Search found 32 matches

by 305144105
Sat Dec 08, 2018 1:02 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Periodic trend of acid strength
Replies: 2
Views: 78

Periodic trend of acid strength

When you move across a period, acid strength increases along with electronegativity. When you move down a group, acid strength increases along with bond length (even though electronegativity increases). Does the increase in bond length always negate the effect of increase in electronegativity? Why i...
by 305144105
Sat Dec 08, 2018 7:25 am
Forum: Bronsted Acids & Bases
Topic: Are all molecules with a H amphiprotic?
Replies: 2
Views: 153

Are all molecules with a H amphiprotic?

Are all molecules with a H amphiprotic?
What makes a molecule not amphiprotic?

How do you represent amphiprotic molecules in a proton transfer equilibria?
Do you write two equations? One in which it acts as a base, one in which it acts like an acid
by 305144105
Fri Dec 07, 2018 8:53 pm
Forum: Ionic & Covalent Bonds
Topic: Bond length
Replies: 2
Views: 74

Re: Bond length

Ozone will have 2 bonds of the same length. Ozone has two resonance structures. In one structure, the double bond is between one pair of oxygens. In the other structure, the double bond is between the other pair. The resonance structures imply that the real structure is somewhere in between the two ...
by 305144105
Fri Dec 07, 2018 7:54 pm
Forum: Bronsted Acids & Bases
Topic: H2PO4 -
Replies: 3
Views: 73

H2PO4 -

Is H2PO4- amphiprotic?

On a test, if we are asked to write the proton transfer equilibria for an amphiprotic species, do we write two equations? one in which it acts as an acid and one in which it acts as a base?
by 305144105
Fri Dec 07, 2018 7:35 pm
Forum: Lewis Acids & Bases
Topic: Why is water always a lewis base?
Replies: 2
Views: 63

Why is water always a lewis base?

Why is water always a lewis base?
Are there exceptions where it is a lewis acid?
by 305144105
Fri Dec 07, 2018 6:01 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Strength of acid
Replies: 4
Views: 95

Re: Strength of acid

As you move down a group, the number of valence shells increase. More valence shells result in a higher shielding effect. Thus, the valence electrons feel a weaker pull from the nucleus, and they are able to more easily dissociate. This results in a stronger acid, as stronger acids dissociate more e...
by 305144105
Fri Dec 07, 2018 5:58 pm
Forum: Ionic & Covalent Bonds
Topic: bond length
Replies: 3
Views: 116

Re: bond length

P has one more valence shell than N. This results in a larger atomic radius, a larger covalent radius, and thus, a longer bond length.
by 305144105
Fri Dec 07, 2018 5:56 pm
Forum: Bond Lengths & Energies
Topic: Shape of molecule
Replies: 4
Views: 187

Re: Shape of molecule

More surface area of the molecule is exposed.
More of the molecule can participate in London dispersion forces.
Thus, the bonds are stronger.
by 305144105
Fri Dec 07, 2018 5:48 pm
Forum: Amphoteric Compounds
Topic: Difference between amphoteric and amphiprotic?
Replies: 4
Views: 98

Re: Difference between amphoteric and amphiprotic?

Amphoteric: A substance which can act as either an acid or a base
Amphiprotic: one which can both donate hydrogen ions (protons) and also accept them

Amphiprotic species must be amphoteric, but the converse is not true. Not all amphoteric substances are amphiprotic.
by 305144105
Thu Nov 29, 2018 10:21 am
Forum: Electronegativity
Topic: What is the relationship between electronegativity and cation polarizability?
Replies: 1
Views: 169

What is the relationship between electronegativity and cation polarizability?

What is the relationship between electronegativity and cation polarizability? Electronegativity: measure of how strongly atoms attract bonding electrons to themselves Polarizability: measure of how easily an electron cloud (belonging to an atom/molecule/ion) is distorted by an electric field (caused...
by 305144105
Wed Nov 28, 2018 9:56 pm
Forum: Hybridization
Topic: 7th Edition 2.45
Replies: 1
Views: 87

7th Edition 2.45

Consider the bonding in CH2=CHCHO. (b) Identify the composition of the bonds and the hybridization of each lone pair—for example, by writing (H1s,C2sp2). 1. Does the composition of the bonds here refer to sigma/pi bonds? 2. I know that because the electron arrangement is trigonal planar, then hybrid...
by 305144105
Wed Nov 28, 2018 8:12 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 4.21
Replies: 2
Views: 39

