Thursday
March 23, 2017

Number of results: 1,709

Physics
(1) A bullet of mass 1.9×10−3 kg embeds itself in a wooden block with mass 0.987 kg, which then compresses a spring (k = 120 N/m) by a distance 3.5×10−2 m before coming to rest. The coefficient of kinetic friction between the block and table is 0.42. What ...
October 8, 2010 by Fred

Physics
Which provides more cooling for a styrofoam cooler, one with 10 lbs of ice at 0 degrees C or one with 10 lbs of ice water at 0 degrees C. Explain. qice=mass*heat of fusion. qH2O=mass*specific heat x delta T However, you aren't given a two temperatures; therefore, you can't ...
November 21, 2006 by Erica

chemistry
A solution was made by dissolving 62.07 grams of a compound in 500.0 g of water. The compound was not ionic. The freezing point of the solution was measured and found to be – 1.86oC. Using the Kf value in your textbook , the molar mass of this compound can be calculated to ...
February 5, 2012 by Anna King

physics
A firefighter at street-level, 55.0 m away from a burning building, directs a stream of water from a fire hose at an angle of 35.0° above the horizontal. If the speed of the stream is 50.0 m/s, at what height will the stream of water strike the building? I started by finding ...
May 16, 2007 by micole

physics (momentum)
A 3 kg ball with an initial velocity = (4.00i + 3.00j)m/s collides with a wall and rebound with a final velocity = (-4.00i + 3.00j)m/s. The ball is in contact with the wall for delta t =2.00E-3s. (specify answers with unit vectors) a) what is the change in the ball's momentum...
April 3, 2007 by Jay

Chemistry
The following reaction can be used to determine the amount of calcium ion present in milk. Before the reaction below is carried out ca2+ is precipitated out of a sample of milk as CaC2O4(s). The CaC2O4(s) is then titrated with MnO4-. 2MnO4-(aq) + 5CaC2O4(s) + 16H+(aq) = 2Mn2+(...
March 29, 2011 by John

AP CHEM
I'm currently working on a lab in which I have to make the solution boil at 245 degrees F. The solution will be a mix of ethylene glycol and I have to caluculate the volumes of water and solute needed to make the solution. here's my work so far. X= mL C2H4(OH)2 175mL-X=mL H20 ...
February 10, 2008 by Jonathan

I really need help on this problem... ===================== Hydrocarbon Formula Delta H (kj/mol) 1,3-Butadiene C4H6(g) 111.9 a) calculate the fuel value in kJ/g for this compound and determine the percentage of hydrogen by mass. I've tried it for hours yet I can't figure out ...
January 9, 2007 by Jina

Finding the Molecular Formula
A certain compound containing only carbon and hydrogen was found to have a vapor density of 2.550 g/L at 100 degrees C and 760 mm Hg. If the empirical formula of this compound is CH, what is the molecular formula of this compound? I had some ideas as to how to solve this ...
December 8, 2012 by Amy

GEOGRAPHY
1)The branches of rivers within a delta are called:(a)tributaries(b)confluences(c)distributaries(d)meanders 2)All of the following are conditions that m,ust be met so that deltas may form except:(a)steep drop in the sea floor(b)area protected from strong ocean currents(c)...
March 8, 2010 by Devaughn

chemistry- can you check my answers?
can you please check my answers?? 9. For the following reaction delta H=2816 kj. 6 CO2(g) + 6 H2O(l) -> C6H12O6(s) + 6O2(g) how is the equilibrium yeild of C6H12O6(s)affected by each of the following? a) increasing pressure of CO2 increase decrease no effect Answer: ...
April 20, 2011 by Lily

Chemistry
Compounds like CCL2F2 are known as chloroflourocarbons, or CFCs. These compounds were once widely used as refrigerants but are now being replaced by compounds that are believed to be less harmful to the environment. The heat of vaporization of CCl2F2 is 289J/g. What mass of ...
December 14, 2006 by Jenn

