Wednesday

February 22, 2017
Number of results: 31,880

**Chemistry**

You need to prepare 100.0 mL of a pH=4.00 buffer solution using 0.100 M benzoic acid (pKa = 4.20) and 0.180 M sodium benzoate How much of each solution should be mixed to prepare this buffer?

*August 13, 2013 by Adam*

**cheMYSTERY**

A 20.00 mL of 0.200mol/L magnesium chloride solution is added to a 95.00 mL of 0.800 silver (I) nitrate solution,Determine the concetration of the silver ions at the end of the reaction and the magnesium ions. and a precipitate is formed.

*April 22, 2014 by sandeep singh*

**Chemistry**

A 1N solution of NaOH is diluted 4/20 then rediluted 1:50. What is the final normality? How many grams of NaOH are present in 100ml of the final solution? I sort of understand the basic concept, but I don't really know how to do normality problems.

*May 20, 2014 by Jennie*

**chemistry**

A solution was prepared using 1,00 liter of water, 59 g glucose, and 2,3 g NaCl. One liter of water weighs 1000 grams. The solution needs to be labeled in terms of % glucose and % sucrose.

*September 19, 2014 by Sergejs*

**chemistry**

What would be the molarity of solution obtained by mixing equal volumes of 30% by mass H2SO4 (d=1.218 g/mL) and 70% by mass H2SO4 (d=1.610 g/mL). If the resulting solution has density 1.425 g/mL, calculate its molarity

*April 17, 2015 by jaimi*

**Chemistry**

you have 5% formic acid solution and a 5% acetic acid solution. You titrate 5mL each with .1868M NaOH. A. Which will need more NaOH to reach the end point? B. How much more?

*November 24, 2015 by jack*

**Algebra**

Meryl needs to add enough water to 11 gallons of an 18% detergent solution to make a 12% detergent solution. Which equation can she use to find g, the number of gallons of water she should be added

*December 14, 2015 by Que*

**Chemistry**

100g of water is added into 10.6M NaOH solution. The diluted NaOH then neutralized completely with H2SO4 . density of NaOH is 1.08g/ml . calculate the mole fraction of NaOH in diluted solution .

*June 28, 2016 by Amy*

**Chemistry**

100g of water is added into 10.6M NaOH solution. The diluted NaOH then neutralized completely with H2SO4 . density of NaOH is 1.08g/ml . calculate the mole fraction of NaOH in diluted solution .

*June 28, 2016 by Amy*

**Chemistry**

A is a solution of tetraoxosulphate(iv)acid.B contains 3.95g of sodium trioxocarbonate(iv) in 750cm3 of solution.if 22.70cm3 of the tetraoxosulphate(iv)acid neutralized 25.0cm3 of sodiumtrioxocarbonate(iv).calculate the concentration of i) B in moldm-3 ii) A in moldm-3

*December 8, 2016 by Yvonne*

**Math**

The smallest real number in the solution set of 2x > 6 is 4. A) True B) False - The smallest real number in the solution set of 2x > 6 is 3. C) False - The smallest real number in the solution set of 2x > 6 is a number greater than 3. For example, 3.01 is a real ...

*October 4, 2011 by Michelle*

**Math**

The smallest real number in the solution set of 2x > 6 is 4. A) True B) False - The smallest real number in the solution set of 2x > 6 is 3. C) False - The smallest real number in the solution set of 2x > 6 is a number greater than 3. For example, 3.01 is a real ...

*October 4, 2011 by Mary*

**chemistry please**

molarity of a solution containing 5mL of a 3.512 x 10^-5M solution (made from .128g of benzophenone and 50mL of ethanol) and then filled to the 50mL line of ethanol would this be (3.512 x 10^-5)(-.04) ?

*February 1, 2009 by john*

**Science**

I need to find out if sucrose, sucrose solution, sodium chloride, sodium chloride solution, water, vinegar, and aluminum are electrolytes and what type of bond they are but I don't know where to look.

