the ionic dissociation of water is given by the following reaction: the deltaH for the reaction is 58 kJ/mol. The Kw for the reaction at 25 degree Celsius is 10 ^-14. Is the pH of 7 acidic or basic at 10 degree Celsius?
2H20 --> H3O+ + OH-
Why is the answer acidic?
Search found 65 matches
- Tue Mar 12, 2019 5:00 pm
- Forum: Van't Hoff Equation
- Topic: Test #2
- Replies: 5
- Views: 726
- Tue Mar 12, 2019 4:48 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Rate dependency on [H2O]
- Replies: 1
- Views: 230
Re: Rate dependency on [H2O]
This is rare because H2O usually exists as the solvent and the concentration is too large to show any significant change.
- Tue Mar 12, 2019 4:42 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: order of a cell diagram
- Replies: 4
- Views: 493
Re: order of a cell diagram
the electrode goes on the outside while the anode is to the left and the cathode is to the right of the double lines (||), indicating a salt bridge. Species that are in the same phase are separated by a comma, while everything else is separated by a single line (|). I'm not sure what you mean by h+.
- Fri Mar 08, 2019 2:34 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: Rate Order Graphs
- Replies: 3
- Views: 439
Rate Order Graphs
What is the logic behind choosing the model with the most linear graph as the rate order?
- Fri Mar 08, 2019 2:32 pm
- Forum: Zero Order Reactions
- Topic: Determining Rate Orders
- Replies: 3
- Views: 387
Determining Rate Orders
How can you tell what the order of each reactant is based on a table of rates and concentrations? Is there a formula or pattern?
- Tue Mar 05, 2019 12:58 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: Units
- Replies: 4
- Views: 412
Re: Units
Zero-order should be M/s. First-order should be s^-1. and second-order should be M^-1 * s^-1.
- Tue Feb 26, 2019 3:24 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Problem 6L.3
- Replies: 1
- Views: 217
Re: Problem 6L.3
It is written that way because on the ride side of the double lines, which indicate a salt bridge, represents the cathode where reduction happens. The Cl2 is being reduced and gaining two electrons.
- Tue Feb 26, 2019 3:19 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: # 14.9 b 6th ed
- Replies: 1
- Views: 220
Re: # 14.9 b 6th ed
When you balance the half reactions and multiply the equations with a constant to get the same moles of electrons exchanged, it should be 6.
- Tue Feb 26, 2019 3:17 pm
- Forum: Balancing Redox Reactions
- Topic: Balancing Rules for Redox Reactions
- Replies: 3
- Views: 336
Re: Balancing Rules for Redox Reactions
Make sure the number of atoms and the charges are equal on both sides.
- Fri Feb 22, 2019 12:34 pm
- Forum: Van't Hoff Equation
- Topic: Van't Hoff Equation
- Replies: 3
- Views: 668
Van't Hoff Equation
What is the purpose and concept behind the Van't Hoff Equation?
- Fri Feb 22, 2019 12:30 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Galvanic Cells
- Replies: 2
- Views: 293
Galvanic Cells
Why do electrons flow from the anode to the cathode?
- Fri Feb 22, 2019 12:29 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Salt Bridge
- Replies: 5
- Views: 537
Salt Bridge
What is the purpose of the salt bridge?
- Thu Feb 14, 2019 12:36 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: buffer
- Replies: 2
- Views: 310
Re: buffer
A buffer is something that limits the change in pH in an acid-base reaction.
- Thu Feb 14, 2019 12:33 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Molar and specific heat capacity
- Replies: 3
- Views: 395
Re: Molar and specific heat capacity
Specific heat capacity is for mass while molar heat capacity is for moles.
- Thu Feb 14, 2019 12:32 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: 6th edition 9.11
- Replies: 1
- Views: 491
Re: 6th edition 9.11
When you divide the pressures, the atm's cancel each other out. Your ending units should be J/ K.