Physics
The Earth has an electric field with magnitude roughly 100 N/C at its surface. A) Assuming there is a point charge at the earth's center creating this field, how much charge does the earth posses? Treat the earth as a sphere of radius 6.37 * 10^6 m. B)As the earth orbits the ...
March 6, 2008 by jenish

Chemistry
I had to perform an experiment for the freezing point depression in which we had to determine the frezzing points of water as a pure solvent, sodium chloride, sucrose, and ethylene glycol. We had to work with a partner so I completed the experiment for water, NaCl, and the ...
February 18, 2012 by Hannah

Physics
The Achilles tendon, which connects the calf muscles to the heel, is the thickest and strongest tendon in the body. In extreme activities, such as sprinting, it can be subjected to forces as high as 13.0 times a person's weight. According to one set of experiments, the average...
November 13, 2007 by Christina

Physics
A cannon shoots a cannonball with an initial speed of 25 m/s at an angle 13. 1. What is the x component of the cannonballs initial velocity Vox? 2. What is the y component of the cannonballs initial velocity Voy? 3. What will be Vy, the y component of the cannonballs final ...
February 17, 2014 by Michelle

Physics
A cannon shoots a cannonball with an initial speed of 25 m/s at an angle 13. 1. What is the x component of the cannonballs initial velocity Vox? 2. What is the y component of the cannonballs initial velocity Voy? 3. What will be Vy, the y component of the cannonballs final ...
February 19, 2014 by Michelle

physics
In a crash test, a truck with mass 2600 kg traveling at 24 m/s smashes head-on into a concrete wall without rebounding. The front end crumples so much that the truck is 0.66 m shorter than before. What is the average speed of the truck during the collision (that is, during the...
November 21, 2010 by Confused again

ap chemistry
I have a lot of questions actually. it's electrochemistry (which is obviously a bunch of fun) 2 electrodes Cr(s)/Cr3+ and Sn(s)/Sn2+ are combined to afford a spontaneous electrochemical reaction. the standard reduction potention in V for Cr3+ and Sn2+ are -.74 and -.14 V ...
May 4, 2009 by raaawr

physics
lead is a soft, dense metal with a specific heat of 0.028 kcal/kg degrees C, a melting point of 328.0 degrees C and a heat of fusion of 5.5 kcal/kg. How much heat must be provided to melt a 250.0 kg sample of lead with a temperature of 20.0 degrees Celsius? q1 = heat to move ...
November 21, 2006 by Erica

CHEMISTRY
really really need help w/this problem I think i figured it out but i have to be sure i did it right in order to do others similar to it please help thanks Metal Specific Heat (J/g-C) Al (s) 0.900 Au(s) 0.129 Cu(s) 0.385 Fe(s) 0.444 Hg(l) 0.139 H2O(l) 4.184 C2H5OH(l) 2.46 A ...
October 24, 2010 by christine

chemistry
When 27.20mL of .5 M H2SO4 is added to 27.20 of 1M KOH in a coffee cup calorimeter at 23.5 degrees C, the temp rises to 30.17 degrees C. Calculate delta H of this reaction. (Assume that the total volume is the sum of the individual volumes and that density and specific heat ...
October 15, 2015 by patrick

chemistry
When 27.20mL of .5 M H2SO4 is added to 27.20 of 1M KOH in a coffee cup calorimeter at 23.5 degrees C, the temp rises to 30.17 degrees C. Calculate delta H of this reaction. (Assume that the total volume is the sum of the individual volumes and that density and specific heat ...
October 15, 2015 by patrick

chemistry
When 27.20mL of .5 M H2SO4 is added to 27.20 of 1M KOH in a coffee cup calorimeter at 23.5 degrees C, the temp rises to 30.17 degrees C. Calculate delta H of this reaction. (Assume that the total volume is the sum of the individual volumes and that density and specific heat ...
October 16, 2015 by patrick

