Monday

August 3, 2015

August 3, 2015

Number of results: 28,067

**Chemistry 3**

How is it possible for me to tell which of these solutes will produce an acidic solution when dissolved in water? LiOH CH3CO2K H2SO3 KOH NaOH NH4NO3 NaOH NaOH can't be the only one... Molecules that produce OH^- when dissolved in water will be basic. Examples:LiOH, KOH, NaOH, ...
*May 24, 2007 by Lindsay*

**chemistry**

a solution is prepared by mixing 2.17g of an unknown non-electrolyte with 225.0g of chloroform. The freezing point of the resulting solution is -64.2 C . The freezing point of pure chloroform is -63.5 C and its kf= 4.68C m^-1 . What is the molecular mass of the unknown? i know...
*February 10, 2014 by hershi*

**Thermodynamics**

Steam in a cylinder-piston arrangement expands from an initial condition of 5 bar, 80% dry to a final state of 2 bar, dry saturated steam. The initial volume of steam is 0.8 m3. The process of expansion can be represented by a straight line on the p–Vdiagram. 5B. What is the ...
*October 17, 2014 by Phy*

**CHEM**

I know I posted this question again but no one is really helping me. Can someone please help me as soon as possible. In a constant-pressure calorimeter, 60.0 mL of 0.340 M Ba(OH)2 was added to 60.0 mL of 0.680 M HCl. The reaction caused the temperature of the solution to rise ...
*February 10, 2012 by Akle*

**chemestry**

A calorimeter contains 16.0 of water at 15.0. When 1.60 of (a substance with a molar mass of 58.0 ) is added, it dissolves via the reaction and the temperature of the solution increases to 27.5. Calculate the enthalpy change, , for this reaction per mole of . Assume that the ...
*November 9, 2011 by Anonymous*

**Chemictry**

A calorimeter contains 32.0 of water at 11.5. When 1.70 of (a substance with a molar mass of 74.0 ) is added, it dissolves via the reaction and the temperature of the solution increases to 26.5. Calculate the enthalpy change, , for this reaction per mole of . Assume that the ...
*November 18, 2011 by Priscilla*

**chemistry**

A chemistry student weighs out 0.172 grams of acrylic acid (HCH2CHCO2) into a volumetric flask and dilutes to the mark with distilled water. He plans to titrate the acid with 0.1800 moles/liter NaOH solution. Calculate the volume of NaOH solution the student will need to add ...
*January 25, 2012 by Lucas*

**chemistry**

The quantity of antimony in an ore can be determined by an oxidation-reduction titration with an oxidizing agent. The ore is dissolved in hot, concentrated acid and passed over a reducing agent so that all the antimony is in the form Sb3 (aq). The Sb3 (aq) is completely ...
*February 24, 2012 by Katie*

**Chemistry**

Are these reactions Exothermic or Endothermic? How do I know? 1.) Mg(OH)2(s)<==>Mg+2(aq) + 2OH-(aq) Saw solution lighten from medium pink to very light when heated in hot water bath. (It had phenolphthalein drop for indicator.) 2.) HSO4-(aq)+ H2O(l)<==>H3O+(aq)+SO4...
*July 11, 2013 by Ann*

**algebra**

Use the discriminant to determine the following equations have that are two different rational solutions:two different irrational solutions or exactly one rational solution or two different imaginary solution. x^2=5x+6
*June 9, 2011 by mema*

**CHEMISTRY**

25cm^3 of a solution of NaOH required 28cm^3 of 1.0 mol dm^-3 H2SO4 to neutralise it. a)Write an equation for the reaction. b)How many moles of H2SO4 were needed? c)How many moles of NaOH were thus neutralised? d)How many moles of NaOH are there in 25cm^3 of solution?
*October 20, 2013 by Ava*

**Prob and Stats**

To estimate the mean height population of male students on your campus, you will measure and SRS of students. Heights of people the same sex and similiar ages are close to normal. You know from government data that the standard deviation of the heights of young men is about 2....
*October 12, 2010 by Susan*

