CHEMISTRY COMMUNITY

Diane Kang 2F

Will the midterm cover any of the sections beyond 4F (“ENTROPY”) from the 7th ed textbook, such as 4G (“Moleuclar Interpretation of Entropy”) and 4H (“Absolute Entropy”)?

Diane Kang 2F

5J.11) Predict shift in equilibria when temperature increases. b) X2 (g) <=> 2X (g) , where X is a halogen. I'm not quite sure how to approach this problem. I don't see the relation between the gas being a halogen and the temperature of the system increasing. Is there a way of telling whether the fo...

Diane Kang 2F

6B.1) Original solution has 200.0 mL NaOH solution. Then, 5.00 mL of the original solution is diluted to 500.0 mL which has pH 13.25 a) What is OH- concentration of the original solution? To find the pH of the original solution, I know we have to use the relation c1V1=c2V2. But I'm not sure if I hav...

Diane Kang 2F

6E.3) Calculate the pH of each of the following solutions of diprotic acids at 25C, ignoring second deprotonations only when the approximation is justified: a) 0.010M H2CO3 (aq); b) 0.10M (C00H)2 (aq); c) 0.20 M H2S (aq) I'm not really sure how to take into consideration the second deprotonation con...

Diane Kang 2F

Why does the presence of an inert gas not effect the equilibrium of a mixture?

When an inert gas is added to a system in equilibrium, total pressure increases. Doesn't this mean the system will tend to work towards minimizing the effect of the increased pressure, by Le Chatelier's Principle?

Diane Kang 2F

Do we need to know how to convert between K and Kc using the equation K = (((c°RT)/(P°))^Δn ) x Kc for the test?

This was not covered during lectures but it is part of the reading outlined in the syllabus (section 5H.3 from the 7th edition).

Diane Kang 2F

When writing equilibrium constant expressions, do we use partial pressures only if the reaction in question represents homogeneous equilibrium of gases? If a reaction involves gases and other phase substances, do we still report the activity of the gases in terms of their partial pressures or in ter...

Diane Kang 2F

A large Kc value also means that the free energy of the reactants state is greater than the free energy of the products, which means energy will be released as the forward reaction occurs.

Diane Kang 2F

Dr. Lavelle mentioned that solids and liquids are not included in K expressions because they are usually in excess.

But what if a solid or liquid in a chemical equation is a limiting reactant, thus not present in excess? Should their concentrations be included in K expressions?

Diane Kang 2F

During class, Dr. Lavelle mentioned the relationship between activity and concentration, introducing the relationship a = γ (concentration).

What exactly is activity? And how does activity relate to why we omit units for molar concentration when calculating equilibrium constants?

Diane Kang 2F

What is the difference between stating the hybridization of an atom and identifying hybrid orbitals of an atom?

Diane Kang 2F

How do you know which of three has the largest dipole moment?

Diane Kang 2F

Why is CH2Cl2 polar?

Don't the dipole moments for the two C-Cl bonds cancel out?

Diane Kang 2F

The textbook describes dissociation energy as the "depth of the well" when potential energy is plotted against internuclear distance. I am referring to the graph given on page 98 (Figure 2D.5) in 7th edition. I don't really understand how this illustrates the definition of dissociation ene...

Diane Kang 2F

The textbook defined Electron Affinity as the following: Let X be some element, X(g) + e-(g) = X-(g) Then, Eea(X) = E(X) - E(X-). Thus, electron affinity is described as energy of the neutral element (X) minus energy of anion of element (X-). This makes the trend for Eea increase across a period and...

Diane Kang 2F

Is Angstrom (10^-10) a SI prefix?

Diane Kang 2F

They're determined experimentally.

Diane Kang 2F

What are some factors that can manipulate the rate at which electrons are emitted? And why exactly doesn't the energy of the incoming photon affect the rate of electron emission from the metal plate?

Diane Kang 2F

The textbook defines a 'black body' as an "object that absorbs and emits all frequencies of radiation without favor." However, quantum mechanics is all about energy existing in packets and thus limit to certain frequencies, meaning not "all" frequencies of radiation is possible. ...

Diane Kang 2F

From what I understand about electron affinity and electronegativity, the two seem to be pretty similar conceptually and in terms of periodic trends--they both increase across the period and decrease down a group.

What exactly is the difference between electron affinity and electronegativity?

Diane Kang 2F

h with a dash over 2p is already accounted for in the denominator in the equation: uncertainty in x = (1.05457 * 10^-34 J s) / (2 * (1.0 * 10^-3 kg) * (2 * 1.0 * 10^-3 m/s) )

But the textbook multiplies an extra 2 to uncertainty in velocity: (2 x 1.0 x 10^-3 m/s).

Diane Kang 2F

I know that the spin magnetic quantum number can take values -1/2 and +1/2, indicating the direction of spin of an electron.