chemistry
When 27.20mL of .5 M H2SO4 is added to 27.20 of 1M KOH in a coffee cup calorimeter at 23.5 degrees C, the temp rises to 30.17 degrees C. Calculate delta H of this reaction. (Assume that the total volume is the sum of the individual volumes and that density and specific heat ...
October 16, 2015 by patrick

chemistry help DR. BOB
When 27.20mL of .5 M H2SO4 is added to 27.20 of 1M KOH in a coffee cup calorimeter at 23.5 degrees C, the temp rises to 30.17 degrees C. Calculate delta H of this reaction. (Assume that the total volume is the sum of the individual volumes and that density and specific heat ...
October 16, 2015 by patrick

Chemistry
Zinc dissolves in acid according to the balanced reaction: Zn(s) + 2H^+(aq) -> Zn^2+(aq) + H2(g) A sample of zinc is placed in the ice calorimeter. If 0.0657g of zinc causes a decrease of 0.109mL in the ice/water volume of the calorimeter, what is the enthalpy change, per ...
October 15, 2012 by Kjd

Physics
I'm trying to prep for an exam, but I am struggling with the practice questions. I have answers for both questions, but I'm 95% sure they are incorrect. 1. Two students decide to run a race. The first student starts off at a constant speed of 5 m/s while the second student isn...
June 19, 2011 by Chelsea

Hey guys I did a lab and I have to answer the questions relating to the lab. I did question can someone please check if these are accurate 1. Calculation to Determine the molecular weight of unknown substance Mass of unknown used: 2.0 g Mass of water used: 50.0 g (0.05kg) Kf...
May 27, 2009 by Saira

Engineering Physics
A car and a train move together along straight, parallel paths with the same constant cruising speed v(initial). At t=0 the car driver notices a red light ahead and slows down with constant acceleration -a(initial). Just as the car comes to a full stop, the light immediately ...
September 16, 2009 by Andrew Rozmarynowycz

World History
True or false. if false, what is the true statement? 1. To ancient egyptians, the most important feature of the river was the many fish that lived in it. 2. Ancient Egyptian civilization was marked by constant change and upheaval over the centuries. 3. Osiris took on an ...
September 5, 2013 by unknown

Chemistry
-CORRECTION- N2 + O2 --> 2 NO change in heat (delta H)= 43.2 kcal based on the reaction, which statement is true? a) 43.2 kcal are consumed when 1.00g of O2 reacts b) 43.2 kcal are consumed when 1.00g of N2 reacts c) 43.2 kcal are consumed when 1.00g of NO is produced d) 43...
November 2, 2009 by Katie Y.

chemistry
A 100.0 ml sample of 0.300 M NaOH is mixed with a 100.0 ml sample of 0.300 M HNO3 in a coffee cup calorimeter. Both solutions were initially at 35.0 degrees celcius; the temperature of the resulting solution was recorded at 37.0 degrees celcius. Determine the delta H (in units...
July 12, 2012 by jen

chemistry/check my work I have to submit today
When 27.20mL of .5 M H2SO4 is added to 27.20 of 1M KOH in a coffee cup calorimeter at 23.5 degrees C, the temp rises to 30.17 degrees C. Calculate delta H of this reaction. (Assume that the total volume is the sum of the individual volumes and that density and specific heat ...
October 16, 2015 by patrick

Chemistry
Ethanol boils at a temp. of 78.29 degrees C. What amount of energy, in joules, is necessary to heat to boiling and then completely vaporize a 23 g sample of ethanol initially at 12 degrees C? I know that the molar enthalpy heat of vaporization is 35.56 kJ/mol and the specific ...
May 14, 2007 by Lindsay

Physics
A 70.0 kg base runner begins his slide into second base while moving at a speed of 4.0 m/s. The coefficient of friction between his clothes and Earth is .70. He slides so that his speed is zero just as he reaches the base. How much mechanical energy is lost due to friction ...
December 5, 2006 by Becca

