Wednesday
April 23, 2014

Posts by DrRuss


Total # Posts: 69

Elementary Algebra
8x-3y=-6, 5x+6y=75 multiply the top one by 2 16x-6y=-12, 5x+6y=75 add the two together 21x=63 can you take it from here?

Chemistry
I have a 40 ml solution of pH 4.36. I need to make this solution at pH 8.5 by adding extra 10 ml of HCl and NaOH. Not sure that this question entirley makes sense. However, if pH is 4.36 then pOH is 9.74 and [OH-] is 1.82 x 10^-10 M if target pOH is 5.5 then [OH-] is 3.16 x 10...

Physics
0n1 + 88X232 ---->ZYA element 88 is radium Ra 0n1 + 88Ra232 ---->88Ra233 There is either infromation missing in the question or is it Ra223 you are starting with? If so the question makes more sense 0n1 + 88Ra223 ---->88Ra224 and Ra 224 under goes alpha decay to 88Ra2...

Chem, Oxidation
I guess your college/school is using an automated response system like the Open Universitiy's iCMA system based on the response. It is difficult to guess what is missing as the formatting is different. My guess would be 2OH^-(aq)--> O_2(g)+2H^+(aq)+4e^-(aq)

chemistry
I don't know your experiment, but the usual reason for diluting the titrating solution is so that there is a sensible volume. Looking at your question it looks as though the NaOH at 6M is 20x too concentrated, which means that if you are using 0.3M you will need 20x the vo...

Chemistry
The atomic nucleus has a + charge. A proton and an alpha particle (He nucleus) also have + charges, so what will happen if you sent one of these two towards a nucleus? The neutron has no charge.

chemistry
It will depend on the gas. In some cases it is temperature and pressure. Others that react with water like CO2, these are also pH dependent.

Pharmacist
Try here as well rpharms(dot)com/home/home(dot)asp and click on the link to 'about pharmacy'

Chemistry
Thionyl chloride first reacts with the alcohol to form an alkyl chloro sulfite, actually forming an intimate ion pair. The second step is the concerted loss of a sulfur dioxide molecule and its replacement by the chloride, which was attached to the sulfite group. SO not A) and...

Integrated Physics and Chemistry
Have a go at answering these and you might get a response. We are not here to do the homework for you.

Chemistry
When (R)-butan-2-ol is treated with TsCl in pyridine and the tosylated alcohol is treated with sodium chloride in acetone we expect an inversion of the chiral centre and a 2-chlorobutane to be formed. There is no 2-chlorobutane in the list so E)none of these. There will also b...

Math
An exact answer is definitely not required. 20% is approximately a fifth (1/5) 78 is nearly 80 a fifth of 80 is 16 so the answer should be near 16

chemistry
What is the concentration of the NaOH?

math
These types of problems are easier if you get in the habit of including the units during the conversion. It then becomes second nature when the units are less familiar. 1 km = 1000 meters so the conversion is 1000 m km-1 1 m = 100 centimeters so the conversion is 100 cm m-1 61...

Chemistry (PLEASE HELP)
"Nuclear fusion produces no long-lived radioactive by-products. " Perhaps it depends on wht you mean by 'long lived' and if only by-products from the actual fusion are considered. There are disposal considerations for radioactive waste from fusion. For info o...

Organic Chemistry
Depending on the materials involved 1. 1H nmr is far more sensitive than mpt when looking for an impurity. This is especially true if the impurity has a prominant peak (say CH3) in an area of the spectrum where the bulk material does not 2. It is often possible to identify an ...

Math
I'll get you started. Draw three intersecting circles. Label one B, one S and one L. From the data given we can place 31 in the intersection of all three. We are told 65 knew the ballroom and swing dances, therefore the number that know ballromm and swing only is 65-31=34 ...

geometry
I assume you mean a regular pentagon and how to do it by maths? If t= length of one side. The formula is area = 5x t^2 x(tan54)/4 which is quite easy to remember! If you evaluate the 5 x tan(54)/4 this is approximtately 1.72 so the area of a regular pentagon is approximately 1...

