Wednesday
May 4, 2016

# Posts by Natash

Total # Posts: 138

statistics/probability
One statistic used to assess professional golfers is driving accuracy, the percent of drives that land in the fairway. Driving accuracy for PGA Tour professionals ranges from about 40% to about 75%. Tiger Woods hits the fairway about 60% of the time. One reason why the Normal ...
June 17, 2010

organic chem/ melting pt lab
why does a soluble impurity reduce the melting point range of a pure compound ? why is it advisable to run a mixed melting point determination on samples of two different compositions before concluding that the two compounds are identical ?
May 27, 2009

chem/solubility
the Ksp of CaF2 = 1.46*10^-10 and Ka of HF = 3.5*10^-4 Calculate the pH of a solution in which the solubility of CaF2 = .0100 moles/liter. so Ksp =[Ca2+][F-]^2 and Ka =[H3O+][F-]/[HF] I'm not sure how to continue...
May 13, 2009

chem
OHHHH got it, without the ICE chart I sort of get confused. Thanx!
May 13, 2009

chem
I know that part, but why are the conc. of OH and HA the same ?
May 13, 2009

chem
the pH of a .100 M solution of sodium formate = 8.37. Calculate the value of Ka of formic acid. okay so I know that the anion of a weak acid is itself a weak base so A- +H2O---> OH- + HA pOH =14-8.37 so conc of OH is 10^-5.63 Ka=[OH][HA]/[A-] so we know the conc of OH and A...
May 13, 2009

chromatography
so we did this lab on chromatography, and in the beaker was 10 mL of HCI and 35 mL of acetone. IF the distilled water used to prepare the HCI solution in this experiment passed through iron pipes, then the HCI will be contaminated with FeCl3. Examine your chromatography paper ...
April 26, 2009

pre lab Q on chromatography
suppose that there are two components, A and B, in a mixture. The chemical affinity of A for the stationary pahse is less than that of B and the chemical affinity of A for the mobile phase is greater than that of B. If the mixture is subjected to paper chromatography, which ...
April 19, 2009

physics pre-lab
By trial and error with your calculator, find the angle theta for which sin theta and theta differ by 5%. This calculation must be done in radians. When you have found theta, express it in degrees. plzzz help thanx
March 22, 2009

chem
I'm thinking its CH3NH3Br + H2O <====>H3O + CH3NH2 is this correct ?
March 8, 2009

chem
a soln. that is .195 M in CH3NH2 and .105 M in CH3NH3Br what is the balanced equation for this ? How do you know ?
March 8, 2009

physics
why is the total distance traveled by a mass traveling in a circle of radius R during n revolutions =2piRn. The average speed is the distance traveled divided by the elapsed time, so: v=2piRn/delta T, where delta T is the elapsed time.
March 8, 2009

physics
why is the total distance traveled by a mass traveling in a circle of radius R during n revolutions =2piRn. The average speed is the distance traveled divided by the elapsed time, so: v=2piRn/delta T, where delta T is the elapsed time.
March 8, 2009

muscle physiology
okay so we did a lab on muscle physiology. acquired one small 2 cm length of psoas muscle . teased the bundle of muscle fibers into individual muscle fibers. aligned 3 individual fibers on each of three different microscope slides and placed 1 fiber on a fourth slide ( control...
February 24, 2009

thermodynamics
A reaction has deltaHrxn=-127 kJ and delta S rxn=314 J/K. At what temperature is the change in entropy for the reaction equal to the change in entropy for the surroundings? so I made delta H-T delta S=0 plugged in values for S and H and solved for T. I got -404.5 degrees K. Is...
February 18, 2009

chem
yes Fe(NH4)2(SO4)2 is the ferrous ammonium sulfate. here is the procedure, if you can try to figure it out that'll be great thank you! 1. prepare and label the following solutions: a.10g of ferrous ammonium sulfate dissolved in 30mL of water containing 2 drops of 6M H2SO4 ...
February 13, 2009

