Sunday

March 29, 2015

March 29, 2015

Number of results: 27,269

**chemistry**

A student needs to make a dilution from a stock solution. The stock solution is 2.) M NaCl. How much should the student use of the 2.0 M NaCl to make 1.0 L of 0.05M NaCl diluted stock.
*April 6, 2011 by Marilyn*

**Chemistry **

A student titrated 1.852 g of a mixture containing potassium hydrogen phthalate, KHP....? A student titrated 1.852 g of a mixture containing potassium hydrogen phthalate, KHP, with 0.163 M NaOH solution. She recorded an initial buret reading of 0.84 mL and a final buret ...
*March 7, 2012 by Cynthia *

**Chemistry**

When an aqueous solution of lithium chloride is mixed with an aqueous solution of ammonium sulfate a precipitate forms a new salt is formed a gas is evolved an acid and base are formed no reaction occurs I either thought it was a precipitate forms or no reaction occurs
*December 11, 2007 by Lauren*

**Chemistry**

Complete this table of initial and final concentrations HF(aq) + KOH(aq) <-> KF(aq) + H20(l) Initial concentrations: HF-2.0M KOH-1.0M KF-0M Final Concentrations? how do I set this up to figure out the final concentrations? How can I tell which of the following best ...
*July 16, 2013 by Cat*

**chemistry**

50.0 mL of a 0.00200 M Cd^2+ solution is titrated with 0.00400 M EDTA in the presence of 0.0750 M NH3 buffered at pH = 9.00. Determine pCd^2+ when 28.5 mL of EDTA solution have been added. Cd^2+ + Y^4- ? CdY^2- Kf= 3.16 x 10^16 Cd^2+ + NH3 ? CdNH3^2+ ß1 = 3.24 x 10^2 Cd^2+ + 2...
*August 13, 2013 by raghu*

**science**

I'm instructed to wrtie a full lab raport for a lab I did a couple of months ago. My aim was to find the most efficient concentration of fertilizer to grow red lentils. I planned to do this by taking the average of the number of lentils sprouted each day for eight days and ...
*March 8, 2014 by Anonymous*

**Chemistry**

You dissolve 5 g of calcium hydroxide in 2 liters of water. What is the molarity of the hydroxide ions in this solution? What is the molarity of the calcium ions in this solution?
*February 12, 2012 by Amanda*

**Math 116**

Identify the solution (s) of the system of equations, if any. x=1 y=1 (A) no solutions (B) (0,0) (c) (1,1) (D) infinitely many solutions Identify the solution (s) of the system of equations, if any. 3x-2y=6 5x=5-25y (A) (28/13, 3/13) (B) (-3/17, 32/17) (C) (2/17,-3/17) (D) (32...
*June 29, 2013 by Queta*

**Fun time**

A concentrated sulfuric acid solution is 65.0% H2SO4 by mass and has a density of 1.55 g/mL at 20°C. What is the mass of 3.00 L of the concentrated sulfuric acid solution?
*July 13, 2014 by Nickcole*

**Math**

Decide whether each equation has one solution, no solutions, or infinitely many solutions. 3(y-3)=2y-9+y A. One solution B. No Solutions C. Infinitely many solutions I did 3*y 3*3=9 2y=9+4 3-*=-6 x-27 Is the answer A?
*September 16, 2014 by Gwen*

**chemistry**

The pKb of ammonia solution, NH3(aq) is 4.76. A buffer solution contains NH4Cl and NH3, has a pH of 9.45, and a total ammonia concentration (all forms) of 0.400 M. What is the concentration of NH4+? (Hint: [NH4+] + [NH3] = 0.400 M)
*May 6, 2013 by Anonymous*

**chemistry**

Calculate the mass of salts needed for constructing a buffer using potassium monobasic phosphate and potassium dibasic phosphate with the total concentration of 100 mM. The solution is to be prepared in DI water and the pKa value for potassium monobasic phosphate is 7.21 and ...
*November 14, 2010 by dave*

**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*

**Physical science**

A silver nitrate solution is added to a solution of potassium chloride.the products formed are silver chloride and potassium nitrate 1.which product is a precipitate 2.write down the reaction in a molecular form.indicate states 3.write down the net ionic equation
*September 10, 2014 by Lesedi *

**Algebra**

Can you please check my answers? Solve the rational inequality and graph the solution set on a real number line. Express the solution set in interval notation. x-2/x+1 <0 my answer: (-infinity,-1) u (2, infinity) -x+8/x-3 > or equal to 0 my answer: (3,8] 2/x-2<1 my ...
*October 23, 2007 by Joss*

