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Dr Russ
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Seasons Greetings to all the questionners and fellow tutors answering questions.
Best wishes for your studies in 2010. Dr Russ
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This looks very much like the S104 TMA04 question?
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we will assume that the aqueous solutions fill the 1 L flask. At start 1 mol A + 2 mol B and 0 mol C At equilibrium 1-2x mol of A and 2-x mol of B and 3x mol of C so x=0.2 M K=x^3/(1-2x)^2(2-x) K=(0.2)^3/(0.6)^2(1.8) K=0.008/(0.36)(1.8) K=0.012 (with no
2C:6H or 1C:3H
I tend to put the mixture in the developing chamber a while before I run the TLCs. Not too important if all you are doing is looking for the disappearance of starting materials/appearance of product. Getting the chamber saturated can be important with
You need to set these up so that if you add up the equations you get the equation in the question. So we need to get to C3H6 (g) + 9/2 O2 (g) -> 3CO2 + 3H2O C(s)+O2 (g) -> CO2 (g) dH= -394kJ and we need three of these so A. 3C(s)+3O2 (g) -> 3CO2 (g) dH=
So lets say we have 100 mL of air then this will contain 20.9 mL oxygen. Thus 100 mL/20.9 of air will contain 1 mL of oxygen. So how many mL of air contain 150 mL of oxygen?
If we take the specific heat of water as 4.18 j/g/K Do this by heat balance Heat before water 250x(25+273)x4.18 metal 41.6x(100+273)xk after water 250x(26.4+273)x4.18 metal 41.6x(26.4+273)xk so 311410J + 15516.8k J = 312873J + 12455k J solve for k I got
Yes, from general knowledge A is exothermic B is exothermic C is endothermic (the reverse reaction is exothermic!) D is the formation of F2(g) from its elements in their standard states. All elements in their standard states have a standard enthalpy of
1. You will have results for this. 2. You need the correct formula which is Na2CO3. To decide if there is a linear relation ship plot the number of moles of CO2 produced (y-axis) against moles of Na2CO3 used (x-axis) To calculate the number of moles this
Again this has come up before http://www.jiskha.com/display.cgi?id=1191713796
This one has coem up before http://www.jiskha.com/display.cgi?id=1270701200
See if you can find one of the periodic table on the internet that shows pictures of the elements. If you do you will see that the vast majority of the elements are shiny metal solids. Those that are not shiny metal solids are the exceptions. There are
Better of you gave an answer for us to comment on. Lets sat we have the decay of uranium (mass=235, atomic number=92) to thorium (mass=231, atomic number=90) plus He nucleus(mass=4, atomic number=2) Note that the mass number (235=231+4) and atomic number
Making the ice surface rough so that it scatters the incoming light is most effective to slow down melting. Alternatively if you can change the colour of the surface under the ice this will affect the rate of melting. Ice on a black road melts faster than
Unless you have been told otherwise I would recommend that you include the units in a conversion such as this. While it might seem pedantic here, it can help a great deal when the units are less familiar. 365 d y^-1 x 24 h d^-1 x 60 min h^-1 x 60 s min^-1
I'll get you started.... 8.00 mass percent means that 100 g of the solution as 8.00 g of ammonia and 94.00 g of water. The 100 g of solution will have a volume of 100 g / 0.9651 g/ml =103.61 ml Thus (based on NH3) the 8.00 g represents 8.00 g /17 g mol
use PV=nRT where n is the total number of moles. Use V=25.00 L P =1.00 atm you needed to calculate n for the first part. Make sure that use the correct value for R based on the units.
Your question doesn't make sense
Please try to get into the habit of using the correct symbols as this aids your communication on the topic. (I will assume here that the reaction is going to completion) Start from a balanced equation 3H2 + N2 -> 2NH3 then calculate the number of moles of
The key here is 'what do YOU think....'
There are no electrons in the first free level of any element. But I suspect it is a typo and it means the first three levels? Silicon has electronic configuation of 1s2 2s2 2p6 3s2 3p2 So I suspect the answer that is being looked for is 10.
As we are not given Kw in the question, my answer would have d)
So we need to factorise x^3+2x^2-x-2=0 If we start off by guessing that one of the solutions is x=-1, i.e. one of the factors is (x+1) then by division (x^3+2x^2-x-2)/(x+1) = (x^2+x-2) for which the factors are (x-1)(x+2) so the solutions are x=-1, x=+1,
3x^7 = 81x^4 divided both sides by 3 x^7 = 27x^4 divided both sides by x^4 x^3 = 27 take the cube root of each side x=3
Try high lighting the whole text and copying and pasting to say a Word page.