Re: 4.21

N cannot form 5 bonds, because it does not have any d-orbital electrons to utilize.
by 305144105
Wed Nov 28, 2018 7:03 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: N2O Lewis Structure
Replies: 2
Views: 70

N2O Lewis Structure

If O is more electronegative than N, then why isn't it the central atom in N2O?
by 305144105
Wed Nov 28, 2018 5:51 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Lone pairs and polarity
Replies: 1
Views: 49

Lone pairs and polarity

How does a lone pair on the central atom affect the polarity of a molecule?
Why is SF4 polar and SF6 nonpolar?
by 305144105
Wed Nov 28, 2018 5:31 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 7th Edition 3.19b
Replies: 1
Views: 36

7th Edition 3.19b

How do you determine the shape of (CH3)2Be?

Do you consider Be the central atom? (and its shape be linear?)
by 305144105
Wed Nov 28, 2018 2:41 pm
Forum: Dipole Moments
Topic: 7th Edition 3F.1
Replies: 1
Views: 54

7th Edition 3F.1

Identify the kinds of intermolecular forces that might arise between molecules of each of the following substances: (a) NH2OH; (b) CBr4; (c) H2SeO4; (d) SO2.
by 305144105
Wed Nov 28, 2018 2:08 pm
Forum: Bond Lengths & Energies
Topic: 7th Edition 2D.7
Replies: 1
Views: 101

7th Edition 2D.7

Are the bond lengths of SO2 and SO3 the same?
Does the lone pair on SO2 affect bond length at all?
by 305144105
Sun Nov 04, 2018 12:22 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: 6th Edition 2.85
Replies: 1
Views: 62

6th Edition 2.85

In the heavier transition-metal elements, especially the lanthanoids and actinoids, there are numerous exceptions to the regular order of orbital occupation predicted by the building- up principle. Suggest why more exceptions would be noted for these elements. Can someone please break this question ...
by 305144105
Sun Nov 04, 2018 11:42 am
Forum: Trends in The Periodic Table
Topic: 6th Edition 2.71
Replies: 4
Views: 66

6th Edition 2.71

2.71 (a) What is a diagonal relationship? (b) How does it arise? (c) Give two examples to illustrate the concept.

I read the textbook but I don't quite understand. Can someone please explain this?
by 305144105
Sat Nov 03, 2018 4:03 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: 6th Edition 2.53
Replies: 1
Views: 77

6th Edition 2.53

2.53 The elements Ga, Ge, As, Se, and Br lie in the same period in the periodic table. Write the electron configuration expected for the ground-state atoms of these elements and predict how many unpaired electrons, if any, each atom has. I know how to write the ground-state electron configurations f...
by 305144105
Mon Oct 22, 2018 6:36 pm
Forum: Photoelectric Effect
Topic: 6th Edition 1.33 (c)
Replies: 1
Views: 89

6th Edition 1.33 (c)

1.33 The velocity of an electron that is emitted from ametallic surface by a photon is 3.6*10^3 km s^-1.
(c) What is the wavelength of the radiation that caused photoejection of the electron?

Can someone please explain what formula to use and why?
by 305144105
Mon Oct 22, 2018 6:32 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: CH 1 1.39 6TH EDITION
Replies: 2
Views: 48

Re: CH 1 1.39 6TH EDITION

1. Calculate the mass of the baseball in g.
m = 5.15 * 28.3 = 145.7g
2. Calculate the velocity of the baseball in m/s.
v = 92miles/hour * 1606.34m/mile * hour/3600s = 41.1 m/s
3. Use the formula λ=h/mv, which is derived from given formulas λ=h/p and p=mv
λ= (6.626*10^-34)/(145.7*41.1) = 1.11*10^-34
by 305144105
Mon Oct 22, 2018 6:24 pm
Forum: Einstein Equation
Topic: Chapter 1 Question 27
Replies: 2
Views: 140

Re: Chapter 1 Question 27

1. Find the total energy that is emitted in the 2s time interval. 32W * 1Js^-1/W * 2s = 64J 2. Calculate the energy that is emitted per photon using the formula E = hc/λ. (Remember to convert 420nm to m.) E = hc/λ = (6.626*10^-34) * (3*10^8) / (420*10-9) = 4.73*10-19 J / photon 3. Calculate how many...
by 305144105
Mon Oct 22, 2018 6:14 pm
Forum: Photoelectric Effect
Topic: Homework Question 1A.7
Replies: 2
Views: 83

