| Subject | Date Asked |
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| Chemistry | 9/12/2009 |
Q: A student weighed 14.1 grams of lead shot and placed it in a graduated cylinder containing 10.2 mL ...
A: Density is mass/volume, so to calculate it you need to know those two things, mass and volume. ...
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| Significant Figures | 9/12/2009 |
Q: If X = 15.4 ± 0.1 and Y = 126.0 ± 0.2, calculate the following, include calculation of error i) X+Y ...
A: You just need to know the number of significant digits in X (3) and Y (4), then follow the rules ...
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| chemistry | 9/10/2009 |
Q: Calculate the energy in joules lost when 15.0g of ethanol, cools from 60.5 degrees Celsius to minus ...
A: The equation you're looking for is: q = mc(Tf - Ti) Where q is the energy lost/gained, m is the ...
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| chemistry | 9/8/2009 |
Q: I am stuck on my chemistry homework, with doing pennfoster online It's hard not having a personel ...
A: MASS NUMBER/ISOTOPES: The number of protons (the "atomic number") in the nucleus is what defines an ...
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| cigarette smoke. | 9/3/2009 |
Q: how does cigarette smoke affect the growth of plants [seedlings]. :tnx!
A: This sounds like an essay question to me, so I will try to point you in the right direction. You ...
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| drinking distilled water | 4/1/2009 |
Q: What are the benefits and dangers if any in drinking only distilled water after raising the ph to ...
A: There is no credible scientific evidence of any health benefits from drinking pH-altered water. ...
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| energy conversion project | 2/21/2009 |
Q: My sixth grader needs to design and construct a homade structure to carry out at least six energy ...
A: I need a little more information on the project requirements before I can help you in a concrete ...
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| Chemistry | 2/21/2009 |
Q: If 1 liter of a chemical waste sample has a concentration of 5000 ppm, how much water would have to ...
A: Just thinking about this problem conceptually, to decrease the concentration by a factor of 1000, ...
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| Stoichiometry | 2/18/2009 |
Q: I don't understand precipitation questions. For example: How many grams of NaCl is needed to ...
A: Well, this particular one is a trick question - barium chloride, as with all chlorides, is a ...
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| Chemistry | 2/17/2009 |
Q: Oxygen and what is needed to burn fuel?
A: Since this is a homework question, I'm going to use the Socratic method. Have you ever seen an ...
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| chemistry | 2/16/2009 |
Q: Hey Kimberly...In terms of composition what is the relationship between stainless steal and iron? ...
A: Certain metals can undergo what's called a "redox" reaction when mixed with strong acids like HCl. ...
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| Acids and Alkalis | 2/16/2009 |
Q: How do acids and alkalis differ in chemistry? I know that acids have a pH of less than 7 and alkalis ...
A: Since ions are the foundation for acid/base chemistry, I will see if I can explain them in a way ...
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| chemistry | 2/16/2009 |
Q: Hey Kimberly...In terms of composition what is the relationship between stainless steal and iron? ...
A: Iron rusts, i.e., it reacts with oxygen from the air to form iron oxide (generally, reaction with O2 ...
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| chemistry | 2/15/2009 |
Q: Hey Kimberly...In terms of composition what is the relationship between stainless steal and iron?
A: Iron is an element (a pure substance), while steel is an "alloy" - a mixture of different metal(s) ...
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| Chemistry- Acids, Bases, and Salts | 2/14/2009 |
Q: I need help with this homework problem. How many grams of selenic acid, H2SeO4, are contained in ...
A: The equation you need, which relates normality to molarity, is: normality = molarity x n normality ...
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| physical science | 2/13/2009 |
Q: i have aexplain how mass and energy are conserved when food is digested.
A: Digestion is basically a series of chemical reactions, and by definition mass is always* conserved ...
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| Mass of a solution | 2/8/2009 |
Q: A bottle contains 325mL of insulin at a concentration of 50.0mg/mL . What is the total mass of ...
A: The calculation is: 325mL solution (50.0mg insulin / mL solution) = 16,250mg Since you start out ...
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| dissolving sugar cube in water and orange juice | 2/7/2009 |
Q: we just completed our science fair project to determine whether a sugar cube would dissolve faster ...
A: First, a caveat: if you were not stirring the solutions while timing the dissolution process, then ...
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| chemistry 115 | 2/7/2009 |
Q: Bromine has a density of 2.93 g/mL. How many grams of PbBr4 can be made from 23.4 mL of bromine?
A: Since this is a homework problem, I will tell you the approach and you can do the calculations. The ...
