Homework Help

Do liquids with lower viscosity freeze faster than those with a higher one? How should I measure the water that did not froze after freezing.

i am not getting it

Can anybody please help!? I know it uses the equations above, but something is going wrong in the last step when I'm trying to calculate the number of channels and conductance...I know what the answers should be; number of channels is 3E6 Data: bilayer area = 1.1E-6m2 bilayer thickness = 2.5E-9m channel radius = 1.5E-9m channel thickness = 2.5E-9 diffusion constant = 1.2E-9 dielectric constant = 2.3 change in energy (i.e U or sometimes E) can anybody help please? I think I am getting stuck when calculating the conductance and unsure what to divide by... Please let me know if you require more info. Thanks

okay this isnt exactly for homework, but i do need help, im trying to reorganize some chemical compositions. i know most of this is hypothetical and may not be strictly possible, but... i cant give it away just yet (the reason). but here are the chemicals i need broken down: HC4,C2H6, HC2H, C3H8, HCN, CH3CN, (CN)2, C2H4. as you notice, there are alot of methyl kind of combinations here, first of all, are any of these able to break down, and what could be made from them? and if you add the others, CO, CO2, H, N, Ar, the last 3 are on their own, but there is some O and thats more or less what i'm trying to generate here, and break down the methane concentration. no, this is…

Hi, I have an excel spreadhsheet filled with data...external and internal concentrations, Vm for potassium, sodium and chloride, however I am struggling with two points.. a) how can I find the internal concentration for K, Na and Cl? I have an increasing exernal concentration, and the membrane voltage of the cell at that particular external voltage. e.g at K(external) = 25mM, and membrane voltage = -31.4mV, I can use inverse log laws and the GHK equation to calculate the internal concentration. However, I have external concentrations between 25 and 300mM - how do I know which internal concentration to use? b) my second question is, how do I calculate per…

I want to test theobromine on Hydra, and although it is poorly soluble, I still want to go ahead. However, theobromine is toxic to some organisms due to slow metabolism. I don't want to kill the Hydra - does anyone know what is the metabolism of Hydra? Also, how much water is needed to dissolve theobromine? Please cite your sources

Hi mates am new on this forum, but seem to have alot of questions already. can someone help me here pls? 1. WHAT ARE THE 3 FACTORS THAT HAVE SIGNIFICANTLY INFLUENCED THE EVOLUTION AND DESIGN OF SYSTEM SOFTWARE ESPECIALLY OPERATING SYSTEM? 2. dESCRIBE 2 DIFFERENT METHODS FOR TRANSMITTING CHARACTERS IN A COMPUTER NETWORK ENVIRONMENT. 3. DEFINE MANAGEMENT INFORMATION SYSTEMS? 4. WHAT ARE THE DISAVANTAGES OF A TIME SHARING SYSTEM 5. DESCRIBE BRIEFLY THE VARIOUS SUBSYSTEMS OF A COMPUTER THAT ARE VULNERABLE TO COMPUTER CRIME AND FRAUD 6. eXPLAIN THE TERM 'TOKEN PASSING' 7 A TELETYPE TYPICALLY SENDS OR RECEIVES TEN ASCII CHARACTERS PER SECOND, IF E…

I need to increase the amount of RNA i am getting. I have a number of aliquots of recently extracted rna (approx 200ng of RNA per tube (20ul volume)). I need to be able to get approx 5ug of RNA in total for the next experiment.This means i would need to perform a further 25 extractions and combine all the aliquots together to get approx 5ug in total. If anyone had any other ideas as to how to improve total amount of RNA. In combining all the aliquots together i wont lose any RNA will i?, but i could change the quality (I check all the RNA on an agilent PICO chip (RINs are between 5.7-6.9). Could i post cleanup this entire pool that i make? Is there a good protocol fo…

Hello, does anybody know what alpha-peptide bond and alpha-amino group mean? Thank you

If a piece of zinc metal is added to the following solutions, will a reaction be expected? If so, write the equation for the reaction. a AlCl3 b AgNO3 c SnCl2 d CuSO4 In my textbook it says the answers are: A33. a no - but why? b Zn(s) + AgNO3(aq) ---> Zn(NO3)2(aq) + Ag(s) - the NO3 isn't balanced here! c Zn(s) + SnCl2(aq) ---> ZnCl2(aq) + Sn(s) - why is it that the Cl2 reacts with Zn and not Sn? d Zn(s) + CuSO4(aq) ---> ZnSO4(aq) + Cu(s) - why is it that SO4 reacts with Zn but not Cu in CuSO4?

I'm doing the biochemistry practical write up and I need to discuss the results including suggestions for improvement and sources of error noted. The practical was about size exclusion chromatography. I separated mixture of gelatine and glucose into 20 fractions and did Benedict's and Biuret tests to confirm the results that were recorded based on the ammount of substance using the scheme: 0 - none 1 - trace 2 - little and so on. I'm really struggling with finding the sources of error. Could it be broken protein molecules? Or may be errors could happen because I was qualifying the substunces but not quantifying? What could be done to improve experiment? I und…

You are given three colourless solutions (A, B and C) known to be sodium nitrate, silver nitrate and lead nitrate but not necessarily in this order. You also have some pieces of magnesium ribbon and copper wire. Describe how you could identify each of the solutions using only the chemicals supplied.

