Answers by visitors named: bonjo

2.46x10^-13

wrong...the mer unit is C4H8 with a molecular weight of 56g/mol therefore n is 3.091e5/56 = 5520

i think you will get an answer asap if you include the main topic.

motion of objects is caused by the force as stated by one of newtons law f=ma (m is mass, a is acceleration). if a constant force is applied on the object, the object moves at constant velocity (zero acceleration). if there is a net force applied, the object will change its velocity. in real life, a net force can be applied in an attempt to slow down or speed up an object. if you hit the break, a friction force from the metal plates will counteract with the angular velocity of the wheel, thus decreasing the velocity. if you hit a softball with racket, you ultimately applied a net force that will bounce back the ball with higher velocity. this examples demonstrate velocity and acceleration. if the force applied at two ends extremes of the object, equal in magnitude, an equilibrium system is created. a see-saw with two identical masses at each extreme is in equilibrium because the torque forces produced cancel out each other. a contact force is formed when two objects contact each other exerting different forces such as in friction force etc. a field force include magnetic force, electromagnetic force, electrostatic force. similarly, their magnitudes determine the motion of the object or particle. if you put the loop carrying a current between bar magnets, you the loop will spin at certain speed. if you use bigger bar magnets, the loop will spin faster. hope that helps

mv^2/r

depend on which element is more reactive silver or lead... as far as i remember, silver is the least reactive among copper, lead and zinc...so the silver ring will remain intact when dropped in lead nitrate solution because, silver will not react with the nitrate (displacement reaction) hope that helps

depend on which metal is more reactive... aluminium is more reactive than chromium and so it will displace chromium to form AlCl3 solution..thus CrCl3 cannot be stored in aluminium container.. hope that helps

first step: break down the equation into half equations for oxidation and reduction reduction reaction; 8H+ + 5e- + MnO4- --> Mn2+ + 4H2O oxidation reaction; Fe --> Fe2+ + 2e- second step: manipulate the equations in order to get the same number of electrons; i.e. multiply reduction equation with 2 to get; 16H+ + 10e- + 2MnO4- --> 2Mn2+ + 8H2O multiply oxidation reaction with 5 to get; 5Fe --> 5Fe2+ + 10e- third step: add the two equations together (cancel variables on different side of the equation)i.e. the electrons are cancelled out. 16H+ + 5Fe + 2MnO4- --> 2Mn2+ + 5Fe2+ + 8H2O

you need to find the pressure for water vapor for certain temperatures. this is given in a table and have been calculated for you. use the dalton's law of Partial pressure. i.e. the Pressure for the dry gas equals the Total pressure of the system - the pressure of water vapor for that temperature. hope that helps.

theoretical yield can be determined using the equation for electrolysis of water and the mass 2H2O --> 2H2 + O2 mole of water is 78.5g/18gmol-1 = 4.36 mole ratio of H2O:H2 is 2:2 i.e. same moles. mole of H2 is 4.36x2 = 8.72moles Theoretical mass or yield of Hydrogen is nMr = 8.72moles x 1 = 8.72g. experimental yield is given as 3.23g percentage yield is (experimental/theoretical)X 100% hope that helps

this test the concept of reacting metal hydride with the ketone. metal hydride reduces ketones. ketones are reduced to secondary alcohol adding water with the product (alcohol) can form carboxylic acid.. that's far as i remembered.

it is emptying at a rate of 50 gallons per hour because, the gradient is negative. don't you think?

the copying of DNA into RNA by RNA polymerase enzyme.

1) find the mole of NaBr in from the solution you want to prepare using c=n/v where c is concentration in mol/L, v is the total volume in mL. 2). find the mass in grams using m=nMr where the mole is in step 1. the mass in step 2 is the mass of NaBr needed to be weighed on analytical mass balance and dissolved in a 600mL volumetric flask with distilled water. hope that helps

less thermal energy because, thermal energy of water depends on the volume. more volume means that more capacity for storing heat energy.

correction: theoretical mass is 8.72moles x 2 = 17.44g

oxidation: Fe2+ --> Fe3+ + e- Reduction: Ag+ +e --> Ag overall is; Fe2+ + Ag+ --> Fe3+ + Ag

simply because iodine will readily react with starch to form a dark blue solution, and therefore interfere with the end point detection. we therefore add starch indicator just as the iodine colour in solution pales i.e. pale yellow indicating that iodine concentration is very low. Near the endpoint, the iodine color is very pale that it can be overlooked. adding starch to a very pale solution gives a clear end point indication by a visual deep blue colour solution. hope that helps

what was the question??

