What is Chem: Definition and 424 Discussions

Homework Statement 100mL of 0.10M HNO3 was added to a 100mL mixture containing 0.30M acetic acid and 0.10M sodium acetate. Ka = 1.8 x 10-5 Homework Equations CH3COOH \rightarrow H+ + CH3COO- CH3COONa \rightarrow Na+ + CH3COO- CH3COO- + H+ \rightarrow CH3COOH The Attempt at...

Ok i got to answer i series of 8 questions, most of them i think rely of the question before it to complete the others.Heres what I am given: A student was trying to determine the concentration of an ammonium chloride solution. he made up a solution of barium hydroxide by dissolving 52.947g...

Homework Statement OK so this is my first time actually posting but I have lurked around. I need help with two of my chemistry problems. Problem 1 Decide which one(s) of these answer choices are correct. A buffered solution is one which can be desribed by which of the following...

Thermodynamics for P Chem NEEd HELP By tomorrow! Homework Statement What are the values of the entropy changes (system, surroundings, and universe) for the cooling of 1 mol of O2 (g) from 298 K to O2 (l) at 90.19 K if the process is done a. Reversibly b. Irreversibly by placing the...

Homework Statement Heat of Reaction for the combustion of Magnesium Data: A. Mass MgO = 0.7975g Volume 1M HCl = 97.5 ml Temp.intial = 24.2 C Temp.final = 29.3 C \DeltaT = 5.1 C B. mass Mg 0.0896g Volume 1M HCl 89.5 ml Temp...

I'm not sure whether to just take Physical Chemistry because I'm interested in it or should I just take Quantum Mechanics? I've already taken Thermodynamics and I heard P-Chem is Thermo and Quantum combined. Is Quantum more in-depth than P-chem?

What is different about introductory chemistry vs. chem 1?(at 2 yr college) Granted, it varies by school, but in your opinion, or based on your own personal experiences with taking these classes? Typically what can you expect to learn in chem 1 that was not in introductory chemistry.

Homework Statement Chem lab on equilibrium. We added the same amount of Fe(NO3)2 (5ml) to varying amounts of KSCN and used a given Beer's law and absorption data to calculate concentration of FeSCN2+ and then calculate the Eq. constant (K). I calculated the Eq. constant, but I'm stuck on...

I'm a high school senior, making my college decision in the next month or two. I applied to schools as an Aerospace engineering major, but I'm really enjoying my AP chemistry class and leaning towards Chem E as a major now. However, I do not wish to totally abandon aerospace, so I was thinking...

i wonder if many people like me and think it physics that very hard and bio easiest.

hey i need help with this 1 i did the experiment but this last problem is killing me Analysis Hint: As you are thinking about this we want you to know that the water in the can and in the pan is only there to heat or cool the air in the can. In 5.07 you studied the relationships of...

Homework Statement Hi all, i have to identify 5 samples (1,2,3 were solids, 4,5 were liquids) by classifying them as 1) Aliphatic or aromatic and 2) Carboxylic acid, amine (primary, secondary, tertiary) or ammonium carboxylate We did a burn test on the solids, tested solubility in water...

I am in general chemistry I, and need a little clarification of the following: When balancing an EQ say CaSO4 + AlCl3 \rightarrow CaCl2 + Al2(SO4)2 The subscript 2 outside of the parentheses confuses me. Do I distribute that 2 to make it S2 & O8? This is a homework problem, but I do not...

Homework Statement Calculate the volume of water expected if the yield of ester were 100%. 19.0mL of n-propanol (0.25 Mol) 18.5mL(0.25 Mol) propanoic acid. 5 drops concentrated sulfuric acid Homework Equations The Attempt at a Solution C3H7OH + C3H5COOH ---> C6H12O2 + H2O (...

These were the only questions out of the 110 question study guide that I didn't understand, I have no clue how to do them since it's been a while since I've done stuff from early chapters. I would love it if anyone can help me and give me a step-by-step! Thank you in advance! Fe2O3 + 3CO -->...

Hi there, I'm new to the forums so pardon me if i make mistakes such as posting to the proper forum. Homework Statement I need to investigate and analyze conditions needed to maximize the efficiency of common natural or industrial reactions and explain how the improved efficiency of the...