**Math**

The National AIDS Behavioral Surveys interviewed a sample of adults in the cities where AIDS is most common. This sample included 789 heterosexuals who reported having more than one sexual partner in the past year. We can consider this an SRS of size 789 from the population of...
*May 6, 2012 by Janel*

**chemistry**

A student determines the zinc content of a solution by first precipitating it as zinc hydroxide, and then decomposing the hydroxide to zinc oxide by heating. How many grams of zinc oxide should the student obtain if her solution contains 42.0 mL of 0.566 M zinc nitrate?
*November 4, 2012 by Anonymous*

**chemistry**

A student determines the cobalt(II) content of a solution by first precipitating it as cobalt(II) hydroxide, and then decomposing the hydroxide to cobalt(II) oxide by heating. How many grams of cobalt(II) oxide should the student obtain if her solution contains 46.0 mL of 0....
*March 3, 2014 by jen*

**Chemistry**

A student determines the iron (II) content of a solution by first precipitating it as iron (II) hydroxide, and then decomposing the hydroxide to iron (II) oxide by heating. How many grams of iron (II) oxide should the student obtain if her solution contains 46.0 mL of 0.426 M ...
*October 16, 2014 by Jessica*

**statistics**

Starting with a population that is normally distributed with a mean of 100 and a standard deviation of 12, answer the following questions (if possible). a. What is the probability of randomly drawing a single score between 100 and 106, p(100 < X < 106)? b. What is the ...
*October 15, 2011 by Daniel*

**Biology**

The absorbance of a protein solution measured in a 1.0 cm cuvette at 278 nm was 1.145. The protein content of that solution, calculated from quantitative amino acid analysis, was 256 micrograms/mL. Calculate the extinction coefficient of the protein in unitsbof mL/mg/cm. ...
*October 12, 2009 by Anonymous*

**chemistry**

We have two liters of a buffer solution that is 0.10 M in CH3COOH and 0.10 M in NaCH3COO. How many moles of solid NaOH are to be added to this solution to increase its pH by 5.0 percent? Assume no volume change due to the addition of solid NaOH. I have the starting pH and what...
*April 15, 2010 by Bharg*

**chemistry**

A student performs a back-titration to determine the cost -effectiveness of an antacid. A tablet with a retail cost of $0.053 is dissolved in 25.00 ml of 1.000 M HCl, then back-titrated with 1.000 M NaOH. Exactly 14.82 ml of NaOH solution is required to reach the endpoint. ...
*April 19, 2010 by Lisa*

**Chemistry**

the following questions are about colligative properties: a)How much would the freezing point change in a 2.5 solution of phenol in benzene? b)how much would the boiling point change in a 1.m solution of magnesium chloride in ethanol? c)Does adding sugar to water raise or ...
*May 2, 2010 by Kim*

**Chemistry (URGENT)**

Calculate the molarity of the Co^2+ ion in each of the solutions 1-5. The new molarity is given by the molarity of the stock solution multiplied by the dilution factor. Solution: Co(NO3)2 Original molarity: 0.160 Dilution #1: none D#2: 12mL to 16mL D#3: 8mL to 16mL D#4: 4mL to...
*December 15, 2010 by John*

**chemistry**

In the following experiment, a coffee-cup calorimeter containing 100 mL of H20 is used. The initial temperature of the calorimeter is 23.0 C . If 3.60 g of CaCl2is added to the calorimeter, what will be the final temperature of the solution in the calorimeter? The heat of the ...
*October 20, 2011 by Colin*

**chemistry**

Experiment: Gravimetric Determination of Phosphorus in Fertilizer Samples 1. Can NH4Cl be used as a substitute to precipitate the phosphorus in the sample? Why or why not? - I think, NH4Cl can be used although I'm not quite sure if Cl- ions have some effects to the ...
*August 17, 2007 by Smiley*

**Chemistry**

Q1 In order to determine the concentration of acetic acid in a sample of vinegar, a student titrated a sample of vinegar with potassium hydroxide solution. Dada from four trials was collected and recorded in a data table. Titiration of 10.0 mL of CH3COOH(aq) with 0.250 mol/L ...
*September 28, 2006 by Brittany Rusk*