Calculus
Consider the function f(x)=(5^x−1)/x. A) Fill in the table values for f(x): x= -0.1, -0.01, -0.001, -0.0001, 0.0001, 0.001, 0.01, 0.1 f(x)= 1.4866, 1.5866, 1.6081, 1.6093, 1.6096, 1.6107, 1.6225, 1.7462 B) Based on the table values, what would you expect the limit of f(x...
September 20, 2012 by Sofia

CHEMISTRY
I put down all the info that I found but I cant figure out the questions 1 & 2 at the bottom!! Empty Calorimeter- 11.6 g Room temp - 21 degrees celcius Three different experiments of 50mL 1(M) HCl reacts with 0.15 g Mg, 0.25g Mg, and 0.35g Mg respectively. The maximum ...
November 8, 2010 by Anonymous

lititure
what are the cause and effect of these things in brave new world? In fiction, as in life, events have causes and, in turn, become causes of subsequent events. Here are some events from Brave New World. Write a sentence that describes a major cause of each event and another ...
November 29, 2011 by amber

Just a repost, in case the old isnt seen
sorry! I never noticed..the mass should be 52000kg sorry about that! For Further Reading physics repost - Alexis, Sunday, October 14, 2007 at 6:07pm so it should be a 52000kg train slows from 25 m/s to 14m/s in 5.0 s. Calculate the work done on the train. so I found the ...
October 14, 2007 by Alexis

science
The specific heat capacity of the lava is 1600 J kg -1 degrees Celsius -1 . When all the erupted lava cools from the eruption temperature of 1050 degrees Celsius to 15 degrees Celsius, the heat released is 2 x 10 15 J. Calculate a value for the total mass of lava that erupted...
May 9, 2007 by k

Physics
At bat a baseball player hits a ball at a height of .889 m. The ball leaves the bat at 51 m/s at an angle of 81 degrees from the vertical. The ball skims the top of a 2.74 m wall as it leaves the field. a.) Draw position, velocity and acceleration graphs describing the ball ...
September 11, 2014 by Anonymous

physics
I have a question based off of the response to the question I posted below. Sorry, i wanted to make sure that i clearly understood,so My question about the third solution is: Is the horizontal force zero N? or is it 721.3N? A dragster and driver together have mass 918.8 kg. ...
July 3, 2011 by alexa

Chemistry
Which solution has the lower freezing point? (a) 90.0 g CH3OH in 100. g H2O 180.0 g CH3CH2OH in 200. g H2O (b) 70.0 g H2O in 1.00 kg CH3OH 70.0 g CH3CH2OH in 1.00 kg CH3OH delta T = Kf m convert 90 g CH3OH to mols mols/kg solvent = m (kg solvent = 0.1) do the same for 180 g ...
January 21, 2007 by Stuck

Music
1. How did the music business change in the early 1970s? 2. In what ways did rock music become more conservative in the 1970s? 3. Name three technological advances in sound or recording that helped change rock in the late 60s and early 1970s. 4. Name three new "styles" of rock...
July 17, 2012 by Jehu Milord

Can you please check my answers. I made the answers in capital letters. Directions, Choose the simple subject in each sentence. 1. The annual kite contest takes place this weekend. KITE 2. Fifty contestants are competing for first prize this year. CONTESTANT 3. The rules ...
September 2, 2009 by Claire

Chemistry
I have a few question about an equilibrium lab we performed. Approximately .1 g of CoCl2 * 6H2O was mixed with 2 mL of 12 M HCl. The solution turned blue. Then, water was added and stirred into the solution in 2 mL incriments until no further color change occured- the final ...
May 29, 2007 by Kim

Physics
1) a car moving at 50km/h crashes Into the barrier and stops in 0.25 m a) if a 10kg child were to be stopped in the same time , what is the average force must be exerted ? c)approximately what is the mass of an object whose weight equals to the force in Part b?Could you lift ...
April 13, 2013 by Malak

