CHEMISTRY COMMUNITY

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When given line structures what should we look for that distinguishes a ketone from an aldehyde since they're pretty similar?

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7b) Derive an expression for the rate of formation of the product E using the pre-equilibrium approach.

The unique rate was 1/2 d[E]/dt, why do we put a 1/2?

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Is it true that for E values Galvanic should be positive and Concentration should always = 0?

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Also Q5 asked the question:
Given the instantaneous rate of rxn is 2.54x10^-2 mol/(Lxs), and intial mass of each reactant is 1.2g confined to a 750mL vessel, what is the rate constant of this reaction?

-What equation are we even using here?

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CHCl3(g) + Cl2(g) ---> CCl4(g) + HClg(g)
The rate of the rxn was first order with respect to chlorine and trichloromethane.

What is the rate law?

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An exam question asked for the value of delta H(c) with given values of 1.000 grams tropinone, heat capacity 25.950kj/C, and a temp increase from 25.262 C to 25.993.
The equations used were q = (Cv)(delta T) and then delta H(c) = q(rxn)/mols burned

What are these two equations?

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Can a reaction order be negative? If so, how?

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The rate of AB4 gas consumption in this Rxn is constant throughout and is given as 0.400M/s/ If your rxn vessel starts with 0.15M of B2C, how long will it take to get to 30.00M of B2C? AB4(g) + C2(g)---> AC2(g) + B2C(g) Can someone walk me through this, what do you do after you balance the equation?

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If you're measuring spontaneity in the amount of moles of gas in an equation for example:
2 N2O(g)—> N2(g) + O2(g)

If the amount of moles are equal on both sides what does that tell about delta S?

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When solving for Q, [P]/[R] what molecules are not including into equilibrium?

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I understand the formula, but what is a more conceptual explanation between big K and little k?

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3a) A tank of liquefied propane is punctured, emitting gaseous propane vapors. Is heat being transferred?
-Is this process releasing heat because the substance is undergoing a phase change? (liquid-->gas)

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Then it asks is the rxn spontaneous?
Is it true that for spontaneity K<1?

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calculate the K of the following redox rxn:
Ag+(aq) + Cu(s) ---> Ag(s) + Cu2+(aq)

How would you start this problem?

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For the formula after we integrate it yields ln[A] = -k x t
Why is the k negative here, and should it be negative for a second order derivation as well?

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What is the reasoning behind why a more negative voltage has more strength? I thought a more positive charge will have more strength?

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When reversing a Half-Rxn for example
Cu2+(aq) + 2e- ---> Cu(s) E=+0.34V
to Cu(s) ---> Cu2+(aq) + 2e-

why doesn't the value of E switch from positive to negative?

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Does a standard potential of a cell occur under certain pH conditions?
Similar to the conditions 25 degrees celsius, 1 bar, etc.

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Is it always true that when log[Q]<1 the result will be negative and when log[Q]>1 the result will be positive?

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In the equation delta G(r)= -RT ln(k)
what does k represent and is it the same as Q?

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For an extensive property the larger the sample, the more heat is required to raise its temperature by a given amount. (Heat capacity)
What exactly is a definition for an intensive property? (Specific heat capacity)

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An open system can exchange both matter and energy with the surrounding - what does it mean by matter is exchanged? Does anyone have an example?

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The book states
When delta S (total) is positive, it is increasing and spontaneous
When delta S (total) is negative, it is decreasing and only the reverse is spontaneous
- Why is only the reverse spontaneous ?

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Do exothermic and endothermic reactions relate to catabolism and anabolism ?

For example, in an exothermic reaction the formation of products is favored by lowering the temperature. Can this be thought as an example of catabolism or anabolism?

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Does an endothermic reaction have the ability to increase spontaneity and entropy in reaction?

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Find the entropy of the surrounding and the system for:
Freezing of 1.00 lol C2H5OH

Would you use the equation delta H over T, just like if it were melting?

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Why are so many exothermic reactions spontaneous?

Using the Gibbs formula is it the negative delta G and delta H values that cause spontaneity?

