Dr Russ
This page lists questions and answers that were posted by visitors named Dr Russ.
Questions
The following questions were asked by visitors named Dr Russ.
Answers
The following answers were posted by visitors named Dr Russ.
Can I suggest that you post your thinking and we will comment on your answers.
18 years ago
You will need to put your question in context. If you mean 120 meters and you have counted them then +/-1 uncertainty may be appropriate, but I can't see how this fits with geometry.
18 years ago
You need to follow the question and plot the data. Plot weights (y) against thickness (x). Then draw a best fit line through the points. This line will pass through (0,c) and have a gradient m, both of which you can determine from the graph. The equation...
18 years ago
Depends where she was located when her weight of 500 N was determined. If she is on Earth at sea level then her mass is 500 N/9.8 m s^2.
18 years ago
Adding the two equations gives 4x=28, and solve for x
18 years ago
Mp/Ms will give you a decimal. It is often more usual to show these as Ms/Mp as it is generally clearer. Hope this helps.
18 years ago
See previous post
18 years ago
Not an unusual problem with disposable pipettes and organic solvents, and is worse with low boiling solvents such as ether and acetone. This is largely due to the vapour pressure of the solvent at room temperature and the low surface tension. A tip is to...
18 years ago
Hate to be picky. While the mass of the brick may be 1 kg its weight is 9.8 N. This is because the mass is a property of the brick so no matter where you take it its mass is 1 kg. The weight, which is a force, is mass x acceleration (m x a) so if the bric...
18 years ago
If I understand the question you are looking at more than one 'plan' here as you are looking at more than one area. In terms of feedback you might like to google 'home school agreements' which are a very effective contributor to a positive feedback loop i...
18 years ago
To gret you started L-lysine has three pKa's: pKa1=2.20, pKa2=8.90 and pKa3=10.28. If we start below pH=2 the charge on the molecule is +2. At pH=7 which of the three groups are protonated?
18 years ago
I assume that you are solving for x. 1. remove the brackets by multiplying out the terms, for example 3(x+2)=3x+6 2. normally you would group the like terms together; so collect the x terms and the number terms together on the LHS. 3. rearrange so that th...
17 years ago
Second para Try to explain why you are stating "that animal-based foods and goods are the most damaging groups", and damaging in what way and to what? The latter will help with the second half of the sentence where you could give examples of remedies. 'th...
17 years ago
Hence go for the largest difference in bp that you can get. An added advantage of using a low boiling solvent is that it is more easily removed from the product. DMF is not good as an extracting solvent as it is miscible with water!
18 years ago
Easiest is to multiply ml x M, add them and divide by total volume (30.0 ml). An SI perfectionist would include a factor to divide ml/1000, but this is not needed as it appears all the way through. If you post the answer I can check it.
18 years ago
Do you mean words ending in morph such as isomorph as you have headed this earth science? Isomorph A substance which is similar to another in crystalline form and composition. Another example is: pseudomorph A pseudomorphous crystal, as a crystal consisti...
18 years ago
No question?? Only one minute to go....
18 years ago
Mom, You are never too old to re-visit maths. Many of my students studying undergraduate maths and chemistry are 35+.
18 years ago
You should post this as a new question. I am not sure what you are asking. Do you need to simplify 5+3(k+7)? then expand the brackets 5+3k+21 and then collect like terms together 26+3k
18 years ago
I think you need to start by defining the problem a little tighter. What do you mean by 'harmful' and 'harmless'. A place to start might be by finding out what is meant by the terms 'Hazard' and 'Risk' as these have specific meanings and are often mis-use...
18 years ago
...or the two directions might be at right angles. I.e. the object might be accelerating in the North direction, but have zero velocity in the Westerly direction.
18 years ago
What are you going to do with the file? My guess is 'input' with Input #filenumber, variablelist
18 years ago
LoadPicture()
18 years ago
If your rotations are Sepcific Rotations (do a Google search for the definition] then DrBob is correct. If your R and S samples are of different concentrations or the path length is different, then you would need to calculate the expected rotation.
18 years ago
A clue to the first part is in the second part of the question. Which of the three types of rock forms sea arches? Do a Google search for Durdle Door. This must be the hardest rock. What shepes of cliffs do you get from the three rocks? The hardest will f...