**Chemistry**

For idometric titration of copper, why is HCl added to KIO3 and then titrated immediatedly? What would happen if iodine-thiosulfate titration was done in a highly acidic solution? If the copper reaction solution was basic, how would the iodine-thiosulfate reaction be influenced?
*November 16, 2011 by Ken*

**Chemistry**

Given a diprotic acid, H2A, with two ionization constants of Ka1 = 4.5× 10–2 and Ka2 = 5.2× 10–7. Calculate the pH and molar concentration of each protonated form for a 0.133 M solution of NaHA. Calculate the pH and molar concentration of each protonated form for a 0.133 M ...
*October 2, 2012 by amanda1012*

**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**

A solution was made by dissolving 62.07grams of a compound in 500g of water. The compound was not ionic. The freezing point of the solution was measured and found to be -1.86degrees celsius. The molar mass of this compound can be calculated to be? I know I already posted this ...
*February 15, 2012 by Hannah*

**Calculus Help **

Farmer Brown wants to fence in a rectangular plot in a large field, using a straight rock wall that is already there as the north boundary. The fencing for the east and west sides of the plot will cost $3 a yard, but she needs to use special fencing, which will minimize the ...
*April 24, 2014 by Chris*

**chemistry**

An alternative approach to bomb calorimetry is toestablish the heat capacity of the calorimeter, exclusive of the water it contains. The heat absorbed by the water and by the rest of the calorimeter must be calculated separately and then added together. A 1.148g sample of ...
*October 11, 2014 by Nancy*

**chemistry**

A solution containing 80g of NaNO3 in 75g of H2O at 50 degrees celsius is cooled to 20 degrees celsius. A. how many grams of NaNO3 remain in solution at 20 degrees celsius? B. How many grams of solid in NaNO3 crystallized after cooling?
*November 21, 2012 by Boo Boo*

**physics**

Dry saturated steam at 100 degree C is passed into 250 gm of a mixture of ice and water contained in a calorimeter of thermal capacity 45J/K.When all the ice has just melted,the mass of the content has increased by 10 gm due to condensed steam.Assuming no heat exchange between...
*March 15, 2012 by AFOLABI .O.*

**Chemistry**

A 0.450-gram sample of impure CaCO3(s) is dissolved in 50.0 mL of 0.150 M HCl(aq). The equation for the reaction is: CaCO3(s)+2HCl(aq) -> CaCl2(aq) + H2O(l) + CO2(g) The excess HCl(aq) is titrated by 9.75 mL of 0.125 M NaOH(aq). Calculate the mass percentage of CaCO3(s) in ...
*April 10, 2012 by Katherine*

**Chemistry**

calculate the final concentration if 4.0 L of 1.5 M NaCl and 2.0 L of 3.0M NaCl are mixed. I am confused about how to calculate the final concentration. We are currently working on solutions. I think first I need to divide the amount of the solution by the amount of the solute...
*January 30, 2008 by Lori*

**Chemistry**

A solution is made by mixing 42.0 mL of ethanol, C2H6O, and 58.0 mL of water. Assuming ideal behavior, what is the vapor pressure of the solution at 20 C in torr? Values at 20C ethanol density: 0.789 g/mL & vapor pressure (torr): 43.9 torr water: denisty: 0.998 g/mL & 17.5 ...
*February 19, 2012 by Joy*

**calculus**

(A) Consider the wave equation with c=1, l=1, u(0,t)=0, and u(l,t)=0. The initial data are: f(x)=x(1-x)2, g(x)=sin2(pi x). Find the value of the solution at x=0, t=10, and at x=1/3, t=0. Find the value of the solution at x=1/2, t=2. (B) Suppose that l=2, c=1/2. Draw the domain...
*October 22, 2013 by lucy*

**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*

**statistics**

Salaries for various positions can vary significantly depending on whether or not the company is in the public or private sector. The U.S. department of labor posted the 2007 mean salary for human resource managers employed by the federal government, as &76, 503. Assume the ...
*August 2, 2014 by Corinne*

**Chemistry**

A buffer contains 5.00 M acetic acid and 5.00 M acetate anion. Gaseous HCl (0.010 mole) is added to 1.00 L of this buffer solution (the total volume does not change). For this buffer solution, the initial pH is_______and the final pH after the addition of the HCl gas is_______...
*May 2, 2010 by Ivana*