I am working on my research term paper for biology. My topic is on telomeres and telomerase. I understand that telomeres are long strings of repetitive nucleotide at the ends of the 3' side of chromosomes. However, I want to make sure I understand this right. During cell division the cell cannot replicate the chromosome all the way to the end. So by having telomeres the cell is able to only does not replicate the unneeded repetitive nucleotides that make up the telomeres. Is this understanding correct?

I'm writing a practical report about size exclusion chromatography and I've been told to give a standard analytical techniques reference in a "materials and methods" part of my report. Could anyone explain me please, how to reference such things and can I use an internet article for that? It's my first science report and I have no idea what I am doing. Thank you for your help!

Where can we find if xenon has alloys? Does it have any alloys? Thanks!

ok i have been looking for about 30 minutes to find..... where would you find archaebacteria? for a biology project and i cant....can anyone help me plz

Hi, I have a worked example of a question to do with forces and i just cant work how he gets to the answer? could you help me? i will upload the example Thanks

Hm so I'm having difficulty in answering this question. This is what I have so far: 1. The problem statement, all variables and given/known data Consider a neuron with resting potential of -65 mV and threshold of -55 mV. It receives two synaptic inputs with similar synaptic conductances, one with reversal potential of -10 mV and the other with reversal potential of -58 mV. Draw the predicted postsynaptic response (change in membrane potential) to stimulation of each synapse alone, and then to simultaneous stimulation of both synapses. Briefly explain what’s going on and why the results might at first be confusing. 3. The attempt at a solution So the ne…

I have found varying answers to this question and I need confirmation . I searched what the two most abundent elements are in the atmosphere and hydrosphere. For the atmosphere I found that 21% is Oxygen and 79 % Nitrogen. For the hydrosphere I found thst the two most abundent elements are Hydrogen and oxygen. But I could not find percentages. Please help me.

I am seeking comment on the method of the following calculations to determine the energy output of combustion of fuel. Any errors in the methodolgy would be appreciated. The method is using total enthalpies with mole quantities The ultimate analysis of the fuel is used to obtain weight values of the composition: C 45 (% weight) 243 (mol) 0 (ΔHf kJ/mol) H 6 433 (including air, water) 218 N 5 23 473 O 35 155 (including air, water) 249 water 5 - ash 4 - CO2 188 (mol/hr) -394 (ΔHf kJ/mol) 37 (Cp J/K/mol) H2O 227 -286 75 N2 3120 - 29 O 620 - 29 fuel feed 5 kg/hr air supply 1500 l/min combustion temperature 1070 K From dQ/dt=Σ H(outlets)-Σ H(in…

What are the chances of the child contracting the following autosomal genetic defect. The child's father gave birth to a son having the defect whilst being with his ex-wife. The child's mother's brother had it. If his mother and father, neither having the defect, mated what would be the chances of the child contracting the defect? I don't know which way to tackle it!

From a point on level ground, an observer measures the angle of elevation to the top of a hill to be 38 degrees The observer then walks 370 meters directly away from the hill and measures the angle of elevation to the top of the hill to be 25 degrees. Determine the height of the hill to the nearest meter. I drew it out and for variables I used "x" as the distance from the first angle measurement to the base of the hill and 370 from the end of the first measurement to the start of the second measurement. I used "h" to represent height. I got cot 38 degrees=x/h and cot 25=(370+x)/h I solved for x in the first equation then plugged it into the second and got finally h=37…

Hi I’m preparing for a presentation and my topic is "Diagnostically significant lipids" this should be connected to medicine and diseases. I would really appreciate a push in the right direction or any help i can get. Thanks

1. A gas of unknown molecular mass was allowed to effuse through a small opening under constant-pressure conditions. It required 67 s for 1.0 L of the gas to effuse. Under identical experimental conditions it required 24 s for 1.0 L of O2 gas to effuse. Calculate the molar mass of the unknown gas. (Remember that the faster the rate of effusion, the shorter the time required for effusion of 1.0 L; that is, rate and time are inversely proportional.) Find g/mol. Don't know what the heck to do. 2. A gaseous mixture of O2 and Kr has a density of 1.110 g/L at 425 torr and 300. K. What is the mole percent O2 in the mixture? Find %. Quote answer from number 1.…

So I am reviewing for my final on Wednesday, and this question just has me baffled: What is the limiting reactant when 31.3 g of manganese (II) chloride, 48.3 g of chlorine, and 25.7 g of water react to produce manganese (IV) oxide and how much hydrochloric acid is produced? I determined that MnCl2 is the limiting reactant. After balancing my equation, I get: 31.3(1/126)(8/1)(36)=70 something The answer it is marking as correct is 36.3g. What am I doing wrong? Thanks.