18 years ago
Not really chemistry! If the speed of Jean is J mph and the speed of Rita is R mph then we can write 3 equations where t=time(hrs) taken by Jean. Jxt=945 R(t-4)=135 J=3R and solve for R
18 years ago
DrBob has essentially covered it. It is not that easy to generalise, you need to consider each halide looking for steric influences, stabilisation of a carbocation and stability of the product. Some general points: E1 is a two-step process of elimination...
18 years ago
Can I suggest that you post here the ten that you have for comment.
18 years ago
You might also like to search for news/articles on Public (=Private) or Independent schools in the UK, altough my understanding that Charter Schools are closer to what were called Grant Maintained Schools in the UK.
18 years ago
It depends on the use of the term 'standard form'. It can mean the usual representation of an equation, for example the equation for a straight line as y=mx+c could be described as standard form. 'In standard form' can also mean 'in scientific notation.'
18 years ago
You haven't stated the third resistance, but both A) and B) are not possible for any value in parallel with two 20 ohm resistors. The only possible answers are C) and D). using 1/R(total) = 1/R +1/R +1/R 1/20 +1/20 =0.1 if the unstated value =x A) so 0.1...
18 years ago
To find the number of millimoles (mmoles) you need the volume and concentration of HCl. So of the concentration of HCl is 0.01 M and the volume is 25 ml then the number of moles is (25 ml /1000 ml l^-1)x(0.01 mol l^-1)moles = which you then multiply by 10...
17 years ago
Try Delta f = fv/c where f=transmitted frequency v=difference in velocity c=velocity of light
17 years ago
Depending on the detail required for your question you may also want to look at human take up/elimination rates.
17 years ago
I think I would convert from 1 mole of a gas occupying 22.4 litres at 273.15 K and 1 atm (STP). So calculate the volume of CO2 at STP (22.4 litres x number of moles of CO2) then convert to 296.15 K using V1/T1=V2/T2 A comment on your calculation of moles:...
17 years ago
In essence I would say: accurate, clear, concise, coherent, and appropriate.
17 years ago
Not sure that I understand the question. "In chemistry and physics, an atom is the smallest particle still characterising a chemical element." It is possible to have a long discussion over how many atoms (1,2 etc) of a chemical element might be required t...
17 years ago
Unless I am out of date or misunderstood the question I thought that all electron affinities were shown as positive values. Those ending np^5 (e.g fluorine or chlorine) have the highest electron affinities.
17 years ago
Also thank you from me for your comments. I aloways like the Wow! I get it moment! I work with a middle school on a voluntary basis and as a School Governor. There may be a school near you that would appreciate some of your time, perhaps to hear a child r...
17 years ago
He is quite well known and does have his own web site so perhaps start there.
17 years ago
You need to give the question in full.
17 years ago
I think you need to explain the posting further.
17 years ago
It depends in what context you are referring to Lantana.... If you mean the film it is set in Sydney, Australia. If you mean a US town there is a Lantana in Florida. If you mean a guest house with this name there is one in Weymouth, England. Strangely I h...
17 years ago
Check your working. Note that dHvap is per MOLE and the answer q1 will be in kJ whereas the answer for q2 will be in J Please get back if you still get the wrong answer.
17 years ago
...there aren't many things you can think of that is not a compound or an element A vacuum? 8-))
17 years ago
It looks similar to an old puzzle 2+6=6 4+1=7 8+3=10 so 5+5=8 based on the number of letters two + six = 6 four + one = 7 eight + three = 10 so five + five = 8 This might give a clue, but I can't see the answer at the moment.
17 years ago
Has this been set as an IT (e.g. Excel)based question? If so there are a few ways to do this, but try this. With the words in a column (say starting at A1) 1. in an adjacent column use =RIGHT(?,3) where ? is the cell address of the word, so A1 for the fir...
17 years ago
I am not a fan of these either apart from as an 'end game' to wind down a lesson.
17 years ago
22.6 minutes is 22.6/60 hours = 0.3737 hours If for simplicity we take the rest stop at the start the total journey time is (0.3767 + t) where t is the driving time. If d is the distance travelled then speed = d/t=85.6 km/h However the average speed is fr...
17 years ago
Substitute the 100 degrees F 100=9/5C+32 subtract 32 from each side 100-32=9/5C 68=9/5C 68x5/9=C so C=37.8 Is this OK. Can you see where you went wrong?