**Chemistry**

A student determined the H of neutralization of nitric acid (HN03) mixed with NaOH solution, using the procedure described in this experiment. Fifty milliliters of 1.00M HN03 was added to 50.5 mL of 1.00M NaOH solution, and the following time-temperature data were recorded. A ...
*May 1, 2013 by Mimi*

**calculus-differential equation**

Consider the differential equation: (du/dt)=-u^2(t^3-t) a) Find the general solution to the above differential equation. (Write the answer in a form such that its numerator is 1 and its integration constant is C). u=? b) Find the particular solution of the above differential ...
*February 5, 2008 by Jeff*

**Chemistry**

The triprotic acid H3A has ionization constants of Ka1 = 6.8× 10–3, Ka2 = 8.1× 10–9, and Ka3 = 5.0× 10–12. Calculate the following values for a 0.0760 M solution of NaH2A [H+] = ? [H2A-]/[H3A]= ? Calculate the following values for a 0.0760 M solution of Na2HA. [H+]= ? [HA2-]/[...
*February 26, 2013 by Nancy*

**chemistry**

At 25 °C, the density of a 50 % (by mass) ethanol/water solution is 0.914 g/cc. Given that the partial molar volume of water in the solution is 17.4 cc/mol, what is the partial molar volume of the ethanol?
*January 16, 2011 by syl*

**Chemitry**

3moles of sodium hydroxide will neutralize 1mole of citric acid,what volume of 2moles of sodium hydroxide solution will neutralize 50cm of citric acid solution?
*January 2, 2012 by Zuhur*

**Trig**

Use a graphical method to find a solution to the following system of equations in the interval –1 ≤ x ≤ 5: y = x2 – 4x + 2 y = x + 2 The solution set to this system of equations in the interval –1 ≤ x ≤ 5 is {} {(2, 0)} {(0, 2), (5, 7)} {(2, 0), (7, 5)}
*January 24, 2014 by Kiki*

**MAT222**

-x+4y=4 x-4y=-4 the system has no solution the system has a unique solution: the system has infinitely many solutions they must satisfy the following equation: y=0 the answer is the system has many solutions i just don't know the answer to the equation y=?
*September 1, 2014 by Kia*

**statistics**

The Vancouver Chamber of Commerce claims that the mean cost of hotels in the downtown area of the city is less than in Edmonton. A random sample of 50 hotels in Vancouver (population 1) had a mean nightly rate of $109 with a standard deviation of $15. An independent sample of ...
*March 27, 2015 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. I understand the...
*February 28, 2013 by Please help*

**STATISTICS**

The number of boxes of girl scout cookies sold by each of the girl scout in a city has a distribution which is approximately normal with a mean=75 boxes and a standard deviation=30 boxes.... 1.) find the probability that scout chosen at random sold between 60 and 90 boxes. 2...
*August 10, 2011 by Mason*

**quantitative chemistry **

Consider a solution made by mixing 500.0 mL of 0.04182 M Na2HAsO4 with 500.0 mL of 0.03645 M NaOH. Complete the mass balance expressions below for Na and arsenate species in the final solution. There are 4 arsenate species, but I only got three of them. I am unsure of what the...
*March 22, 2013 by Jackie*

**Pre-Calc**

An open box with a volume of 1500cm^3 is to be constructed by taking a piece of cardboard of 20 cm by 40 cm, cutting squares of sides length x cm from each corner and folding up the sides. Show that this can be done in two different ways, and find exact dimensions of the box ...
*January 14, 2014 by Andy G*

**Science**

an aquatic plant known as elodea is shown in the image below. If you observe Elodea leaves over a period of several minutes, you see bubbles forming on the leaf surface that eventually break away and rise to the surface of the water. These bubbles form as a result of ...
*March 4, 2015 by Indigo Aivery*

**statistics HELP!**

A data set includes body temperatures of healthy adult humans for which 98.1F and s= 0.56F. What is the best point estimate of the mean body temperature of all healthy humans? Using the sample statistics, construct a confidence interval estimate of the mean body temperature of...
*December 16, 2014 by Jenny*

**Math**

5. The following random sample was selected : 4, 6, 3, 5, 9, 3. Find the 95% confidence interval for the mean of the population. 6. In a sample of 35 high school seniors, 14 of them are attending college in the fall. Find the 95% confidence interval for the true proportion of ...
*May 9, 2013 by Anonymous*