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| Reverse Osmosis | 2/6/2009 |
Q: I would like to creat an experiment on reverse osmosis and was woundering if you had any input. I ...
A: Well, not to be too negative, but reverse osmosis is such a simple concept, and has been understood ...
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| Test ph and have a boy or girl? | 2/6/2009 |
Q: Is it true that having a ph of high alkaline will favor having a boy since y sperm live better in ...
A: I doubt there's any truth to it, and here's why. Since sperm are manufactured via meiosis, all men ...
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| Chemistry 115 | 2/5/2009 |
Q: What is the difference between Covalent bonds and Ionic bonds?
A: Well, the simplest answer is that a nonmetal + another nonmetal is covalent, while nonmetal + metal ...
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| Fission Rate | 2/4/2009 |
Q: Why do we need to slow down the fission rate in nuclear power plants?
A: Inside a nuclear power plant's reactor, a nuclear reaction called fission takes place. Certain ...
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| calcium and fluoride | 2/3/2009 |
Q: I asked this question of Kristin and she was wonderful! She couldn't answer it for me and was ...
A: Since CaF2 (calcium fluoride) is highly insoluble, if a calcium ion meets a couple of fluoride ions ...
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| h2o | 2/3/2009 |
Q: can u Take hydrogen and oxygen and combine the two to actually make water?
A: Definitely. In fact, this is how hydrogen cars work: the hydrogen (H2) in the tank is the fuel, and ...
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| chemistry | 2/2/2009 |
Q: Our class was doing the same old water and vegetable oil density experiment. One of the students ...
A: Acetone (p = 0.785g/cm^3) is an organic liquid that is less dense than vegetable oil (p ~ 0.9g/cm^3) ...
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| electron rich lewis structures | 12/18/2008 |
Q: i am working on a chem worksheet from today. the formula is IF3. i have got 28 VE's 6 used in bonds, ...
A: Good question! Your Lewis structure should have two lone pairs on the central I atom, in addition ...
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| dissolving sugar cube in sugar solution | 12/18/2008 |
Q: My 3rd grade daughter just completed the experiments for her first science fair project, and we are ...
A: There's no reason that the dissolving rate *should* be any different for any of those solutions, ...
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| Minerals - Blossite | 12/17/2008 |
Q: Can you please tell me what the mineral Blossite uses are. Both my mom an I have checked a ton of ...
A: In general, most minerals are useful to humans as "ores," i.e., raw material for producing pure ...
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| chemistry | 12/16/2008 |
Q: hey, well here is the question i can't solve: Chlorine is produced by the reaction 2HCl(g)--> ...
A: Since this is a homework problem, I will give you the general approach. You are asked to produce ...
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| hot water freezes | 12/12/2008 |
Q: Kimberly. Its nice to meet you. Can you explain why my hot water pipes keep freezing in the winter. ...
A: It would seem that way, wouldn't it, since the water in the cold pipe is closer to freezing ...
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| No Fog Mirrors | 12/10/2008 |
Q: Kim, several months ago I purchased a nice shower clock/radio with large fog free mirror. The mirror ...
A: I can certainly tell you about the science behind it. I don't know what was on your mirror, but ...
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| Milk and Litmus paper | 12/10/2008 |
Q: Are there any health risks with ingesting milk that has been in contact with litmus paper for an ...
A: First of all, I wouldn't recommend ingesting *anything* that's seen the inside of a chemical ...
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| Chemistry Molecular Shapes/Polarity | 12/9/2008 |
Q: I was wondering if you could please explain how to tell whether a Molecule is Polar or Nonpolar if ...
A: You've got most of those right, with the following exceptions: HBr is linear; all two atom ...
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| greek prefixes | 12/6/2008 |
Q: when do i use the greek prefixes when doing ionic naming. and when do i use the roman numerals
A: You never use the greek prefixes when doing ionic naming (unless it's part of a polyatomic ion's ...
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| medicine at 10% | 12/3/2008 |
Q: I was going to purchase a medicine for my sheep that is at 10%. The container has 100 ml. Another ...
A: Container 1: 100mL of 10% Container 2: 100mL of 50mg/mLWhich container has more doses per mL? At ...
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| Sunscreen Project | 12/2/2008 |
Q: I am a high school student doing a science fair project (AP Chemistry). My project is on testing the ...
A: What a great idea for a project! By definition, a control (or set of controls for a standard cure, ...
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| titrations | 12/1/2008 |
Q: when doing a strong acid- strong base titration, why do you put the base in the burette?
A: In a standard acid-base titration, you have an acid sample and you want to figure out how many moles ...