Chemistry
Given data collected for a liquid. Equilibrium vapor pressure in torr: 4.6, 17.5, 149.4, 525.8 T in *C 0., 20., 60., 90. *Find T in K, Find 1/T in K-1 and 1n VP. *Then make a graph of 1n vapor pressure (1n VP) versus 1/T (where temperature is in units of Kelvins.) Using linear...
July 29, 2008 by Anonymous

Thermodynamics
Hi, I am trying to do a prelab and I am really stuck... I have no idea how to go about this, I don't knwo if its worded funny or waht, so any help would be greatly apprecaited. The question is: (This is for a bomb calorimeter of constant volume) Benzoic acid is often used to ...
October 3, 2007 by Tracy

MATHS
demand function for kerosene: Kd=a0+a1Pk supply function for kerosene: Ks=b0+b1Pk+b2Pg demand function for gasoline: Gd=c0+c1Pg+u1 (ul here shows a exogenous random shock to the demand of gasoline) supply function for gasoline: Gs=d0+d1Pk+d2Pg a) if gasoline and kerosene are ...
September 9, 2010 by May

chemistry
1(a) when 25.0ml of 0.500 mol.dm3 H2SO4(AQ) SOLUTION IS added to 0.025dm3 of 1.00 moldm3 KOH SOLUTION , THE TEMPERATURE OF THE REACTION MIXTURE RISES FROM 23.50 CELCIUS TO 30.17 CELCIUS . THE SPECIFIC HEAT CAPACITY AND DENSITY OF WATER 4.20j.g.celcius and 1.00 g.cm. the ...
February 9, 2012 by mustafe

Chemistry Lab
Data and Calculations: 1. Volume of water in calorimeter: 100.0 mL 2. Mass of water in calorimeter (water's density 1.00g/mL): 100.0g 3. Initial Temperature of water in calorimeter:19.5 degrees Celsius 4. Final Temperature of water in calorimeter: 3.0 degrees Celsius 5. Final ...
February 7, 2017 by Coolest

physics
A ball is tossed from an upper-story window of a building. The ball is given an initial velocity of 9.50 m/s at an angle of 24.0° below the horizontal. It strikes the ground 5.00 s later. (a) How far horizontally from the base of the building does the ball strike the ground? ...
May 16, 2007 by micole

Physics
A uniform cylindrical spool of mass M and radius R unwinds an essentially massless rope under the weight of a mass m. If R = 12 cm, M = 400 gm and m = 50 gm, find the speed of m after it has descended 50 cm starting from rest. Solve the problem twice: once using Newton's laws ...
March 31, 2015 by Nora

Inorganic Chemistry
Which aqeuous solution has a freezing point closest to that of 0.30M C12H22O11? A) 0.075M AlCl3 B) 0.15M CuCl2 C) 0.30M NaCl D) 0.60M C6H12O6 I know the answer but I don't know the reason or rationale behind it. Please explain. I suggest you review Raoult's Law at http://...
August 5, 2007 by Vic

Chem 1
Given the bond energy data below, which is the best prediction for the bond energy of the bond between the nitrogen and the oxygen atom in N2O? bond energy (kJ/mol) N-O single bond 201 N-O double bond 607 Indicate if it will be the single bond, double bond or an intermediate ...
November 16, 2006 by Rossina

chemistry
A calorimeter consists of an interior metal bomb (container) surrounded by 2.22 kg of water all contained within an insulated exterior wall. A sample of propane, C3H8, weighing 6.89g, was burned in the calorimeter with excess oxygen. As a result of the combustion, the interior...
July 16, 2008 by Anonymous

thermochemistry
what is the enthalpy change in kilojoules for the combustion of 1 mol of ethanol, C2H5OH (l), to form gaseous carbon dioxide and gaseous water? use bond energies to calculate your answer. (hint: there is a double bond in carbon dioxide and oxygen) the answer is supposed to be...
January 23, 2007 by Sienna

