CHEMISTRY COMMUNITY

Krupa Prajapati

Are you made of copper? Cause I Cu in a relationship with me.

Krupa Prajapati

Avogadro says, "Hey ladies, take my number: 6.02 X 10^23"

Krupa Prajapati

Helium walks into a bar. The bartender says "We do not serve noble gases here." He does not react.

Krupa Prajapati

Anyone know any jokes about sodium?

Na.

Krupa Prajapati

Chemistry jokes are sodium funny! I slapped my neon that one.

Krupa Prajapati

Hi! We can find k by first finding the rate law, through comparing the change in concentrations versus the change in initial rates. After doing this, we will then find the order of each of the reactants and can write the rate law. since the rate law is initial rate = k[reactant 1][reactant2] and so ...

Krupa Prajapati

What fruit contains Barium and double Sodium? BaNaNa

Krupa Prajapati

What is a cation afraid of? A dogion

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What do you call a tooth in a glass of water? A one molar solution

Krupa Prajapati

I wish I was adenine so I could get paired with U

Krupa Prajapati

Hey baby, I've got my ion you!

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Forget Hydrogen, you're my number one element

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Are you a carbon sample? Cuz I want to date you.

Krupa Prajapati

Aha! The element of surprise.

Krupa Prajapati

All the good chemistry jokes Argon

Krupa Prajapati

Hi! From looking at some of the answers in the solution manual, I don't think you divide the Gibb's free energy by the coefficient of a molecule in a reaction.

Krupa Prajapati

Hi! I think the Gibbs free energy is zero because the system is at equilibrium. The rate of reaction for liquid water turning into a gas is the same as the rate of reaction for gas turning into a liquid.

Krupa Prajapati

Hi. To add onto that, the explicit equation we can use is lnK = (delta G)/(-RT) or e^((delta G)/(-RT)). We can then find this answer and plug it into the Van't Hoff's Equation.

Krupa Prajapati

Mercury has a high entropy of vaporization because there are metallic bonds between the mercury atoms, which make it more organized.

Krupa Prajapati

Another useful way to memorize the different types of equations, is to see what factors ARE changing. For example, in the equation delta S = Cm/v*ln(T2/T1), we know that the volume is constant because it is specific heat for a constant volume. We know that temperature is changing, and since pressure...

Krupa Prajapati

Hi all. I was wondering why in question 9.13, the solution manual says to use the equation delta S = nRln (T2/T1). Isn't the equation for entropy change involving temperature nC(T2/T1)?

Krupa Prajapati

Hi! The second law of thermodynamics states that total entropy can never decrease over time for an isolated system, and stays constant if the system is in equilibrium or in a reversible process. We use this law because it correlates with spontaneity, as spontaneity is a function of entropy.

Krupa Prajapati

Hi! I was looking at question 8.31 in the textbook and I was confused because for calculating both Cpm and Cvm the book used the R value 8.31 J/mol*K but uses the temperature change in degrees Celsius. Why is there such a discrepancy? Thanks!

Krupa Prajapati

Hi all! I am still confused as to what the actual definition of spontaneity is, if we do not use the word "disorder." I know Dr. Lavelle went over it in class, but a little clarification would be much appreciated!

Krupa Prajapati

Hi! I was just wondering if we will be required to know the derivation for the work equation, w = (-p)*(delta v), involving the integral for the exam.

Krupa Prajapati

Hi! I believe that is true, that no work is being done, because if there is no increase or decrease in the net amount of moles of gas being produced, the volume of the container will not need to change and thus no work is being done.

Krupa Prajapati

Hi! When elements form bonds they are in a more stable state and thus have a lower potential energy. Thus, when we form bonds energy is released as atoms move to this lower potential energy. This value is negative, as energy is being released (energy of products (atoms in a bond) < energy of reactan...

Krupa Prajapati

Hi Grace, I think higher heat capacities have less steep slopes because specific heat means the amount of heat required to raise the temperature of 1g of the substance by 1 degree Celcius. Therefore, a substance with higher heat capacity requires more heat to raise the temperature, and therefore the...

Krupa Prajapati

Hi Grace, Since q simply represents the amount of heat transferred to a system, q ice = -q water. The ice, the system, is gaining heat while the water, the surrounding, is loosing the same amount of heat. Therefore, when we substitute q for m*c*(t final - t initial) we put a negative in front of the...

Krupa Prajapati

Hi Rucha, We use KJ/mole usually when we want to know the enthalpy of formation for a certain molecule. However, when we are finding the change in enthalpy for an overall reaction we only use KJ because we are not finding the change for any molecule in particular, so we cannot use KJ/mole. Hope this...

