CHEMISTRY COMMUNITY

josephyim1L

Is it important that we understand/are able to implement graphs of rate laws and integrated rate laws for solving problems?

josephyim1L

what is the difference between a reaction rate and rate law?

josephyim1L

What is the difference between reaction rate (change in reaction/change in time) vs. unique reaction rate?

josephyim1L

Can someone explain: 15.5 Ethene is a minor but important component of natural gas, and its combustion has been thoroughly studied. At a certain temperature and pressure, the unique rate of the combustion reaction C2H4(g) + 3 O2(g) 2 CO2(g) 2 H2O(g) is 0.44 mol/L/s. (a) What is the rate at which oxy...

josephyim1L

Can someone explain this to me: 15.3 In 20. s, the concentration of nitrogen dioxide, NO2, decreases from 450 mmol/L to 320 mmol/L in the reaction 2 NO2(g) 2 NO(g) O2(g). (a) Determine the rate of reaction of NO2. (b) Determine the rate of formation of O2. (c) What is the unique rate of the reaction?

josephyim1L

Can someone explain: 15.1 Complete the following statements relating to the production of ammonia by the Haber process, for which the overall reaction is N2(g) + 3 H2(g) S 2 NH3(g). (a) The rate of consumption of N2 is ________________ times the rate of consumption of H2. (b) The rate of formation o...

josephyim1L

Can someone explain 14.91 in the 6th edition to me please:

14.91 A voltaic cell functions only when the electrical circuit
is complete. In the external circuit the current is carried by the flow of electrons through a metal wire. Explain how the current is carried through the cell itself.

josephyim1L

Is a porous disc the same as a salt bridge?

josephyim1L

What is the role of the inert metal and how should it be put into the skeletal diagrams? Ex: Pt(s)

josephyim1L

Can someone walk through this question with me: 11.17 (a) Calculate the reaction Gibbs free energy of N2(g) ->3 H2(g) S 2 NH3(g) when the partial pressures of N2, H2, and NH3 are 4.2 bar, 1.8 bar, and 21 bar, respectively, and the temperature is 400. K. For this reaction, K = 41 at 400. K. (b) Indic...

josephyim1L

What are the different applications of the Van't Hoff Equation? Example from the homework: 11.15 (a) Calculate the reaction Gibbs free energy of I2(g) S 2 I(g) at 1200. K (K = 6.8) when the partial pressures of I2 and I are 0.13 bar and 0.98 bar, respectively. (b) What is the spontaneous direction o...

josephyim1L

How do I determine if a reaction is spontaneous or non spontaneous? E.g. is water melting spontaneous? How do I think through these different scenarios given?

josephyim1L

are entropy and enthalpy always correlated?

josephyim1L

can someone explains the conditions for measuring gibbs free energy?

josephyim1L

Can someone explain the difference between Gibbs free energy and enthalpy/entropy/heat?

josephyim1L

what is the formula for finding the heat of a phase change?

josephyim1L

A 50.0 g ice cube at 0.0° C is added to a glass containing 400.0 g of water at 45.0° C.
What is the final temperature of the system? Assume that no heat is lost to the surroundings.
can someone explain how to work out this problem...

josephyim1L

Can someone explain why burns from steam cause more damage than burns from hot water?

josephyim1L

What does calculation of a reaction enthalpy refer to? Does it refer specifically to the heat of a reaction? I'm having trouble understanding this concept

Also, of the 3 methods Dr. lavelle described in class, which is the most-frequently used/"best method"?

josephyim1L

2 questions: how do the thermodynamic equations change depending on the type of system used (closed, open, isolated...)

also, why does internal energy change = heat + work?

josephyim1L

what is the best "guiding principle" for how to answer questions implying "Le Chatelier's Principle"/change in physical conditions? Will questions that ask about temperature always give whether or not the question is exothermic or endothermic?

josephyim1L

For acid and base reactions, what is the general chemical equation? I know that for common acids and bases the acid/base loses/gains a hydrogen and water will either gain or lose a proton, but is there a general guideline to know in preparation for the test?

josephyim1L

How do I understand the differences between pOH and pKb? Are they interchangeable?

josephyim1L

Can someone explain the following question to me: 11.41 A 25.0-g sample of ammonium carbamate, NH4(NH2CO2), was placed in an evacuated 0.250-L flask and kept at 25 C. At equilibrium, 17.4 mg of CO2 was present. What is the value of Kc for the decomposition of ammonium carbamate into ammonia and carb...

josephyim1L

13. State whether the equilibrium shifts towards products, reactants, or neither when the given change occurs. 2 HI(g) + Cl2(g) ⇌ 2 HCl(g) + I2(s) delta H° = -238.0 kJ.mol-1 i. The volume of the system is compressed. ii. The temperature of the system is decreased. Can someone explain the answer to t...

josephyim1L

Are solids included in the calculation for the equilibrium constant when using partial pressure?

josephyim1L

What are the units that we are supposed to use for each element of PV=nRT?

josephyim1L

what is the R value for PV=nRT that we are using in order to solve for partial pressure or concentration (n/V) ?

josephyim1L

Can someone explain this question to me: 15. Carbonyl chloride (COCl2 ), also called phosgene, was used in World War I as a poisonous gas. The equilibrium concentrations for the reaction between carbon monoxide and molecular chlorine to form carbonyl chloride at 74℃ are [CO] = 1.2 x 10-2 M, [Cl2 ] =...

josephyim1L

is it best to memorize the different names of common compounds/others such as oxalate and diethylene and carbonato....?

josephyim1L

i'm a bit confused, working through the material since the last test, on how exactly to approach questions involving acids and bases, are there any particular things to look out for in these kinds of questions? What is the best way to identify an acid/base? Is it best just to memorize the most basic...