17 years ago
Your original post is around properties, where as your discussion is around stability. I agree the stability will affect the chemical properties, but also consider physical properties. How will having groups on the same side or opposite sides affect physi...
17 years ago
HgO -> Hg + O2 You will need to balance the equation as you have one atom of O on the left hand side and two on the right hand side.
17 years ago
Another tip. With this type of study it is worth thinking in advance what you will do with the results. Are you going to compare for example male v female and/or age ranges? These will have an impact on how large your population size needs to be which I t...
17 years ago
I would also have said a).
17 years ago
An interesting question. I would imagine that the bell jars serve several purposes, for example a) reducing the airborne contaminations that the standard picks up and b) ensuring that the mass is at the same temperature as the room. I believe the mass is...
17 years ago
I have taught maths as part of undergraduate chemistry for many years. I currently teach chemistry (I am an organic chemist)which includes maths as part of general study skills for a UK university.
17 years ago
In the first part as Dr BOB says the HCl is in excess (both HCl and NaOH have the same concentration but there is a greater volume of the HCl solution). Thus the excess moles of HCl we can get from the excess volume (8.00 - 2.80)ml = 5.20 ml. as the solut...
17 years ago
Packaging something that can't/shouldn't be handled but you want to put into water. A suggestion could be radioactive or biologically contaminated clothing that needs to be transported/handled on its way to being washed. To stop the operator becoming cont...
17 years ago
There is no reaction between cyclohexanol and bromine in dichloromethane. The solution will remain coloured. With cyclohexene the bromine adds across the double bond and the solution will become colourless. The predominant product is trans-1,2 dibromocyco...
17 years ago
1. calculate the molecular mass of the ferrous salt. RMM 2. calculate the number of moles of ferrous salt. 1.041/RMM 3. from the equation 1 mole of permanganate reacts with five moles of the ferrous salt, hence the number of moles of permanganate is 1/5 o...
17 years ago
Because there is no change in the Fe2+. It is Fe2+ as the ion and Fe2+ in the hydroxide.
17 years ago
Hint. Do you know of a simple chemistry reaction that shows the presence of carbonate?
17 years ago
You need to type the question.
17 years ago
I don't understand the expression as the text you have given. "the nth root is 4square root of 5 times the nth root is 4 square root of 5" Is this exactly as presented in the question you were given?
17 years ago
The short hand configuration is quite straight forward For Eu it is [Xe] 4f7 6s2 the [Xe] is the electron configuration of xenon, the nobel gas before Eu, which has full electronic configuration of 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 or if you l...
17 years ago
Do you mean percentile?
17 years ago
Why 55.845/342? 1. I get the RMM to be 392 g mol-1 (please check my maths!) So step 2. is 1.041g/392 g mol-1 = moles which gives you the number of moles of Fe in the starting mass of the salt. Now go from here....
17 years ago
This is quite straight forward if taken stepwise. There are only 5 possible values which are given in the question. Start with D and work through the values. D+D=M If D=1 M can't = 2 (2 is not a possible value) If D=3 M can't = 6 if D=4 M=8 if D=7 M=4 if...
17 years ago
OK 4sqrt5 x 4 sqrt5 another way to write this (struggling with the limits of text only!) is 5^(1/4)x5^(1/4) (^ means to the power of so 10^2=100) or 5 to power quarter x 5 to power quarter. When you multiply two numbers with powers together you add the po...
17 years ago
Yes
17 years ago
You have a total of 40 items (people). Therefore each item corresponds to 360/40 degrees or 9 degrees. Therefore the Coast Guard is 9 degress of the circle, National Guard is 18 degrees etc.
17 years ago
How about one sentence: HMS Repulse is a submarine powered by nuclear propulsion. The judge was unable to repulse the argument. (used here in the sense of defeat) Stephenson's Rocket used steam for propulsion.
17 years ago
You seem to be having trouble with the font/format. I think you are cutting and and pasting from somewhere else to here. It is usually more successful to type the question in plain text, rather than cutting and pasting.
17 years ago
Ooops thank you DrBob!
17 years ago
Assuming the calculation is 2.26=(1.000+x)/(1.000-x) Multiply both sides by (1.000-x) which gives 2.26-2.26x=1.000+x Solve for x.
