Saturday

August 27, 2016
Total # Posts: 293

**Chemistry**

When given a chemical reaction, how would I know whether a reaction is endo or exothermic and whether work is done on the system or by the system. Without using any calculations. So I have a couple reactions which I have to use chemical reasoning to to determine. 2 Cl(g) -->...
*November 20, 2007*

**Chemistry**

You have to determine the molar mass of CaCO3, by getting the molar mass of Ca and the molar mass of C, and the molar mass of O multiplied by 3 (since there are 3 oxygen atoms). You would get 100.087 g/mol. You would then do the mass/molar mass. 30.6/100.87 = your answer
*November 20, 2007*

**Chemistry**

How did you get 1 cal/g*c....is that a calculated constant or is manual conversion required? The answer I get using your method is 96.4kg, which is correct.
*November 20, 2007*

**Chemistry**

Wait, I did it wrong. q = mH(Tf - Ti) m = q/H(Tf-Ti) m = 675/[4.18x7] m = 23.06 But its still the wrong answer.
*November 20, 2007*

**Chemistry**

m = q/[(H)(Tf-Ti)] m = (4.18)[(675)(37-30)] m = 8.84 x 10^-4 I'm pretty sure this is wrong.
*November 20, 2007*

**Chemistry**

A person falls in water at 0 degrees C. After 20 minutes of exposure, they are suffering acute hypothermia, as their core body temperature has dropped to 30.0 degrees C. Assume that a person’s heat capacity can be approximated by the heat capacity of water, 4.18 J/g/oC. ...
*November 20, 2007*

**Chemistry**

So for ii) If HClO2 is the stronger base, then does that mean that ClO2 is also the stronger base?
*November 20, 2007*

**Chemistry**

Sorry, for iii) I meant that I think Cl3CCOO- is the stronger base.
*November 20, 2007*

**Chemistry**

For each of the pairs of bases below, choose the stronger base: (i) NH2- or NH3 (ii) ClO3- or ClO2- (iii) Cl3CCOO- or Cl2HCCOO- For i) I think it is NH2-, because it has a stronger ability to attract an H+ atom to become de-ionized. For ii) I don't know how to determine it...
*November 20, 2007*

**Chemistry**

Do I have to make equations and see which one forms a precipitate again? I don't think its H2CO3 or HCl because that would not minimize the effect of acid rain. So its either the 2 bases or CCl4. CCl4 + SO2 ==> CO2 + SCl4 ClOH + SO2 ==> CO2 + SOH Ca(OH)2 + SO2 ==>...
*November 18, 2007*

**Chemistry**

Stelco has been recently legislated to reduce total SO2 emissions from iron smelting operations. Select the most effective chemical reagent to desulfurize Stelco’s gas emissions as a strategy to minimize the environmental impact of acid rain in eastern Canada and why? ...
*November 18, 2007*

**Chemistry - DrBob222**

Alright. Thank you so much for the help today.
*November 11, 2007*

**Chemistry - DrBob222**

About these: NaCl + Zn No reaction CaCl2 + NaOH No reaction CaCl2 + Zn No reaction CaCl2 + Na2SO4 No reaction How would these give no reaction. NaCl + Zn ==> ZnCl + Na CaCl2 + NaOH ==> Ca(OH)2 + NaCl CaCl2 + Zn ==> ZnCl + Ca CaCl2 + Na2SO4 ==> CaSO4 + Na
*November 11, 2007*

**Chemistry - DrBob222**

Wait, AgNO3 with any unknown with Cl present would form a precipatate. So I can use that to tell between HNO3 and HCl. So now is the whole thing correct?
*November 11, 2007*

**Chemistry - DrBob222**

Alright, I've made a list of reactions that would produce precipatations. NaCl + Zn CaCl2 + NaOH CaCl2 + Zn CaCl2 + Na2SO4 CuSO4 + NaOH CuSO4 + Zn NaOH + AgNO3 NaOH + Zn BaOH2 + AgNO3 BaOH2 + Zn BaOH2 + Na2SO4 So this way I can figure if it is NaCl, CaCl2, CuSO4, NaOH,Ba(...
*November 11, 2007*