Homework Statement 1)The complete combustion of 1.47 g of methanol produces 29.3 kJ of heat. Determine the ΔH° for the reaction and its sign. CH3OH(l) + 3/2O2(g) → CO2(g) + 2H2O(g) 2) The value of ΔH° for the reaction below is -126 kJ. How much energy is released when 2.00 mol of NaOH is...

This is for a friend: The worksheet says: Name the following comounds: It has a picture, which is a benzene ring with 2 PhD groups off the 1 and 2 positions. Is also says "THis one is a pun. See if you can figure it out!" Thanks, nkk

If an element Z forms a compound with the formula AgZ, which of the following is a correct chemical formula? -CaZ2 -Al2Z3 -H2Z -NaZ3 I don't really understand this at all and there is going to be decent amount of them on my final exam! please any help

I was sick so I actually missed this lesson in class and this wasn't mentioned in the notes I got from a fellow student, nor is it in my textbook. I can't even find a definition for what it means that the heat of condensation is "evolved," so if anyone can fill me in on that I'd greatly...

I am currently a junior in the chemical engineering program at my school and have now started debating possible paths I can take after I graduate. What I'm interested in are what type of possibilities are out there for engineers who choose to Master in Physics and not in their respective...

Homework Statement A question on a pretest asks me to name this. I know it's either (1R,2R) or (1S,2S)1,2-Cyclopentanediol because the OH's are facing in opposite directions, but I'm not sure how to figure out if the OH's are S or R 2. The attempt at a solution I somewhat have an...

Hi guys, I've got a question which i couldn't solve. Both napthalene (two benzene ring join together) and benzoic acid are aromatic compounds which exist as white solids. Based on their physical ahd chemical properties, describe how you could separate the components of a mixture of these...

First of all, how do you know if a combustion process produce h2o(g) or h2o(l)? It depends on the temperature, but how do you figure that out? I found the heat released during the combustion processes, which should equate the work done by the system (theoretically). But according to w =...

Hi all, i have access to the two software: (Isis draw and Chem draw ultra.). I want to know how to draw a pentagon (cyclopentane) with a semicircle in it (to represent the alternative bond)..this kind of representations are widely use in many journals.. Can anyone help to how to draw it in a...

ok i am doing my lab report ow, and i am compeltely lost with some of these questions. it was a titration neutralization lab can get some help? 1- why is it necessary to dissolve the khp in water? 2- why is necessary to swirl the flask during the titration? i think the second one is so...

Chloroform is used to extract caffeine from water.If the distribution coefficient, KD=10.What relative volume of chloroform-water should be used to extract 90% of the caffeine present in one single extraction? Now i know that KD=Co/Cw and I've solved a question on how much weight of an acid...

I'm currently a high school senior. I self-studied for AP Chemistry (using Zumdahl) in 10th grade and would like to continue studying chemistry this year. My question is: what textbook should I use? In AP Physics last year, teacher simply gave us a whole bunch of formulas to memorize. I went...

Homework Statement A bicycle tire is filled with air to a pressure of 68 psi, at a temperature of 28°C. Riding the bike on asphalt on a hot day increases the temperature of the tire to 58°C. The volume of the tire increases by 3.9%. What is the new pressure in the bicycle tire? Homework...

Homework Statement Predict if the following salts are acidic, basic, neutral or undetermined. Homework Equations a. NaOCl b. NH4I c. Sr(ClO3)2 d. KCN The Attempt at a Solution A. NaClO = Na+ and ClO- So, if Na+ gives up a proton, that would turn it into Na... and...

http://www.google.com/hostednews/ap/article/ALeqM5gbl9HOrXrN5zLTpmFDu7ZnL88vTgD9B80NL80 And it seems nobody has a clue about the motive.

Homework Statement This is a chem problem for adding sig figs with base ten. The problem is: 3.15x10^-4 + 6.99x10^1 + 5 all divided by 7.73x10^-4. I was trying to help my daughter with this. Homework Equations The Attempt at a Solution I can do sig figs pretty well and these kinds of...

Homework Statement I've been balancing equations but this one has me really confused please help. C3H5(NO3)3----> CO2 +N2 + H2O + O2 Homework Equations The Attempt at a Solution So I know that it is a single replacement reaction, (well I think so) but I don't know how to make the...

Using average bond enthalpy values estimate ΔH (kJ/mol) for the following gas phase r Using average bond enthalpy values estimate ΔH (kJ/mol) for the following gas phase reaction. CH2=CH2 + Br2 --> CH2BrCH2Br I followed this topic...