chem
sorry I'm a bit confused. These are the solutions we had to prepare a. 10g of ferrous ammonium sulfate dissolved in 30mL of water containing 2 drops of 6M H2SO4. Which I got 8.87g b. 6g of oxalic acid in 50mL of water. I got 4.4008g c. 6.6 g of K2C2O4*H2O in 18mL of water...
February 13, 2009

chem
Okay so Im doing a lab on preparation of K3[Fe(C2O4)3]*3H2O The final weight I got 2.835g. How can I find the theoretical yield of this? What do I need?
February 13, 2009

chemical kinetics
2H2O2 --->2H2O + O2 What is the instantaneous rate of formation of O2 at 50s? THeres a graph with the concentration of H2O2 as a function of time. at 50s the conc. is .2 But isnt this the concentration of H2O2, I dont understand. Also what is the difference between ...
February 4, 2009

chemmm helppppppppp
Consider the following reaction: 2N2O(g)--->2N2(g) + O2(g) a. express the rate of the reaction with respect to each of the reactants and products. b.In the first 10.0 s of the reaction, .018 mol of O2 is produced in a reaction vessel with a volume of .250L. What is the ...
February 1, 2009

chem
why are sig. figs important?
December 16, 2008

physio
satiety would be induced by all of the following EXCEPT a. cholecystokinin b. naloxone c. morphine d.seratonin I know its not a or c, because those induce satiety. I'm stuck between b and c ...i think its b though
December 11, 2008

physiology
Ghrelin is postulated to ba a satiety factor. True or False. I think its false, but im not sure
December 11, 2008

Physiology
Glucagon and cortisol increase lipolysis. True or False Plz if your not a 100% sure don't answer, THanx!
December 11, 2008

trig
Find cosq and sinq if the terminal side of q lies along the line y = - 2 x in quadrant IV.
December 8, 2008

Math
December 7, 2008

chem
Rank the following compounds in order of decreasing boiling point: KCI CO2 CH2O
December 7, 2008

chem
what is the appropriate hybridization for the carbon atom in CO2? the explanation I was given is 2 electron groups around the center atom carbon suggest sp hybridization. the 2 unhibridized p orbitals on carbon form the 2 pi bonds. My question is why pi bonds? Isn't it ...
November 24, 2008

chem
order the elements Mg, K, Ca, S according to second ionization energy I know that K would have the highest second ionization energy, then come S bec it takes more energy to remove an electron from a nonmetal than a metal, which is next ?
November 24, 2008

chem
what is the orbital diagram for Au+, how do you fit the f orbitals in?
November 23, 2008

trig
Prove that cos4x=8cos^4x-8cos^2x+1 so I'm guessing you begin with the left side cos4x=cos2(2x) then im kinda lost
November 23, 2008

trig
thats what I did, but it's giving me a wrong answer
November 22, 2008

trig
solve the following equation in the interval [0,2pi]. Give the answer as a multiple of pi. Do not use decimal numbers (sin(t))^2=3/4
November 22, 2008

trig
Find all solutions of the equation 2sin^2x-cosx=1 in the interval [0,2pi) x1= ? x2=? x3=?
November 22, 2008

trig
Use an addition or subtraction formula to write the expression as a trigonometric function of one number: tan75degrees-tan15degrees/1+tan75tan15=tanAdegrees =square root B Its asking for the value of A and B. I know A =60 degrees, what I can't figure out is B, I dont ...
November 15, 2008

trig
simplify and write the trigonometric equation in terms of sine and cosine. tan^2x-sec^2x
November 15, 2008

trig
November 15, 2008

physiology
dizziness during hyperventilation is due to a decrease in cerebral blood flow. The decreased blood flow is caused by a. vasodilation b. decreased stroke volume c.vasoconstriction d. decreased respriation
November 11, 2008

physiology
Pulmonary fibrosis may be caused by a.smoking b.allergic reactions c.breathing in coal dust. d.increased mucus production I'm having trouble with this because doing research I found it to be smoking and breathing in coal dust. So I'm a bit confused.
November 11, 2008

physiology
the primary drive to breath is elicited by which of he following: a.reduced PO2 b.reduced PCO2 c.increased PO2 d.increased PCO2
November 11, 2008