17 years ago
1. In gas chromatography, two measurements are made. Identify the qualitative and quantitaive measurements. dye color No The question is about GAS chromatogrpahy so it is a property of a gas you would want. However I don't think the question is asking for...
17 years ago
In the absence of other information (temperature) write molecular formula for calcium hydroxide and complete the word equation below as a chemical equation. calcium hydroxide = calcium ions + hydroxide ions This will tell you how many moles of hydroxide i...
17 years ago
One disadvantage of LOW equatorial orbits is that the satellites are not visible over the United States. Or Northern Europe 8-)) Think about other types of satellites such as weather or Earth mapping. Is it an advantage or disadvantge to be placed in orbi...
17 years ago
There is another use for 'Housekeeper' which is job in a Hotel and which is typically a supervisor of the (hotel) maids.
17 years ago
The following came up top of the list of a Google search. "A satellite in geosychonous equatorial orbit (GEO) is located directly above the equator, exactly 22,300 miles out in space. At that distance, it takes the satellite a full 24 hours to circle the...
17 years ago
Shadow zone
17 years ago
DrBob has given you the equation to use: k2 = [H^+][SO4^-]/[HSO4^-] and the values to substitute [H^+] = 0.01 + x [SO4^-2] = x [HSO4^-] = 0.01 - x k2 = 1.2 x 10^-2 you need to substitute these and solve for x. Remember that you are after 0.01+x [H^+] to c...
17 years ago
projector lens and objective lens are both 13 letters but no e at the end.
17 years ago
Phenol is moderately soluble in water at about 8 g /100 ml. It forms clear colourless solutions in water. For the last one the pKa of phenol is about 10.
17 years ago
Force between two objects is given by: Fg=GxM1xM2/d^2 G=Gravitatinal constant, M1= mass of object 1 M2=mass of object 2 d=distance between them Does this help?
17 years ago
Perhaps if you divide up the questions to different postings and add your answers, we will then be able to comment.
17 years ago
4x-2y=-5 -x+2y=2 Adding the two equations together gives 4x-2y+-x+2y=-5+2 the ys on the LHS cancel to give 4x-x=-3 3x=-3 x=-1 substitute x=-1 into one of the starting equations. 4(-1)-2y=-5 -4-2y=-5 -2y=-1 y=1/2 Have a go at the others.
17 years ago
Have another go, I got 27.93
17 years ago
This and the other posting relate to a popular school's quiz in the UK where the pupils have to find a bird, flower etc for each letter of the alphabet. Not too difficult especially with so many web sites devoted to birds and plants. For a start try the R...
17 years ago
I have seen it done with a cake by baking a different colour mix in the cake for the nucleus, green mix for chloroplasts and so on. The cake was divided up into sections to show the structure and then eaten by the class!
17 years ago
If you would like to suggest an answer we will comment.
17 years ago
I think you need to post a suggestion for the equations for us to work from. You could start by writing word equations for which you have the basis in your 'My observations' section. Remember that the acid is a catalyst here.
17 years ago
Charlotte, I would go careful here with Amethysts's explanation. There are two effects that ozone has on the Earth as a result of being in the atmosphere. Effect 1. Ozone absorbs ultra violet light. Ultra violet light is divided up into UVA, UVB and UVC....
17 years ago
You will need at least 21 columns (3 weeks + at least one for a label for rows). Each column is then 1 day of the job search. For the rows think of the activities that you might need to do for a job search, e.g. write resume(CV), search Ads, write letter(...
17 years ago
Good site DrBob. Useful to think what is meant by "without sewer-sludge fertilizers, most synthetic fertilizers and pesticides, genetic engineering (biotechnology), growth hormones, irradiation and antibiotics." This is often abbreviated to as "without ch...
17 years ago
You need to post some suggestions for us to help you with.
17 years ago
You might find Darwin's "Origin of Species": A Biography (Books That Shook the World) by Janet Browne useful. It is a short book and easy to read. It has a time line and also includes information about others who were thinking along the same lines at the...
17 years ago
Do you mean today or in the mid 19C?
17 years ago
The obvious (to me!) example is penicillin production. I am sure if you google 'penicillin production' or similar this will come up with a number of sites. Not really a drug but xanthan gum is made by bacteria on a large scale (it is used a thickner in th...
17 years ago
I imagine that the question is looking for the full electronic config. in each case. So for Na 1s^2 2s^2 2p^6 3s^1
17 years ago