*December 20, 2009 by Anonymous*

**Chemistry**

4.00 grams of NaOH have been added to 2.0 liters of water. The molarity of this solution is ____M. the concentration of this solution is ______ grams of NaOH per liter of water

*August 6, 2010 by Maria*

**Chemistry**

Calculate the amount of water (in grams) that must be added to (a)5.00 g of urea (NH2)2CO in the preparation of a 16.2 percent by mass solution, and (b)26.2g of MgCl2 in the preparation of a 1.5 percent by mass solution.

*September 19, 2010 by Diana*

**APC Chemistry**

Suppose you have a solution containing both an iron (II) salt and an iron (III) salt. How would you proceed to identify both Fe2+ and Fe3+ in this solution?

*September 29, 2010 by Anonymous*

**chem**

a solution of A (molar mass 100g/mol) and B (molar mass 1.10 x 10^2 g/mol) is prepared by mixing equal masses of the two. Find the mole fractions of each component in solution

*January 27, 2011 by Angela*

**Chemistry**

A quantity of 100 mL of .5M of HCl (aq) is mixed with 100 mL of .5M of NaOH (aq) in a constant pressure calorimeter. The initial temperature of the solutions is 22.30 C and the final temperature of the mixed solution is 25.00 C. What is "q" for solution and "q" for reaction?

*April 8, 2012 by Dante*

**chemistry**

A chemist want to make a 10% Chlorine solution from 30% Chlorine solution and pure water. How much of the two should the chemist mix together to make 20mL. Please help with calculations. Thank you

*August 31, 2012 by kate*

**Chemistry**

Assuming that the [Potato extract] is .001 M and I am going to make a 10 ml solution and each drop is 1/20th of a mL, how do I calculate the [Potato extract] in each reaction solution, using 20 drops, 15, 10, and 5 drops for each one?

*February 6, 2013 by Patricia*

**Chemistry**

A solution is made by mixing 37.0 mL of ethanol, C2H6O, and 63.0 mL of water.? Assuming ideal behavior, what is the vapor pressure of the solution at 20 °C? ethanol: 0.789 g/mL 43.9 torr water : 0.998 g/mL 17.5 torr

*March 2, 2013 by Dee*

**chemistry**

for an aqueous solution having Calcl2 (2molar) and Mgcl2 (5molal) and specified gravity of solution is 1.145 calculate molality of chloride ion and molality if chloride ion.

*May 10, 2013 by riya*

**Quatitative Analysis**

What is the correct charge balance equation for an aqueous solution of MnCl2 that ionizes to Mn2 , Cl–, MnCl , and MnOH ? What is the correct mass balance equation for the same solution?

*September 17, 2013 by Whitney*

**chemistry**

Knowing the concentration of a solution allows us to find all of the following except A. the mass of a solute. B. the mass of the solvent. C. the volume of the solvent. D. the concentration of a solution when conditions change.

*March 19, 2014 by Natalie*

**math**

A hallway measuring 90 feet x 7 feet requires 1/2 a fluid ounce of cleaning solution per square foot. How much cleaning solution is required to clean the hallway

*June 11, 2014 by Anonymous*

**Math**

Use the quadratic formula to solve the equation for x in terms of y and y in terms of x. (Enter your answers as a comma-separated list. If there is no solution, enter NO SOLUTION.) 2x^2 + 7xy + 1 − y^2 = 0 (a) x in terms of y x = (b) y in terms of x y =

*September 14, 2014 by Liam*

**chemistry**

A buffer solution is made by dissolving 0.45 moles of a weak acid (HA) and 0.23 moles of KOH into 720 mL of solution. What is the pH of this buffer? Ka = 6.2 × 10−6 for HA. Answer in units of pH. i need the answer

*January 31, 2015 by Anonymous*

**Chemistry**

20.00mL of 0.55M CH3COOH solution is mixed with 9.95mL of 1.0M NaHCO3 solution. The reaction occurring is CH3COOH + NaHCO3 --> CH3CHOO + Na + H2O +CO2. Which is the limiting reagent in this reaction?

*April 30, 2015 by Kate*

**Algebra 2**

Is the solution to this rational expression extraneous? The problem: (2x-3)/7 -(7x)/14 My answer: x = -9/4 My teacher wants to know if the solution is extraneous and I know I have to plug my answer back into the expression to check but I still don't understand.