- Tue Feb 05, 2019 1:17 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: ΔH and ΔU
- Replies: 6
- Views: 834
Re: ΔH and ΔU
Since delta H and delta U values can differ depending on the conditions the reaction is happening in, the degree symbol tells us that the reaction is happening under a standard condition of 1atm.
- Tue Feb 05, 2019 1:07 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Enthropy
- Replies: 2
- Views: 841
Re: Enthropy
Entropy values are usually given to us in a table.
- Tue Feb 05, 2019 1:01 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Microstate
- Replies: 7
- Views: 782
Microstate
What is a microstate and how does it relate to entropy?
- Tue Jan 29, 2019 3:14 pm
- Forum: Phase Changes & Related Calculations
- Topic: temperature
- Replies: 3
- Views: 368
Re: temperature
The temperature doesn't change because a phase change is happening. The heat being put into the system is causing the phase change and causing the molecules to overcome all the attractive forces, which allows a substance to go from solid to liquid and a liquid to a gas.
- Tue Jan 29, 2019 3:12 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Method #3
- Replies: 2
- Views: 360
Re: Method #3
Method #3 is focused on the heat capacity, which is the heat required to raise the temp of an object by 1 degree C. The change in heat or enthalpy can be solved by this equation: qp = enthalpy = nCpdeltaT (The p's are subscripts). Cp represents the molar heat capacity at constant pressure. DeltaT is...
- Tue Jan 29, 2019 3:06 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: enthalpy
- Replies: 4
- Views: 528
Re: enthalpy
A state function means that we only care what happens at the beginning and at the end and it isn't dependent on the path taken. So, enthalpy is a state function because we can add and subtract heat to get the change in enthalpy.
- Tue Jan 22, 2019 3:07 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 7th Edition 6E.3
- Replies: 1
- Views: 169
Re: 7th Edition 6E.3
Ka2 represents the second reaction that polyprotic compounds often go through. In this case, H2SO4's second reaction (HSO4- +H20 --> SO42- +H3O+) produces an insignificant amount of H3O+ that we ignore the second ionization.
- Tue Jan 22, 2019 3:05 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Ka and Kb
- Replies: 2
- Views: 261
Re: Ka and Kb
Ka and Kb values should be given to us
- Tue Jan 22, 2019 3:04 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Hmwrk 11.77 6th edition
- Replies: 2
- Views: 272
Re: Hmwrk 11.77 6th edition
For part b, the bond holding X2 together is broken to form 2X. Breaking bonds is an endothermic reaction that requires the absorbance of heat/energy.
- Tue Jan 22, 2019 3:02 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Ka and Kb
- Replies: 3
- Views: 219
Re: Ka and Kb
If the Ka or Kb is greater than 10^3, then it is a strong acid or base. If the Ka or Kb is less than 10^-3, then it is a weak acid or weak base
- Wed Jan 16, 2019 5:12 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Taking x away in a Ka calculation
- Replies: 5
- Views: 398
Re: Taking x away in a Ka calculation
Sometimes, the x is so small that it doesn't have an effect on the overall concentration. For instance, let's say the initial concentration is 1 x 10^-1 and the K value is extremely small, we would know that the numerator/reactants would also have to be extremely small so that the ratio will equal t...
- Wed Jan 16, 2019 5:07 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Solids and liquids in K
- Replies: 6
- Views: 2146
Re: Solids and liquids in K
Solids aren't included because they don't have a concentration. Liquids aren't included because they are usually solvents and don't change much in concentration throughout the reaction. Liquids would just show up on both sides of the equation and cancel each other out.
- Wed Jan 16, 2019 5:04 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Percentage Ionization
- Replies: 4
- Views: 389
Re: Percentage Ionization
Miya Lopez 1I wrote:Also, what does it mean to be "completely ionized"?
In class Dr. Lavelle stated that "Ba(OH)2 (aq) is a strong base, essentially completely ionized."