**Chemistry**

I posted before about designing a procedure to determine two unknowns (1 solid, 1 solution). The possible solutions were: NaCl, CaCl2, CuSO4, NaOH,Ba(OH)2, HCl, HNO3, or H2O. The reagents given are: NaOH, HCl, AgNO3, Zn metal, Na2SO4, and H2O. The procedure I've designed ...
*November 11, 2007*

**Calculus**

f(x) = x(x^2 + 1)^(1/2) f'(x) = (x)(1/2)(x^2+1)^(-1/2)(2x) + (1)(x^2+1)^(1/2) f'(x) = (x^2)(x^2+1)^(-1/2) + (x^2+1)^(1/2)
*November 11, 2007*

**Chemistry**

Oh thanks. But can you tell me what this means "quantify the amount of solute in the solution".
*November 11, 2007*

**Chemistry**

I have to do lab experiment where I design a procedure to determine the identity of two unknowns given to me. One will be a solid and one will be a solution. I also have to quantify the amount of solute in the solution. The possible solids it could be are NaCl, KNO3, KHP, Zn, ...
*November 11, 2007*

**math**

This is probably really easy to work out: x^2=(x-2)(x+3) ^meaning to the power of I've got to: x^2=x^2+x-6 Don't know what to do next
*October 31, 2007*

**math**

Solve the following equations giving any roots in terms of pi in the .......? interval -2pi ≤ 0 ≤ 2pi. a) 2cos²Θ + sin²Θ = 0 b) 2cos²Θ + sin²Θ = 1 c) 2cos²Θ + sin²Θ = 2
*October 29, 2007*

**Chemistry**

Copper dissolves in nitric acid, producing copper (ll) nitrate. After reaction with sodium hydroxide and heating, copper nitrate changes to copper (ll) oxide. Calculate the percent yield of this process if 1.235 g of copper produced 1.452 g of copper oxide.
*October 28, 2007*

**Physics**

Mars' moon Phobos has a mass of 1.07x1016 kg and a mean radius of 11.1 km. Let's say our rocket blasts off from the surface of Phobos when Phobos is 9500 km from the surface of Mars. Does the rocket have to work harder to escape from the gravitational pull of Phobos or...
*October 21, 2007*

**science**

to find the vertical velocity we use 40*cos(30)=34.6 m/s W= KE = 1/2 mv^2 =1/2*0.15*34.6^2= 89.797 J or 90 J
*October 21, 2007*

**algebra**

70 = (75+63+68+x)/4 ...with x being what he must get. So you solve that: 70(4)-75-63-68 = x x = 74 So therefore, Sam must get a 74 or above to get a C grade. x => 74
*October 10, 2007*

**Physics**

Oh nvm, you mean F = 1/d^2 Got it...thanks.
*October 10, 2007*

**Physics**

but what is the 3^2 for? If the 3 is for the distance being tripled...what about the exponent 2?
*October 10, 2007*

**Physics**

If the distance between two objects is tripled, by what factor will the gravitational force between them change?
*October 10, 2007*

**Chemistry**

A sample of solid monoprotic acid with molar mass equal to 137.9 g/mol was titrated with 0.1879 M sodium hydroxide solution. Calculate the mass in grams of acid to be used if the volume of NaOH to be used is 25 mL.
*October 8, 2007*

**Chemistry**

If 1.000 kcal of heat is added to 1.700 L of oxygen in a cylinder at constant pressure of 1.00 atm, the volume increases to 2.100 L. Calculate the total energy change for this process.
*October 8, 2007*

**Science**

At what latitude (on Earth) is the elevation of the South Celestial Pole greatest?
*September 25, 2007*

**Trigonometry**

is that supposed to be zero or theta? if its theta: 1) theta = 23.6 2) theta = 53.1
*September 25, 2007*

