CHEMISTRY COMMUNITY

Maggie Doan 1I

So can we assume we always assume that when the pH is 7 then it will be pH + pH = 14 in which we will divide by 2.

Maggie Doan 1I

How is there 2pH?

Maggie Doan 1I

When would ΔG=0?

Maggie Doan 1I

For the first order reaction A \rightarrow 3B + C, When [A]0 = .015 mol/l, the concentration of B increases to .018 mol/ L in 3.0 min. a) What is the rate of constant for the reaction expressed as the rate of loss of A? I got the answer 1.7 minutes but the answer is .17 minutes. I was wondering how ...

Maggie Doan 1I

7b. The combustion of a gas used to heat a BBQ at a pool party.

Would this be a spontaneous reaction?

Maggie Doan 1I

5. The ionic dissociation of water is given by the following reaction: The ΔH for the reaction is 58kJ/mol. The Kw for the reaction at 25°C is 10^-14. Is a pH of 7 acidic or basic at 30°C? 2H2O(l) \leftrightarrow H30+(aq) + OH-(aq) What is the pH? I used the nerst equation but I'm not getting the ri...

Maggie Doan 1I

When do we use a comma for the cell diagram?
Do we also use a conductor when there is no solid present?

Maggie Doan 1I

How do you find the order for the reactants and overall order?

I'm confused on when to use each experiment?

Maggie Doan 1I

In the reaction CH3Br + OH- $\rightarrow$ CH3OH + Br-, when the OH- concentration alone was doubled, the rate doubled; when the CH3Br concentration alone was increased by a factor of 1.2, the rate increased by a factor of 1.2. Write the rate law for the reaction.

How do you determine the rate law?

Maggie Doan 1I

Write the half reactions, balanced equation for the cell reaction and the cell diagram.
d) Au^+(aq) $\rightarrow$ Au(s) + Au^3+(aq)

Why do we use the solid Au for the anode?

Maggie Doan 1I

Thank you I forgot about the negative charge on OH so I put the electrons on the wrong side.

Maggie Doan 1I

When calculating the standard reaction GIbbs free energy how do we find n?

Maggie Doan 1I

Balance each of the following skeletal equations by using oxidation and reduction half reactions.

a) O3 + Br- $\rightarrow$ O2 + BrO3-

How do you balance the half reaction of O3 $\rightarrow$ O2?

Maggie Doan 1I

Balance each of the following skeletal equations by using oxidation and reduction half reactions.

d) Cl2 $\rightarrow$ HClO + Cl2

Maggie Doan 1I

What does it mean for part 1c to comment on the relative stability of the reactants and products?

Maggie Doan 1I

Suggest a reason why the entropy of ice is nonzero at T= 0; think about how the structure of ice is affected by the hydrogen bonds.

Maggie Doan 1I

Calculate the entropy of a sample of a solid in which it is supposed that a substituted benzene molecule, C6H5F, may be found in any one of six orientations with the same energy at T=0. Suppose there is 1.0 mol of molecules in the sample.

Why is one mole of the molecule multiplied with the equation?

Maggie Doan 1I

To solve for bond enthalpies, do we have to know the lewis structure of the molecules?

Maggie Doan 1I

Calculate the change in entropy when the pressure of 1.5mol Ne(g) is decreased isothermally from 15.0 atm to .500 atm. Assume ideal behavior.

Maggie Doan 1I

The internal energy of a system increased by 982 J when it was supplied with 492 J of energy as heat.
How much work was done?
I got that work done was 490J but the book answer is 9.0 x 10^2J.

Maggie Doan 1I

Air in a bicycle pump is compressed by pushing in the handle. The inner diameter of the pump is 3.0 cm and the pump is depressed 20.cm with a pressure of 2.00 atm.
How do you calculate the change in internal energy?

Maggie Doan 1I

Why is it -πr^2?

Maggie Doan 1I

Determine the shift in equilibrium, if any, which will occur for the following reactions when the temperature is increased a) Photosynthesis: 6 CO2 (g) + 6 H2O (l) ⇌ C6H12O6(s) + 6 O2 (g) delta H° = +2802 kJ.mol-1 b) The hydrolysis of ATP: ATP (aq) + H2O (l) ⇌ ADP + PO42-(aq) delta H° = -30 kJ.mol-1...

Maggie Doan 1I

A researcher fills a 1.00 L reaction vessel with 1.84 x 10-4 mol of BrCl gas and heats it to 500 K. At equilibrium, only 18.3 % of the BrCl gas remains. Calculate the equilibrium constant, assuming the following reaction is taking place. 2BrCl(g) ⇌ Br2 (g) + Cl2(g) I keep getting 19.8 but I know tha...

Maggie Doan 1I

CO + H2O ⇌ CO2 +H2
c) If the concentration of CO is increased, what happens to the concentration of H2?
Why would H2 increase?

Maggie Doan 1I

Thanks, I did forget to convert.

Maggie Doan 1I

A reaction vessel of volume .500L at 700. K contains 1.20 mmol SO2, .50 mmol O2, and .10 mmol SO3. At 700 K, Kc= 1.7 x 10^6 for the equilibrium 2SO2 + O2⇌ 2SO3.
Calculate the reaction quotient Qc.
I got 6.9 x 10^-3 but the answer was 6.9.

Maggie Doan 1I

If Q=1.0 for the reactin N2 + O2 $\rightarrow$ 2NO at 25 C will the reaction have a tendency to form products or reactants, or will it be at equilibrium?

How to you find the K value of the equation?