physiology
Hypotension could be induced by a.excessive renin secretion b.excessive antidiuretic hormone secretion c.excessive aldosterone secretion d.excessive atrial natriuretic factor secretion
November 11, 2008

physiology
Blood flow is increased by a.hypotension b.anemia c.vasoconstriction d.edema I don't see how any of these can be the answer
November 11, 2008

physiology
what drug that is used as a treatment for asthma, promotes bronchodilation by selectively stimulating beta2-adrenergic receptors? A.singular B.albuterol c.Terbutaline d.epinephrine i think its between b and c
November 10, 2008

chem
what is the electron configuration for Au+ ? where does f block fit in?
November 1, 2008

chem
in the ground state electron configuration of Fe3+, how many unpaired electrons are present? I thought it was 1, but im getting a wrong answer.
November 1, 2008

chem
How much energy is required to ionize a hydrogen atom in its ground (or lowest energy) state? What wavelength of light contains enough energy in a single photon to ionize a hydrogen atom?
October 27, 2008

chem
The minimum energy required to change the conformation of 11-cis-retinal within the eye is about 164kJ/mol. Calculate the longest wavelenght visible to the human eye
October 27, 2008

chem
consider the following thermochemical equation for the combustion of acetone C3H6O(l)+4O2(g)---->3CO2(g)+3H2O(g) delta H rxn=-1790kJ. If a bottle of nail polish remover contains 179mL of acetone, how much heat would be released by its complete combustion? the density of ...
October 17, 2008

chem
A 25.0 g aluminum block is warmed to 65.2 C and plunged into an insulated beaker containing 55.3g of water initially at 22.0C. the aluminum and water are allowed to come to thermal equilibrium. Assuming that no heat is lost, what is the final temperature of the water and ...
October 17, 2008

math
divide both sides by (b1+b2)so u get A/(b1+b2) then divide both sides by 1/2. A/(b1+b2)*2=2A/(b1+b2)
October 17, 2008

physiology
during the absolute refractory period a supramaximal stimulus can bring the cell to threshold true or false
October 11, 2008

Physiology
Glial cells normally lose their mitotic ability prior to birth True or False Which of the following is NOT a function of astrocytes? a. can take up NT from a synapse b.can stimulate or inhibit neurons c.needed to form synapses in the CNS d.Phagocytose foreign material in the ...
October 11, 2008

chem
Find the percent by mass of sodium chloride in a 1.15M NaCl solution. The density of the solution is 1.07g/mL.
October 1, 2008

chem
How many CO2 molecules would be formed from the reaction mixture that produces the greatest amount of products? 2CH3OH(g)+3O2(g)--->2CO2(g)+4H2O(g)
October 1, 2008

chem
How many CO2 molecules would be formed from the reaction mixture that produces the greatest amount of products? 2CH3OH(g)+3O2(g)--->2CO2(g)+4H2O(g)
October 1, 2008

chem
For the reaction shown, find the limiting reactant for each of the following initial amounts of reactants. 4Al(s)+3O2 (g)-->2Al2O3 (s) 4 mol Al 2.6 mol O2
October 1, 2008

CHem
Sterling silver is a mixture of silver and copper having a mole ration of silver to copper equal to 7.8 what is the mass percent composition of this mixture? Ok I know the answer to this and I know how its done: 1 mol Cu weighs 63.5 g 7.8 mol Ag weigh 7.8(107.87)= 841g what i ...
September 23, 2008

chem
I want to know why indium and oxygen form In2O3, where does the 3 come from ?
September 23, 2008

chem
The American Dental Association recommends that an adult female should consume 3.0mg of flouride per day to prevent tooth decay. If the flouride is consumed as sodium flouride (45.24% F)what amount of sodium flouride contains the recommended amount of flouride in mg?
September 20, 2008

chem
If 17.0g of MgSO4*7H2O is thoroughly heated,what mass of anhydrous magnesium sulfate will remain ? I don't even know where to begin on this one
September 20, 2008

chem
How many oxygen atoms are in 1.90g og quartz (SiO2)? ok so 1.90g SiO2(1mol/60.0843g SiO2)(2 O mols/1 mol SiO2) (6.022*10^23atoms/1mol) what am i doing wrongg???
September 20, 2008

physiology
anaerobic respiration is triggered when the ratio of ________falls below a critical level. a.carbon dioxide supply to oxygen need b.oxygen supply to glucose need c.glucose supply to glucose need d.oxygen supply to oxygen need the electron transport chain is responsible for the...
September 17, 2008

physiology
the scientific method is only concerned with experimentation True or False
September 16, 2008