josephyim1L

how might one solve question 34? Should the overall concentration be found or is it only necessary to find the concentration of HCL is 1 Liter of water?

josephyim1L

Hi, I had a couple of questions regarding acids and bases... I have a lot of trouble identifying acids and bases and being able to identify whether or not something is acidic, polyprotic, amphiprotic, amphoteric, etc. Is there a systematic way of identify acids and bases in a reaction and based on t...

josephyim1L

what's the easiest and most systematic way of determining if a molecular structure is polar/nonpolar? Do I have to look at the Lewis structure or know the VSEPR structure?

josephyim1L

Can someone explain what a ligand is, how to identify it, and what it means that a ligand binds at "monodentate" or "bidentate"?

josephyim1L

Can someone explain the differing hybrid orbitals and examples of each?

also, I'm not quite sure I understand how to determine which orbitals get hybridized and which ones remain at their original energy levels...

For the test do we have to know all the way up to d2sp3?

josephyim1L

What's the easiest way to predict the type of hybrid orbital while predicting the molecular shape?

josephyim1L

What's the easiest, systematic way to predict intermolecular interactions?

josephyim1L

What does VSEPR imply about gases?

josephyim1L

i notice that certain carbon-containing molecules have the "bent" shape, what is a "bent" shape and how do we determine it?

In a separate vein, what is the quickest and easiest way to determine the type of molecular interactions that molecules experience?

josephyim1L

Once the lewis structure is determined, the molecular shape is ultimately determined by the principle of stability. Due to electron-electron repulsion, the differing bond-pairs or lone-pair electrons want to be distanced as far away as possible on a 3 dimensional plane, this is manifested in the dif...

josephyim1L

Do lone pair electrons influence the name of the molecular shape? In the molecular geometries such as seesaw, don't lone pairs affect the name given to it, or is it just the bound electrons that influence it? lone pair electrons influence the shape of the molecular shape but don't impact the actual...

josephyim1L

Can someone explain to me the reactive potential of radicals in comparison with that of halogens? Which are more reactive?

josephyim1L

Can someone explain to me why single bonds are weaker than double bonds which are weaker than triple bonds? Shouldn't single bonds be the strongest?

josephyim1L

What's the difference between london forces and dispersion forces?

josephyim1L

Does the overall formal charge of an atom (addition of formal charges of individual atoms) always have to add up to the overall charge of the compound? If the overall charge of the compound is +1 does the addition of the fc of each atom have to add up to +1?

josephyim1L

In determining the preferred Lewis Structure diagram for a given molecule, what is more important to consider: achieving and maintaining an octet or having a formal charge of 0?

Will there ever be a case when a formal charge of no 0 (1,2,-1,-2) will be preferred to having an octet?

josephyim1L

The textbook doesn't do a very good job of showing how to determine if a double bond should be added, can someone clarify how to know if a double bond or triple bond should be added for a Lewis structure?

josephyim1L

How might a change in wavelength/frequency impact the heisenberg indeterminacy principle?

josephyim1L

In "ejecting electrons" during the photoelectric experiment, doesn't the ability of the electron to be excited with kinetic energy contradict the rule that electrons only absorb energy in quantized amounts?

josephyim1L

Does the energy of a 2s electron lower than the energy of a 2p orbital? In essence, can electrons with the same principle quantum number have higher or lower energy levels than each other?

josephyim1L

In class today, Lavelle mentioned that the cone around the dz orbital is a nodal plane as well as an area of reactivity, can someone explain this in more detail?

josephyim1L

Can someone give an example of the Shrodinger Equation or the spdf orbitals being used in a practice problem? I'm having a hard time understanding applications of the orbitals and the very abstract equations.

josephyim1L

Can someone explain the primary significance of H(psi) = E(psi) and its relationship to finding the density probability of an electron. How this equation relates to the orbitals explained in class was very confusing.

josephyim1L

Hi,

Can someone give context regarding increases and decreases in electron level? I'm having a hard time understanding the emission/line/atomic spectra (the graph that was shown in class that had the Balmer and Lyman series with the lines on it?

josephyim1L

∆E = hv

Hi, for the above equation; can someone explain or give application to finding finding the change in energy level of an electron (∆E)? I'm having a hard time understanding what ∆E means and the nature of its behavior (quantized increases/decreases in energy level).

josephyim1L

Hi, Can someone explain to me the whole concept behind electrons being excited to higher energy levels? I understand that incoming EM radiation excites an electron to a higher energy level, but Monday's lecture revolved around "ejecting" electrons. What is the difference between ejecting e...

josephyim1L

For limiting reactant questions; once I've found the ratio; maybe if I have .3 moles of a substance in a 1:3 ratio with the product, i will produce at most .3 moles of the product. Now I want to find how many grams that it, do I use the molar mass of the product times 3, since its a 1:3 ratio? Or do...

josephyim1L

Im a bit confused on how to use different methods to solve for empirical and molecular formulas... Is it necessary to find the percent composition in order to find the empirical formula? For example, the question involving 339.20 g of cobalt and fluorine gas to produce 996.08 g of a product, and i'm...

josephyim1L

Please try use all the free resources I am offering students in my classes: Peer Facilitated Learning Sessions https://lavelle.chem.ucla.edu/forum/viewtopic.php?f=157&t=15397&sid=5b2d5158e781ed3535e1ecb3d1e0be81 Teaching Assistant Office Hours https://lavelle.chem.ucla.edu/forum/viewtopic.p...

josephyim1L

I don't quite understand what the coefficients in a chemical equation represent. Today in class, Professor Lavelle mentioned that the coefficients represent moles, and that the # of moles aren't the same, but the number of atoms are... Don't the coefficients for each element or molecule just represe...

Search found 61 matches