*October 7, 2015 by Wade*

**Chemistry**

determine the vapor pressure lowering at 27 C of a solution of 750g of sucrose, dissolved in 180g of water. The vapor pressure of pure water at 27 C is 26.7 torr. Assume the solution is ideal

*October 11, 2015 by Anonymous*

**Chemistry**

you need to prepare 100 ml of ph=3.50 buffer solution using 0.100 M formic acid and 0.200 M sodium formate. how much of each solution shoudl be mixed to prepare this buffer?

*December 14, 2015 by Navi*

**math**

The equation for the pH of a substance is pH = –log[H+], where H+ is the concentration of hydrogen ions. A basic solution has a pH of 11.2. An acidic solution has a pH of 2.4. What is the approximate difference in the concentration of hydrogen ions between the two solutions?

*March 9, 2016 by Anonymous*

**Chemistry - Answer Check**

Find the molarity given 1.5 Liters of solution containing 62.5 g MgO. - 1.03 M Mgo There are 0.32 Liters of a 2.5 M HF solution. How many moles and grams of hydrofluoric acid are there? - 0.8 mol and 16 grams

*April 21, 2016 by Anonymous*

**chemistry**

I need a formula for: 0.5 grams of sodium chloride is dissolved to make 0.05 liters of solution. next 0.5 grams of sodium chloride is dissolved to make 0.05 ml of solution. next 670 grams of Pb (C2H3O2)4 are dissolved to make 3.5 ml of solution.

*May 19, 2011 by venita*

**statistics**

Terms and Definitions matching ___ Statistics ___ Discrete variable ___ Statistics ___ Continuous variable ___ Population ___ Qualitative data ___ Population parameters ___ Quantitative data ___ Sample ___ Mean ___ Bias ___ Mode ___ Representative sample ___ Median ___ ...

*December 14, 2010 by Anonymous*

**science**

i need help with a packet that im struggling with my questions are write the total number of atoms present for the following questions: a. 4SO2 now i tried and got 8O'S and 1S b. 8O2 i tried and got 16 all together c. 3Al2(SO4)3 i tried and got 6Al, 3S, and 12O my next ...

*January 12, 2015 by maddy*

**Statistics**

Suppose the U.S. president wants an estimate of the proportion of the population who support his current policy toward revisions in the Social Security system. The president wants the estimate to be within 0.028 of the true proportion. Assume a 99 percent level of confidence. ...

*March 31, 2013 by Adam Dane*

**NEED HELP!**

A mixture contained CaCO3 and MgCo3. A sample of this mixture weighing 7.85g was reacted with excess HCl. The reactions are-- CaCO3 + 2HCl --> CaCl2 + H2O + CO2 MgCO3 + 2HCl --> MgCl2 + H2O + CO2 Is the sample reacted completely and produced 1.94L of CO2, at 25 degrees C...

*November 5, 2009 by Mary*

**chemistry help!**

A mixture contained CaCO3 and MgCo3. A sample of this mixture weighing 7.85g was reacted with excess HCl. The reactions are-- CaCO3 + 2HCl --> CaCl2 + H2O + CO2 MgCO3 + 2HCl --> MgCl2 + H2O + CO2 Is the sample reacted completely and produced 1.94L of CO2, at 25 degrees C...

*November 6, 2009 by Mary*

**Science- Chemistry**

A test tube containing a mixture of compounds X, Y, and a small amount of Z weighs 25.4886 g. The tube is emptied into a beaker and the empty tube is reweighed, giving a value of 10.2586 g. The mixture is separated into two components by dissolving in water, filtering off the ...

*October 13, 2012 by Sonia*

**CHEMISTRY PLEASE HELP**

Using the data collected for part c on your data sheet and assuming the density of the vinegar is 1.00g/mL, 1) calculate the molar concentration of acetic acid (CH3COOH) in the vinegar sample using the average volume of NaOH. 2) calculate the mass percent of acetic acid in the...