Geometry
area of a rhombus is (d1 x d2)/2 where d1 and d2 are the lengths of the diagonals. Substitute the area and the diagonal to find the other diagonal.

english
You need to make sure that the 'word below' appears.

Math!!!!!!HELP!!! :(
I will depend on the density of the material. What is the material?

math
the rate of delivery is 150 g h^-1 so the length of time is 3000 g/150 g h^-1 20 h Note the unit conversion to g. Note that the unit g cancels and we end up with just h, unit of time, which is what we want.

maths
Let the pen have sides length a and b (both in ft) If we assume that the sides for the separate internal pens are parallel to the sides of the outer pen then 3a+3b=1200 ft or a+b=400 ft and the area=ab or a=area/b substitute in the equation above area/b + b = 400 ft area = 400...

Chemistry
Magnetospehere as it is a long way beyond the Earth's atmosphere. The question it self is flawed as the magnetosphere is not part of the Earth's atmosphere.

organic chemistry
What was the experiment? Experiments with these two molecules are usually to demonstrate the electron withdrawing power (greater electronegativity) of Cl than I.

Organic Chemistry
Acetanilide is much less soluble in water than this, about 1g per 200 ml of cold water. There are a couple of ways to get it to dissolve, depending on why it needs to be dissolved. If the intention is to recrystalise it then heating the water will help dissolve the sample. If ...

Math
Find the difference between the x coordinates which is 0--5 = 5 Find the difference between the y coordinates which is 12-5 = 7 Then use pythag. distance^2 = 5^2 + 7^2 distance^2 = 25 + 49 I am sure you can find the distance from this

art
I thought it was a Hans Christian Andersen story that was turned into a film of this title? Sounds like a Google search is needed.

Physical Geology
My choices would be ability to find oil and water.

science(chemistry)
Even after reading the thread I am not sure I understand the questions. The solvents you list will not themselves leave a stain on the plate. However, depending on the make of plate and how it has been manufactured some of the polar solvents do shown a slight change in the sha...

organic chemistry
I have posted an answer to this already, at least some questions as it is not clear the method being used.

chemistry
Are you asking why? If you are the benzyl radical (Ph-CH.CH2CH3)is the more stable of the three possible.

Organic Chemistry
I assume that this is TLC on silica. The more polar solvent is needed to move the more polar molecule. b) are the least polar molecules and so you would try hexane to separate them. a) are the next polar pair, so as you say methylene chloride would be a good choice. c) the mos...

chemistry
What is the question?

anthropology
By what category? GDP, Education, leading oil producer, value of exports, by ratio of number of nobel prozes to population....

Organic Chemistry
Yes B

chemistry
Do you mean isotopes that undergo radioactive decay? There are quite a few of these. Some are used as medical tracers, Tc-99 is one see the applications section of some radioisotopes are used in the oil industry as tracers. C-14 is used in radiodating materials. K-40 is used t...

Organic chemistry
I don't know where in your studies you are, as there are many answers to these. 2-hexanone can be reduced by many reducing agents and the choice will be largely governed by the cost and availability of the reagent and solvents. 2-hexanone can be reduced by sodium borohydri...

School Projects
Without seeing his work and the brief from the teacher it is difficult to answer. At grade 4 this is can be their own autobiography or a simulation, i.e. putting themselves in the position of someone else and writing their autobiography. Some teachers use historical characters...

college-history
We do not do the home work for you. If you want to post some answers we will critique these and offer advice.

math
Substitute 10 for y in the second equation so that: 10=8-4x now solve for x

Physical Science
use mgh to calculate the gravitational potential energy If the book falls 2.00 m to the ground then it will hit the ground with kinetic energy that is the same as the gravitational potential energy at the top. (note it is kg and not Kg)

