Saturday

September 24, 2016
Number of results: 30,913

**Probability and Statistics**

The proportion of adults living in a small town who are college graduates is estimated to be p = 0.6. To test this hypothesis, a random sample of 15 adults is selected. If the number of college graduates in the sample is anywhere from 6 to 12, we shall not reject the null ...

*November 28, 2013 by Katy*

**maths**

how do you know when an equation has infinitely many solution? How do you know when an equation has no solution

*July 29, 2008 by olabisi*

**college**

How do you know when an equation has infinitely many solution and when an equation has no solution?

*November 20, 2009 by Linda*

**chemistry**

Aqueous solution with a pH of 10.6 is diluted from 1 L to 1.5 L. What is the pH of the diluted solution?

*March 14, 2010 by elizabeth*

**chemisry**

A technician needs to determine the concentration of lead ions in a sample of water a) Suggest a test chemical that can be added to the water sample to preciitate the lead ions. Show a chemical euation for the formation of the precipitate b) after a precipitate forms, it is ...

*August 16, 2010 by Kelsey*

**chemistry**

Can anyone help me with these Chemistry questions? I am trying to study for an upcoming test and its just not sinking in as well and I thought. This is Thermochem for a heads up: Suppose 33mL of 1.20M HCl is added to 42mL of a solution containing excess sodium hydroxide in a ...

*December 3, 2009 by Dina*

**math**

The lengths in inches (x and y) of two fish are related by the equation 5x – 4y = 24. The two ordered pairs that follow are solutions to the equation: (4, -1) (12,9) Which statement best evaluates whether these two solutions make sense in this situation? A. The solution (4, -1...

*November 4, 2013 by samone*

**Chemistry**

A base has a Kb of 2.5 x 10–11. Which of the following statements is true? A.This is a concentrated base. B.This base ionizes slightly in aqueous solution. C.This is a strong base. D.An aqueous solution of this base would be acidic. My answer is D...?

*February 12, 2013 by Cassie*

**Statistics**

The average mpg usage for a 2004 Ford Expedition 2WD for a sample of 10 tanks of gas was 17.0with a standard deviation of 0.8. For a Ford Explorer 2WD, the average mpg usage for a sample of 10 tanks of gas was 18.5 with a standard deviation of 1.0. (a) Assuming equal variances...

*September 19, 2010 by Kim*

**Please Check Answers for Health**

Please check my answers because I need to do good at this. 1. When consuming fats the healthiest choice is foods high in? A. saturated fats B. unsaturated fats * C. trans fat D. cholesterol 2. The body's main energy source should come from what essential nutrient? A. protein* ...

*November 6, 2014 by Ella*

**statistics**

1. A state’s department of education reports that 12% of the high school students in that state attend private schools. The state university wonders if the percentage is the same in their applicant pool. Admissions officers plan to check a random sample of the over 10,000 ...

*November 17, 2011 by fast eddie*

**statistics**

The following table shows the summary statistic of the cholesterol levels of two groups of men in 2014. From 25 to 40 years old, the mean is 224, standard deviation is 5.5 and the sample size is 12. From 41 to 55 years old, the mean is 230, standard deviation is 7 and the ...

*November 15, 2014 by poon*

**chemistry**

An aqueous solution is made by dissolving 15.6 grams of nickel acetate in 373 grams of water. The molality of nickel acetate in the solution is

*June 20, 2011 by Adanna*

**Algebra**

an equation and two ordered pairs are given. show that each pair is a solution of the equation. Then graph the two pairs to determine another solution. 6x-3y=3; (1,1), (-1, -3)

*July 12, 2011 by Poochie*

**chemistry**

A solution of ammonia and water contains 2.70×1025 water molecules and 7.60×1024 ammonia molecules. How many total hydrogen atoms are in this solution?