**Math**

Find all values of x in the interval [0, 2 pi] that satisfy 2 cos x-1 = 0. cos x = 1/2 x = 60 How do I find the other value of x?
*September 25, 2007*

**Chemistry**

That means that AgNO3 is the limiting reactant as it has 0.0033 moles compared to 0.0039 for silver nitrate. But I don't get the last part you said. What same number of moles of silver bromate would I get? Do you mean same number of moles as the limiting reactant? Meaning ...
*September 23, 2007*

**Chemistry**

0.658 g of potassium bromate and 0.562 g of silver nitrate are added to 388 mL water. Solid silver bromate is formed, dried, and weighed. What is the mass, in g, of the precipitated silver bromate? Assume silver bromate is completely insoluble. I've calculated the moles ...
*September 23, 2007*

**Chemistry**

A 35 mL solution of HCl, reacts completely with 20 mL of 0.25 M KBr. What is the molarity of the HCl solution?
*September 23, 2007*

**Calculus**

A spherical balloon with a radius "r" inches has volume V(r)=(4/3)(pi)(r^3). Find the function that represents the amount of air required to inflate the balloon from a radius of "r" inches to a radius of r+1 inches.
*September 22, 2007*

**Calculus**

What is wrong with the following reasoning??? f(x) = 2^x f'(x) = x[2^(x-1)] Although n x^(n-1) is the derivative of x^n, you cannot apply similar rules when x is the exponent and the number being raised to a power is a constant. The derivative of b^x, where b is a constant...
*June 13, 2007*

**Chemistry**

Are propane, methoxymethane, and ethanol soluble in water? yes http://www.chem.lsu.edu/lucid/tutorials/solubility/Solubility.html Henry is wrong.
*June 11, 2007*

**Chemistry**

Calculate the end point pH, when 25 mL of 0.01 mol/L HCl solution reacts exactly with 25 mL of 0.1 mol/L NH4OH solution. NH3 Kb = 1.8 x 10^-5 This will be the pH of NH4Cl solution. NH4+ + HOH ==> NH3 + H3O^+ Ka = Kw/Kb = (NH3)(H3O^+)/(NH4^+). Solve for H3O^+, then pH = - ...
*May 31, 2007*

**Chemistry**

Calculate the pH of a solute where 24.5 mL of 0.1 mol/L HCl is added to 25.0 mL of 0.1 mol/L NaOH. How much excess OH is there? .5ml .1M or 5E-5 moles. That is in a volume of 49.5ml So if OH concentration is that moles/volume, what is the H+ concentration? Remember the product...
*May 31, 2007*

**Chemistry**

Classify the following as: Weak or strong acid, weak or strong base, salt (from weak/strong acid and base). If appropriate, split the formula into its component ions. HNO3 So far, all I have is: HNO3 + H2O -> NO3^- + H3O^+ And I know HNO3 is a strong acid. What would I do ...
*May 26, 2007*

**Chemistry**

Use the Bronsted-Lowry definitions to identify the two conjugate acid-base pairs in the following acid-base reaction: H20 + H20 <-> H30^+ + OH^- Let's see what you think on this after the previous post. Just remember, the acid is the one that HAS the H and the base ...
*May 26, 2007*

**Chemistry**

Use the Bronsted-Lowry definitions to identify the two conjugate acid-base pairs in the following acid-base reaction: HCO3^- + S^2- <-> HS^- + CO3^2- I got it. HCO3^- is the base in the pair with CO3^2-. S^2- is the acid in the pair with HS^-. Would you believe you have ...
*May 26, 2007*

**Chemistry**

Zn + PbCl2 --> ZnCl2 + Pb The initial mass of a zinc strip is 2.684. After being left overnight in a lead (II) chloride solution, the mass of zinc is 2.581g. Calculate the Ksp of lead (II) chloride. So far I have: PbCl2 --> Pb(aq)2+ + 2Cl(aq)- Ksp = [Pb(aq)2+] [Cl(aq)-]^...
*May 23, 2007*