DrBob222
I know I posted this but you didn't answer! Please help!!!! Consider the following reaction at 298 K: C(graphite) +2Cl2 (g) -----> CCl4(l) Calculate the following quantities. Delta H: -139 kJ/mol deltaS(sys)=? J/mol*K deltaS(surr)=? J/mol*K deltaS(univ)=? J/mol*K My answer ...
March 15, 2012 by Kelsey

physics
a.)At rest, a car's horn sounds at a frequency of 410 Hz. The horn is sounded while the car is moving down the street. A bicyclist moving in the same direction with one-third the car's speed hears a frequency of 381 Hz. What is the speed of the car? b.)Is the cyclist ahead of ...
August 5, 2007 by sanchi

Physics
An ice chest at a beach party contains 12 cans of soda at 3.05 °C. Each can of soda has a mass of 0.35 kg and a specific heat capacity of 3800 J/(kg C°). Someone adds a 7.15-kg watermelon at 25.0 °C to the chest. The specific heat capacity of watermelon is nearly the same ...
November 17, 2006 by Sara

Chemistry
I need to calculate the molecular mass of ehtylene glycol based on the freezing point depression. The teacher said that for glycol i=1 and to use the equation m=delta T / Kf X i Kf = -1.86C/m so I did -2.5C / -1.86 X 1 = 1.344 I know that 1.344 can't be the weight for glycol ...
February 21, 2012 by Hannah

Chemistry
A 63 gram block of an unknown metal at 88 degrees C was dropped into an insulated flask containing approx. 30 g of ice and 30 g of water at 0 degrees C. After the system had reached a steady temp. it was determined that 12.1 g of ice had melted. What is the specific heat of ...
May 15, 2007 by Lindsay

more thermo
For the following question I was able to find the heat transfer and the entropy but I am having trouble finding the work done. When i solved delta E = Qnet - Wnet I got Win = Wout but Im not sure that is correct. I think that i need to solve for the final temp and pressure but...
June 18, 2007 by jody

Chemistry DR BOB help!!
I don't know why it was marked wrong. This is what it said: Where is the 5.64 coming from? (thank you) HINT To balance the equation, make sure that the number of each atom on the reactant side is the same as the number on the product side. Should the enthalpy change for this ...
October 20, 2015 by patrick

Chemistry DR BOB help!!
I don't know why it was marked wrong. This is what it said: Where is the 5.64 coming from? (thank you) HINT To balance the equation, make sure that the number of each atom on the reactant side is the same as the number on the product side. Should the enthalpy change for this ...
October 20, 2015 by patrick

chemistry..anybody!
I don't know why it was marked wrong. This is what it said: Where is the 5.64 coming from? Is this a typo?(thank you) HINT To balance the equation, make sure that the number of each atom on the reactant side is the same as the number on the product side. Should the enthalpy ...
October 21, 2015 by patrick

S.S (DAMON)
1.B 2.A 3.D 4.B 5.B 1. A tropical climate is key to which economic activity in the lowlands of central emerica and the carribean? A. commerce and manufacturing B. production of cash crops C. animal husbandry D. mining 2. Which country has the regions most stable democracy? A. ...
March 13, 2014 by dalia

Physics
The De-orbit Burn The Shuttle must reduce its velocity at a pre-calculated point in its orbit in order to return to Earth. In order to reduce the velocity and change the orbit of the Shuttle, a maneuver called the de-orbit burn is performed. For this maneuver, the Shuttle is ...
December 28, 2011 by Rory

Physics
A cross country team race is about to begin and team Delta decides to use their one-dimensional kinematics knowledge that they learned from their first year physics course. Each team consists of two people and one horse. The clock is started when the team crosses the starting ...
September 12, 2011 by victor