Re: Homework Question 1A.7

The work function cannot be used because the velocity of the ejected electron is unknown. Instead, you can use the formula λ=c/v.
λ= c/v = (3*10^8) / (2.0x10*18) = 1.5*10^-10 m = 150pm
by 305144105
Mon Oct 22, 2018 6:07 pm
Forum: Photoelectric Effect
Topic: Help with 33 (6th edition) [ENDORSED]
Replies: 3
Views: 131

Re: Help with 33 (6th edition) [ENDORSED]

1. Convert 3.6*10^3 km s^-1 to m s^-1
3.6*10^3 km s^-1 = 3.6*10^6 m s^-1

2. Use this value in the formula λ = h/mv. This formula is derived from given formulas λ = h/p and p=mv.
λ = h/mv = (6.626 * 10^-34) / ((9.109*10^31) * (3.6 * 10^6)) = 2.02 * 10^-10m
by 305144105
Mon Oct 22, 2018 6:02 pm
Forum: Photoelectric Effect
Topic: The Photoelectric Effect
Replies: 3
Views: 70

Re: The Photoelectric Effect

Experimentally, determining what frequency of light needed to eject an electron could help determine the work function of the metal. Different metals have different work functions. This could be useful in comparing metals and their respective configurations.
by 305144105
Fri Oct 19, 2018 3:10 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: 6th Edition 1.43
Replies: 2
Views: 36

6th Edition 1.43

What is the minimum uncertainty in the speed of an electron confined to within a lead atom of diameter 350. pm? Δp Δx ≥  h/4π Δx = 350 * 10^-12, h = 1.5457 * 10^-34 Δp * (350 * 10^-12) ≥  (1.5457 * 10^-34) / 4π Δp ≥ ((1.5457 * 10^-34) / 4π) / (350 * 10^-12) Δp ≥ 3.516 * 10^-26 Δp = mΔv mΔv ≥ 3.516 *...
by 305144105
Tue Oct 16, 2018 7:40 pm
Forum: Properties of Light
Topic: 6th Edition 1.13(a)
Replies: 2
Views: 45

6th Edition 1.13(a)

The question: Use the Rydberg formula for atomic hydrogen to calculate the wavelength of radiation generated by the transition from n=4 to n=2.

How do I determine which value is equal to n1 and n2 in the Rydberg formula?
Is n2 always the larger integer? In this case, n2 = 4 and n1 = 2?
by 305144105
Tue Oct 16, 2018 6:36 pm
Forum: Properties of Light
Topic: 7th Edition 1A.3
Replies: 4
Views: 76

7th Edition 1A.3

1.3 Which of the following happens when the frequency of electromagnetic radiation decreases? Explain your reasoning. (a) The speed of the radiation decreases. (b) The wavelength of the radiation decreases. (c) The extent of the change in the electrical field at a given point decreases. (d) The ener...
by 305144105
Sun Oct 07, 2018 5:09 pm
Forum: SI Units, Unit Conversions
Topic: 6th Edition E27, First Part
Replies: 5
Views: 73

Re: 6th Edition E27, First Part

Converting one H2O molecule to moles using dimensional analysis:
=1 molecule * 1 mol / 6.022*10^23 molecules
=1.66 * 10^-24 mol of H2O

Solving E27(a) using dimensional analysis:
Mass of 1 water molecule = (1.008*2 + 15.999)g/1mol * 1mol/6.022*10^23 molecules = 2.99 * 10^-23 g
by 305144105
Thu Oct 04, 2018 4:50 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: diatomic molecules
Replies: 5
Views: 70

Re: diatomic molecules

Since we are given a periodic table, it may be helpful to know where the diatomic molecules are located. They form a "7" (3 across, 4 down), with the exception of hydrogen.
by 305144105
Thu Oct 04, 2018 4:37 pm
Forum: Molarity, Solutions, Dilutions
Topic: Q E14
Replies: 2
Views: 59

Re: Q E14

1. Find out the mystery metal
74.10g - (15.999*2 + 1.008*2)g = 40.086g
The element with the closest mass to 40.086g is Ca, with a molar mass of 40.078g.

2. Find out the sulfide of Ca (calcium sulfide), which is CaS.

3. Calculate the molar mass of CaS.
=40.078g + 32.065g
=72.143g

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