**Chemistry**

A solid weak acid is weighed, dissolved in water and diluted to exactly 50.00 ml. 25.00 ml of the solution is taken out and is titrated to a neutral endpoint with 0.10 M NaOH. The titrated portion is then mixed with the remaining untitrated portion and the pH of the mixture is...
*April 14, 2015 by JUNDY*

**Statistics**

The American Academy of Pediatrics (AAP) recommends that kids 2-5 years old watch no more than (on average) 1.6 hours a day of quality programming. A researcher selected a sample of 101 kids in the neighborhood and asked their parents how many hours per day they allow their ...
*October 4, 2013 by Chris*

**statistics**

2) Two individuals are running for mayor of Tallahassee. You conduct an election survey (N = 561) a week before the election and find that 57% of the respondents prefer candidate A. Can you predict the winner (α = 0.01)? (Hint: Use 50% as the proportion of votes needed ...
*March 18, 2009 by taryn*

**statistics**

4. Are women getting taller? In one state, the average height of a woman aged 20 years or older is 63.7 inches in 1990. A random sample of 100 women is taken to test if women’s mean height today is different from 1990. The mean height of the 100 surveyed women is 63.9 inches. ...
*December 16, 2013 by Amanda*

**statistics**

The International Air Transport Association surveys business travelers to develop quality ratings for transatlantic gateway airports. The maximum possible rating is 10. Suppose a simple random sample of 50 business travelers is selected and each traveler is asked to provide a ...
*April 21, 2014 by Vanessa*

**statistics (6)**

The International Air Transport Association surveys business travelers to develop quality ratings for transatlantic gateway airports. The maximum possible rating is 10. Suppose a simple random sample of 50 business travelers is selected and each traveler is asked to provide a ...
*April 22, 2014 by Vanessa*

**statistics (6)**

The International Air Transport Association surveys business travelers to develop quality ratings for transatlantic gateway airports. The maximum possible rating is 10. Suppose a simple random sample of 50 business travelers is selected and each traveler is asked to provide a ...
*April 23, 2014 by Vanessa*

**chemistry**

when 50.0 ml of 2.00M KOH is reached with 50.0 ml of 2.00M HCl, the temperature rose from 20.0 degree celcus to 28.7 degree celcus. What is the heat generated by this neutralization? (Assume that the density fo the two 2 M solution is 2.00g/ml and that the heat capacity of the...
*February 28, 2010 by Tim*

**Chemistry**

What Occurs as a salt dissolves in water? the number of ions in the solution increases and the freezing point decrease the number of the ions in the solution increase and the freezing point increase the # of ions in the solution decrease and the freezing point increase the # ...
*March 26, 2007 by Kat*

**Chemistry**

why mass cannot be used as a property to identify a sample of matter?
*September 6, 2007 by John*

**chemistry**

How many phosphorus atoms are in a 0.3352 g sample of Ca3(PO4)2 ?
*November 25, 2007 by Rog*

**alg**

Find the sample size that produces the margin of error ± 3.0%
*May 12, 2008 by jerson*

**algebra**

Find the sample size that produces the margin of error ± 3.0%
*May 12, 2008 by jerson*

**English**

Can you please show me a sample of a diagrammed sentence with phrases?
*July 20, 2008 by Tyler*

**computers**

where can i play a sample online mixing turntables with music to dj with
*September 18, 2008 by carlos*

**chemistry**

what is the volume of a 2.00 gram sample of helium gas at STP?
*March 5, 2009 by crystal*

**business statistics**

If a sample of size 30 is selected, the value of A for the probability p(>- A) = 0.01 is?
*August 1, 2009 by Bryant*

**Stragies**

What does a sample outline look like for a thesis paper
*May 29, 2010 by Jodi*

**physics**

a 20.0L sample of hydrogen gas has a mass of 1.80g. What will its density be in g/ml?
*July 13, 2010 by Jen*

**Chemistry**

How many grams of iron are there in a sample of Fe3O4 which weighs 8.338 g?
*September 20, 2010 by Diggs*