Algebra
distribute the 5 first m+5m-5=7 6m-5=7 6m=12 m=2
September 14, 2008

trig
Ok so I have a right triangle with the hypothenuse = to 5, one side =3 and the other =4 and X is the angle between the hypothenuse and the side that =3. I'm supposed to find the sin, cos, tan, cot, sec, csc of X. I can't seem to get the answer for the sec and csc. If ...
September 14, 2008

trig
If tan(x)=8/3 and sin(x)<0, then find cos (x) sec(x) csc(x) i dont understand how u do this problem
September 14, 2008

Chemistry
Why are titanium and gallium not very similar while lithium and sodium would be most similar ?
September 10, 2008

chemistry
Na is a metal O, Si, Kr, B are nonmetals Mn is a semimetal why am i getting this wrong ?
September 9, 2008

chemistry
Rank the size of a change in temperature of one degree fahrenheit, one degree celsius, and one kelvin. Ok I can't seem to get this question right no matter what I do. Isn't one fahrenheit degree the largest then celsius and kelvin? There are 180 fahrenheit degrees ...
August 30, 2008

evolutionary bio
following a drought on Daphne Major, the beaks of the offspring of the surviving medium ground finches (average 14mm) were larger than the beaks of the entire population prior to the drought ( 12mm average). Based on the prior study, it is known that the heritability of beak ...
June 7, 2008

evolutionary bio
if a mutation would be beneficial, is it more likely to occur? a. yes, bec. it helps the species survive b. No the answer is B, however I'm not sure why. wouldn't a mutation that is beneficial be more likely to occur for the sake of the species ?
June 7, 2008

evolutionary bio
which is more parsimonious? the horse and the zebra are more closely related than either is to the chicken, or the chicken and the horse are more closely related than either is to the zebra ? horse and zebra ?
June 4, 2008

evolutionary bio
If a mutation would be beneficial, is it more likely to occur? a)Yes, because it helps the species survive b)No
June 4, 2008

Bio
1. What are the qualities of H bonds? give some examples of H bonds. 2.examples of saturated and unsaturated fats
May 12, 2008

chemistry
determine the vapor pressure of a solution at 55 degrees C that contains 34.2g NaCl in 375 mL of water. The vapor pressure of pure water at 55 degrees C is 118.1 torr. so Psolution=XsolventPsolvent I don't know why I'm not getting the correct answer... so from 34.2g ...
May 11, 2008

chem
Calculate the mole fraction of total ions in an aqueous solution prepared by dissolving .400 moles of MgCl2 in 850.0g of water. mole fraction =amount solute(in mols) /total amount of solute and solvent (in mols) so wouldn't it be .400/ .400+ 47.2 which is the moles of water?
May 11, 2008

chem
In the reaction of calcium metal and water, 50.0 mL of hydrogen gas is collected over water at 25.0 degrees C with a total pressure of 752 mmHg. Calcualte the number of moles of hydrogen gas that was produced. Do we just plug this into n=pv/rt ? or is there like an extra step?
May 11, 2008

chem
which of the following substances should have the highest melting point? Xe F2 SrS MgO CO2 the answers D, is it because its an ionic compound?
May 11, 2008

chem
HOw much energy is required to heat 36.0g H2O from a liquid at 65C to a gas at 115C? The following physical data may be uselful. Hvap=40.7kJ/mol C liquid=4.18 C gas=2.01 C solid= 2.09 T melting=0 C T boiling=100 C The answers about 87.7 kJ However I'm not sure how you get ...
May 11, 2008