To completely ionized means to completely dissociate. For instance, BaOHsub2 will dissociate completely into Ba2+ and OH-
- Wed Jan 16, 2019 5:03 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Percentage Ionization
- Replies: 4
- Views: 389
Re: Percentage Ionization
Percent ionization shows how much something dissociated. It can be calculated by taking the concentration of its ions divided by the original compound and multiplied by 100. For instance, weak acids will have a varying percent ionization because only a small percent of it will dissociate. Percent io...
- Tue Jan 08, 2019 5:28 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: K vs. Q
- Replies: 2
- Views: 170
Re: K vs. Q
Q shows whether the reaction will move more to the right or to the left, producing either more products or reactants. For instance, if Q<K, then the reaction will shift toward the right. This will produce more products and eventually, Q will equal K.
- Tue Jan 08, 2019 5:22 pm
- Forum: Ideal Gases
- Topic: R in PV=nRT
- Replies: 34
- Views: 5842
Re: R in PV=nRT
R is the gas constant and it is important to note that it differs depending on whether atm, torr, or bar is used for the pressure unit.
- Tue Jan 08, 2019 5:20 pm
- Forum: Ideal Gases
- Topic: Solid/Liquid in Reactions
- Replies: 4
- Views: 204
Re: Solid/Liquid in Reactions
Solids are not included because they don't have a concentration because solids are usually pure. Liquids are not included because they usually exist as a solvent and thus has such a large concentration that it barely changes throughout the reaction.
- Mon Dec 03, 2018 9:26 am
- Forum: Hybridization
- Topic: s character
- Replies: 3
- Views: 327
Re: s character
S-character is the ratio of the S to the P. For instance, an sp hybrid orbital would have a 1:1 and sp2 would be 1:2. And so, sp would have more s-character than sp2.
- Mon Dec 03, 2018 9:21 am
- Forum: Naming
- Topic: Latin Names
- Replies: 5
- Views: 766
Latin Names
What are all the elements that have latin names do we need to know?
Anions
Do we end all names of anions with an -ate even if the overall charge or the anion is not negative?
- Fri Nov 30, 2018 2:00 pm
- Forum: Sigma & Pi Bonds
- Topic: Sigma bonds
- Replies: 6
- Views: 736
Re: Sigma bonds
Sigma bonds are when two orbitals bond at one point, while pi bonds are when two orbitals bond at two points.
- Fri Nov 30, 2018 1:56 pm
- Forum: Lewis Structures
- Topic: Lewis Structures for Molecules with H- AND O- atoms
- Replies: 3
- Views: 438
Re: Lewis Structures for Molecules with H- AND O- atoms
When you see an OH in a molecular formula, the H usually goes on the O. However, to be sure, calculate the formal charges and make sure it aligns with how you are drawing the molecules.
- Fri Nov 30, 2018 1:50 pm
- Forum: Ionic & Covalent Bonds
- Topic: Polar and Nonpolar
- Replies: 3
- Views: 275
Re: Polar and Nonpolar
A molecule is polar when the electron distribution is not equal and the dipole moments do not cancel out. However, when thinking about whether a molecule is polar or not, it is important to think of it in 3-D. For instance, CCl4 is tetrahedral and nonpolar.
- Fri Nov 30, 2018 1:47 pm
- Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
- Topic: H-Bonding and Dipole Dipole
- Replies: 2
- Views: 325
Re: H-Bonding and Dipole Dipole
Hydrogen Bonding is a specific dipole-dipole bonding. H-Bonding only occurs between Hydrogen and Fluorine, Oxygen, or Nitrogen.
- Fri Nov 23, 2018 12:04 pm
- Forum: Hybridization
- Topic: d-block
- Replies: 3
- Views: 349
Re: d-block
The energy will be between the orbitals because it is an average of the orbitals that are hybridizing.
- Fri Nov 23, 2018 12:03 pm
- Forum: Hybridization
- Topic: reason for hybridization
- Replies: 9
- Views: 10091
Re: reason for hybridization
Hybridization occurs molecules/atoms can bond with other molecules/atoms. To my understanding, looking at the electronic configuration, electrons aren't always in the spot to bond. For instance, carbon's electronic configuration is 1s22s22p2. It only has 2 unpaired electrons even though we know that...