Is it possible for spin magnetic quantum number to equal 0?

Diane Kang 2F

The textbook says the radial distribution function (P) can be used to calculate the probability of finding an electron around the nucleus: P(r) = r^2 R^2 (r). How is this equation derived and what do its components (r) (R) mean? And does this equation to apply to any electron in any shell/subshell/o...

Diane Kang 2F

The Heisenberg Uncertainty Principle is (uncertainity in p) (uncertainity in x) is greater than or equal to (1/2) h bar.

What is exactly is linear momentum p? And why is it important in the context of quantum mechanics and electrons?

Diane Kang 2F

For question (a) the question asks to estimate the minimum uncertainty in the position of a marble of mass 1.0g given that its speed is known to within +/- 1.00 mm s-1. In the evaluation of the question, the textbook gives dx = (1.05457 * 10^-34 J s) / (2 * (1.0 * 10^-3 kg) * (2 * 1.0 * 10^-3 m/s) I...

Diane Kang 2F

Yes, you do not need to know the exact measurements of the atomic radii in order to set those elements in order of decreasing atomic radius. Using the periodic table, the atomic radius increases as you go down a group and decreases as you go across a period from left to right.

Diane Kang 2F

In double and triple bonds, more than one electron is involved in the covalent bond. For example, in a CO2 molecule, each oxygen atom shares two of its electrons with the carbon atom in order to fill the valence shell—this makes two double bonds between the 2 oxygen atoms and 1 carbon atom. As for a...

Diane Kang 2F

(a) To identify the excess reactant use the reaction mole ratio of ClO2 and BrF3, which is 6 mol ClO2 : 2 mol BrF3 (5 mol BrF3) (6 mol ClO2 / 2 mol BrF3) = 15 mol ClO2 , which shows that 5 mol of BrF3 must react with 15 mol ClO2 for BrF3 to go to completion. But since only 12 mol of ClO2 is availabl...

Diane Kang 2F

You multiply (1 mol Na2CO3) / (2 mol Na+) instead of (2 mol Na+) / (1 mol Na2CO3) because the Na+ and Na2CO3 do not cancel out if you multiply (2.15 * 10^3 mol Na+) / (0.076 mol Na2CO3 / L). [(2.15 * 10^3 mol Na+) / (0.076 mol Na2CO3 / L)] * [(1 mol Na2CO3) / (2 mol Na+)] simplifies to [(2.15 * 10^3...

Diane Kang 2F

To my understanding, yes, you treat repeating decimals numbers, such as 1/3, as numbers with a finite number of decimal places. There are no special rules for significant figures for nonterminating decimals. When performing your calculations do not round nonterminating decimals. So on your calculato...

Diane Kang 2F

When ions dissolve in aqueous solutions, they undergo ionic dissociation, meaning the individual ions are freed from their bonds. For example, when NaCl is dissolved in water, the cation Na+ and anion Cl- completely separate. So, no, it really shouldn’t matter what ion the ion you are solving for is...

Diane Kang 2F

First, convert the given mass 5.15 g MgSO4*7H2O into moles using the molar mass of MgSO4*7H2O, which is 246.483 g/mol: (5.15 g MgSO4*7H2O) (mol / 246.483g) = 0.02089 mol MgSO4*7H2O Then, use the molar ratio of MgSO4*7H2O and oxygen, which is (11 mol O / 1 mol MgSO4*7H2O), to find the moles of oxygen...

Diane Kang 2F

For every 1 mole of the molecule, CuCl24H2O, there are 2 moles of the Cl atom involved, giving the molar ratio of 1:2 for CuCl24H2O and Cl, respectively. It’s just like how in every 1 mole of H20, there are 2 moles of H atoms involved.

CHEMISTRY COMMUNITY

Search found 33 matches

MIDTERM 7th ed

5J.11 (b) 7th edition

6B.1 7th Edition

6E.3 7th Edition

Inert Gases

K and Kc (Section 5H.3 7th Edition)

Partial Pressure

Re: Kc Value

Solids and Liquids

Activity and Concentration

Difference between hybridization and hybrid orbitals

2E.29 (7th edition)

Polar vs Nonpolar for CH2Cl2

Dissociation Energy

Electron Affinity

Angstrom and SI Units

Re: Bond Lengths

Rate at which electrons are emitted

Black Body

Electron Affinity and Eletronegativity

Re: 7th Edition Example 1B.5 (Page19)

Spin Magnetic Quantum Number

Radial Distribution Function

Heisenberg Uncertainity Principle

7th Edition Example 1B.5 (Page19)

Re: Question 1F: 1

Re: Double and Triple Bonds???

Re: Question M.5 (Sixth Edition)

Re: Dilution Question

Re: Repeating Decimal

Re: Ions in dilutions

Re: Fundamentals E.9

Re: Confusion on number of moles