*October 9, 2011 by Anonymous*

**Chemistry**

What volume (in mL) of 0.45 M Na2SO4 solution is needed to precipitate all the barium, as BaSO4(s), from 14.5 mL of 0.15 M Ba(NO3)2 solution? Ba(NO3)2(aq) + Na2SO4(aq)= BaSO4(s) + 2 NaNO3(aq)

*December 2, 2012 by John*

**Chemistry **

A solution of ammonia and water contains 1.60×1025 water molecules and 8.50×1024 ammonia molecules. How many total hydrogen atoms are in this solution?

*October 8, 2014 by R*

**chem**

A solution of ammonia and water contains 3.80×1025 water molecules and 5.80×1024 ammonia molecules. How many total hydrogen atoms are in this solution?

*January 21, 2015 by todd*

**Chemistry**

A solution of ammonia and water contains 3.70×1025 water molecules and 7.10×1024 ammonia molecules. How many total hydrogen atoms are in this solution?

*September 9, 2015 by Mel*

**Chemistry**

I have 93.954 mL of a generic cola solution. The solution contains: Molarity of H++1.005e-7 Molarity of OH- = 1.005e-7 Molarity of Sucrose(aq) = 6.386e-1 Molarity of Dye= 5.322e-3 Calculate the mass percent, molarity, molality and mole fraction.

*November 3, 2011 by Emily*

**Chem question Redox Stoichiometry**

A 2.80 mol/L solution of iron (II) dichromate is combined with 5.00L of a 2.25 mol/L acidic solution of tin (II) bromide. Calculate the volume of iron (II) dichromate required. FeCr2O7 + SnBr2 --> SnCr2O7 + FeBr2 Is this the right formula? or no?

*May 16, 2007 by Mistra*

**ap chem**

A certain volume of a .50 M solution contains 4.5g of a certain salt. What mass of the salt is present in the same volume of a 2.5 M solution? Indicate the concentration of each ion/molecule: A mixture of 50.0 mL of .2M KClO3 and 25.0 mL of a .20M Na2SO4. How would you answer ...

*September 13, 2007 by lily*

**AP Chem**

A solution of potassium phosphate is mixed with a solution of calcium acetate. I am supposed to write a net ionic equation. Doesn't need to be balanced. Here is what I did: K3PO4(aq) + Ca(C2H3O2)2 --> KC2H3O2 + Ca3PO4 3K+ + PO4-3 + Ca+2 2(C2H3O2-) --> K+ + C2H3O2 + 3Ca+2...

*October 3, 2007 by Please check*

**biochemistry lab**

A) If you make up a solution of 50 mL of 0.1 M TRIS in the acid form, what will be the pH? B) If you add 2 mL of 1M NaOH to the solution in part A, what will be the pH? If it is needed, here is some addition information: TRIS pka= 8.3 mw of TRIS-HCL= 157.6 g/mol; mw TRIS (...

*February 2, 2008 by erin*

**CHEMISTRY..please help..thanks**

Calculate the new molarity if each of the following dilutions is made. Assume the volumes are additive. (a) 52.3 mL of water is added to 27.1 mL of 0.124 M KOH solution (b) 110. mL of water is added to 54.2 mL of 0.808 M NaCl solution ((please show work, thank u so much)

*November 10, 2010 by Jasmin*

**Biology Lab**

Can you please show me how to answer this question using C1V1=C2V2 A scientist receives a vial containing a protein at at concentration of 35mg/ml and is asked to add 0.25ml of it to 6.75mls of Biuret solution. What is the concentration of protein in the Biuret solution in mg/ml?

*June 17, 2012 by Mandy*

**math**

Ms. Banyas bought adult tickets and children’s tickets to a lacrosse game. She spent a total of $145. The equation that follows describes the relationship between and : 25x + 15y = 145 The ordered pair (4,3) is a solution to the equation. What does the solution (4,3) represent?

*November 4, 2013 by samone*

**chemistry**

Calculate the concentrations of all ions after 50.0 mL of a 0.100 M AgNO3 solution is mixed with 100.0 mL of a 1.00 M Na2SO4 solution.For Ag2SO4 Ksp = 1.2 x 10-5 Do I first do MiVi=MfVf and then using the two concentrations I use ksp value? I'm just so confused.