**English**

How is Hamlet a hypocrite towards Ophelia? I have one example, which is that he says he loves her but is the cause of her death because he rejects her and kills her father, which causes her madness and subsequent death. I need one more example, but I can't think of him ...
*May 16, 2007*

**English**

I posted this yesterday, that I need to modernize an Ancient Greek myth. bobpursely replied with an idea that I could do the Siren sisters as cheerleaders, but I couldn't find a myth about them, they're in two different myths. Like I've been thinking of myths such ...
*May 10, 2007*

**English**

I have to modernize an Ancient Greek myth, does anyone have any ideas? Sure. Reset the place and time of the Siren sisters (cheerleader sisters?) occupying a booth at the local Ice Creame shop, tempting Jason (basketball dude hero), Argo (Computer Programmer dude), and ...
*May 9, 2007*

**Calculus**

Why can't a equal 1 in y=log(base a) x. And why is x always positive in that? Hmmmm. a^y=x (from the problem statement). If a were to equal 1, then x would be 1 (1 to any power is 1). So if a is not one, but a positive number, then x has to be a positive number, if one is ...
*May 8, 2007*

**Calculus**

Find the inverse of each relation: y = (0.5)^(x+2) and y = 3log base 2 (x-3) + 2 For the first one I got y=log base 0.5 (x+2)...but the answer in the back of the textbook says that it is not x+2, but x-2. Can someone tell me why it would end up being x-2 and help me with the ...
*May 6, 2007*

**Calculus**

Express in exponential form: y = -log x with base 2 the - in front is like a -1 multiplied so write it as y = log2 x-1 then 2y = 1/x
*May 6, 2007*

**English**

How is Hamlet hypocritical with Rosencrantz and Guildenstern? Provide 2 examples. Please note that we don't do students' homework for them. Our tutors try to give you the information to help you complete your assignment on your own. Be sure to go back into your ...
*May 3, 2007*

**Calculus**

If f(x) is a continuous function, find the constants a and b such that f(x) = { -x -3 <= x <= -2 ax^2 + b -2<x<0 b x=0
*April 26, 2007*

**Calculus**

4) f(x)= { 3x^2 x< and equal 1 { ax+ b x > 1 What is the relation between a and b if the function is continuous for allof x.
*April 26, 2007*

**Calculus**

Create a function that has a graph with the following features: Two vertical asymptotes: x=1, x=3. One horizontal: y = -1. And x intercepts= -2, 4 how about f(x) = ((x+2)(x-4))/((3-x)(x-1)) ?
*April 26, 2007*

**English**

Hi, I'm writing an essay on "what makes a city world-class"...I have all of my points and everything set, I'm just stuck on how I should start my essay. I can't think of any good introductory sentence. Your introductory sentence should be something VERY ...
*April 9, 2007*

**Biology**

How is commercial root beer carbonated? Yeast-carbonated root beer contains a small amount of alcohol. ... which contain the same sort of artificial colors and flavors as commercial root beers. Since this is not my area of expertise, I searched Google under the key words "...
*April 1, 2007*

**Chemistry**

Can hypochlorite ions oxidize bromide to bromine? In acid solutions, yes. That's the old qual test for bromide. Shake a solution of the unknown with NaOCl, this oxidizes bromide to bromine, and the bromine colors the carbon tetrachloride layer (added previously) yellow. Of...
*March 20, 2007*

**Chemistry**

When hypochlorite ions act as an oxidizing agent, hydroxide ions are formed. What will this do to iron (II) or to iron (III) ions? Both Fe(OH)2 and Fe(OH)3 are insoluble in an aqueous solution.
*March 20, 2007*

**Biology**

What are the components of a photsynthetic unit, and what roles do they play? In which part of the chloroplast are photosynthetic units located?
*March 15, 2007*

**Biology**

Write an equation to summarize the photo reaction of photosynthesis. Since this is not my area of expertise, I searched Google under the key words "photosynthesis equation" to get these possible sources: (Broken Link Removed) http://en.wikipedia.org/wiki/...
*March 15, 2007*