Krupa Prajapati

Hi! From my understanding, either pKb or Kb are acceptable for understanding how strong a base is. In table 21.1 we se HBrO has pKa = 8.69. We know that since pKb = 14 - pKa, we find that pKb for BrO- is 5.31. Since the lower the Kb value the stronger the base, 5.31 < 5.79, we can conclude that BrO-...

Krupa Prajapati

HI! In addition, it may be helpful to know a couple of the amphoteric oxides so they are easier to recognize. The textbook gives the example of BeO, Al2O3, Ga2O3, GeO2, As2O3, In2O3, SnO and SnO2, Sb2O3, PbO and PbO2, and finally Bi2O3. Hope that helps :)

Krupa Prajapati

Hi! In equilibrium, if there is compression the reaction will favor the side which has the least moles of gas. Does this also apply to aqueous solutions? If not, how do changes in pressure affect changes in equilibrium for aqueous solutions?

Krupa Prajapati

Hi, although most of the times reactants are -x and products are +x, this is only true when we know that Q < K and thus favors products. If we find that Q > K, then reactants are favored, and the reactants are +x while the products are -x.

Krupa Prajapati

Hi! I am going to explain how to do part a, which is very similar to the other two parts. First, we must construct the equilibrium reaction equation. Cl2 (g) <-> 2Cl (g) Now, since the problem says there is 2.0 mmol of Cl2 and a 2.0L vessel, we can calculate the molarity of the Cl2 gas, which is fou...

Krupa Prajapati

Hi! For question 53, when we use the ICE box to find the equilibrium concentrations for H2, I2, and 2HI, we use subtraction. For finding the equilibrium concentration of H2, we take 0.133 M and subtract 0.800 M. The result is we have 0.053 M of H2, which is only 2 significant figures. When we calcul...

Krupa Prajapati

Hi! I found this very interesting article about the uses and importance of copper in the body. Hope you find it interesting too!

http://www.drlwilson.com/articles/coppe ... ndrome.htm

Krupa Prajapati

Hi! I was just wondering how exactly we determine if a compound can form chelating complexes. I was having some difficulty with question 17.35, and some guidance would be greatly appreciated!

Krupa Prajapati

Hi Jason. Another rule of thumb is if the electronegativity difference between the two atoms is less than 0.5, than generally we assume the molecule is nonpolar. If the difference is greater than 0.5 but less than 1.5, we can assume the molecule is polar. Hope this helps!

Krupa Prajapati

Hi! I was just wondering if a molecule's polarity affects its VSEPR shape. Since the electrons are being pulled unequally, will that affect the bond angles in the shape?

Krupa Prajapati

Hi! I was just wondering how we can predict an ionic or covalent bond will form. Is it typically that a nonmetal and metal form an ionic bond, and two nonmetals form covalent bonds? Also with regards to polarity, how do we determine precisely if a molecule is polar or non polar. I remember in high s...

Krupa Prajapati

Hi! I was still a little unclear as to what coordinate covalent bonds are exactly. From what I understand, when a central atom of a molecule does not have a full octet, another atom can bond to this central atom and share electrons. The other atom which attaches to the central atom forms a coordinat...

Krupa Prajapati

Hi! I was just wondering if when we have a transition metal, do the valence electrons come from the d block or the s block? Also, does the d orbital have lower energy than the s orbital? For example, in Iron, does 4s2 or 3d6 have higher energy? Thank you!

Krupa Prajapati

Could someone please explain the inert pair effect and how exactly that relates to the concept of variable valence? Thank you!

Krupa Prajapati

S^-2 is also larger because it has more electrons in its outer shell, which causes repulsion. This is called the shielding effect, and leads to S^-2 having a greater atomic radius than O^-

Krupa Prajapati

Hi! I believe the atomic orbitals are all various solutions to Schrodinger's equation. The solutions are called wave functions, synonymous to atomic orbitals, to remind us that electrons have wave like properties.

Krupa Prajapati

In addition to converting keV to Joules, another way to start this problem is to use the equation:

wavelength = (hc)/E

h and c are both constants, so we only need to plug in our value for energy for Joules to start the problem. Hope this helps!

Krupa Prajapati

Hi! Something to also remember for solving this problem is that Hertz can be converted to seconds^-1. This way, when you are solving the problem the units will cancel and solving the problem will be easier to follow. Hope this helps!

Krupa Prajapati

To add on to that response, I also think it is important to remember which precipitate is going to form at the end of the reaction. You only include the ions which make up the precipitate as the reactants on the left side, and only include the precipitate on the right side. While it is possible to a...

Krupa Prajapati

Hi! I believe in Ramya's explanation of her way to solve the problem, she forgot to mention that she found the amount of moles in 10 mL of the solution, instead of 4.9 * 10^-7 molecules per Liter. I solved it in this fashion and got the same answer! Hope this helps.

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