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| Chemistry | 12/1/2008 |
Q: We have a 0.20 M solution of MgSO4 osmotic pressure of 7.8 atm Temperature of 25°C. May you ...
A: "Colligative properties" are properties of a solution that depend on the number of particles in a ...
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| Chemistry | 12/1/2008 |
Q: We have a 0.20 M solution of MgSO4 osmotic pressure of 7.8 atm Temperature of 25°C. May you ...
A: The Van 't Hoff factor (i) is the number of moles of solute actually in solution per mole of solid ...
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| Weak base kb problem | 11/26/2008 |
Q: A 0.10 M solution of NaCN is found to have a pH of 11.15. Using this information, calculate the Kb ...
A: Using the standard pH/pOH equations: pH = -log[H+] and [H+] = 10^(-pH) pOH = -log[OH-] and ...
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| Amount of substance | 11/25/2008 |
Q: Magnesium carbonate reacts with hydrochloric acid to form magnesium chloride, water and carbon ...
A: I mis-typed the rough answer there, sorry! You should get 0.0134mol MgCO3, which is (molar mass = ...
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| Amount of substance | 11/25/2008 |
Q: Magnesium carbonate reacts with hydrochloric acid to form magnesium chloride, water and carbon ...
A: This is a multi-step problem. Since this is a homework problem, I will explain the approach. The ...
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| chemistry help | 11/24/2008 |
Q: Chemistry help ..mechanism for the SN2 reaction ? The rate of SN2 reaction of three bromoalkanes (1, ...
A: A good illustrated explanation of the SN2 reaction mechanism is here: ...
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| chemistry | 11/24/2008 |
Q: 1.The equilibrium constant Kc for the equation CS2(g) + 4H2(g) = CH4(g) + 2H2S(g) at 900oC is 27.8. ...
A: For the first problem, those equations are equivalent (it's the same reaction - the coefficients are ...
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| Chemistry Ionic Equations and Finding the Solid | 11/24/2008 |
Q: Ba(NO3)2 + NaSO4 into an ionic equation = BaSo4+Na(NO3), right? Well, I'm supposed to be able to ...
A: The order the compounds (cation + anion pair) themselves are in doesn't matter. But it definitely ...
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| Chemistry Ionic Equations and Finding the Solid | 11/23/2008 |
Q: Ba(NO3)2 + NaSO4 into an ionic equation = BaSo4+Na(NO3), right? Well, I'm supposed to be able to ...
A: That is essentially correct, and the solid is the BaSO4, since sodium salts (and almost all ...
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| hydrocarbon | 11/23/2008 |
Q: i was studyiung hydro-carbon chapter and when i reached nomenclature part ,,,i reached naming ethene ...
A: You're close! It's actually: buta-1,2,3-triene Alkenes with more than one double bond have the ...
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| fractional distillation | 11/21/2008 |
Q: I was wondering why we don't care about the holdup in the fractionating column when fractionally ...
A: If the goal is to completely separate the ketone from the water, it's better to use fractional ...
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| boiling water | 11/17/2008 |
Q: it is possible to boil 100% ultra pure H2O or does it need impurities to make it bubble away
A: It is definitely possible to boil 100% pure water. When you heat a liquid, its vapor pressure ...
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| electrolysis of water | 11/17/2008 |
Q: in electrolysis of water why does hydrogen go to the negative tube and oxygen go to the positive ...
A: In the electrolysis ("lysis-" is Greek for "loosening") of water, charged electrodes induce ...
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| physical chemistry | 11/17/2008 |
Q: Kimbery, In my science project I have to find which direction of egg withstand greater force than ...
A: Evolution has resulted in the chicken egg having a unique shape that confers mechanical strength ...
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| chemistry question | 11/16/2008 |
Q: Consider the following unbalanced equation H2+N2 yields NH3 a. To run this reaction in a balanced ...
A: The first thing you need to do here is balance the given equation: H2 + N2 ---> NH3 The ratio ...
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| chemistry question | 11/15/2008 |
Q: If you react 5 grams of SCL4 with 1.04 grams of H2O How many grams of HCL will you form?
A: First, write out the balanced chemical equation: SCl4 + 2H2O ---> SO2 + 4HCl Notice that you ...
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| biochem | 11/14/2008 |
Q: how would i make up 1ooml of 10xZ from: (where the stock solution = 14.3M) 0.6M Na2HPO4 0.4M NaH2PO4 ...
A: First of all, I just want to clarify. Some questions: You're trying to make up 100mL, or 1.00mL? ...
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| Hybridization | 11/13/2008 |
Q: How do you determine the hybridization of an atom in a molecule?
A: You can find a complete, illustrated version of this explanation here: ...
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