get the balanced equation reaction of PCl5 and phosphoric acid. from the balanced equation, obtain the mole ratio between the two compounds. convert the mass of phosphoric acid to moles using n=mass/molar mass determine the mole of PCl5 using the mole ratio covert the mole of PCl5 to the mass using m=nMr. hope that helps

you can either construct your formula OR go step by step until you reach 4pm. at 10am, 4 minutes is ahead at 10:30am, 2 minutes ahead at 11:00, 0 minute ahead at 11:30, 2 minutes late at 12:00pm, 4 minutes late and so on... hope that helps..

fraction remain = (1/2)^n where n is the number of half life half life = p/n where p is the period of decaying i.e. 47 years so, first find n (number of half life using the half life equation and then find the fraction remain. convert this fraction to % hope that helps

quantity here refers to the volume you need to extract from the 75% ethanol to make 25% ethanol in 300ml. i would use a dilution equation c1v1=c2v2 and find v2 such that; v1=(c2/v2)/c1 where c1 is 75%, c2 is 25%, v2 is 300ml. hope that helps

power is voltage multiplied by current.

use vector addition to determine your average velocity and then use that to determine the distance you covered in 44min with that velocity.

first construct the balance equation for sulphuric acid and aluminium hydroxide reaction. take note of the mole ratio between the two compound from your balanced equation. determine the actual mole of Al(OH)3 using c=n/v where c is the concentration in mol/L, n is the unknown mole, and v is volume in mL use the mole ratio to determine the mole of sulphuric acid calculate the volume of sulphuric acid using the same formula c=n/v hope that helps

no effect

what's the 25.2??? is it a mass?

i think this question is based on your experiment in the lab??? you have to use your results. if you have already determined the concentration, then you are able to calculate the mass. say your concentration is 0.2mol/L. to determine the mass in grams for a 1L bottle of vinegar, you just need to convert the 0.2mol into grams. hope that helps

construct the balance equation for NaOH and HCl reaction obtain a mole ration i.e. 1:1 determine the actual mole of NaOH reacting using c=n/v where c is 0.1 and v is 54 use this mole to find the concentration of HCl using c=n/v hope that helps

construct the balance reaction equation of Acetic acid and NaOH. take note of the mole ratio calculate the actual mole(n) of NaOH reacting with acetic acid using n=cv use the mole ration to determine the mole of acetic acid from the reacted NaOH mole. calculate the concentration of acetic acid by dividing its mole by its volume hope that helps

determine the mass in grams by treating the percentage values as masses (by mass composition) calculate the mole of each element by mass/molar mass divide each mole with the lowest mole and round off to whole number, to give you the empirical formula to determine the molecular formula, just divide the molecular mass by the empirical mass. hope that helps!!

there are two types of nerves as far as i know; the effectors and the sensors. the sensors are the ones that detect the environmental stimulation such as touch, heat etc..these nerves are connected to the brain (to the pariental lobe) thus carrying the information to the brain. the information is in the form of electrical impulses, carried by ions such as calcium ions and facilitated by channels between each nerve endings called the dentrites. once the electrical impulse reaches the brain, it is interpreted by the parental lobe telling the body what type of stimulation encountered. if the stimulation is heat, the brain will send electrical impulses to the effector nerves. these nerves are attached to the muscles or glands that responds according to the type of stimulation. if you are under a hot sun, you feel hot because the brain interpret that from the information send from the sensory nerves. if it gets too hot, you get sweaty because, the effector nerves attached to the sweat glands stimulate the glands to release water for cooling. if someone put fire on your palm while you are sleeping, you immediately feel the heat followed by a rapid withdrawal of your palm from the source. hope that helps..the book called Toratora helps a lot..

how about applying some simple electric circuit?? lets say you construct a simple electric circuit with a copper wires as your spinal cord and the bulb as the brain. when the spinal cord got brutally damaged leading to paralyzing, you cut the wire stopping the current to the bulb..??? hope that helps..

