## Search found 29 matches

Sun Jul 30, 2017 11:02 pm
Forum: Bronsted Acids & Bases
Topic: HW Problem 12.19
Replies: 1
Views: 209

### HW Problem 12.19

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'm having a difficult time understanding this problem. Can someone please explain how to solve this? Thank you!
Sun Jul 30, 2017 8:01 pm
Forum: Calculating the pH of Salt Solutions
Topic: HW Problem 12.65
Replies: 1
Views: 344

### Re: HW Problem 12.65

Also, with part d, I'm running into the same issue. Why are they substituting the anions with H2O?
Sun Jul 30, 2017 7:58 pm
Forum: Calculating the pH of Salt Solutions
Topic: HW Problem 12.65
Replies: 1
Views: 344

### HW Problem 12.65

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. I'm having trouble with part e) AlCl3 Can someone please explain how to do this? I looked at the solutions m...
Sun Jul 30, 2017 4:31 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Approximation in Calculations
Replies: 5
Views: 440

### Re: Approximation in Calculations

Thank you!
Sun Jul 30, 2017 4:30 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibrium value
Replies: 2
Views: 324

### Re: Equilibrium value

When you get a value that is larger than your initial concentration you don't use it because you can't have a higher equilibrium concentration than your initial concentration. I think this is due to the law of conservation of mass. Hope that helps!
Sun Jul 30, 2017 4:27 pm
Forum: Lewis Structures
Topic: Le Chatelier's Principle
Replies: 1
Views: 292

### Re: Le Chatelier's Principle

I don't think I quite understand every aspect of Le Chatelier's Principle, but my limited understanding has helped me get through the hw problems so maybe it'll help you. From what I understand, if you increase the pressure on a system, then there is a decrease in volume, causing the equilibrium to ...
Sat Jul 29, 2017 3:47 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Approximation in Calculations
Replies: 5
Views: 440

### Approximation in Calculations

When going through the ICE box calculations for weak acids and bases, how do you know when it is ok to assume that x is really small and just approximate? Thanks!
Sat Jul 29, 2017 1:24 pm
Forum: Conjugate Acids & Bases
Topic: Question 12.3
Replies: 2
Views: 453

### Re: Question 12.3

I would write it to be sure because you don't want to accidentally consider something in your calculations if it is a solid or liquid. I personally think it's better to have everything written out to know what you're doing.
Sun Jul 23, 2017 8:30 pm
Forum: Hybridization
Topic: HW Problem 4.77
Replies: 3
Views: 387

### Re: HW Problem 4.77

That's true! Didn't realize this corresponded to that topic. Thanks guys!
Sun Jul 23, 2017 8:29 pm
Forum: Hybridization
Topic: Homework Problem 4.43
Replies: 2
Views: 379

### Re: Homework Problem 4.43

Thank you!
Sun Jul 23, 2017 8:27 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Polar and Nonpolar
Replies: 3
Views: 398

### Re: Polar and Nonpolar

Nonpolar covalent bonds occur between two atoms that have similar electronegativities. As a result, they equally share the bonding electron pair. Polar covalent bonds occur between two atoms that have different electronegativities. In this case, there is an unequal sharing of the bonding electron pa...
Sun Jul 23, 2017 8:20 pm
Forum: Lewis Structures
Topic: Energy in lewis structures
Replies: 3
Views: 331

### Re: Energy in lewis structures

And also, do you mean problem 3.53?
Sun Jul 23, 2017 8:19 pm
Forum: Lewis Structures
Topic: Energy in lewis structures
Replies: 3
Views: 331

### Re: Energy in lewis structures

I believe you can tell which one has the lowest energy by looking at the formal charges of each atom in the structure. I think the one with the lowest charges should be the one with lower energy.
Sat Jul 22, 2017 2:40 pm
Forum: Hybridization
Topic: HW Problem 4.77
Replies: 3
Views: 387

### HW Problem 4.77

This homework problem mentions antibonding orbitals. Can someone please explain antibonding orbitals and how they are different from bonding orbitals? Thank you!
Sat Jul 22, 2017 2:20 pm
Forum: Hybridization
Topic: Homework Problem 4.43
Replies: 2
Views: 379

### Homework Problem 4.43

For homework problem 4.43 it reads: Noting that the bond angle of an sp3 hybridized atom is 109.5 degrees, and that of an sp2 hybridized atom is 120 degrees, do you expect the bond angle between two hybrid orbitals to increase or decrease as the s-character of the hybrids is increased? The solutions...
Sun Jul 16, 2017 11:27 pm
Forum: Resonance Structures
Topic: Delocalized
Replies: 7
Views: 547

### Re: Delocalized

From what I understood in class, I believe this means that the electrons in that structure are not bound to one specific covalent bond between two atoms but are instead shared amongst many of the atoms in that molecule. Hope this helps.
Tue Jul 11, 2017 9:32 pm
Forum: Trends in The Periodic Table
Topic: 1st and 2nd ionization energy? [ENDORSED]
Replies: 7
Views: 2202