Homework Statement http://carlodm.com/images/chem.png The Attempt at a Solution The attempt is in the image. HOW IS THIS WRONG?? I've looked at it for hours now!

Calculate the change in energy when the following transition occurs in the hydrogen atom. n = 4 ----> n = 1 equation E = -Rh/n^2 eventually my answer is 2.04E-18J because my book tells me to take 1 over n(low) squared minus 1over n(high) squared and multiply by rydberg constant.. so...

Homework Statement On a dry day, your body can accumulate static charge from walking across a carpet or from brushing your hair. If your body develops a charge of -18 (microcoulombs), how many excess electrons has it acquired? The Attempt at a Solution i don't know what to do...

Which grads are in greater demand right now?

Im try to make sure i understand something right. I have two jars on the left is oxidation takes place and on right reduction takes place. A wire connects them to allow electrons to move. electrons move from left side to right side. This makes the left side negative cause it produces electrons...

Homework Statement "Calculate the grams of acetic acid per liter of vinegar" Homework Equations Previous problem stated the multiply the average molarity of diluted vinegar times 10= 2.7 M Vinegar (acetic acid)= H(C2H3O2) molecular weight= 60.06 g The Attempt at a Solution...

I need to review 6 journal articles (approx. 150 words/article) relating to chemistry of the car (any topic). I need a topic which is going to allow me to easily identify the biases of the people who wrote the article, and that will be somewhat controversial, interesting and relevant to our...

Homework Statement When 100 mL of an aqueous solution containing 1.0 g of caffeine is extracted with 10 mL of chloroform at room temperature, 0.5 g of caffeine is transferred to the chloroform layer. Calculate the distribution coefficient of caffeine between chloroform and water at room...

The value of H° for the reaction below is -1107 kJ: 2Ba(s) + O2(g) --> 2BaO(s) How many kJ of heat are released when 5.75 g of Ba(s) reacts completely with oxygen fo form BaO(s)? i worked out the moles of Ba which was 0.0412 then times by -1107 whcih is 46.4 however the answer is...

hey guys I've got another problem, any conceptual help and help would the questions would be greatfully apprectiated. thanks Homework Statement From a consideration of the data below determine which of the given species will oxidize Fe to Fe2+: Data Fe2+ + 2e- --> Fe; E° = -0.44 V...

Homework Statement Refer to the cell below: Pt / MnO4-(0.10 M), Mn2+(0.20 M).H+(0.010M) // Cr3+(0.40 M), Cr2O72-(0.30 M), H+(0.010M) / Pt The standard reduction potentials are as follows: MnO4- + 8H+ + 5e- --> Mn2+ + 4H2O; E° = 1.51 V Cr2O72- + 14 H+ + 6e- --> 2 Cr3+ + 7H2O; E° = 1.33 V...

Homework Statement NaCl is added slowly to a solution that is 0.010M in each Cu+, Ag+ and Au+. Ksp's are 1.9x10^-7, 1.8x10^-10 and 2.0x10^-13 respectively. Which compound will precipitate first? Can anyone tell me how the Ksp is different from Ka? and the relationship to precipitation?

Homework Statement Calculate the mass of nitrogen dissolved at room temperature in an 80.0L home aquarium. Assume a total pressure of 1.0 atm and a mole fraction for nitrogen of .78. Homework Equations Mole fraction= moles solute/moles solution Sgas=KH x Pgas KH = 6.1 x 10-4...

Homework Statement 2NS(g) + 2H2(g)<---> N2(g) + 2H2S(g) @ equilibrium in a 4.L flask @ 25o C. 2.5 mol of eah component initially is put into the flask. At equilibrium, 2.5 mol of NS is present. what is Kc for the rxn at this temp?? Homework Equations Kc=[products]/[reactants] M=moles/L...

Hello. I have a couple of questions. Why are the boiling points of alkenes lower than alkanes? My thinking: something with van der waas forces?. Not sure. Why do haloalkanes have higher boiling points than alkanes? My thinking: dipole-dipole forces? What is an experiment that can...

Hello, I am curious on how azeotropic distillation works. I know it has to do with the gas law, PV=nRT but I would like to know in depth analysis how this process works. I have organic 2 lab final coming up (this Tuesday) and it may happen we might be asked to explain how azeotropic...