a fission reaction involves the splitting of the larger nucleus to smaller daughter nuclei accompanied by highly energized neutrons. nuclear fission does not occur on its own; requires an input of energy. this is done by bombarding larger nuclei with neutrons in special containments. the common isotope is uranium and plutonium (these isotopes are used in nuclear fission bombs) as in the ones dropped at nagasaki and hiroshima during the second world war... for the nuclear reactor power plant to work, it must contain several compartments; the reactor, the boiler, the cooling system, the turbines, the cooling tower and the pumps. the reactor contains the isotope constantly undergoing fission reaction with high amount of energy. the this heat energy is passed on to the the boiler where water is boiled to produce a steam. the steam is pumped into the cooling system, absorbed and used to spin the turbines for energy generation such as electricity. the temperature from the steam is controlled by the cooling tower, releasing tonnes of steams into the atmosphere. hope that helps..

i guess this is one of the eDX CH3.091 final exam question???

compare the e values with silver and i think you will see why...

welcome

Ok...an exothermic reaction is a type of chemical reaction that releases heat energy to the surrounding, so definitely it is hot when you touch it (exo=release, thermic=heat). You can try that by mixing water and sodium hydroxide pellets in a flask and you will feel that the flask gets hotter which indicates the reaction to be exothermic. burning fuels or combustion reactions are examples of exothermic reactions. it is that simple, but the complication is when you are dealing with the energy diagram where you will see a drop in energy though you feel heat from the mixture!!!. keep in mind that the heat you feel is the one that been released to the surrounding i.e. the flask. so externally, heat energy is increased, but internally for a system, heat energy is decreased because it is been given out to the surrounding. The energy diagram only shows the energy profile for the internal system not the surrounding. an opposite to exothermic is endothermic (endo=into) and you can prove that by mixing water and ammonium chloride..the flask will get colder because, heat energy is been absorbed from the surrounding, so the heat moves from the surrounding (flask or air) to the system so you felt that as cold. but internally, the system is higher in energy. hope that helps sorry for too long description...

it should be..

the delta H in the equation indicates the type of reaction exo or endo. a positive value means an endo whereas a negative value means an exo rxn..in terms of energy been dissipated, exothermic reaction are more effective in producing more energy, and they are our main source of heat in our everyday life such as respiration. Endo reactions are sometimes used in medical purposes such as ice-bags where you just crushed the back containing water and salt (such as ammonium chloride) to generate coldness to apply on minor injuries and even used for temporary cooling of water bottles etc..so in terms of energy storage, endo reactions mostly suited... hope that helps...

ok..how about i do the talking and you do the calculations??..hope this is a best way we help each other, by working together, not just by giving the answer so that others can just jump in and take it without knowing its derivatives..its better to have postings leading to answers... ok, the question ask for the N-N bond. so we need to rearrange the Bond Energy equation BE(NCl) = sqrt[BE(N-N) x BE (Cl-Cl)] + 96.3[X(N)-X(Cl)^2 rearrange the equation to make BE(N-N) the subject. then we can use the de Broglie equation to find the wavelength.. can anyone try that??...i have 1 more submission left for this question..

yeb

thanks

6.3e4

topic??? chemistry, biology physics??

when temp decreases, water will decrease in solubility or in ionization and the reaction will favour the backward reaction; H+ + OH- --> H2O so we know that the backward reaction is endothermic and the forward is exothermic.

or both..alpha helix and hydrogen bond

apply vector addition forming a right angle triangle and finding the resultant (hypotenuse) using pythagoras theorem.. 3.5^2 + 5^2 = y^2 12.5 + 25 = y^2 y = sqrt(37.25) = 6.10m/s hope that helps...

1/3 of her try will be a foul i.e. 90x1/3 = 30. so 30 attempts are foul. the remaining 60 attempts would be her best shot... hope that helps..

rearrange the formula BE(NCl)= sqrt[BE(NN)x BE(ClCl)] + 96.3[X(N)- X(Cl)]^2 to find the bond energy for N-N. then use the de Broglie equation to find the wavelength.

the velocity of the electron is sqrt(2E/m) where E is the bond energy for NN and m is the mass of electron.

never chiral

No, there is.....

haven't done it yet..am struggling with it..need help...

v is the velocity which can be derived from E=1/2mv^2 (kinetic energy). the X(N) is the electronegativity for Nitrogen and so as Cl obtained from the periodic table.

it is shown on the graph; just look for NaNO3 at temperature 30, the gram of solute (NaNO3) is roughly 96g.