**English**

I need to prove that Hamlet cares about/loves his mother or cared about her/loved her at one point. Since this is not my area of expertise, I searched Google under the key words "Hamlet mother love" to get these possible sources: http://72.14.253.104/search?q=cache:...
*March 12, 2007*

**Chemistry**

Does the conversion of hydrogen peroxide to oxygen involve oxidation or reduction? What substance is acting as the oxidizer or reducer? and Does the conversion of hydrogen peroxide to water involve oxidation or reduction? What substance is acting as the oxidizer or reducer? ...
*March 10, 2007*

**English/GuruBlue**

I needed to write an essay on how Hamlet is a hypocrite and my three points were that he doesn't obey his father right away, he says he loves his mother but treats her badly, and he says he loves Ophelia but he is the cause of her madness. But now, my topic has been ...
*March 6, 2007*

**GuruBlue/English**

Yesterday, I asked the question about my thesis statement for Hamlet. Heres what I wrote: Hi, I'm writing an essay on how Hamlet is a participant of hypocrisy. Can anyone help me write a thesis statement. My points are that his father tells him to avenge him, but Hamlet ...
*March 5, 2007*

**English**

Hi, I'm writing an essay on how Hamlet is a participant of hypocrisy. Can anyone help me write a thesis statement. My points are that his father tells him to avenge him, but Hamlet takes a long time to do it, how Hamlet says he loves Ophelia but is the cause of her death, ...
*March 4, 2007*

**English**

Hi, If anyone has read Hamlet...I have to write an essay showing how Hamlet is a hypocrite or similar. I need 3 main points of proof. I only have one, which is that Hamlet says he loves Ophelia but hes the cause of her death and he shunned her. I need two more points. His ...
*March 3, 2007*

**Chemistry**

How come two non-polar substances are able to easily mix? Like dissolves like. Yes, I know that, but is there any explaination to that relating to the bonds? http://www.newton.dep.anl.gov/askasci/chem03/chem03348.htm
*March 1, 2007*

**Chemistry**

Look up the boiling points and relative molecular masses of water, hexane, and ethanol. Try to explain the relative magnitudes of their boiling points in terms of polarity. I know that ethanol and water are polar and that hexane is non-polar. Also, 6)
*February 27, 2007*

**Biology**

How do nucleaotides join to form nucleic acids? Name the bond formed. http://www.sparknotes.com/biology/molecular/structureofnucleicacids/section1.html
*February 25, 2007*

**Chemistry**

How would you make a starch molecule? What is the name of the bond formed between glucose molecules? I think I got it. They are formed by long chains of glucose molecules joined together by a glycosidic link. Can anyone confirm if this is correct? I believe you are right. ...
*February 25, 2007*

**Chemistry**

How would you make a starch molecule? What is the name of the bond formed between glucose molecules? Answered above.
*February 25, 2007*

**Chemistry**

Using molymods make 2 ring structures of glucose and join them through a condensation reaction between carbon 1 on one molecule and carbon 4 on the other. What molecule is formed through this procedure?
*February 22, 2007*

**Biology/Chemistry**

What kind of isomers can amino acids form? Which isomer is present in most living organisms? don't major compounds of living organisms consist of modifications of hydrocarbons Although D amino acids can be found in nature, only the L isomers are used to form proteins. The ...
*February 21, 2007*

**Biochemistry**

What kind of isomers can amino acids form? Which isomer is present in most living organisms?
*February 21, 2007*

**Chemistry**

When the halogens form ionic compounds, what is the ion charge of the halide ions? negative one
*February 15, 2007*

**Calculus**

Factor the following: y = (x-a)^5 . (x-c)^5 . (a-c)^5 It looks already factored to me
*February 14, 2007*

**Chemistry**

What is the empirical distinction between emission and absorption spectra? In general terms, how did Niels Bohr explain each of these spectra? In general terms, emission spectra are obtained when the electron is at a high energy level and it falls to a lower energy level. In ...
*February 7, 2007*

