Search found 28 matches

by Annah Khan 1B
Tue Aug 01, 2017 8:59 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Fall 2015 Final Exam Question 8D
Replies: 1
Views: 293

Fall 2015 Final Exam Question 8D

"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...
by Annah Khan 1B
Tue Aug 01, 2017 5:13 pm
Forum: *Titrations & Titration Calculations
Topic: Question 13.33
Replies: 1
Views: 422

Question 13.33

"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 ...
by Annah Khan 1B
Sun Jul 30, 2017 5:30 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Question 11.39
Replies: 3
Views: 247

Question 11.39

"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...
by Annah Khan 1B
Sun Jul 30, 2017 4:24 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Question 12.65
Replies: 1
Views: 204

Question 12.65

"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 ...
by Annah Khan 1B
Sun Jul 30, 2017 2:38 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Question 12.19
Replies: 3
Views: 310

Question 12.19

"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!
by Annah Khan 1B
Sun Jul 30, 2017 2:35 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: 12.49
Replies: 5
Views: 403

12.49

"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!
by Annah Khan 1B
Sun Jul 23, 2017 5:54 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Question 11.13
Replies: 3
Views: 285

Question 11.13

"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...
by Annah Khan 1B
Sat Jul 22, 2017 6:58 pm
Forum: Hybridization
Topic: Question 4.39 [ENDORSED]
Replies: 2
Views: 276

Question 4.39 [ENDORSED]

"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 ...
by Annah Khan 1B
Sat Jul 22, 2017 6:47 pm
Forum: Dipole Moments
Topic: Question 4.29
Replies: 1
Views: 794

Question 4.29

"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...
by Annah Khan 1B
Sun Jul 16, 2017 9:27 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Question 2.41
Replies: 1
Views: 244

Question 2.41

"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...
by Annah Khan 1B
Sun Jul 16, 2017 9:17 pm
Forum: Octet Exceptions
Topic: Question 3.55
Replies: 3
Views: 413

Question 3.55

"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.
by Annah Khan 1B
Sat Jul 15, 2017 11:03 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Ionization energy vs. electron affinity [ENDORSED]
Replies: 5
Views: 395

Ionization energy vs. electron affinity [ENDORSED]

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!
by Annah Khan 1B
Sat Jul 15, 2017 5:23 pm
Forum: Lewis Structures
Topic: Question 3.39
Replies: 1
Views: 237

Question 3.39

"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...
by Annah Khan 1B
Sun Jul 09, 2017 9:55 pm
Forum: Coordinate Covalent Bonds
Topic: Polar covalent bonds & partial charges
Replies: 1
Views: 467

Polar covalent bonds & partial charges

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!
by Annah Khan 1B
Sun Jul 09, 2017 4:24 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Question 2.39
Replies: 1
Views: 257

Question 2.39

"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.
by Annah Khan 1B
Sat Jul 08, 2017 3:15 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Graphs on page 44 of the textbook
Replies: 1
Views: 201

Graphs on page 44 of the textbook

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!
by Annah Khan 1B
Sat Jul 08, 2017 3:02 pm
Forum: Trends in The Periodic Table
Topic: Question 2.81
Replies: 1
Views: 305

Question 2.81

"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...
by Annah Khan 1B
Sun Jul 02, 2017 6:30 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: 1.7 Self-Assessment 1.7A
Replies: 1
Views: 197

1.7 Self-Assessment 1.7A

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.
by Annah Khan 1B
Sun Jul 02, 2017 5:36 pm
Forum: Quantum Numbers and The H-Atom
Topic: Electron configurations
Replies: 3
Views: 321

Electron configurations

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!
by Annah Khan 1B
Sat Jul 01, 2017 7:14 pm
Forum: Limiting Reactant Calculations
Topic: Question M.3
Replies: 1
Views: 319

Question M.3

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 ...
by Annah Khan 1B
Sat Jul 01, 2017 2:04 pm
Forum: DeBroglie Equation
Topic: Question about 1.33 Part C
Replies: 1
Views: 301

Question about 1.33 Part C

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...
by Annah Khan 1B
Sun Nov 20, 2016 9:22 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7609
Views: 1020242

Re: Post All Chemistry Jokes Here

A chemistry joke:

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

Haha!
by Annah Khan 1B
Sun Nov 13, 2016 10:31 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7609
Views: 1020242

Re: Post All Chemistry Jokes Here

A chemistry joke-

Chemistry is FUN (Flourine, Uranium, and Nitrogen)

Hope you enjoyed this!
by Annah Khan 1B
Mon Nov 07, 2016 2:10 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7609
Views: 1020242

Re: Post All Chemistry Jokes Here

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

Haha, hope you like it!
by Annah Khan 1B
Sun Oct 23, 2016 11:12 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7609
Views: 1020242

Re: Post All Chemistry Jokes Here

Q: What is the chemical formula for coffee?
A: CoFe2
by Annah Khan 1B
Sun Oct 16, 2016 2:52 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7609
Views: 1020242

Re: Post All Chemistry Jokes Here

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

hahaha :)
by Annah Khan 1B
Fri Oct 07, 2016 10:47 pm
Forum: Phase Changes & Related Calculations
Topic: Chemistry Humor
Replies: 26
Views: 2585

Re: Chemistry Humor

Q: What element is derived from a Norse [censored]?
A: Thorium
by Annah Khan 1B
Fri Sep 30, 2016 10:16 pm
Forum: Student Social/Study Group
Topic: A classic joke
Replies: 3
Views: 766

Re: A classic joke

Good joke! I have another:

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

Haha, hope you like it!

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