**chemistry**

How many moles are in a sample of cobalt containing 5.0x10^23 atoms?
*October 21, 2010 by Nathan*

**Science**

How old id an artifact if only 1/4 of the hydrogen 3 in the sample remains?
*January 5, 2011 by Diane*

**Science**

How many days will it take for 3/4 of a sample of polonium 210 to decay?
*January 6, 2011 by Diane*

**chemistry**

a sample of freshly pressed apple juice has a pH of 3.76. Calculate [H+].
*January 20, 2011 by jaycab*

**statistics**

what is teh standard error when sample n = 16 mu=150 and sigma = 36
*January 30, 2011 by Jokes*

**math**

What is the sample space for choosing a letter from the word mathematics
*April 29, 2011 by mia*

**statistics**

Would it be unusual for the mean of a sample of 3 to be 115 or more?
*August 2, 2011 by john*

**chemistry**

What is the density of air if a 5000ml sample has a mass of 0.125?
*September 25, 2011 by eliza Higgins *

**chemistry**

What is the density of air if a 5000ml sample has a mass of 0.125?
*September 25, 2011 by eliza Higgins *

**Science**

How would you obtain a sample of the salt potassium chloride?
*October 16, 2011 by Muhammad tanvir hussain *

**Staitstics**

What statistical test would be appropriate for a sample size of 25
*November 8, 2011 by Tommy*

**Statistics**

Find t-value for sample size n = 16 and area to the right 0.10
*February 22, 2012 by Tina*

**chemistry**

what is the density of a sample of 65.0 ml of automobile oil having mass of 59.82 g
*March 4, 2012 by yvette*

**statistics**

create a survey results that have a sample proportion of 23%
*March 16, 2012 by douglas*

**chemistry**

how many grams of magnesium carbonate are in a sample that has 1.58 x 10^24 oxygen atoms?
*April 24, 2012 by liz*

**Chem**

Can a 100ml sample of 3.0m H2 SO4 could be neutralized by 100 ml of 3.0m NH3
*July 16, 2012 by natalie*

**chemistry**

determine the number of moles of FeSO4 in sample Y that you use
*August 2, 2012 by methove*

**chenistry**

how many calories are required to melt a 135.0g sample of ice at 0.0 c
*September 5, 2012 by barb*

**statistics**

for a sample of 3 to have a mean of 115 would this be unusual
*September 30, 2012 by lillie*

**chemistry**

A sample of oil has a mass of 65g and a volume of 80.0 mL. What is the density?
*October 4, 2012 by sherry*

**chemistry**

how many atoms are in a sample of 175 g of sodium (Na)? 4.58 x 1024 or 1.42 x 1027?
*November 12, 2012 by Anonymous*

**statistics**

What is the standard deviation of 31 sample values with a mean of 2954?
*February 22, 2013 by glenzy*

**Chemistry **

How many moles of ethyl alcohol C2H6O are in a 25.0 sample? How do I calculate?
*March 21, 2013 by Yaneth*

**chemistry**

Which of the following will increase the strength of a sample of 90% SiO2 - 10% MgO
*April 26, 2013 by Anonymous*

**chemistry**

If a 1.60 M sample of A is heated to 500 K, what is the concentration of B at equilibrium? A(aq)<---> 2B(aq) Kc=9.63x10^-6
*April 11, 2014 by Anna*

**statistics**

simple randon sampling uses a sample size n
*June 30, 2014 by Anonymous*

**chemistry**

Calculate the number of C atoms in a .25mg sample of C8H10N4O2
*September 20, 2014 by frank*

**math**

Let x1,x2,x3,x4,x5 be random sample of f(x)=(x+1)/2,-1<x<1,zero elsewhere, find P(four of{x1,x2,x3,x4,x5}>0)
*December 28, 2014 by assma*

**math**

Let x1,x2,x3 be random sample of f(x)=exp(-x),x>0,zero elsewhere,if y1=x1/x2,y2=x3/(x1+x2),y3=x1+x2 find g(y1,y2,y3),g(y1),g(y2,y3)
*December 28, 2014 by assma*