S.S (DAMON)
please check these answer damon or anyone else 1. A tropical climate is key to which economic activity in the lowlands of central emerica and the carribean? A. commerce and manufacturing B. production of cash crops C. animal husbandry D. mining 2. Which country has the regions...
March 13, 2014 by dalia

Chem
Chloroform, CHCl3, was once used as an anesthetic. In spy movies it is the liquid put in handkerchiefs to render victims unconscious. Its vapor pressure is 197 mmHg at 23 degrees C and 448 mmHg at 45 degrees C. Estimate its a) heat of vaporization b) normal boiling point I ...
March 19, 2007 by Chris

English
Africa was one of the sites where agriculture began. Archaeological investigations suggest that knowledge of cultivation moved west from the ancient Judaea (southern Palestine) and arrived in the Nile Delta in Egypt about the fifth millennium before Christ. Settled agriculture...
March 14, 2013 by Amy

Physics question help/ check my answers
The middle two question please check my answers and tell me if I am correct or if there is something I am missing. The first and the last question I need help to understand and complete it. Thank you in advance!!! 1. What is the electric force between a +2 µC point charge and...
May 8, 2014 by Brianna

Chemistry
I just wanted to see if my answers made sense. 1. What effect would each of the following have on your calculated value of Kf (too high, too low, or no effect)? In each case explain your answer. a) There was a small bubble in the thermometer, causing all the temperature ...
June 2, 2013 by Jason

Physics - Repost because of no response
1. A stationary curling stone is struck in a glancing collision by a second curling stone of equal mass. If the first stone moves away at a velocity of 0.92 m/s [N71oW] and the second stone moves away at a velocity of 1.25 m/s [N44oE], what was the initial velocity of the ...
January 19, 2016 by Chanz

Chemistry
Construct a cooling curve (looks the same as a heating curve) for a substance with a molar mass of 200 that has a gas phase specific heat capacity of 2.9J/g K, a boiling point of 525 K,a liquid phase specific heat capacity of 3.24 J/g K, a freezing point of 352 K, a solid ...
February 7, 2016 by Neveah

Physics - Am I correct?
1. A stationary curling stone is struck in a glancing collision by a second curling stone of equal mass. If the first stone moves away at a velocity of 0.92 m/s [N71oW] and the second stone moves away at a velocity of 1.25 m/s [N44oE], what was the initial velocity of the ...
January 19, 2016 by Chanz

SCIENCE
What type of bonding holds the compound, sodium cyanide, together? The CN bond is covalent. The Na to CN bond is, in most minds, an ionic bond. The electronegativity of C is about 2.1 and that of Na is about 1; therefore, with a difference of about 1 it is polar covalent. ...
February 7, 2007 by MARK

math
Take the greatest care with your significant digits. If you don’t, this question is not “do-able”. Llyn y Gweision (a Welsh lake) has a surface area of 10 km2. It is fed by two rivers: the Afon Chwefru and the Nant Aeron. The Chwefru has a catchment area of 1250 km2. The...
October 27, 2009 by mohan

chemistry
is that a -56? Dr. BOb. thank you When 27.20mL of .5 M H2SO4 is added to 27.20 of 1M KOH in a coffee cup calorimeter at 23.5 degrees C, the temp rises to 30.17 degrees C. Calculate delta H of this reaction. (Assume that the total volume is the sum of the individual volumes and...
October 17, 2015 by patrick

chemistry-Dr Bob
is that a -56? Dr. BOb. thank you When 27.20mL of .5 M H2SO4 is added to 27.20 of 1M KOH in a coffee cup calorimeter at 23.5 degrees C, the temp rises to 30.17 degrees C. Calculate delta H of this reaction. (Assume that the total volume is the sum of the individual volumes and...
October 18, 2015 by patrick

LAB!!
I have to find the molar enthalpy of combustion of pentane. I have this info: 5C(s) + 6H2 >>> C5H12 Hf= -173.5kJ C+O2>>> CO2 Hf= -393.5kJ H2 + 1/2O2 >>> H2O Hf= -241.8kJ H2O >>> H2O Hf= +44.0kJ THEN I am given this: mass of pentane= 2.15g ...
August 6, 2006 by Hey!