*April 29, 2015 by Anon *

**math**

The sides of two squares differ by 25cm while the sum of their areas is 2425cm. What is the length of the sides of each square. I know the answer--45&20 but I don't know the step by step solution. (40)-(20)=25 (40)^2+(20)^2=2425 2025+400=2425 Please give the solution Sir & Mam...

*August 15, 2016 by Nimuel*

**Stats**

An article (N. Hellmich. "'Supermarket Guru' Has a Simple Mantra,” USA Today, June 19, 2002, p. 70) claimed that the typical super market trip takes a mean of 22 minutes. Suppose that in an effort to test this claim, you select a sample of 50 shoppers at a local supermarket. ...

*August 13, 2008 by Student*

**Math**

An article (N. Hellmich. "'Supermarket Guru' Has a Simple Mantra,” USA Today, June 19, 2002, p. 70) claimed that the typical super market trip takes a mean of 22 minutes. Suppose that in an effort to test this claim, you select a sample of 50 shoppers at a local supermarket. ...

*April 20, 2010 by Statistics baby*

**chemistry**

A glucose solution contains 55.8g of glucose (C6H12O6) in 455g of water. Calculate the freezing poing and boiling point of the solution. (Assume a density of 1.00 g/ml for water. This what I did, I got moles of C6H12O6, 0.89 moles C6H12O6 then I got the mass of the solution ...

*November 4, 2011 by Monique*

**Chemistry**

Predict the most likely redox reaction and use the spontaneity rule to predict whether the reaction will occur spontaneously. 1. An aqueous solution of potassium permanganate was reacted with an acidic solution of sodium bromide and an orange-born substance was formed. Can ...

*February 27, 2008 by Alex*

**chemistry**

Can Anyone Help Me With This Solubility Problem? An aqueous solution of 1.90 M AgNO3 is slowly added from a buret to an aqueous solution of 0.0100 M Cl- and 0.250 M I-. b) When the second ion begins to precipitate, what is the remaining concentration of the first ion? ...

*April 21, 2010 by anonymous*

**chemistry**

Calculate the pH at 25 ° C when 120 mL of a HCl solution having a concentration of 50 mM is added 50.0 mL of a 120 mM ephedrine solution. Assume no change in temperature. Amitriptyline is a drug used in treating depression. It is typically formulated as the hydrochloride ...

*September 9, 2016 by Maria*

**analytical chemistry**

Any help is greatly appreciated 5mL of a solution A (unknown concentration) was transferred into sic 25mL volumetric flask. The following volumes of a standard solution of A with with a concentration 75ppm were added to the flask: 0mL, 0.5mL, 1mL, 1.5mL, 2mL, and 2.5L. The ...

*May 8, 2015 by Katy*

**chemistry**

Assayed for LDH activity were 5 microliters of a sample that was diluted 6 to 1. The activity in the reaction vessel, which has a volume of 3 mililiters, is 0.30 U. What is the ΔA/min observed? What is the relative activity of the original sample? Here are the formulas: U...

*February 15, 2008 by stew*

**Are these correct?**

A) How do you make 200 mL of a 0.1 M solution of a substance that has a molecular weight of 121.1 g/mol? Answer I got: 200mL = 1/0.1M x 1/(121.1g/mol) x mass of the substance. mass of the substance = 0.2L x 0.1M x 121.1g/mol=2.42g Note that my answer doesn't reveal how to do ...

*February 1, 2008 by Anonymous*

**math**

As a a test of a new measurement process, 10 measurements are made on pieces of glass known to have conductivity 1. The average of the 10 measurements is 1.07. Indicate whether 1 and 1.07 is a parameter or statistic and explain why. I know 1.07 is a statistic. Please explain ...

*February 27, 2013 by Please help*

**Statistics**

A national opinion poll found that 44% of all American adults agree that parents should be given vouchers good for education at any public or private school of their choice. Suppose that in fact the population proportion who feel this way is p=0.44. A) Many opinion polls have ...