**chemistry**

Calculate the volume in milliliters of a 5.41-g sample of a solid with a density of 3.01 g/mL
*January 21, 2015 by Drea*

**Statistics**

Pop. Mean =87 Standard deviation=8 Sample size=64
*February 2, 2015 by Denise*

**Calculus**

Silly question here, but I am not getting a certain part in the solution in a problem. Evaluate the integral of [(sin(ln(39x)))/x]dx. We are supposed to take u=ln(39x), and get du=(1/x)dx, and the then whole thing is simply solved using integration formulas. But my confusion ...
*December 4, 2009 by O_o Rion*

**chemistry**

calculate the mass of NaOH neded to prepare 500mL of a 0.10 M solution. I'm pretty sure the answer is 2g, but how do I get to that? Another question: calculate the molar amount of KHP used to neutralize the NaOH solution. .51 g of KHP was added to 50 mL of distilled H2O and a ...
*October 14, 2007 by Rebecca*

**chemistry **

In the REDOX reaction in basic solution Zn-->Zn(OH)4+H2 I know that the first half reaction is 4H20+Zn-->Zn(OH)4 +4H+e but the second one is either 2e+2H2O--->H2+2OH (WHICH IS THE ANSWER GIVEN ON THE WORKSHEET) OR 2e+2H-->H2 I think both leads to the same answer= ...
*November 4, 2010 by george*

**math**

A nurse wants to add water to 18 ounces of a 10% solution of benzalkonium chloride to dilute it to an 8% solution. How much water must she add? (Hint: Water is 0% benzalkonium chloride.)
*September 18, 2011 by N/A*

**chemistry**

2.) Substances A, B, and C can all act as oxidizing agents. In solution, A is green, B is red, and C is yellow. In the reactions in which they participate, they are reduced to A-, B-, and C- ions respectively, all of which are colorless. When a solution of A is mixed with one ...
*March 2, 2011 by kate*

**chemistry**

2.) Substances A, B, and C can all act as oxidizing agents. In solution, A is green, B is red, and C is yellow. In the reactions in which they participate, they are reduced to A-, B-, and C- ions respectively, all of which are colorless. When a solution of A is mixed with one ...
*March 2, 2011 by kate*

**Physical Chemistry**

Determine the temperature change when 18.0 g of the following salt is dissolved in 190. g of water. The specific heat capacity of water is 4.184 J·K-1g-1. The enthalpies of solution in the table are applicable. Do not take the added mass of the salt into account when ...
*February 10, 2010 by Trixie*

**Algebra Quadratic Equations**

When a quadratic equation has one solution, there will be one x-intercept; when there are two solutions, there will be two x-intercepts and when the equation has no solution, the graph will have no x-intercepts",is there another way of determining this?
*February 13, 2008 by Marysvoice*

**chemistry**

25.0 ml of 15% NH4NO3 solution is diluted to 300.0 ml. What is the concentration of the diluted solution? My Work: Total molar mass of NH4CO3 = 80.052 .15 x 80.052= 12.0078 25.0 ml (12.00 M) = 300.0 ml (c2) 300.19/300.0ml = The concentration is = 1.0M
*April 15, 2015 by Anonymous*

**Statistics **

What price do farmers get for their watermelon crops? In the third week of July, a random sample of 51 farming regions gave a sample mean of = $7.08 per 100 pounds of watermelon. Assume that is known to be $1.80 per 100 pounds. Find a 99% confidence interval for the population...
*July 7, 2012 by Desperate *

**Hypothesis Test**

A test of hypothesis is performed to determine whether the proportion of Montrealers (population 1) who want the decriminalization of marijuana is greater than the proportion of Torontonians (population 2) who want decriminalization of marijuana. A random sample of 120 ...
*November 16, 2013 by Simon*

**Statics**

Total plasma volume is important in determining the required plasma component in blood replacement therapy for a person undergoing surgery. Plasma volume is influenced by the overall health and physical activity of an individual. Suppose that a random sample of 44 male ...
*July 19, 2011 by Faith*