- Fri Nov 23, 2018 11:59 am
- Forum: Dipole Moments
- Topic: Bond Angles
- Replies: 8
- Views: 832
Re: Bond Angles
I would suggest memorizing the basic angles like tetrahedral is 109.5, trigonal planar is 120, and linear is 180. Then, you should understand how lone pairs affect those angles. Lone pairs push the bonded atoms together making the angles smaller. For instance, a trigonal pyramidal is <109.5.
- Fri Nov 23, 2018 11:56 am
- Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
- Topic: Distinctions between intermolecular forces
- Replies: 2
- Views: 236
Re: Distinctions between intermolecular forces
All those intermolecular forces are the same, so you should be able to name that force with whichever name.
- Fri Nov 16, 2018 12:30 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Polarizability
- Replies: 3
- Views: 434
Re: Polarizability
Polarizability is how much the electrons in an atom can be distorted. For example, atoms with more electrons tend to be more polarizable.
- Fri Nov 16, 2018 12:22 pm
- Forum: Sigma & Pi Bonds
- Topic: Sigma and Pi bonds
- Replies: 4
- Views: 691
Re: Sigma and Pi bonds
What are the purposes of sigma and pi bonds? Do they just create a bigger area for electron movement? I believe sigma and pi bonds give you a more specific visual representation of how two atoms/molecules bond. For instance, sigma bond is where they bond at one point, and a pi bond is where they bo...
- Fri Nov 16, 2018 12:19 pm
- Forum: Sigma & Pi Bonds
- Topic: Significance of sigma and pi bonds
- Replies: 2
- Views: 369
Re: Significance of sigma and pi bonds
Sigma and Pi bond tell you more specifically how two atoms/molecules bond. For instance, a sigma bond is where two atoms/molecules bond at one point, while a pi bond is where two atoms/molecules bond at two points.
- Fri Nov 09, 2018 9:44 am
- Forum: Dipole Moments
- Topic: HCl
- Replies: 6
- Views: 539
Re: HCl
HCl has a permanent dipole because Cl is one of the most electronegative element while H isn't. So, Cl has the tendency to pull all the electron, creating a dipole.
- Fri Nov 09, 2018 9:41 am
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Disperson forces
- Replies: 4
- Views: 608
Re: Disperson forces
The more electrons a molecule has, the more polarizable it is. Because there are more dispersion forces happening in larger molecules because of the number of electrons, the interactions are likely to be a liquid substance over a gaseous substance. This is evident in why F2 is a gas and Br2 is a liq...
- Fri Nov 09, 2018 9:36 am
- Forum: Dipole Moments
- Topic: Van der Waals forces
- Replies: 2
- Views: 190
Re: Van der Waals forces
Molecules can be neutral/nonpolar because all the electrons are orienting themselves around the central atom evenly. However, since they still have electrons, the electrons move around, creating a temporary dipole moment that interacts with other molecules with a temporary dipole moment.
- Fri Nov 02, 2018 1:49 pm
- Forum: Ionic & Covalent Bonds
- Topic: Ionization Energy
- Replies: 2
- Views: 250
Re: Ionization Energy
The ionization energy increases because there is a stronger positive nuclear charge that pulls the electron towards the center. In addition, as there are more electrons in one cloud, the more it wants to fill up the octet rather than getting rid of the electrons.
- Fri Nov 02, 2018 1:43 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Formal Charge of Ions
- Replies: 9
- Views: 935
Re: Formal Charge of Ions
You want each individual atom to be as close to zero as possible, but the overall formal charges should add up to the charge of the molecule.
- Fri Nov 02, 2018 1:37 pm
- Forum: Ionic & Covalent Bonds
- Topic: electronegativity troughout a covalent bond
- Replies: 3
- Views: 427
Re: electronegativity troughout a covalent bond
Yes, the more negative atom will be the more electronegative atom since they want to attract electrons to fill their outer shell.
