correct number of significant figures in units of kilojoules, kJ. NaOH + HCl --> NaCl + H2O ...
*April 25, 2013 by sarah*

**Chemistry**

The empirical formula for Brilliant Blie dye is C37 H34 N2 O9 S3 Na2, and the formula weight is 792.86 g/mol. How would you prepare a 4.73 X 10^-6 M solution of Brilliant Blue dye? How many grams of the dye do you need to add to a 1.00 L of water to make this solution? I have ...
*October 12, 2011 by Hannah*

**CHEMISTRY**

Calculate the H rxn for the following reaction. H f [H2S(g)] = -21 kJ/mol; H f [SO2(g)] = -297 kJ/mol; H f [H2O(l)] = -285.8 kJ/mol; 2H2S(g) + SO2(g) 3S(s) + 2H2O(l) a. 232.6 kJ b. 910 kJ c. -232.6 kJ d. -910 kJ
*August 22, 2010 by Lucinda*

**Chemistry**

write a balanced equation for the combustion of benzene. All hydrocarbons, like benzene are, are the same. Add O2. C goes to CO2 and H goes to H2O. C6H6 + O2 ==> CO2 + H2O I will let you balance it. Let me know if you have a problem with it. would it be... C6H6 + 14O2 -->...
*August 6, 2007 by Anonymous*

**Math**

Alyssa is a chemist with Gemco Pharmaceutical Company. She needs to prepare 12 ounces of 9% hydrochloric acid solution. The only solution she currently has available are 4% and 12% hydrocholoric acid. How much should she use of each solution to obtain the needed solution.
*March 9, 2011 by John*

**math who me step by step**

25g of a sample of ferrous sulphate was dissolved in water containing dilute h2s04 and the volume made up to one litre. 25ml of this solution required 20ml of N/10 kmn04 solution for complete oxidation. Calculate the percentage of fes047h20 in the sample the right answer 88.96...
*January 1, 2014 by Fai*

**College-Chemistry**

NaOH(s)+ H2SO4(aq)=Na2SO4(aq) + H2O(l) Consider the unbalanced equation above.A 0.900 g sample of impure NaOH was dissolved in water and required 37.0 mL of 0.145 M H2SO4 solution to react with the NaOH in the sample. What was the mass percent of NaOH in the sample?
*February 26, 2010 by Tiffany*

**Chenistry**

A 0.8870g sample of a mixture of nacl and kcl is dissolved in water and the solution is then treated with an excess of agn03 to yield 1.913g of agcl. Calculate the percentage by mass of nacl in the mixture 1.913g/ 143 = 0.0133 M agcl x/58 + Y/74 (0.887g-x) = 0.0133 Who helps ...
*January 19, 2014 by Carlos*

**Mass Transfer**

Solution of methanol and ethanol are substantially ideal. (a) Compute the vapour-liquid equilibria for this system at 1 and at 5 atm abs pressure, and plot xy and txy diagrams at each pressure (b) For each pressure compute relative volatilities , and determine an average value...
*April 8, 2014 by RHS*

**chemistry**

When 0.949 g of CaO is added to 200.0 mL of 0.500 M HCl(aq), a temperature increase of 389C is observed. Assume the solution's final volume is 200.0 mL, the density is 1.00 g/mL, and the heat capacity is 4.184 J/gC. what is molar heat of reaction, Hrxn, for the reaction of CaO...
*February 15, 2010 by blasting*

**Chemistry**

For each of the following unbalanced equations, suppose that exactly 15.0g of each reactant is taken. Determine which reactant is limiting, and calculate what mass of each product is expected. assume the limiting reactant is completely consumed. a)Al+HCL->AlCl3+H2 b)NaOH+...
*February 16, 2009 by Megan*

**PhysicsPLEASE HELP**

i have a lab where we used VI method to calculate resistance of a LARGE resistor... circuit is as follows..(--- indicates wire) source---ammeter---resistor(voltmeter connected in parralel to resistor)---(connected back to source) the R value calculated was wrong. i need to ...
*February 9, 2010 by SAM*

**Chemistry**

A mixture of CuSO4 and CuSO45 H2O has a mass of 1.235 g. After heating to drive off all the water, the mass is only 0.830 g. What is the mass percent of CuSO45 H2O in the mixture?
*September 22, 2010 by Noelle*

**Chemistry**

How do I find the molarity of NaCl for different dilutions? You calculate the number of moles per liter of solution.
*April 8, 2007 by Colleen*

**Chemistry**

Hydrogen cyanide is a weak acid with Ka = 4.9 x 10-10. Calculate the pH of a solution (to 2 decimal places) containing 2.28 g of Sr(CN)2 per 158 mL.
*January 7, 2008 by Andrew*

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