**Physics**

A hockey puck travelling at 26 m/s [E 22* S] rebounds off the board at 21 m/s [E 22* N]. The puck is in contact with the board for 0.0025 seconds. Determine the average acceleration of the puck over the interval. average acceleration= change in velocity/time a= (Vf - Vi)/time ...
*January 25, 2007*

**english**

i am unable to this question complete the following by adding noun clause a)the fact is that__________________ b)this is a clear proof_______________ complete the following by adding noun clause a)Thefact is that______________________ b)This clearly proof__________________ The...
*January 23, 2007*

**Algebra & Discrete Geometry**

Determine a vector of magnitude 2 that is parallel to a=(-3, 4).
*January 21, 2007*

**Physics**

Calculate the period of the wave if it makes 10 vibrations in 2 seconds. Does anyone know the formula for this? frequency = (number of waves) divided by(observation time) = 10/2 = 5 Hertz period = 1/frequency = ?
*January 21, 2007*

**Physics**

When most people are asked what makes rockets lift off they say it's caused by the push of the exploding fuel against the ground. Explain why this is wrong. For every action, there is an equal and opposite reaction. That's from Newton, I think, but it may have been ...
*January 18, 2007*

**Chemistry**

What is the chemical equation for the combustion reaction between methanol and air? CH4 + O2 ==> CO2 + H2O. All hydrocarbons produce CO2 and H2O when they are combusted in air. The above equation isn't balanced. I assume you can do that? If not, ask OR take a shot at it...
*January 18, 2007*

**Calculus**

Find the sum of two numbers whose sum is 70 and whose product is as large as possible. Ok i got that one equation is y = 70 - x...but how do I show an equation for a product which is as large as possible. The product is P = x (70 - x), where x is one of the two numbers. Set dP...
*December 31, 2006*

**Data Management**

List all permutations of the elements of the set {+, -, *) List all subsets (combinations) of the elements of the set {+, -, *)
*December 20, 2006*

**Analytical Proof**

The Theorum of Apollonius states in triangle ABC, if M is the midpoint of BC, then AB^2 + AC^2 = 2AM^2 + 2MC^2. Prove this theorum using analytic methods. http://www.google.com/search?hl=en&sa=X&oi=spell&resnum=0&ct=result&cd=1&q=Theorem+of+Apollonius+proof&spell=1
*December 6, 2006*

**Geometry and Algebra**

AB is a diameter of a circle with centre O. P is on BA extended, and PT is tangent to the circle. Use the corollary to the Intersecting Secants Property to prove that PT is perpendicular to OT. Here is the diagram (Without the dashes in the "com" and periods instead ...
*December 5, 2006*

**Physucs**

A clerk pushes a filing cabinet of mass 22.0 kg accross the floor by exerting a horizontal force of magnitude 98 N. The magnitude of the force of kinetic friction acting on the cabinet is 87 N. The cabinet starts from rest. Use the law of conservation of energy to determine ...
*November 30, 2006*

**Pre-Algebra**

Solving it would give u x = -4...but I am not sure how you would graph that. You see, a linear inequality is an inequality that has one of the following four forms: Ax + By < C Ax + By > C Ax + By < C Ax + By > C PLZ!Somebody tell me the answer! PLZZZ! umm,, It ...
*November 28, 2006*

**Geometry and Discrete Mathematics (Proofs)**

Observe that the last two digits of 7^2 are 49, the last two digits of 7^3 are 43, the last two digits of 7^4 are 01, and the last two digits of 7^5 are 07. Prove that the last two digits of 7^201 are 07. 7^2 = ...49 7^3 = ...43 7^4 = ...01 7^5 = ...07 7^201 = ...07 Break 201 ...
*November 28, 2006*

**Algebra and Discrete Geometry**

A large family wedding for the Smiths will require 113 trays of sandwiches, 116 trays of hors d' oeuvres, and 144 trays of sweets. Hands-Off caterers can make 15 trays of sandwiches, 10 trays of hors d'oeuvres, and 12 trays of sweets in one day. Hands-Free caterers can...
*November 23, 2006*