- Fri Oct 26, 2018 8:04 pm
- Forum: Ionic & Covalent Bonds
- Topic: Bonding Between Cations and Anions
- Replies: 3
- Views: 237
Re: Bonding Between Cations and Anions
(NH4)2+ and (SO4)2- are cations and anions which form an ionic bond through the transferring of electrons.
- Fri Oct 26, 2018 8:02 pm
- Forum: Ionic & Covalent Bonds
- Topic: Valence Electrons
- Replies: 4
- Views: 689
Re: Valence Electrons
You base it off of the group the elements are in. For example, Group 1 would have 1 valence electron. However, the transition metals will vary in how many valence electrons they will have.
- Fri Oct 26, 2018 8:00 pm
- Forum: Ionic & Covalent Bonds
- Topic: Chemical Bonding and Periodic Trends
- Replies: 4
- Views: 356
Re: Chemical Bonding and Periodic Trends
Yes. For example, if an element has a high ionization energy, it is less likely to have an electron removed. Rather, it would accept electrons to meet the octet rule. Vice versa as well.
- Fri Oct 26, 2018 7:57 pm
- Forum: Properties of Light
- Topic: Speed of Light
- Replies: 12
- Views: 934
Re: Speed of Light
No, I don't think anything is faster than the speed of light.
- Tue Oct 16, 2018 10:19 am
- Forum: Photoelectric Effect
- Topic: Spectroscopic series
- Replies: 2
- Views: 554
Re: Spectroscopic series
I think the lyman and balmer series are the only ones we need to know. Lyman series is when an electron drops back down to n=1 while Balmer is when an electron drops back down to n=2.
- Tue Oct 16, 2018 10:12 am
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Formula
- Replies: 3
- Views: 250
Formula
Why is there a negative in E=-hR/n^2?
- Tue Oct 16, 2018 10:11 am
- Forum: Properties of Light
- Topic: Vocab
- Replies: 5
- Views: 450
Vocab
What does it mean for something to be quantized?
- Fri Oct 12, 2018 12:52 am
- Forum: Photoelectric Effect
- Topic: Threshold energy
- Replies: 5
- Views: 4432
Re: Threshold energy
Threshold energy is the minimum amount of energy needed to eject an electron
- Fri Oct 12, 2018 12:48 am
- Forum: Balancing Chemical Reactions
- Topic: Balancing Chemical Equations [ENDORSED]
- Replies: 4
- Views: 378
Re: Balancing Chemical Equations [ENDORSED]
For combustion reactions, a hydrocarbon is usually reacted with oxygen to form water and carbon dioxide. To arrange reactants and products, you need to know what is actually going on in the reaction and what type of reaction it is.
- Fri Oct 12, 2018 12:46 am
- Forum: Molarity, Solutions, Dilutions
- Topic: memorizing [ENDORSED]
- Replies: 4
- Views: 641
Re: memorizing [ENDORSED]
Writing out the units usually helps with understanding what the next step is. For example, molar mass is g/mol and to find the number of mols for a certain mass. You would take the mass and divide it by the molar mass. This would cancel out the grams.
- Wed Oct 03, 2018 6:34 pm
- Forum: Limiting Reactant Calculations
- Topic: Finding theoretical yield
- Replies: 6
- Views: 631
Re: Finding theoretical yield
The amount of product the limiting reactant produces will be the actual yield because you can't produce more if there is not enough of one of the parts.
- Wed Oct 03, 2018 6:32 pm
- Forum: Limiting Reactant Calculations
- Topic: Limiting reactants product of moles
- Replies: 4
- Views: 690
Re: Limiting reactants product of moles
You can convert the mass of CaCO3 to moles and then use the mole to mole ration from the chemical equation to find the moles of CO2.
- Wed Oct 03, 2018 6:27 pm
- Forum: Balancing Chemical Reactions
- Topic: Combustion
- Replies: 6
- Views: 597
Re: Combustion
Combustion requires the presence of O2 and will always form H2O and CO2.