*October 24, 2011 by Josh*

**Chemistry**

How do you calculate alkalinity in chemistry? Ex: List the values for total alkalinity for Sample A and Sample B A 104 drops of titrant (5.25mL) 3 drops of C20 H14 O4 B 81 drops of titrant (4.25mL) 3 drops od C20 H14 O4

*August 15, 2016 by anon*

**science**

which is the correct balanced equation for a given titration process, (a) or (b)? a) 6H+ + 2MnO4- + 3H2O2 -> 4O2 + 2Mn2+ + 6H2O b) 6H+ + 2MnO4- + 5H2O2 -> 5O2 + 2Mn2+ + 8H2O Process: Make a solution in a 100mL volumetric flask using 1g of NaBO3*4H2O, 20mL of 1M H2SO4, ...

*March 30, 2011 by sarah*

**science**

you need to make a 3.5 Molar solution of Ca(OH)2, however, you only want to make 50ml of this Ca(OH)2 solution. How many grams of Ca(OH)2 will you need to weigh out and add to 50ml of water? Mass=VolumeinLiters*Molarity*Molmass

*December 12, 2006 by brittany*

**algebra**

Is (5,2) a solution of 4x-2y=-6 I said no, am I right? I am working on another problem where they want to know if this system of equations is perpendicular or parallel or neither, I said neither. Is this right? I am to solve by using elimination: 2x+3y=1, 4x+6y=2 I keep ...

*January 8, 2010 by Lara*

**math**

Is (5,2) a solution of 4x-2y=-6 I said no, am I right? I am working on another problem where they want to know if this system of equations is perpendicular or parallel or neither,5x+4y=2, 4x-5y=4 I said neither. Is this right? I am to solve by using elimination: 2x+3y=1, 4x+6y...

*January 8, 2010 by Lara*

**Word Problem**

It is necessary to have a 40% antifreeze solution in the radiator of a certain car. The radiator now has 60 liters of 20% solution. How many liters of this should be drained and replaced with 100% antifreeze to get the desired strength?

*October 20, 2010 by Ford*

**Chemistry**

40.0 ml of an acetic acid of unknown concentration is titrated with 0.100 M NaOH. After 20.0 mL of the base solution has been added, the pH in the titration flask is 5.10. What was the concentration of the original acetic acid solution? [Ka(CH3COOH) = 1.8 ´ 10–5]

*November 9, 2010 by Kelly*

**Physical Science**

Suppose you dissolve 40g of potassium nitrate in 100 cm3 of water at 100 C. If half the solution os poured out, how many grams of potassium nitrate will the remaining solution contain?

*February 7, 2011 by Matthew*

**maths**

Hi Please can you help Find the particular solution of the differential equation from f(x)=(x^2-6x+23)^(3/2)for which y=2 when x = 1, and then give this particular solution in explicit form? Am I correct that the following is the explicit form (not confident). 2^2=(4/81)(1^2-6...

*March 30, 2011 by Claire*

**calculus**

Please help. I have an implicit answer to a differential equation of 18y*sqrt(y)=(2(x^2-6x+23)^3/2)/3 plus arbitrary constant. What is the particular solution to this for which y=2 when x=1. And then express this particular solution answer in an explicit form. Please help and ...

*May 20, 2011 by paul*

**ap chemistry**

When 50.0 mL of a 0.010 M CuNO3 solution is mixed with 150.0 mL of a 0.010 M NaCl solution, a precipitate forms (Ksp = 1.9 x 10^-7). a) Determine all final ion concentrations b) Determine the mass of the precipitate formed. How do i do this?

*March 28, 2012 by alex*

**algebra**

A chemistry laboratory has supplies of two sulfuric acid solutions only. One is 10% concentrated and the other is 50% concentrated. How much of each solution should be mixed to make a 40 mL 25% sulfuric acid solution?

*September 14, 2015 by Nica*

**Algebra**

Find the discriminant and solutions for the following equations. #1) 9x^2+6x+1=0 #2) -2x^2+3x-2+0 I will be happy to critique your work. what is b^2-4ac? #1) 9^2-4(6)(1)= 81-4(6)= 81-24=57 so then 57 is the solution but what is the discriminant or is 57 the discriminant? #2) -...

*May 15, 2007 by Algebra Student*

**chemistry**

Assuming that sea water is a 3.5 wt% solution of NaCl in water, calculate its osmotic pressure at 20 deg C. The density of a 3.5% naCl solution at 20 deg C is 1.023 g/mL. How do I go about solving this?