*December 17, 2013 by JJ*

**Math - system of equations**

write two other equations that have the same solution as this system od equations. 3x-4y=-14 -x+3y=18 I found the solution to the system it is (6,8) there after how do i go about it?

*September 7, 2010 by Shaila*

**chemistry**

a solution is made by dissolving 25 g NaCl in enough water to make 1.0 L solution. Assume that density of the solution is 1.0 g/mL. calculate the mass percent, molarity, molality, and mole fraction of NaCl. help please 25g/58.44g NaCl=.428 mol 1000 grams of solvent H20 25g/58,...

*January 6, 2015 by an*

**Algebra Multiple Choice help!!**

I need help with these! I got B for 1. C for 2. and D for 3. Thanks for the help! 1.) Find the values of a, b, and c that will make the statement true. [5 a -2] [5 102] [3 4 –b] = [-3 -4 3] [2c 5 9] [-2 5 9] a.) 8R1-R2--> =R2 b.) -8R1-R2 -> =R2 c.) –8R1 +R2 -> =R2 d...

*March 28, 2013 by Kris*

** Reiny please help!Algebra **

I need help with these! I got B for 1. C for 2. and D for 3. Thanks for the help! 1.) Find the values of a, b, and c that will make the statement true. [5 a -2] [5 102] [3 4 –b] = [-3 -4 3] [2c 5 9] [-2 5 9] a.) 8R1-R2--> =R2 b.) -8R1-R2 -> =R2 c.) –8R1 +R2 -> =R2 d...

*March 28, 2013 by Becca*

**Chemistry**

Question: you have .420 Litters of a solution containing Ag3PO4 (s) in equilibrium with its ions. write an algebraic equation which when solved will geive the molar concentration of Ag^+1 after the addition of .200 moles of Na3Po4(s) to the .420 liters of solution. in your ...

*May 11, 2009 by Eliz*

**chemistryyy**

Answer the following two questions about the equivalence point for the titration of 27.8 mL of 0.235 M hypobromous acid (pKa = 8.64) with 0.214 M KOH. 1)Predict if the solution will be acidic, basic or neutral at the equivalence point. 2)Calculate the pH of the solution at the...

*September 21, 2011 by Rachel *

**chemistryyy**

Answer the following two questions about the equivalence point for the titration of 27.8 mL of 0.235 M hypobromous acid (pKa = 8.64) with 0.214 M KOH. 1)Predict if the solution will be acidic, basic or neutral at the equivalence point. 2)Calculate the pH of the solution at the...

*September 21, 2011 by Rachel *

**chemistry**

A student is asked to standardize a solution of barium hydroxide. He weighs out 0.986 g potassium hydrogen phthalate (KHC8H4O4, treat this as a monoprotic acid). It requires 27.8 mL of barium hydroxide to reach the endpoint. A. What is the molarity of the barium hydroxide ...

*October 5, 2015 by charlotte*

**chem 101 **

State,in a stepwise fashion how 250mL of a 0.100m sodium hydroxide solution can be made from sodium hydroxide pellets. .. Then calculate the needed volume of solutions above. ,in order to make a diluted 5L solution of 0.05m sodium hydroxide

*February 10, 2016 by pelonomi Tito*

**Algebra I**

4 - t = 3(t - 1) - 5 a. 3 b. 6 c. no solution d. identity A? 8x - 2(x + 1)= 2(3x - 1) a. 0 b. 2 c. no solution d. identity D? 3(c - 2)= 2(c - 6) a. 2 b. -6 c. no solution d. identity B? 0.5(m + 4) = 3(m - 1) a. -2 b. 2 c. no solution d. identity B?

*September 27, 2013 by Anonymous*

**Applied Stats**

Based on the data collected by the National Centre for health Statistics and made available to the public in the Sample Adult database, it was found that the percentage of adults who have at some point in their life been told that they have hypertension was 24 percent. Suppose...

