CHEMISTRY COMMUNITY

Annah Khan 1B

"During a strong-base strong-acid titration calculate the pH when 49.00 mL of 0.100 M NaOH has been added to 50.00 mL of 0.100 M HCl." The answer states: Moles of NaOH present = (49.00/1000) x 0.1 = 4.9x10^-3 Moles of HCl present = (50.00/1000) x 0.1 = 5.0x10^-3 I was confused as to why we...

Annah Khan 1B

"Suppose that 4.25 g of an unknown monophonic acid weak acid, HA, is dissolved in water. Titration of the solution with 0.350 M NaOH(aq) required 52.0 mL to reach the stoichiometric point. After the addition of 26.0 mL, the pH of the solution was found to be 3.82. (a) What is the molar mass of ...

Annah Khan 1B

"Use the information in Table 11.2 (pg. 428) to determine the value of K at 300 K for the reaction 2 BrCl (g) + H2 (g) <--> Br2 (g) + 2 HCl (g)." I understand the concept of the question and what it is asking, but I am not sure how to solve it and why that would be the answer. If someone c...

Annah Khan 1B

"Determine whether an aqueous solution of each of the following salts has a pH equal to, greater than, or less than 7. If pH > 7 or pH < 7, write a chemical equation to justify your answer. (a) NH4Br; (b) Na2CO3; (c) KF; (d) KBr; (e) AlCl3; (f) Cu(NO3)2." I understand what the question is ...

Annah Khan 1B

"The concentration of HCl in hydrochloric acid is reduced to 12% of its initial value by dilution. What is the difference in the pH values of the two solutions?"

I am having a difficult time answering this question. Where do I start? Can someone please explain this to me? Thank you!

Annah Khan 1B

"Which is the stronger base, the hypobromite ion, BrO-, or morphine, C17H19O3N? Justify your answer."

I understand what the problem is asking, but I'm not entirely sure how to find the answer. Could someone explain this to me please? Thanks!

Annah Khan 1B

"Write the reaction quotient Q for: (a) 2 BCl3(g) + 2 Hg (l) --> B2Cl4 (s) + Hg2Cl2 (s) (b) P4S10 (s) + 16 H2O (l) --> 4 H3PO4 (aq) + 10 H2S (aq) (c) Br2 (g) + 3 F2 (g) --> 2 BrF3 (g)" As I understand, Q is equal to [products]/[reactants]. However, the answer for (a) is 1/PBCl3^2, and I am...

Annah Khan 1B

"White phosphorus, P4, is so reactive that it bursts into flame in air. The four atoms in P4 form a tetrahedron in which each P atom is connected to three other p atoms. (a) Assign a hybridization scheme to the P4 molecule. (b) Is the P4 molecule polar or nonpolar?" I successfully figured ...

Annah Khan 1B

"There are three different isomers of dichlorobenzene, C6H4Cl2, which differ in the relative positions of the chlorine atoms on the benzene ring. (a) Which of the three forms are polar? (b) Which has the largest dipole moment?" I was having trouble figuring this question out. How do I know...

Annah Khan 1B

"Of the following sets of four quantum numbers {n, l, ml, ms}, identify the ones that are forbidden for an electron in an atom and explain why they are invalid: (a) {4, 2, -1, +1/2} (b) {5, 0, -1, +1/2} (c) {4, 4, -1, +1/2}" So far, I've solved that the first configuration is possible, but...

Annah Khan 1B

"Which of the following species are radicals?
(a) NO2-
(b) CH3
(c) OH
(d) CH2O"

I was having trouble answering this question. If someone could help me answer the question and explain to me why that is the answer, I would really appreciate it.

Annah Khan 1B

Hello! I'm still not sure what the difference is between ionization energy and electron affinity. Can someone please explain these concepts to me further? Thank you in advance!

Annah Khan 1B

"Write the complete Lewis structures for each of the following compounds: (a) ammonium chloride (b) potassium phosphide (c) sodium hypochlorite" I can draw the Lewis structures for the compounds, but I am having trouble determining them from the name (ex. methane instead of CH4). Does anyo...