**statistics**

The National AIDS Behavioral Surveys interviewed a sample of adults in the cities where AIDS is most common. This sample included 782 heterosexuals who reported having more than one sexual partner in the past year. We can consider this an SRS of size 782 from the population of...
*March 26, 2013 by Anonymous*

**Math**

( / means absolute value) Solve: 3+/2y-1/>=1. Graph the solution set on a number line. The number line I have is: -5 -4 -3 -2 -1 0 1 2 3 4 5 6 First solution: 3+2y-1>=1 2y-4>=1 2y>=5 y>=5/2 I'm stuck b/c I had to correct the first part. I had a whole different ...
*February 24, 2008 by Jon*

**stoichiometry**

When Ba(NO3)2 and K2CrO4 (sorry, i don't know how to do subscripts, but all the numbers should be subscripts!) react in aqueous solution, the yellow solid BaCrO4 is formed. Calculate the mass of BaCrO4 that forms when 3.50 x 10^(-3) mol of solid Ba(NO3)2 is dissolved in 265 mL...
*June 5, 2008 by em*

**Chemistry **

The following is given: 20 ml of HCl (2.0 M) added with 5 ml of Na2S2O3 (0.3 M) with 5 ml of H2O S2O3^-2(aq) + 2H^+1 (aq) --> S (s) + SO2 (g) + H2O (l) Calculate the following: a) Reaction rate when 30 mg of sulphur is formed (in 30 ml of solution) after 55 seconds. b) Rate...
*October 20, 2010 by Stephanie*

**chemistry 12 lab**

We did a lab on equilibrium and this is one of the following questions: When Ag ions are added to FeSCN ions (which are red in colour), the colour disappears, and a white precipitate of AgSCN forms. The question is.. Explain why Fe can be used as an indicator in a reaction to ...
*November 5, 2010 by cel*

**pre-calculus**

solve the logarithmic equation. be sure to reject any value of x that is not in the domain of the orginal logarithmic expression. In square root of x+2=2 (If I try to make the square root sign it will not come out right so I wrote it out instead) What is the exact solution. A...
*October 6, 2012 by ladybug*

**chemistry**

In a coffee-cup calorimeter, 1.91 g of NH4NO3 is mixed with 75.0 g of water at an initial temperature of 25.00oC. After the solution of the salt, the final temperature was 20.94oC. Assuming the solution has a heat capacity of 4.18 J/(goC) and assuming no heat loss to the ...
*October 9, 2012 by Shawn*

**Chemistry - %v/v**

1. How many mL of acetone are needed to prepare a 10% v/v solution in 500 mL of methanol? 2. If a 500mL solution of n-propanol in water is prepared with 4mL of alcohol, what is the concentration of alcohol in % v/v? I've never worked with %v/v before so I'm not sure if I ...
*June 2, 2013 by double checking*

**Chemistry**

A solution buffered at a pH of 5.00 is needed in an experiment. Can we use acetic acid and sodium acetate to make it? If so, how many moles of NaC2H3O2 must be added to a 1.0L of a solution that contains 1.0 mol HC2H3O2 to prepare the buffer. The Ka of acetic acid is 1.8x10^-5...
*June 20, 2014 by Veronica*

**chemistry **

To dissolve an ionic solid in water, you must first disrupt the ionic bonds that are holding the ionic lattice together. This is an endothermic process, yet many ionic solids have an exothermic heat of solution. (Heat is released when the ionic solid is dissolved.) This is ...
*March 17, 2015 by Cortney*

**science**

In 91% (by volume) isopropyl alcohol (a large [compared to water], flammable molecule) solution, there are only two substances: the alcohol, and water. So when I poured 50 mL of 91% isopropyl alcohol into a graduated cylinder, how many milliliters were alcohol? How many were ...
*February 6, 2012 by edward*

**chemistry**

pure zinc metal into a solution of copper(II) sulfate, the zinc will slowly dissolve to produce zinc sulfate solution, and the copper(II) ion of the copper(II) sulfate will be converted to metallic copper. Write the unbalanced equation for this process. (Include states-of-...
*October 2, 2010 by astoeck*