*August 8, 2016 by Anonymous*

**chemistry**

The Fe(ox)33– complex ion creates an emerald green solution when dissolved. The observed solution color of the complex indicates the size of o is: A. large. B. small. C. in between. D. inconclusive, more information is needed. The observed solution color of the complex ...

*June 30, 2010 by Jin*

**marketing**

Binomial probability distributions are used in business, science, engineering, and other fields. Suppose you work for a marketing agency and have to create a television ad for Brand A toothpaste. The toothpaste manufacturer claims that 40% of the toothpaste buyers prefer Brand...

*September 27, 2012 by Mark*

**solutions**

How many molecules of glycerol (C3, H8, O3) would be present in 1 L of M glycerol solution? I am thinking it is 6.02 x 10^23 but have also heard conflicting opinions. You don't give the molarity of the C3H8O3. 1 mole of anything contains 6.02 x 10^23 molecules of that "thing...

*September 17, 2006 by sarah*

**chemistry **

A mixture contained zinc sulfide, ZnS, and lead sulfide, PbS. A sample of the mixture weighing 6.12 g was reacted with an excess of hydrochloric acid. The reactions are given below. ZnS(s) + 2 HCl(aq) → ZnCl2(aq) + H2S(g) PbS(s) + 2 HCl(aq) → PbCl2(aq) + H2S(g) If ...

*October 24, 2010 by caroline*

**accounting**

You have been assigned the task of testing the accuracy of the final inventory compilation for Mt. Hood Furniture. You may assume that you have separately observed the inventory and that you are satisfied that the inventory was accurately counted. However, you need to test ...

*July 17, 2010 by renegade*

**Statistics (45)**

In developing patient appointment schedules, a medical center wants to estimate the mean time that a staff member spends with each patient. How large a sample should be taken if the desired margin of error is two minutes at a 95% level of confidence? How large a sample should ...

*May 6, 2014 by Mia*

**Chemistry**

A base has a Kb of 2.5 x 10–11. Which of the following statements is true? This is a concentrated base. This base ionizes slightly in aqueous solution. This is a strong base. An aqueous solution of this base would be acidic.

*March 9, 2012 by Rachel*

**maths**

(a)(i)use the composite rule to differentiate the function f(x)=(x^2-6x+23)^(3/2). (ii)use the composite rule and your answer to part (a)(i) to show that the function g(x)=(x-2)/(x^2-6x+23)^(3/2) has derivative g'(x)=(5+9x-2x^2)/(x^2-6x+23)^(5/2). (iii)find any staionary ...

*May 20, 2011 by alan*

**chemistry**

Expressing concentration in units of μg/mL or mg/mL are common in biochemistry, where accurate molecular weights of biomolecules are not always known. The plot below is the standard curve of a Bradford assay, a colorimetric method used to determine the concentration of ...

*September 17, 2013 by Libbie*

**Chemistry**

In a titration for the determination of the chloride ion, a solution of 0.1M agno3 is used against a solution, the volume of which is 100ml. At the completion of the titration, the residual concentrations of silver and chloride ions are equal and the total volume is now 125ml...

*October 22, 2014 by Michelle *

**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*

**Math**

Let x be a random variable representing the monthly cost of joining a gym. We may assume that x has a normal distribution and that the population standard deviation is $5.20. A fitness magazine advertises that the mean monthly cost of joining a gym is $35. You work for a ...

*December 22, 2012 by Alison*

**chemistry**

he Fe(ox)33– complex ion creates an emerald green solution when dissolved. The observed solution color of the complex indicates the size of o is: A. large. B. small. C. in between. D. inconclusive, more information is needed. The observed solution color of the complex ...

*June 30, 2010 by ....*

**Chemistry II**

Acetone, C3H6O, is the main ingredient of nail polish remover. A solution is made up by adding 35.0mL of acetone(d=0.790g/mL) to 50.0mL of ethyl alcohol,C2H6O(d=0.798 g/mL). Assume that the volumes are additive. From this information calculate the molarity of acetone in the ...