Annah Khan 1B

Hi, I'm having trouble understanding the concept of polar (and nonpolar) covalent bonds, as well as partial charges. Can someone please explain this further to me? And how do they relate to each other? Thank you in advance!

Annah Khan 1B

"Determine whether each of the following electron configurations represents the ground state or an excited state of the atom given."

I was confused as to why only (d) is the configuration for the ground state atom and why the others represent an excited state.

Annah Khan 1B

I looked over the graphs on page 44 of the textbook (in chapter 2). I am not quite understanding what the graphs represent and how they are significant to electron orbitals. I attached a photo below (hopefully), and I would appreciate it if someone could explain this more to me. Thank you in advance!

Annah Khan 1B

"Ionization energies usually increase on going form the left to right across the periodic table. The ionization energy or oxygen, however, is lower than that of either nitrogen to fluorine. Explain this anomaly." I am not sure about how to answer this question and why that would be the ans...

Annah Khan 1B

A proton is accelerated in a cyclotron to a very high speed that is known to within 3.0 x 10^2 km/s. What is the minimum uncertainty in its position?

The answer the book gives is 0.11 pm, but I'm not sure where to start and how to get there.

Annah Khan 1B

Hi, I was wondering why there are multiple ways of writing electron configurations? For example, why do we write the configuration for a magnesium atom as 1s^2 2s^2 2p^6 3s^2, as well as [Ne] 3s^2? What significance does the shorter version have compared to the longer version? Thank you in advance!

Annah Khan 1B

When limestone, which is principally CaCO3, is heated, carbon dioxide and quicklime, CaO, are produced by the reaction CaCO3(s) --> CaO(s) + CO2(g). If 17.5g of CO2 is produced from the thermal decomposition of 42.73g of CaCO3, what is the percentage yield of the reaction? I was able to convert the ...

Annah Khan 1B

The velocity of an electron that is emitted from a metallic surface by a photon is 3.6 x 10^3 km/s. (a) What is the wavelength of the ejected electron? (b) No electrons are emitted from the surface of the metal until the frequency of the radiation reaches 2.50 x 10^16 Hz. How much energy is required...

Annah Khan 1B

A chemistry joke:

I don't trust atoms...they make up everything...

Haha!

Annah Khan 1B

A chemistry joke-

Chemistry is FUN (Flourine, Uranium, and Nitrogen)

Hope you enjoyed this!

Annah Khan 1B

Q: What is the chemical formula for banana?
A: BaNa2

Haha, hope you like it!

Annah Khan 1B

Q: What is the chemical formula for coffee?
A: CoFe2

Annah Khan 1B

Q: what do you call a joke that is based on cobalt, radon, and yttrium?
A: CoRnY

hahaha :)

Annah Khan 1B

Q: What element is derived from a Norse [censored]?
A: Thorium

Annah Khan 1B

Good joke! I have another:

Q: Do you know any good jokes about sodium?
A: Na

Haha, hope you like it!

CHEMISTRY COMMUNITY

Search found 28 matches

Fall 2015 Final Exam Question 8D

Question 13.33

Question 11.39

Question 12.65

Question 12.19

12.49

Question 11.13

Question 4.39 [ENDORSED]

Question 4.29

Question 2.41

Question 3.55

Ionization energy vs. electron affinity [ENDORSED]

Question 3.39

Polar covalent bonds & partial charges

Question 2.39

Graphs on page 44 of the textbook

Question 2.81

1.7 Self-Assessment 1.7A

Electron configurations

Question M.3

Question about 1.33 Part C

Re: Post All Chemistry Jokes Here

Re: Post All Chemistry Jokes Here

Re: Post All Chemistry Jokes Here

Re: Post All Chemistry Jokes Here

Re: Post All Chemistry Jokes Here

Re: Chemistry Humor

Re: A classic joke