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For a monatomic gas the value is 3/2R, what is R’s value? Is it a constant or a rate?

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Will there ever be an instance where the natural log of the volumes not be needed? I noticed some notations for irreversible work of expansion as w= -nRT(V2/V1) without the ln, is it just implied?

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Is there a formula sheet that was posted? If so, is it on Chem. Community or the Class Website? Thanks

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In Gibbs Free Energy, should we always use Kelvin, and is that because we want a positive value?

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I know that it is true for a closed system the internal energy changes as a function of heat & work, however, what about an open or isolated system? How does the first law apply to these two other systems?

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What do bounds V1 & V2 represent in the equation and also concecptually?

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When would you use “ion” at the end of compound?

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How can you tell if something has measurable wavelike properties?

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Practice Problem

How many grams of NaOH do you need to prepare a 3.00x10^2 mL stock solution of 2.00M NaOH?
---> 24.0g

So in the next set: How many milliliters of the stock solution would you need to make a 250 mL of 0.650M NaOH solution?
how would you do this problem?

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What is the concept behind Paramagnetism?

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Does a tetrahedral shape always have 109.5 degree angles?
For what shapes are the angles >109.5 and <109.5 ?

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Does electronegativity refer to the value associated with atoms?
For example Group 1 is 1+, Group 2 is 2+, Group 13 is 3+, Group 15 3-, etc.

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How many electrons in an atom can have the quantum numbers:
n=4, l=2, ml=+1, ms=+1/2

These quantum numbers represent the subshell 4d, so would it be 10 electrons ?

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A Sigma bond is present in all single, double, and triple bonds.
Double and triple bonds are distinguished because they contain pi bonds.

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Practice Problem

What is the full electron configuration for carbon in the ground state? How many unpaired electrons?
For the ground state would it be 1s^2 2s^2 2p^2 ?
And the for unpaired electrons are there 4?

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Ground State Configuration

Fe^2+
I thought the ground state would be [Ar]3d^4 4s^2 because of its 2+ state?

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What are the definitions of monodentate, bidentate, and tridentate?

In that case what makes NH2CH2CH2NH2 a bidentate?

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Octet Rule

Why does the molecule NO2 not obey the octet rule?
Is it because of the lone pair that is placed on the central figure N?

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Practice Question (pt.3)

How many milliliters of the stock solution would you need to make 250mL 0.650M NaOH solution?
Im not sure how to go about this problem? Any advice?

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Practice Question (pt.2)

How many grams of NaOH do you need to prepare a 3.00 x 10^2 mL stock solution of 2.00M NaOH?

so first 2.00M x 3L which gives 0.6.
Why do you multiply this value by NaOH Molecular Weight (40.069)? Shouldn't you divide because of the formula MI VI = MF VF?

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Practice Question: SOLUTIONS You need to make a stock solution of 0.0800M of sodium carbonate-Na2CO3 How much sodium carbonate would you add to a 250ml volumetric flask before filling to 250ml with water to make a 0.0800M aqueous solution of sodium carbonate? I know you should multiply 0.0800M x 25...

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4.22

Also unsure of the molecule IO6^5- shape I am getting an incorrect answer, any help?

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4.26

Write the Lewis Structure and determine whether the molecule is polar or nonpolar.
SiO2

I got the Lewis Structure but am unsure what property makes it polar/nonpolar?

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Regarding the work posted above for part b of question #7-
So did you take (4.0*10^18) divided by 1/2(9.11*10^-31), then once you get that value square root it because velocity is V^2? I tried that and was unable to get 3.03*10^6

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Test 2, Question #5 Determine the frequency of the emitted photon when an electron in a hydrogen atom drops from the quantum state of n=3 to n=1. I used the formula -hR/n^2 and calculated: n=3... -1/9hR = -2.42x10^-19 n=1... -1hR = -2.18x10^-18 Using these two values I then used N(final)-N(intial),...

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An example from section "E"
What mass of NaHSO4 should you weigh out to obtain .20 mol NaHSO4?

How would you start this problem off? Im confused would this be Mass Percentage Comp.?

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