*February 28, 2008 by Sarah*

**Algebra**

How many milimiters of pure acid must be added to 150 milimiters of a 30% solution of acid to obtain a 40% solution? I know that the answer is 25 milileters. Could someone show me with steps how to get the answer.

*September 19, 2010 by Mark*

**Intermediate Algebra**

If a system has an infinite number of solutions, use set−builder notation to write the solution set. If a system has no solution, state this. y = x + 2, 3y − 2x = 4

*November 11, 2010 by Donna*

**Chemistry**

A 21.18 mL of 0.250 M NaOH is titrated with a H2SO4 solution. The initial volume of H2SO4 was 13.28 and the final volume of H2SO4 was 28.29 mL when the solution turned very slightly pink. What is the concentration of H2SO4?

*December 7, 2010 by Ivy*

**algebra**

eq1 y = 2x + 3 eq2 y = 1x + 2 What is the solution for eq1 and eq 2? Remember we are looking for the "common" x and y pairs that solve BOTH equations. Are any of the following (x,y) pairs a solution to the above systems of equations? (2, 4) ? (-1, 1) ? Why?

*March 16, 2011 by bianca, pleeease help i'm lost*

**Chemistry**

How much 12 M HCl do you add to 1 L of water to obtain 0.2 HCl? Use this same approach to do the math for the dilution of 5.5 M of barium hydroxide solution to 0.5 M barium hydroxide solution.

*February 19, 2012 by Amanda*

**Chemistry**

How much 12 M HCl do you add to 1 L of water to obtain 0.2 HCl? Use this same approach to do the math for the dilution of 5.5 M of barium hydroxide solution to 0.5 M barium hydroxide solution.

*February 19, 2012 by Amanda*

**chemistry(Please Check)**

You dissolve 6.55 g of potassium nitrate in enough water to make a 250. mL solution. What is the molarity of this solution ?Answer: 0.0262 Please Check my answer

*April 23, 2012 by Wurola*

**Chemistry**

A glucose solution contains 55.0g of glucose C6H12O6 in 475g of water. Compute the freezing point and boiling point of the solution. Assume a density of 1.00g/mL for water.

*September 18, 2012 by Monica*

**Chem**

In the lab a 3.3mol per liter solution was prepared by adding H2O to 140mL of a 4.3mol Per Liter solution of HCL. How much water was added?

*March 19, 2014 by BILL*

**Science**

80ml of methyl alcohol water are mixed to give a solution that has a final volume of 154ml. What is the concentration of the solution expressed as percent by volume methyl alcohol?

*July 7, 2014 by Araceli*

**Algebra**

Find the values of a in the domain of f for which f(a)equals the given number. (If there is no solution, enter NO SOLUTION.) f(x) = x2 − 4x − 19; f(a) = 13 a = ____ (smaller value) a = ____ (larger value)

*October 13, 2014 by Kim*

**Chemistry**

Make 50.0 mL of a 0.500 M solution of acetic acid (CH3COOH) from the 1.00 M CH3COOH using a 50.0 mL graduated cylinder. 1. Show your calculations and explain how you made the acetic acid solution.

*February 25, 2015 by Kate*

**SCIENCE**

Indicate how to mix two of the first concentration 3.2 M hydrochloric acid solution and the second to 15% by weight and density 1.30Kg / L to obtain 2.5 L of hydrochloric acid solution in 4.2M concentration

*February 17, 2016 by ATTILIA*

**Chem 205**

A solution of ammonia and water contains 3.50×1025 water molecules and 9.00×1024 ammonia molecules. How many total hydrogen atoms are in this solution? Any help would be appreciated, thank you!

*September 11, 2016 by Melissa*

**Chemistry**

The concentration of ammonium ion in the solution of the salt called ferrous ammonium sulfate, formula [Fe(NH4)]2(SO4)3, is 0.360 M. The concentration of sulfate ions in this solution is?

*September 27, 2016 by Colby*

**chemistry**

Assume that it is necessary to determine the [FE^3+ in a solution that may be 0.0001 to 0.0005 M range . Outline the spectrophotometric method that would accurately give the required data. Be spectific about the solutions that you would use. I know I have to work up a ...