1. Annie Webb Blanton accomplished all of the following EXCEPT (1 point) found Delta Kappa Gamma. serve as a professor at the University of Texas in Austin. become Texas Secretary of State. serve two terms as superintendent of public instruction. 2. Texas women helped the war ...
March 21, 2015 by SmartyPants

I'm confused and am hoping someone could help me understand energy can neither be created nor destroyed... great... so in physics classes we can set up problems and stuff were KEo + PEo = KE + PE Energy intial equals energy final sense energy is conserved but then when ...
October 19, 2009 by Physics

English
hi for my english project i have to draw a map of the war my character was in..My book was the things they carried so it was the vietnam war, i was wondering if you had any pictures of were the vietnam war was fought. The directions also say i need countries, cities and ...
January 28, 2007 by Jojo

chemistry-Dr BOB
Hi Dr. Bob, I first want to tank you for all your help. Secondly, I don't understand why this was marked wrong. When 27.20mL of .5 M H2SO4 is added to 27.20 of 1M KOH in a coffee cup calorimeter at 23.5 degrees C, the temp rises to 30.17 degrees C. Calculate delta H of this ...
October 18, 2015 by patrick

Physics, Math, Aerospace, Engineering
A de-orbit burn, similar (but not the same) to that presented in the previous math problem, has been performed. During this de-orbit burn a pre-calculated ∆V (delta V, change in velocity) of 99.1 meters per second will be used to decrease the Shuttle’s altitude from ...
January 3, 2015 by Wolf

lab+chem.
Hey can u guys help on this lab, I don't get it. I have to figure out the: prediction, Analysis, and evaluation. Problem: what is the molar enthalpy of ice? Evidence: mass of calorimeter: 3.76g mass of calorimeter+ water: 103.26g mass of calorimeter+ water+melted ice: 120.59g ...
August 5, 2006 by David

Chemistry
From the information below, identify element X. a. The wavelength of the radio waves sent by an FM station broadcasting at 97.1 MHz is 30.0 million (3.00 e7) times greater than the wavelength corresponding to the energy difference between a particular excited state of the ...
April 12, 2007 by Gabriela

math+ confused!
okay the question is as follows: write the first three teerms of tn= 5(2)^ n-1. what is the value of tn/tn-3? I did not get I asked my teacher and he said: plug in n=1, n=2, n=3, to find t_1, t_2, t_3. plug in n-3 and n separately. then take the ratio of the terms. I am ...
October 18, 2006 by eva!

physics
A de-orbit burn, similar to that presented in the previous math problem, has been performed. During this de-orbit burn a pre-calculated ∆V (delta V, change in velocity) of 290 ft/s (or 88.4 m/s) will be used to decrease the Shuttle’s altitude from 205 miles to 60 miles...
January 20, 2012 by Levi B.

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

Statistics
Question 1 Use the following research question and data for questions 1 - 6. A researcher is examining the effects of a computer-based training program designed to teach algebra. The researcher randomly selects subjects for two groups and gives one group the computer training ...
October 18, 2008 by J

ship problem
A [B]ship P [/B] is travelling due [B]East at 30 km/h[/B] and a [B]Ship Q[/B] is travelling due [B]South at 40 km/h. [/B] Both ships keep constant speed and course. [B]At t=0 they are each 10 km [/B] from the point of intersection of their courses and moving towards the point...
July 15, 2006 by rav

Check my answers in history PLZ
Who is "they" referred to in the following quotation? They also established a number system based on six, dividing the hour into 60 minutes and the circle into 360 degrees, as we still do today. A)The Akkadians B)The Sumerians* C)The Babylonians D)The Assyrians 2. What is one ...
September 7, 2016 by Nintendon't