### Re: 1st and 2nd ionization energy?[ENDORSED]

First ionization energy is basically the energy required to remove an electron from a neutral atom while in a gas state. The second ionization energy is the energy required to remove another electron from that atom, so you're technically removing an electron from a 1+ ion since that atom already los...
Tue Jul 11, 2017 9:28 pm
Forum: Trends in The Periodic Table
Topic: Exercise 2.67
Replies: 4
Views: 455

### Re: Exercise 2.67

Could it be that it's just an exception? I don't remember going over anything of the such in class but maybe I just missed it.
Tue Jul 11, 2017 9:25 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: HW #2.51
Replies: 3
Views: 363

### Re: HW #2.51

I think you wrote down the elements from problem 2.52. But either way you'd go about answering the question the same way. I just wrote down the electron configurations and then drew out the aufbau diagram with the arrows just to make it more visibly clear. For question 2.51 part a for example, I loo...
Tue Jul 11, 2017 6:39 pm
Forum: DeBroglie Equation
Topic: question on how to determine if something has wavelike properties.
Replies: 6
Views: 1140

### Re: question on how to determine if something has wavelike properties.

You would determine if something has wavelike properties based on the answer you get. Generally things with large mass and large momentum such as traditional objects like cars and balls do not have wavelike properties. I remember asking Dr. Lavelle a similar question and I think he said when you see...
Sun Jul 09, 2017 3:24 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Question about Effective Nuclear Charge
Replies: 3
Views: 356

### Re: Question about Effective Nuclear Charge

Effective nuclear charge is the charge that a valence electron experiences as a result of the attractive forces of the positive nucleus. However, the inner electrons create a shielding effect and limit how much the nucleus can pull on the valence electrons. This trend increases left to right across ...
Sun Jul 09, 2017 3:06 pm
Forum: Student Social/Study Group
Topic: Electron Configuration
Replies: 2
Views: 358

### Re: Electron Configuration

From what I understood in class, it seems that 4s and 3d energies are very close to each other. 4s usually has more energy than 3d except when it comes to the elements Potassium and Calcium. For these two elements, 4s has slightly less energy than 3d. Hope that helps!
Sat Jul 08, 2017 11:50 pm
Forum: Limiting Reactant Calculations
Topic: Excess reactant
Replies: 1
Views: 342

### Re: Excess reactant

I'm assuming that you could be able to work backwards by using mole to mole ratios of each reactant to find the amount of limiting reactant that would react with the excess reactant that is not used. If you know the amount excess reactant not used then I think you should be able to do this.
Mon Jul 03, 2017 7:36 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: chapter 1 question 57
Replies: 2
Views: 320

### Re: chapter 1 question 57

How do we know that the fifth energy level is n=7?
Mon Jul 03, 2017 7:27 pm
Forum: Photoelectric Effect
Topic: role of wavelength
Replies: 2
Views: 321

### Re: role of wavelength

During the photoelectric experiment, light did not act like a classical wave because even as the intensity of a certain light source was increased, electrons were still not ejected from the metal. Intensity in this case meant increasing the number of photons being emitted from the light source. Howe...
Sun Jul 02, 2017 12:20 pm
Forum: Properties of Light
Topic: What exactly did the Photoelectric experiment show?
Replies: 2
Views: 288

### Re: What exactly did the Photoelectric experiment show?

The photoelectric effect basically showed that electromagnetic radiation not only has wave-like properties, but also has particle-like properties. This is due to the fact that even when they increased the intensity (amplitude) of a light source with lower frequencies (ex: red light), electrons were ...
Wed Jun 28, 2017 10:28 pm
Forum: Empirical & Molecular Formulas
Topic: Question about Formula Units [ENDORSED]
Replies: 1
Views: 406

### Re: Question about Formula Units[ENDORSED]

Formula units can be paralleled with the word molecules. The word molecule is used to describe substances that are covalently bonded, whereas the phrase formula unit is descriptive of ionic compounds and represents the smallest ratio between the cations and anions that form those ionic compounds. Fo...
Wed Jun 28, 2017 10:12 pm
Forum: Molarity, Solutions, Dilutions
Topic: Exercise E.1 - Question on Units
Replies: 3
Views: 418

### Re: Exercise E.1 - Question on Units

I was wondering the same thing while doing the problem. I think they listed the answer in km simply because the value is so large that it would be more convenient to write it in km than it would be to write it in smaller units such as m or pm.
Wed Jun 28, 2017 5:27 pm
Forum: Empirical & Molecular Formulas
Topic: Difficulty with HW Question F.21 [ENDORSED]
Replies: 1
Views: 330

### Difficulty with HW Question F.21[ENDORSED]

F.21: In 1978, scientists extracted a compound with anti tumor and antiviral properties from marine animals in the Caribbean Sea. A sample of the compound didemnin-A of mass 1.78mg was analyzed and found to have the following composition: 1.11mg C, 0.148mg H, 0.159 mg N, and 0.363 mg O. The molar ma...

Go to advanced search