**chemistry**

The triprotic acid H3A has ionization constants of Ka1 = 9.9× 10–2, Ka2 = 2.7× 10–8, and Ka3 = 5.9× 10–11. a). Calculate the following values for a 0.0570 M solution of NaH2A H+ ?? [H2A^-/H3A]?? b). Calculate the following values for a 0.0570 M solution of Na2HA. H+ ?? [HA^2-/...
*March 28, 2013 by Laura*

**Math**

Hi! Can someone help me with these? I just learned about them yesterday but I'm really confused. All my teacher wants me to do is solve each equation and that's all the directions she gave. Thanks so much! 1.) 3cot^2 x-1=0 Location on Unit Circle: Period: General Solution: 2...
*January 24, 2015 by Stephanie*

**statistics **

A random sample of the houses in a particular city is selected and the level of radon gas is measured for each house in the sample. The values collected are given below in parts per million (ppm). Experience has shown that radon gas level is approximately normally distributed ...
*March 26, 2012 by tea*

**lesson planning**

Where could I find a sample unit that focuses on animals that live in water?
*March 23, 2008 by Ashley*

**chemistry**

In the solid phase extraction and fractionation of grape juice, why is the ph of the sample adjusted to 7?
*December 9, 2008 by Johnjoe*

**chemistry**

describe how to prepare laboratory test Co2 through a dry sample?
*February 11, 2009 by dickson omari*

** chemistry**

A sample of C3H8O that contain 200 molecules contains ________carbon atoms??
*September 13, 2009 by Mercy*

**chemistry**

A sample of silver chromate (Ag2CrO4) has a mass of 29.0 g. How many CrO42- ions are present?
*January 20, 2010 by w*

**statistics**

If sample number is 1,000 and mean is 7.2 on a scale from 1-10 how do I determine standard deviation.
*February 13, 2010 by mark*

**Chemistry**

How do i calculate the amount of heat required to raise the temperature of an 89 sample of water from 40 to 60.
*February 20, 2010 by Kesha*

**chemistry**

what is the pressure exerted by a 0.500 mol sample of nitrogen in a 10.0 L container at 20 degrees C?
*April 8, 2010 by james*

**Chemistry**

a gaseous sample occupies 32.4 mL at -23 degrees C and 0.75 atm. What volume will it occupy at STP?
*June 3, 2010 by Anonymous*

**Chemistry**

Calculate the amount of heat required to raise the temperature of a 54 g sample of water from 5°C to 20.°C.
*September 15, 2010 by Ben*

**chemistry**

Calculate the amount of heat required to raise the temperature of a 25 sample of water from 7 to 25.
*September 20, 2010 by Anonymous*

**10th grade**

What would be the percentage composition of carbon in 10g sample of methane is?
*September 27, 2010 by Sibusiso*

**chemistry**

what would be the mass of an Au sample whose volume is 2.85mL?( the density of gold is 19.3g/mL)
*October 3, 2010 by Jazz*

**chemistry**

what would be the mass of an Au sample whose volume is 2.85mL?( the density of gold is 19.3g/mL)
*October 3, 2010 by Jazz*

**physical science**

a sample of metal has a mass of 100 g and a volume of 2mL what is its density?
*November 10, 2010 by Max*

**chemistry**

How many grams of H2(g)can theoretically be produced from a 5-g sample of magnesium metal and excess HC1(aq)?
*November 11, 2010 by Brit*

**College Chemistry**

A 50.0 mL sample of 6.0 M HCL is dulited to 200.0 mL. What is the new concentration of the acid?
*December 8, 2010 by Sa ndra*

**10th grade**

How many grams of water vapor (H2O) are in a 10.2 liter sample at 0.98 atmospheres and 26°C?
*December 20, 2010 by jeremy*

**chemistry **

What substance could be used to test if a sample of petrol contains any water as an impurity?
*January 22, 2011 by anonymous*

**Chemistry**

what would be the effect on a chromatographic peak of introducing the sample at too slow a rate
*January 31, 2011 by noel*

**Chemistry**

If you were given 0.021 milligrams of the compound,H3PO4, what would the mass of H in the sample be?
*February 16, 2011 by Ariana*

**chemistry**

a 25.0 sample of nitrogen has a volume of 50.0L and a pressure of 630. mmHg. what is the temperature of the gas?
*March 29, 2011 by Anonymous*

**Statistics**

in populations that are different from others. I would like to figure a sample of 10 with a mean of 44
*March 25, 2011 by Carmen*

