## Search found 52 matches

Sat Mar 16, 2019 7:10 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Catalyst in rate law?
Replies: 6
Views: 1021

### Re: Catalyst in rate law?

They could be included because they are present in the original reactants. But i'm not sure because in class we learned that catalysts are not consumed so they in may cancel out.
Sat Mar 16, 2019 7:05 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Intermediates in Rate Law
Replies: 4
Views: 184

### Re: Intermediates in Rate Law

No, they are not included because they are not present in the original reactants or in the final products.
Sat Mar 16, 2019 7:02 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: What is a porous disk?
Replies: 3
Views: 184

### Re: What is a porous disk?

It's like a salt bridge in that it prevents ion build up by providing a pathway for ions to move to the other side. HOWEVER, in a cell diagram the salt bridge is drawn by 2 vertical lines, but a porous disk is drawn with only 1 vertical line.
Sat Mar 16, 2019 6:57 pm
Forum: Second Order Reactions
Topic: reaction intermediate
Replies: 4
Views: 379

### Re: reaction intermediate

A reaction intermediate is a molecule that is formed by the reaction, usually in step 1, and is used up by a later step of the reaction. It does not appear in the original reactants or final products.
Sat Mar 16, 2019 6:55 pm
Forum: General Rate Laws
Topic: Exergonic reaction
Replies: 3
Views: 331

### Re: Exergonic reaction

It is similar to exothermic(releases heat) in that exergonic means it is releasing energy.
Sat Mar 16, 2019 6:51 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: K'
Replies: 4
Views: 192

### Re: K'

k' is the rate constant for the reverse reaction. It's used when your making a rate law. Remember k/k'=K(reaction equilibrium constant).
Sat Mar 16, 2019 1:32 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: 6B.9
Replies: 1
Views: 600

### 6B.9

I don't understand the solutions in the solution manual for this question. Why can't I divide Kw by the conc. of H3O+ to find OH-. Also, when I take the -log of the H3O+ conc it gives me a negative of the actual solution.
Sun Mar 10, 2019 8:45 pm
Forum: Balancing Redox Reactions
Topic: Oxidation vs Reduction Half Rxn
Replies: 9
Views: 421

### Re: Oxidation vs Reduction Half Rxn

Oxidation half reaction is where electrons are being released from the reactant, so the electrons are written on the product side. Reduction half reactions is where electrons are being added to the reactant to form a product, so the electrons are written on the left side.
Sun Mar 10, 2019 8:37 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Midterm
Replies: 5
Views: 235

### Re: Midterm

A comment of the stability of products and reactants means an explanation of what the reaction tends to and why.
Sun Mar 10, 2019 8:36 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell diagram
Replies: 6
Views: 211

### Re: Cell diagram

To conduct electricity, move ions, the reaction needs electrodes to move them. So if there is no metal solid in the reaction there is no electrode. So platinum is used as a conductor.
Sat Mar 02, 2019 5:58 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Order of Cell Diagrams
Replies: 13
Views: 513

### Re: Order of Cell Diagrams

Solids always go on the outmost side, furthest from the salt bridge. A TA told me to write the reactant on the left and product on the right. Also aq solutions should be closest to the salt bridge.
Sat Mar 02, 2019 5:55 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagrams (Using Platinum)
Replies: 10
Views: 363

### Re: Cell Diagrams (Using Platinum)

A metal is used as a cathode or anode to conduct electricity so a reaction without a metal would not transfer ions. To make the circuit work for solutions with aq or gas reactants platinum needs to be added as a conductor.
Sat Mar 02, 2019 5:52 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: E˚ vs E
Replies: 13
Views: 1895

### Re: E˚ vs E

E˚ is the standard and E is in a specific reaction. E˚ does not change through a reaction because the element is in its most stable state but E changes as the reaction goes on because the element may change because its not in its most stable state.
Sat Mar 02, 2019 5:49 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: w vs wmax
Replies: 5
Views: 205

### w vs wmax

What is the difference between the measurement of work and work max. Does an expanding reaction have a work max?
Sat Mar 02, 2019 5:48 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: H+ and OH
Replies: 3
Views: 205

### H+ and OH

Why are H+ and OH included in the cell diagram if they are not included in the original equation and are just used to balance and sometimes cancel out?
Sun Feb 24, 2019 10:26 pm
Forum: Balancing Redox Reactions
Topic: Skeleton Equations
Replies: 3
Views: 113