chem
A 4.55L sample of water contains .115g of sodium ions. Determine the concentration of sodium ions in ppm if the density of the solutions is 1.00g/mL. Ok so ppm=mass of solute/mass of solution *10^-6 so we have the mass of the solute .115g and for the solution we use 4.55 L and...
May 9, 2008

chem
I'm glad you googled that up ;) Ummm no actually that wouldn't be the answer, it's far from being the answer, it's just a tiny part you need, to come up with the answer. So if you don't know what the question is plz refrain from your remarks of "We don...
May 5, 2008

chem
I didn't ask you to do my homework, those were specific questions I needed help with. All I needed was the condensed structure.
May 5, 2008

chem
How many isomers of C2H3Br3 are possible? explain.
May 5, 2008

chem lab
My lab is on Comparison of the B-carotene content of raw and cooked carrots...if you use a single 5.0g piece of carrot, do you expect to extract more or less B-carotene than with the finely cut carrot sample? explain.
May 5, 2008

chemistry
yes I know can you just write out the structures, for ex. C2H6O , ethanol CH3CH2OH and dimethyl ether CH3OCH3 those are the 2 isomers
May 5, 2008

chemistry
what are the 3 isomers of C2H2Cl2 what are 2 isomers of C2H3Br3, are any other isomers possible? explain.
May 5, 2008

algebra
I believe you just add 29+31+33+35+37+39+41+43+45+47+49 which are 11 terms =429
May 5, 2008

chem
Ohhhh thats right you have to look at each C separately, thats where I got mixed up, thanx.
May 5, 2008

chem
what kind of e-pair geometry, molecular geometry, and bond angles does C4H10 exhibit? I'm confused.
May 5, 2008

chem
Is dimethyl ether a polar molecule? between dimethyl ether and ethyl alcohol, which molecule is expected to be more soluble in water? explain.
May 5, 2008

biology
why do plants of arid environments have fewer smaller vessels than plants of moist environments?
May 4, 2008

chem
so if the electronegativities are not the same it has a net dipole? Is this only in a linear molecule?
May 1, 2008

chem
choose the compound below that contains at least one polar covalent bond, but is nonpolar a. ICl3 b SeBr4 c. CF4 d. HCN Im stuck between C and D C is a tetrahedral which has no net dipole so is non polar, and D is linear which also makes it non polar.
May 1, 2008

chem
draw the lewis structure for NO2- including any valid resonance structures. which of the following statements are true? a. the nitrite ion contains 2 N-O bonds that are equivalent to 1 1/2 bonds. b. the nitrite ion contains 2 N=O double bonds c. the nitrite ion contains 1 N-O ...
May 1, 2008

chemistry
use the data given below to construct a Born-Haber cycle to determine the lattice energy of CaO Ca(s)--->Ca(g) 193 Ca(g)--->Ca+(g) + e- 590 Ca+(g)--->Ca2+(g) +e- 1010 2O(g)---->02(g) -498 O(g) +e--->0-(g) -141 O-(g) + e---->O2-(g) 878 Ca(s) +1/2 O2(g)---> ...
May 1, 2008

chemistry
which molecule or compound below contains a polar covalent bond? why? C2H4 LiI NCL3 ZnS AgCl
May 1, 2008

chem lab
I'm doing a lab on helium and hydrogen emission spectra. so I got violet 20.35cm blue/green 21.70cm green 22.75 light green 23.08 yellow 27.70 red 31.70 faint red 33.95 and I also have the wavelenghts for helium spectra, its given. like for ex. violet is 380-420, my ...
April 28, 2008

chem lab
ok I'm having trouble with graphing this chemistry lab. It's on atomic emission spectra. In this experiment we observed the line spectrum of first helium, and here is the data: color: distance: wavelenght: violet 20.35cm light blue 21.70cm green 23.08cm light green 22....
April 28, 2008

chem
1. under what circumstances is the molecular geometry around a single central atom the same as the electron group geometry around the central atom? 2.If all of the electron groups around a single central atom are bonding, and the same outer atom is bonded to the central atom ...
April 28, 2008

chem
In the trigonal bipyramidal geometry, which position- axial or equatorial- do nonbonding electrons prefer? why? I know its equatorial but I'm not exactly sure why
April 27, 2008

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