*November 13, 2016 by jxv*

**Statistics**

The number of books sold over the course of the three-day book fair were: 365, 303, 401. Assume that samples of size 2 are randomly selected with replacement from this population of three values. a. List the different possible samples, and find the mean of each of them. b. ...

*July 20, 2015 by Elizabeth*

**chemistry**

how would i calculate; a 50g sample of water at 100 degrees is poured into a 50g sample of water at 25 degrees. with a specific heat of water (l) being 4.184 j/g degrees C.what will be the final temperature of the water? heat gained + heat lost = 0 [massH2O*specificheat*(Tf-Ti...

*January 14, 2007 by Noreen*

**Statistics**

The president of a bank selected a sample of 1500 applications to check if the approval or rejection of an application depends on which one of the two loan officers handles the application. The information obtained from the sample is summarized in the following 2 way table. ...

*April 16, 2013 by Bettie*

**Chemistry**

Using the data collected for part c on your data sheet and assuming the density of the vinegar is 1.00g/mL, 1) calculate the molar concentration of acetic acid (CH3COOH) in the vinegar sample using the average volume of NaOH. 2) calculate the mass percent of acetic acid in the...

*October 24, 2011 by Josh*

**Math**

Suppose that you have a supply of a 25% solution of alcohol and a 75% solution of alcohol. How many quarts of each should be mixed to produce 90 quarts that is 60% alcohol?

*January 29, 2013 by Chanelle*

**chemistry**

A nitric acid solution containing 71.0% by mass of the acid has a density of 1.42g/ml how many grams of nitric acid are present in 1.0L of this solution

*May 3, 2013 by cheryl*

**sails math**

A chemist has a solution that is 70% acid and another that is 45% acid. How many liters of each should he mix to obtain 300 liters of a solution that is 65% acid?

*April 29, 2016 by Brooke*

**Biology**

In class, I did an experiment with water and iodine solution in a beaker and also starch in a dialysis tube tied and placed in the beaker. There were discussion questions I couldn't answer surely... please check my answers. 1. a)Use your results to determine the direction of ...

*April 3, 2012 by CrissyXD*

**chem**

Liquids A and B form an ideal solution. A certain solution contains 25 mole % of A, whereas the vapor in equilibrium with the solution at 25 degrees C contains 50. mole % of A. The heat of vaporization of A is 5 kcal/mol; that of B is 7 kcal/mol. a) Calculate the ratio of the ...

*March 28, 2007 by Chris*

**Chemistry**

Concentrated sulfuric acid is 18.4 molar and has a density of 1.84 grams per milliliter. After dilution with water to 5.20 molar the solution has a density of 1.38 grams per milliliter. This concentration of H2SO4 is often used in lead storage batteries(like a car battery). 1....

*January 13, 2011 by K*

**Statistics**

part 2 - An entertainment company owns and operates movie theaters in Wyoming. The president of the company is concerned that film rentals are hurting the business. They directed a staff member to estimate the total number of films rented by households in wyoming in a ...

*March 2, 2007 by Jason L*

**Stats**

Childhood participation in sports, cultural groups, and youth groups appears to be related to improved self-esteem for adolescents. (McGee, Williams, Howden-Chapman, Martin & Kawachi, 2006). In representative study, a sample of n = 100 adolescents with a history of group ...

*November 16, 2016 by Adriana*

**Chemistry**

40.0 ml of an acetic acid of unknown concentration is titrated with 0.100 M NaOH. After 20.0 mL of the base solution has been added, the pH in the titration flask is 5.10. What was the concentration of the original acetic acid solution? (Ka(CH3COOH) = 1.8 × 10−5)

*April 10, 2011 by Bob*

**Chemistry**

Compound Z has a MW of 100. Your lab partner weighed 25 grams of compound Z and dissolved it in water to a final volume of 1 liter. a) What is the concentration of the solution expressed as a percentage by weight (w/v)? b) What is the concentration of the solution expressed as...

*August 29, 2011 by Ty*

**Chemestry**

Have two tanks of 100 liters each, with salt solution. One is at 9% and 4% other. How many liters at least must be removed from each container, so that upon mixing which is removed to obtain a 7% solution of salt concentration?