We need the molarity so we will need to be working in moles and therefore need the molar mass of the steroid. I make this C. 12 x 20 = 240 H. 29 x 1 = 29 F. 19 x 1 = 19 O. 3 x 16 = 48 total = 336 i.e. 336 g mol^-1 If 10.0 mg is dissolved taken then this is
You weigh out 196.07mg ferrous ammounium sulfate (FW 392.14) to prepare 250mL of solution which is 0.002M with respect to that compound. The salt is quantitatively transferred into a 250mL volumetric flask and 8mL of 3M H2SO4 is added and then diluted to
There are a couple of possible reasons. I don't know what red leaf extract is?? Is it red tea extract? I take it that the stationary phase of the TLC is silica gel? It is quite likely that the extact contains a number of nitrogen containing compounds, such
Thank you DrBob, I missed that. Dr Russ
Be sure your answer has the correct number of significant digits.. As both the starting values are to 2 sig figs, and assuming that you use molar masses that have 3 sig figs or greater then the answer should be to 3 sig figs.
Not solveable You need to know: what the reaction was quantities of materials used units of 5.70 (g, kg, lb, oz, mole?)
if you react 37.0ml of .762M sulfuric acid..... with what??
Use P=nRT/V n=27 g /18 g mole^-1 V and T are in the question. You need to find the correct value for R
Answered below
My understanding is that is not possible. The only blood groups from an O mother are O, A or B, depending on the blood group of the father, but not AB. The mother would have to be A, B or AB. So I would conclude that the mother is not the child's natural
If a solution is 1.54% w/w then for 100 g of solution 1.54 g of the soluton is NaCl and the other 98.46 g is water. If we have 2 x 1.54 g of NaCl we must have 2 x 98.46 g of water. So if we have 6.96 g of NaCl how much water?
Assume 4 tyres and mass evenly distributed. Then use pressure= force/area 1 Pa = 1 N m^-2 force = mass x acceleration I would assume that g= 9.8 m s^-2
I take we are taking about the visible spectra (Balmer Series)? The two spectra have similar number of lines as below, although some are very feint. That a line apears in the visible spectrum will depend on the separation of the energy levels. We do not
For the first one Use Ke = 0.5 mv^2 Ke = 200 MJ or 2 x 10^8 J m= 100,000 tonnes or 1 x 10^8 kg substitue and solve for v. the same approach will answer the second one. Note that speed is in km per hour not Km per hour.
You have essentially two possibilities, life started on Earth abiogenesis ((Broken Link Removed) or it arrived here from elsewhere (Panspermia see (Broken Link Removed) If you google abiogenesis or panspermia you will get more information. The above two
You need to choose an atom. Helium is the easiest which has protons, neutrons and electrons. I presume you are looking for a Bohr/Rutherford Model ((Broken Link Removed) Thus for helium you will need a nucleus of 2 protons and 2 neutrons around which there
Please do not write in capitals, it is considered to be the equivalent of shouting. Roots cannot be decomposers as they are not an organism. A decomposer is an ORGANISM whose ecological function involves the recycling of nutrients by performing the natural
This sounds like an elimination reaction problem, in which case the answer is usually a discussion of E1 v E2 so see http://en.wikipedia.org/wiki/Elimination_reaction
You are calculating w/w%, which is mass (A) x100%/(total mass A + M) From the density we can find the mass of ethanol M=0.789 g/ml x 175 ml A=42.9 g
How about suugesting an answer?
You need to know the Kw for water at the temperature of the fruit. There is a table of Kw versus temperature here http://www.chemguide.co.uk/physical/acidbaseeqia/kw.html then use [H+][OH-]=Kw to find [H+] the find pH Alternatively find pOH find pKw then
Nitrous acid is HNO2
from the equation HCl + KOH -> KCl + H2O 1 mole of HCl reacts with 1 mole of KOH Then if we use M1V1=M2V2 42.5 ml x 0.110 M = 25.0 ml x X X=42.5 ml x 0.110 ml/25.0 ml [Incidently you can use 'school boy logic' here to eliminate amswers. If we only have
There are a number of tutors who volunteer to answer questions and who are in various time zones/countries. Consquently there may not be always be a specialist available for some questions. The easiest way for us to spot an unanswered question is a single