Powerpoint (URGENT)
If you include information from one source on one slide I would put the reference on that slide. Otherwise I put the bibliography on a slide at the end. I don't tend to project the bibliography slide, but include it in the handouts.

chemistry
This is a substitute (usually a functional group) in the pane of the ring as opposed to axial which is perpendicular to the ring. The terminology is usually used for cyclohexanes in the chair form, but is also for rings systems on the diamond lattice such as cyclododecanes. Th...

organic chemistry
Both are carboxylic acids so it will difficult to predict the Rf. The mefenamic acid also has an amine group. This will also make the Rf pH dependent.

math
You need to type the question. Generally you cannot cut and paste to here as it is plain text. Have another go.

half-life of radioisotope
Just a word of caution on the wording and me being pedantic. The half life is referring to the original isotope so I like to see the answer referring to this. The mass of the sample may have changed only very slightly.

science
'pure' is probably the term that immediately comes to mind. As you are talking about gold then pure gold is referred to as 24 carat.

spelling
I can't see a problem with these. I would spell it neighbours, but it depends where in the world you are.

chemistry
Have a look at a 12 inch/30 cm ruler. Most have inches on one side and centimetres on the other. Which is the larger unit?

math
You need to post a question.

Science
It is likely that they are looking for a Bohr type model, so concentric rings of electrons around a nucleus of protons and neutrons. You will need to use a periodic table to find the number of protons, neutrons.

math
Do you need to solve for t? Hint - take logs.

Chemistry
1 mole contains 1.02 x 10^23 molecules. Hence you can calculate the number of moles 1.02 x 10^24 molecules represents. If you calculate the mass in grams of one mole of NaCl from the atomic masses, you can find the answer.

biology
Enzymes

brain teasers
3 sides to a triangle Any more? 64 s on a C B

Chemistry
The sequence (called a homologous series) is methanol, ethanol, propanol, butanol, pentanol... Butanol's molecular formula is C4H10O. There is more than one isomer with this molecular formula. It is difficult to show structural formulae on here. One structural formula with...

chemistry
What two properties of the solid do you need to know to calculate the density? When you have decided on them think of ways that you could measure them.

Chemistry
"and a carboxylic acid salt (or a carboxylate ion and the metal ion from the base)"... You could name the salt and/or the ions for a more complete answer, but otherwise this looks OK.

Chemistry
Still difficult to decide on the experiment. Perhaps you could give a little more detail. Is the horizontal temp axis at zero volume?

Organic Chem
If you want to post a more specific question I will have a go. IUPAC naming is quite systematic, although it can be difficult to work with with large molecules.

Organic Chem
If you draw out the chain you wil see that in (ii) Cl can be cis or trans to the main chain. You need to draw each of these, it is hard just from the names.

Organic Chem
The larger group will be equatorial and as they are trans 1,3 then the methyl must be axial. Yes A.

Science
What a good question. Covalent bonding is a form of chemical bonding that is characterized by the sharing of pairs of electrons between atoms. In order to do this the electrons have to be of a similar energy and when the bond is formed it has to be of lower energy than the sta...

Science
Another defence is that the brown hare is well camouflaged against the ground. Both species of hare tend to sit in scrapes (a shallow dip in the ground) and will sit very still when danger approaches.

Science
Yes, a brown hare does not grow white fur.

Science
Think about what might trigger flowering, temperature, amount of sunlight and length of day.

Trig
tan(7pi/8) = tan(7pi/4/2) hence tan(7pi/8)=sin(7pi/4)/(1+cos(7pi/4)) sin(7pi/4)=-(root2)/2 cos(7pi/4)=(root2)/2 so tan(7pi/8)= -(root2)/2/(1+(root2)/2) and then tidy up. Sorry about the expressions, not easy to do in text.

Physics
If you draw a picture of this you will see that you have a right angled triangle 1.5 metres (vert) x 2.5 metres x 2.0 metres (horiz.). Note it is a 3,4,5 triangle, which should help for the next bit. Post your attempt and we can help further.

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