*June 4, 2013 by RFT*

**chemistry**

use the Henderson-Hasselbalch equation to calculate the pH of a buffer solution prepared by mixing equal volumes of 0.20 M NaHCO3 and 0.10M Na2CO3.(Ka=5.6x10^-11). how would you prepare NaHCO3-Na2CO3 buffer solution that has the pH of 10.40.

*February 28, 2014 by abc*

**AP Chemistry**

The Ksp of Ni(CN)2 is 3.0 × 10−23. What is the molar solubility of Ni(CN)2 in a 0.065 M KCN solution? Answer in units of mol/L. I found that the normal molar solubility is 1.957x10^-8, but I don't know how the KCN solution affects it. Sig figs aren't accounted for.

*January 20, 2015 by Q*

**chemistry**

You wish to prepare 100.0 mL of a 800.0 ppm w/v sodium (MW = 22.9897 g/mol) solution. How many grams of sodium dichromate dihydrate (Na2Cr2O7·2H2O, MW = 297.998 g/mol) are needed to prepare this solution?

*January 26, 2015 by Chase*

**Math Check**

Hi! Can someone check these two answers? Thanks! Directions: Find the correct number of solutions for the following system of equations. 1.) 5x - 3y + 2z = 3 2x + 4y-z = 7 x - 11y + 4z = 3 2.) 2x + y- 3z = 4 4x + 2z = 10 -2x + 3y - 13z = -8 A.) One Solution B.) Infinitely Many...

*March 6, 2015 by Gigi*

**chemistry**

Calculate the approximate pH of a 0.1 M solution of ethanoic acid at 298 K, given that the dissociation constant, Ka, is 1.75 x 10-5 mol/L at 298 K.Ethanoic acid dissociates in aqueous solution as follows: CH3COOH(aq) + H2O H3O+(aq) + CH3COO-(aq)

*April 28, 2015 by Emily*

**Chemistry**

If you try to carry out a double displacement reaction by mixing together equal volumes of a solution that contains dissolved NaF and a solution that contains dissolved NaCl. Would you expect a reaction? Why or why not?

*November 28, 2016 by Rebecca*

**Chemistry**

Phthalic acid, H2C8H404, is a diprotic acid used in the synthesis of phenolphthalein indicator. Ka1= 1.2x 10^-3, and Ka2 = 3.9 x 10^-6. a) Calculate the hydrongen-ion concentration of a .015 M solution. b) What is the concentration of the C8H4O4^2- ion in the solution?

*November 29, 2016 by Crystal*

**physics**

Define STPD, ATPD, BTPS and list the values. I'm in college and our books haven't came in from the bookstore. I don't understand how the prof. is still making us do this HW. my younger brother told me I should try to get help from this site since it helped him. This is all I ...

*January 27, 2008 by jamie*

**Statistics- quick! Is this right?**

I need to verify one of my answers quickly...the problem is: The mean annual salary for classroom teachers is $43,658. Assume a standard deviation of $8000. 1) Determine the sampling distribution of the sample mean for a sample of size 256. Interpret your answer in terms of ...

*November 1, 2007 by Laura*

**math**

Ok, so when you are solving an equation, and you have an answer such as 5x=0 , does that mean that it is no solution or all real #s? And, when the answer is 4=4 , does that mean it is no solution or all real #s? And when the answer is 2x=2x, does that mean it is no solution or...

*May 7, 2013 by K*

**statistics**

The average age of evening students at a local college has been 21. A sample of 19 students was selected in order to determine whether the average age of students had increased. The average age of the students in the sample was 23 with a standard deviation of 3.5. Determine ...

*January 4, 2011 by carrie*

**Chemistry Check Please!**

A solution is prepared by dissolving 3.44 g of sucrose, C12H22O11, in 118 g of water. a) What is the molality of the resulting solution? b) What is the mole fraction of water in this solution? B) moles of h2o=118g/18(g/mol)=6.5556 mol moles of c12h22O11= 3.44g/342.3(g/mol)=0....

*January 16, 2014 by Kate*

**math URGENT!**

28. You are surveying students to find out their opinion of the quality of food served in the school cafeteria. You decide to poll only those students who buy hot lunch on a particular day. Is your sample random? Explain. 29. Ira wants to determine the fast–food restaurant ...

*April 27, 2012 by jksl*