*September 27, 2009 by Mandy*

**Chemistry**

Which of the following pairs would make a good buffer solution in an aqueous solution? A) H2SO4 and NaHSO4 B) Ca(NO3)2 and HNO3 C) HCl and NaCl D) HF and NaOH E) none of them I know the answer is D but I don't understand why. I would think it would be C since a goo buffer is a...

*March 20, 2013 by Jonah*

**chemistry**

What is the pH of a buffer solution that is made by adding 21.0 grams of sodium fluoride to 1.00 Liter of 0.15M hydrofluoric acid? (see the Table above for the Ka of hydrofluoric acid; calculate the pH to 2 decimal places) hint: you will have to find the molarity of NaF in ...

*June 16, 2013 by dennis*

**chemistry**

What is the pH of a buffer solution that is made by adding 21.0 grams of sodium fluoride to 1.00 Liter of 0.15M hydrofluoric acid? (see the Table above for the Ka of hydrofluoric acid; calculate the pH to 2 decimal places) hint: you will have to find the molarity of NaF in ...

*June 16, 2013 by Dennis*

**Chemistry**

What is the pH of a buffer solution that is made by adding 21.0 grams of sodium fluoride to 1.00 Liter of 0.15M hydrofluoric acid? (see the Table above for the Ka of hydrofluoric acid; calculate the pH to 2 decimal places) hint: you will have to find the molarity of NaF in ...

*June 17, 2013 by D.J.*

**Anyone please help(math)**

Which number is a solution of the inequality? g>6.4 a. 7 b. 6 c. 6.4 d. -7 Which number is a solution of the inequality? g+3>6 a. 3 b. 4 c. -3 d. -4 Which number is a solution of the inequality? 12<y(8-y) a. 0 b. 1 c. 2 d. 3

*January 9, 2014 by Ashley mccgarvey*

**chemistry help!!! (clueless)**

1. Consider the conductance meter and the titration method of determining the salt content of a brine sample. Discuss at least two advantages and two disadvantages of each method. 2. A corrosion technologist pipetted a 50.00 mL sample of an unknown brine and titrated it with ...

*June 19, 2006 by lightning*

**Chemistry**

Titration was used to determine the molarity of acetic acid in vinegar. A primary standard solution of KHP was used to standardize the NaOH. 1. When performing this experiment, impure KHP was used to standardize the NaOH solution. If the impurity is neither acidic or basic, ...

*March 28, 2014 by Sandy*

**Math**

The owner of a large company is conducting a survey about job satisfaction, including questions about salary, hours, stress, and other conditions. There are about 800 employees in the company, including 100 executive positions, 650 middle-management positions, and 50 custodial...

*August 7, 2012 by Fatima*

**math help pls pls**

Maya had $27. She spent all the money on buying 3 burgers for $x each and 2 sandwiches for $y each. If Maya had bought 2 burgers and 1 sandwich, she would have been left with $11. A student concluded that the price of each burger is $5 and the price of each sandwich is $6. ...

*December 21, 2015 by Oscar*

**statistics**

Workers in several industries were surveyed to determine the proportion of workers who feel their industry is understaffed. In the government sector, 37% of the respondents said they were understaffed, in the health care sector 33% said they were understaffed, and in the ...

*October 20, 2014 by tia*

**Statistics**

The standard deviation of GPAs (grade point averages) of all male students at a college is .35 and the standard deviation of GPAs of all female students at the same college is .34. Suppose we take one sample of 40 male students and another sample of 50 female students from ...

*October 22, 2010 by Lisa*

**Statstics**

Let x be a random variable representing dividend yield of Australian bank stocks. We may assume that x has a normal distribution with \alpha =2.3% A random sample of 18 Australian bank stocks has a sample mean of x bar = 6.1%. For the entire Australian stock market, the mean ...

*August 7, 2011 by Justina*

**chem??????????????????**

YEs, it is the correct balanced equation bobpursley A 2.80 mol/L solution of iron (II) dichromate is combined with 5.00L of a 2.25 mol/L acidic solution of tin (II) bromide. Calculate the volume of iron (II) dichromate required. FeCr2O7 + SnBr2 --> SnCr2O7 + FeBr2 Is this ...