Joe weighs 30lbs less than 2wice kens weight J=2x-30 ken gains 10lbs, then 2gether would weigh 250 (x+10)+J = 250 J=joe's weight. solve them simultaneously.. hope that helps

1. trigonal pyramid; three hydrogen and 1 lone pair around As atom. 2. sp3 3. tetrahedral 4. polar 5. slightly less than 109.5 6. covalent bond

you need to construct simultaneous equations from the information; first equation is from; Joe weighs 30lbs less than 2wice kens weight. and x is ken's weight. so twice kens weight is 2x. 30lbs less than twice kens weight is 2x-30. these equals to Joes weight J=2x-30 (1) we cannot work with this equation alone because, there are two unknowns J and x. so we need another equation which is obtained from; If ken gains 10 pounds then together they would weigh 250 pounds. i.e. if ken gains 10lbs (x+10), then together (with J) will equal to 250. (x+10)+J = 250 (2) Now we can solve for each weight either by substitution or elimination method..

synthetic plant hormones are the ones that synthesized by plant themselves such as auxin, gibberilin etc..

Nitrogen

sp2

Are you sure this is Biology?...sounds Physics to me..

energy sources apart from fossil fuels. for example; renewable energy sources such as wind, solar and thermal. hope you can deduce the disadvantage for each...

the main lifestyle of the hiv/aid is that it uses our white blood cells to replicate. by replicating inside the host white blood cells, it left them completely destroyed, thus decreasing the ability of the immune system. as more viruses are produced, more WBC are destroyed and the immune system is in chaos leading to possibility of any invasion from diseases. I say hiv/aids is a selfish organism, showing no mutual relationship with the host compared to other microorganisms. The only way to end its lifestyle is to die along with it!!!

the molecular geometry is tetrahedral..but the structure is trigonal pyramid i.e. three surrounding atom with 1 lone pair of electron around As. but the overall arrangement of the electron density is tetrahedral (four sites occupied). trigonal planar structure exist in molecules consisted of a central atom bonded to 3 surrounding atoms, with no lone pair. Arsenic cannot be trigonal planar because, it has 5 valence electrons as in Nitrogen (2 paired and 3 unpaired which is used for the bond).

a) staggered structure (i.e. the CH3 are at 180 degrees) b) eclipsed structure (i.e. the CH3 are on the same plane)

i think b only ask for the expression, not the actual value????...beside, in order to get the actual value of lattice constant, we need the radius...is the radius given or can it be determined???... i tried expressing the lattice constant for the BCC as 4r/sqrt3 but can't get the correct format.

i don't know whats wrong with my answers in this question. it ask for the directions i.e. the vector (xyz) so the first crystal has vector pointing down one unit for the z value i.e. -1. and x is 1/3, whereas y is 0 so i gave (1/30-1) and got it wrong with the others...

then somethings off..i got that ticked...it says 'The grader on this problem has been corrected, and the number of attempts has been increased to 10', so the answer has changed i guess..but why still i got the green tick??...

1. the solution is diluted by 5/475 dilution factor i.e. 1/95x so you can also use this factor to find the initial molarity (M1) by dividing the final molarity (0.1M) with 1/95..i.e. 0.1x95 = 9.5M. 2. c1v1=c2v2 and we are looking for v2 so; v2=(c1v1)/c2 = (7x16)/2.5 = 44.8mL i got the same answer with you..if you are in doubt, then you can calculate the dilution factor and use it to determine the final concentration; so, initial volume is 7mL and final is 44.8mL; dilution factor = 7/44.8 = 0.15625x multiply this with the initial concentration and see what happens... if it gives 2.5M then 44.8mL is correct... hope that helps..

20-vol is 6% w/v of hydrogen peroxide i.e. 6g in 100mL. so we can find the concentration; 6g/(34) = 0.176mol in 100mL in 1liter = 0.176molx10 = 1.76mol Molarity = 1.76mol/L the question asks for how many liters for one mole so; 1L = 1.76mol xL = 1mole xL = 1/1.76 = 0.568L hope that helps..

the balance equation; (NH4)2Cr2O7(s) → Cr2O3(s) + N2(g) + 4H2O(g) 50g of ammonium dichromate is 0.198 mole (50/252.07). according to the equation, 1mole of ammonium dichromate produces 1 mole of nitrogen gas, so 0.198mole of dichromate produces 0.198mole of nitrogen gas. mass of nitrogen gas = 0.198molex28g/mol = 5.54g use the density of nitrogen gas to find the volume... hope that helps..

if not, then recall that for any ideal gas at STP, 1mol=22.4L. and already we have the mole for nitrogen (0.198mole). so we can find the volume; 1mol=22.4L 0.198mol=x x = 4.435L = 4435mL of Nitrogen gas.

the question is based on the decomposition of calcium carbonate through heating; CaCO3(s) --> CaO(s) + CO2(g) 50 grams of calcium oxide is 0.893moles. the theoretical mole is 1:1 between caCO3 and CaO, so 0.893moles of CaCO3 is needed. mass of CaCO3 = moles of CaCO3 x Molar mass of CaCO3 hope that helps...