**Chemistry**

What is the pressure exerted by a .500 mol sample of nitrogen in a 10.0L container at 20C?
*May 2, 2011 by Morgan *

**medical office asistant**

does anyone have a sample of a penn foster discharge summary
*June 26, 2011 by Anonymous*

**chemistry**

at what temperature will a gas sample occupy 6.6L if it originally occupies 14.1L at 14.4 degrees celcius
*June 29, 2011 by cindy*

**algebra**

The weight of a rock sample is measured to be 2.5 pounds. What is the percent of error in the measurement?
*July 28, 2011 by Sally*

**science**

a sample of metal has a mass of 94.5 grams and a volume of 7 cubic centimeters. what is its density?
*September 12, 2011 by zeke*

**science**

A sample of metal has a mass of 94.5 grams and a volume of 7 civic centimeters. What is its density?
*September 18, 2011 by sarah*

**science**

Find the mass of 1.6 mol of magnesium, Mg. How many atoms are present in such a sample?
*October 25, 2011 by Sheryl*

**chemistry**

if a sample of NO2 gas has 4.5ml. what is the cooled constant pressure from 45 to 5 degrees?
*November 6, 2011 by kp*

**Chemistry**

What is the strongest intermolecular force in a sample of butanoic acid, and why? H H H O . . . .. H .C .C. C .C .O.H . . . H H H Is this structure right?
*November 16, 2011 by Sam*

**Chemistry**

A sample of 50.0 mL if sulfuric acid that has a density of 1.84 g/mL would have a mass of how many grams?
*February 6, 2012 by Mike*

**statistics**

Select a sample of 20 individuals and the test the hypothesis =225 for IQ level. Use a=0.05
*February 14, 2012 by Anonymous*

**Chemistry honors**

You have 2.657 x 10^2 mL of oxygen gas (O2) at 7.02 x 10^2 mm of Hg and 46 oC. What is the mass of the sample in milligrams?
*March 22, 2012 by haley*

**Chemistry**

How many grams of H2(g) can theoretically be produced from a 5-g sample of magnesium metal and excess HCl(aq)?
*April 2, 2012 by Polly*

**Chemistry**

A 55.0-mg sample of Al(OH)3 is reacted with 0.200M HCl. How many milliters of the acid are needed to neutralize the Al(OH)3.
*May 1, 2012 by Emily*

**Finite Math**

Let A,B be events in a sample space. you are given the following probabilities: P(A)=0.8, P(B|A)=0.3, P(B|A^c)=0.8 Find: 1) P(B) 2) P(A|B) 3) P(A^c|B^c)
*July 23, 2012 by Preet*

**basic statistics**

What is construct a 95 percent confidence interval about the sample mean N= 11?
*August 6, 2012 by Tracy*

**chemistry **

the density of alcohol is 0.789 g/ ml at 20 degree celcius . calculate the mass of a 30 ml sample?
*August 28, 2012 by CHEM HELP*

**chemistry**

calculate the volume in milliliters of a 5.55g sample of solid with density of 3.67g/ml
*September 26, 2012 by nikki*

**chemistry**

What is the density of a sample of 65.0mL of automobile oil having a mass of 59.82g
*October 1, 2012 by tina sayers*

**chemistry**

what is the molarity of the acid in when a 30mL sample of HCl is titrated with 10mL of 6M NaOH?
*November 24, 2012 by Boo Boo*

**chem**

How many moles of CoCO3 are there if sample has 2.84 times 10 to the 16th power carbonate particles
*November 29, 2012 by punkin*

**chem **

what is the number of moles of manganese (II) iodide in a sample whose mass is 650 g?
*December 18, 2012 by simon*

**Science**

If you are given a sample containg 1.204 x 10 24 molecules of NaCl, what is its weight in grams?
*February 5, 2013 by DeAnna*

**chemistry**

How many moles are contained in 3.25 L sample of an ideal gas at 25 Celsius and 204 kPa?
*April 6, 2013 by Shellby*

**Problem**

If an Elements has a half life of 20mins what is the radioactive decay of a 200gram sample?
*June 11, 2013 by Half life*

**chemistry lab**

obtaining a smaller amount of sio2 than was present in the original sample
*October 4, 2013 by miranda*

**chem**

If 7.59 moles of an ideal gas has a pressure of 4.41 atm, and a volume of 71.59 L, what is the temperature of the sample?
*December 1, 2013 by dinah*

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