*May 16, 2007 by bobpursley*

**Algebra **

A dehydrated patient needs a 3.82% saline IV. Unfortunately, the hospital only has bags of 4% and 3% saline solutions. How many liters of each of these solutions should be mixed together to yield 5 liters of the desired concentration? So far I've come up with this: x= 4% ...

*October 11, 2010 by JerryJ*

**CHEMISTRY**

Lysozmyne is an enzyme that breks bacterial cell walls. A solution containing 0.150g of this enzyme in 210ml of solution has an osmotic pressure of 0.217kPa at 25*C. What is the molar mass of Lysozmyne? I cant find the chemical formula anywhere. I have used the osmotice ...

*October 15, 2010 by lulu78*

**Chemistry**

Suppose you tired to carry out a double-replacement reaction by mixing together equal volumes of a solution that contained dissolved NaF and a solution that contained dissolved NaCl. Would you expect a reaction, if so write the balanced chemical equation?

*April 25, 2011 by Anonymous*

**chemistry**

2Na3PO4(aq)+3 Ba(NO3)2(aq)---->Ba3(PO4)2(s)+6NaNO3(aq) a solution containing 3.50g of Na3PO4 is mixed with a solution containing 6.40g of Ba(NO3)2 how many grams of product can be formed? and if the above reaction resulted in 3.659 g of white powder, what is the percent ...

*November 17, 2011 by mckayla*

**Chemistry**

1 g of acid was mixed with 120 ml of distilled water and the solution was filtered into a clean dry beaker. A 25 ml aliquot of this solution was titrated with 0.1120 M NaOH. The pH of the acid was recorded to be 4.42. Calculate the initial concentration of the weak acid and ...

*March 25, 2013 by Annie*

**Chemistry**

How do you calculate the standard enthalpy change for the reaction of an aqueous solution of barium hydroxide, Ba(OH)2, with an aqueous solution of ammonium nitrate, NH4NO3, at 25 degrees C? The complete ionic equation is: Ba2+(aq) + 2OH-(aq) + 2NH4+(aq) + 2NO3-(aq) ---> ...

*April 2, 2013 by Lisa*

**Organic-Chem Lab Question Need Help!!!**

a) Would 2-propanol be a suitable solvent to extract caffeine from an aqueous tea solution? Explain? b) You want to use 45 ml total of your extraction solution. Is it better to use three extractions of 15 ml each or one extraction of 45 ml? Explain your answer? Thanks!

*September 13, 2014 by Layla*

**Chemistry**

Suppose you tired to carry out a double-replacement reaction by mixing together equal volumes of a solution that contained dissolved NaF and a solution that contained dissolved NaCl. Would you expect a reaction, if so write the balanced chemical equation?

*January 29, 2015 by Keely*

**Chemistry Help**

How many milliliters of 0.534 M Ba(OH)2 solution are needed to completely neutralize 34.5 mL of 0.220 M HBr solution? The reaction is Ba(OH)2(aq) + 2HBr(aq) → BaBr2(aq) + 2H2O(l) I did 0.0345 * 0.220 = 0.00759 Moles of HCl =2*0.00759= 0.01518 0.01518*1000= 15.18 mL ...

*February 27, 2015 by Matthew*

**Chemistry**

I have water pH 7.0 insulation with various other things that do not affect pH, I am trying to add X amount of HCL to lower the solution to a pH of 1.5 I know pH=-log[HCl] but I'm not sure how to approach this problem, after this I am then trying to add NaOH to return the ...

*April 24, 2015 by Margaret*

**Chemistry**

In a constant-pressure calorimeter, 50.0 mL of 0.300 M Ba(OH)2 was added to 50.0 mL of 0.600 M HCl. The reaction caused the temperature of the solution to rise from 23.77 °C to 27.86 °C. If the solution has the same density and specific heat as water (1.00 g/mL and 4.184 J/g·K...