Maggie Doan 1I

Write the equilibrium constant expression for the unbalanced chemical equation.
NO2 (g) + H2 (g) ⇌ NH3 (g) + H2 O (l).

Is the answer (NH3)^2/ (H2)^9(NO3)^2?

Maggie Doan 1I

c) Assuming that the initial pressure of X2 was .10 bar, calculate the value of K for the decomposition.

Maggie Doan 1I

Why are equilibrium constants useful?

Maggie Doan 1I

Decide 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. f) Cu(NO3)2 I don't understand how f) is less than 7. Also how would you write the chemical equation to justify?

Maggie Doan 1I

a)potassium hexacynidochromate (III) - the answer is K3 [Cr(CN)6] How come the formulas don't have a charge when writing from the coordination compounds and why is it K3? d)soduim bisoxaltodiaquaferrate(III) - Na[Fe(OH2)2(CO3)2] Does the order of the ligands matter because I mixed up the (CO3)2 and ...

Maggie Doan 1I

In lecture, there was an example of [Ni(CN)6]-2 and the name was tetracynonicelate(II). I was confused on the -ate part because I know you add the -ate if the metal has a negative charge but I thought Ni would have a positive charge.

Maggie Doan 1I

How do you find the charges of each of the elements with the complexes?

Maggie Doan 1I

How do you find out the coordination number?

Maggie Doan 1I

How do you tell if molecules have an ion- ion force or a dipole- dipole force? Like I don't understand why HCl is dipole- dipole.

Maggie Doan 1I

Rank the following in terms of increasing boiling point:
LiCl, C3H7OH, C4H8, N2

Does boiling point depend on the strength of the intermolecular force?

Maggie Doan 1I

Are ion- ion forces stronger than ion- dipole forces?

Maggie Doan 1I

Which one has higher polarizability?
a) Be 2+ or Li 1+
b) Mg 2+ or Be 2+

I tried using the ideas of the polarizability trend but it didn't work.

Maggie Doan 1I

d) Draw the lewis structure, VESPR formula, molecular shape, and bond angles: N2O
Why doesn't the lewis structure for N2O have a lone pair?

Maggie Doan 1I

What value is expected for the ClICl bond angle?

Maggie Doan 1I

What is the difference between molecular shape and geometry? Which one depends on lone pairs?

Maggie Doan 1I

How do you determine which compounds have ionic bonds?
And why is BaBr2 primarily more ionic than BeBr2 and BBr3?

Maggie Doan 1I

How do you determine which compounds have a higher boiling point such as CHCl3 and CCl4?

Maggie Doan 1I

Which has a higher electron affinity, chlorine (Cl) or Neon (Ne)?

I know that chlorine has the higher electron affinity but why?

Maggie Doan 1I

What is the effect of electrons on the size of the atom?

Maggie Doan 1I

What type of orbital with principal quantum number 4 has one more nodal plan than the 4s orbital?

Maggie Doan 1I

How do you find the possible number of electrons given by quantum numbers?

Ex: n=2, l= 1
n=4, l=0, ml=-2, ms= -1/2

Maggie Doan 1I

When writing the quantum numbers for an orbital, do you include all the values of m?

Maggie Doan 1I

What does degeneracy mean?

Maggie Doan 1I

In the hydrogen atomic spectrum, what is the wavelength of light associated with the n = 2 to n = 1 electron transition?

When I worked this problem out, I got -1.22 x 10^-7 as the answer but this isn't correct.

Maggie Doan 1I

If a proton and an electron have the same de Broglie wavelength do they have the same speed?

Maggie Doan 1I

What is the wavelength of radiation emitted by a hydrogen atom in a transition from the n = 6 to the n = 5 energy level?

Maggie Doan 1I

The meter was defined in 1963 as 1,650,763.73 wavelengths of radiation emitted by krypton-86 (it has since been redefined). What is the wavelength of this krypton-86 radiation? To what region of the electromagnetic spectrum does this wavelength correspond (i.e. infrared, ultraviolet, x-ray, etc.)? W...

Maggie Doan 1I

I used the equation Ek= 1/2mv^2 for this problem. The problem already gives you the velocity and the mass of the electron is 9.109 x 10^-31 kg (which is a constant provided in the back of the textbook). I got 1.98 x 10^-19 J as the answer.

Maggie Doan 1I

In a photoelectric experiment light hits a metal surface and if the energy of the ________ light is ________ enough it causes electrons to be ejected from the metal surface. A. outgoing, large B. outgoing, small C. incoming, large D. incoming, small E. None of the above I know that the first blank i...

Maggie Doan 1I

5.00 g of KMnO4 is dissolved in a 150.00 mL flask of water. If 20.00 mL of this solution is removed and placed in a new 2nd 250.00 mL flask and filled with water, what is the concentration of the solution in the 2nd flask? Molar Masses: K (39.10 g/mol), Mn (54.94 g/mol), O (16.00 g/mol) Why do you u...

Maggie Doan 1I

What volume of 0.0380 M KMnO4 is needed to prepare 250 mL of 1.50 x 10-3 M KMnO4?
Would you just need to set them equal to each other?

Maggie Doan 1I

Based on the molar ratios in a balanced chemical equation a student expects 0.20 moles of product. If the molar mass of the product is 81 g.mol-1 what is the theoretical yield?
Do I just multiply the expected moles with the actual product? And why?

Maggie Doan 1I

My calculations for the answer were off by the hundredth decimal point. For example I calculated 78.96% when the answer is 78.90%. Would I get the answer wrong?

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