@ bobpursley..your equation is incorrect so i came up with this one...

which question is this?

total mass of the solution is 400+80 = 480g. mass% of solute = mass of solute/total mass of solution hope that helps...

you only cheat if you don't do anything at all and then come here and ask for the answer..its an online course so for others outside the US, it is hard to gain 100% from the course because internet is not 100% reliable. so for me, its not cheating..its adapting to the new way of learning. If am in the US especially at MIT attending lectures, or have full access to video lectures downloading them within minutes, i won't come here to get the answer. But i will come here to help others so that when i ask for help, i get one in return... so if you are not here to help anyone or looking for any help, then mind your own business..i bet you are the top student for the course 3.091

a is the first choice and so on..

8.87

why is tat

right i forgot the *100

yeb..wrong again

the question does not make sense..the resultant vector is always longer than the two vectors because it is formed by the 90degrees intersection of the smaller forces!!!..so how come the resultant vector form a 90degree with another smaller vector??? the smaller vectors should form a 90degrees...

KE = 1/2mv^2 and v = sqrt[(2KE)/m] and momentum = mv = (m)x[sqrt(2KE)/m] = msqrt[(2KE)/m] where KE is the bond energy in kJ/bond.

the alkane is saturated i.e. the carbon bonds to 4 atoms. It contains only single bonds and contains no functional group. The alkene has a double bond between two of the carbon atoms. this double bond makes the alkene unsaturated and so determines the reactivity of the alkene i.e. functional group.

thanks picha lite...the BRACKETS are what that have puzzled me all these hours..@ Anonyms, the question asks for the direction of the vectors in the x,y and z directions i.e. [xyz] not (xyz). So the first vector is pointing downward 1 unit along the vertical direction i.e. z=-1. Then it goes 1/3 along the x i.e. x=1/3. Finally, the y direction is not taken i.e. y=0. Then applying the previous posts esp by picha will help you with the rest of the other vectors...

is this Chemistry??? by the way, apply the normal rule for the volume i.e. Length x width x height

when you convert kj/mol to meters, you get grams..

first find the limiting agent because this determines the amount of water produced. this is done by calculating the mole of each gas and see which has a mole that satisfy the reaction; for hydrogen; 7.30/2 = 3.65moles for oxygen; 7.30/32 = 0.228moles so hydrogen is excess in amount; the required mole is 2 (according to the equation). oxygen is less than expected so it is the limiting agent which determines the amount of water produced. use the mole for oxygen to determine the mole of water. then find the mass by multiplying the molar mass of water with its mole. hope that helps.

water has 2 lone pairs and 2 surrounding atoms oxygen gas has 2 lone pairs on each atom bonded in a double bond 1 lone pair on nitrogen bonded (single) to 3 hydrogen atoms nitrogen is bonded to 4 hydrogen atoms, and it should have a positive charge.

convert calories to joules. take note of the delta H for its sign.

moles = mass/Molar mass the mass is given and the molar mass can be obtained from the periodic table.

1.mole of NaOH added = cv = 0.365x15e-3 = 5.48e-3 moles. Reaction; HI + NaOH --> NaI + H2O pH = -log[H+] the [H+] is the concentration of the acid as 15ml NaOH has been added. the equation states that, 1 mole of NaOH neutralize 1 mole of HI. So, after adding 15ml, we introduce 5.48e-3 moles of NaOH in the solution. So, this mole should also neutralize 5.48e-3moles of HI. concentration is moles/volume. The volume of acid is 25mL. with that, use -log[H+]. 2. again, find the mole for 40ml of NaOH to find the mole of HI been neutralized. then use that mole to calculate the concentration.. hope that helpss..

in order for the hydrogen bond to form in a molecule, the molecule must have an hydrogen atom attached to either oxygen, nitrogen or fluorine. so, the oxygen in C=O bond is not attached to hydrogen and so can't form hydrogen bond.

density is mass/volume. be careful with the unit.

iron oxide and hydrogen gas are produced.