*April 11, 2016 by Paul83*

**chemistry**

At equilibrium, a solution of formic acid at 25°C has a pH of 2.18. The pKa of formic acid, HCOOH, is 3.74. Which of the following is the initial concentration of the solution? Not sure what to do my thoughts: use henderson hasselback equation pH = pKa + log [conj base/acid] ...

*June 8, 2016 by James*

**Algebra Multiple choice!!! Help**

1.) Find the values of a, b, and c that will make the statement true. [5 a -2] [5 102] [3 4 –b] = [-3 -4 3] [2c 5 9] [-2 5 9] a.) 8R1-R2--> =R2 b.) -8R1-R2 -> =R2 c.) –8R1 +R2 -> =R2 d.) 8R1-R2 -> =R2 2.) Solve the system by triangularizing the augmented matrix and...

*March 28, 2013 by Kris*

**Physics**

If a supersaturated sugar solution is allowed to evaporate slowly, sugar crystals form in the container. Hence, sugar molecules go from a disordered form (in solution) to a highly ordered, crystalline form. Does this process violate the second law of thermodynamics? Explain.

*November 25, 2012 by S*

**Math**

1. –9p – 17 = 10 (1 point) –3 16 18 –16 2. w over four – 4 = 3 (1 point) –4 28 3 11 3. d over three+ 10 = 7 (1 point) 51 20 0 –9 4. –2(m – 30) = –6m (1 point) –15 –13 –8 8 5. 3n + 2= 8 + 2n (1 point) 3 4 5 6 Simplify the expression. 6. –6 – 7(c + 10) (1 point) 64 – 7c –76 – 7c...

*January 18, 2013 by plz help*

**Chemistry**

I just need this checked over. I am not sure about the last part D. Temp c KBr 20 65 40 80 60 90 80 100 100 110 At 100 C, 10.5 g KBr/10gH2O = 105 g/100 g (just multiply the top and the bottom by 10 to give you 100 g H2O) B) Since the solubility at 100C is actually 110, no, it ...

*May 19, 2011 by Monster*

**chemistry**

PLEASE NOTE: Titration requires several steps in order to obtain exact results. The procedures described in this lab assume that you have already done the TITRATION TUTORIAL and are familiar with the technique. 1. Prepare the NaOH solution by dissolving approximately 4g of ...

*April 15, 2011 by Zach*

**Chemistry please help**

Elemental mercury was first discovered when a mercury oxide was decomposed with heat, forming mercury metal and oxygen gas. When a 0.204-g sample of the mercury oxide is heated, 0.189 g of mercury metal remains. a)what is mole ratio of mercury to oxygen in the sample? would it...

*February 15, 2012 by Adam*

**Chemistry**

An aqueous solution contains 2.0 % NaCl by mass. (1) Calculate the molality (NOT molarity!) of the solution. (2) Calculate the mole fraction of the solution. I know how to solve both but the problem is missing one other compound/element. I know that molality is moles per kg of...

*January 26, 2010 by .*

**chemistry**

A buffer is made by adding 0.300 mol HC2H3O2 and 0.300 mol NaC2H3O2 to enough water to make 1.00 L of solution. The pH of the buffer is 4.74 . Calculate the pH of this solution after 0.020 mol of NaOH is added.

*December 10, 2009 by Ericka*

**chemistry**

A solution is 2.0×10−2M in both chromate and sulfate anions and . To this solution, 0.55M Pb(NO)3 is slowly added. What is [Pb2+] at the point at which the second anion begins to precipitate (in M)? The second anion being the, sulfate anion.

*April 14, 2011 by nahang*

**Chemistry**

When 5.00 g of NaOH(s) are added to 100 g of water using a calorimeter, the temperature rises from 25.0 to 37.5 °C. Calculate the molar heat of solution. NaOH(s)--->Na(aq)+OH(aq) Assume that the specific heat capacity of water is 4.18 J/gK and that of the NaOH(aq) solution ...

*November 14, 2012 by FIrst_lady*