### Re: Skeleton Equations

The skeleton equation doesn't include water or electrons. But water is used to balance the equation if there's an H or O on one side and not on the other.
Sun Feb 24, 2019 10:24 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Salt Bridge
Replies: 3
Views: 126

### Re: Salt Bridge

The salt bridge allows for ion transfer and it keeps the amount of ions at equilibrium so that there isn't an excess or not enough ions on either side to do the reaction.
Sat Feb 23, 2019 10:09 pm
Forum: Balancing Redox Reactions
Topic: H OH and H20
Replies: 2
Views: 96

### H OH and H20

How do I know what side to balance with H or OH or H20?
Sun Feb 10, 2019 10:36 pm
Forum: Calculating Work of Expansion
Topic: Work Formula Involving Integral
Replies: 3
Views: 109

### Re: Work Formula Involving Integral

In this class, yes the integral is only used to find the -PdV equation that we use. The integral is solved in order to show that pressure is constant and that volume is changing in small steps so we can just say that dV=V2-V1.
Sun Feb 10, 2019 10:13 pm
Forum: Calculating Work of Expansion
Topic: Reversible Using V or P
Replies: 1
Views: 85

### Reversible Using V or P

Since volume and pressure both change in reversible, isothermic system can you switch ln(V2/V1) and ln(P1/P2) whenever you want? Will you get the same answer?
Sun Feb 10, 2019 2:57 pm
Forum: Calculating Work of Expansion
Topic: Reversible vs Irreversible
Replies: 9
Views: 339

### Reversible vs Irreversible

What makes a reaction or movement irreversible in a system and what makes it reversible? Why are the pressures different?
Sun Feb 03, 2019 8:41 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Isolated System Example
Replies: 4
Views: 209

### Re: Isolated System Example

An isolated system means that there is no matter or energy transfer between the contents in the inside and its surroundings. The most general example of a truly closed system is the universe because there is nothing that exists outside of the universe so nothing can be transferred between it and its...
Sun Feb 03, 2019 8:34 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: open system
Replies: 8
Views: 344

### Re: open system

An open system means that matter and energy is transferred between the solution and its surroundings. The pressure in the beaker is the same as its surroundings because it is open to air and the same as normal air. This is 1atm.
Sun Feb 03, 2019 7:36 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: 1st law of thermodynamics
Replies: 7
Views: 253

### Re: 1st law of thermodynamics

An isolated system means that there is no matter or energy change/transfer between the internal objects and their surroundings. Using the universe as an example - there is nothing known outside of the universes therefore it is impossible for energy or matter to be transferred to the surroundings bec...
Sun Jan 27, 2019 9:56 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Order of Hess's Law
Replies: 1
Views: 32

### Order of Hess's Law

When adding the two enthalpies, getting the net enthalpy telling whether the whole reaction is exothermic or endothermic do all of the reactions happen simultaneously or individually depending on availability of reactants. If it is the latter could a reaction be exothermic for a set amount of time a...
Sat Jan 26, 2019 9:22 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Sign changes
Replies: 3
Views: 123

### Sign changes

When adding two enthalpies can the total change signs, such as if the enthalpy of the first is positive and you add a negative one and the negative one is higher and what would that mean for the reaction?
Sat Jan 26, 2019 9:20 pm
Forum: Phase Changes & Related Calculations
Topic: Enthalpy signs
Replies: 13
Views: 491

### Enthalpy signs

When is the change in H, Enthalpy, positive and when is it negative?
Sun Jan 13, 2019 1:25 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: (aq) in calculating K
Replies: 9
Views: 242

### Re: (aq) in calculating K

Aqueous and gases are included in the equilibrium constant and solids and liquids are not because molar concentrations of a pure substance, solids and liquids, does not change in a reaction.
Sun Jan 13, 2019 1:22 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Heterogeneous and homogeneous equilibria [ENDORSED]
Replies: 8
Views: 294

### Re: Heterogeneous and homogeneous equilibria[ENDORSED]

Homogeneous equilibria is where all reactants and products are in the same phase. Therefore if they are all gasses all of the components would be incorporated in the equilibrium constant equation. Heterogeneous equilibria is when one or more of the reactants or products are in a different phase. If ...
Sat Jan 12, 2019 11:10 pm
Forum: Ideal Gases
Topic: Q
Replies: 5
Views: 200

### Q

K is the equilibrium constant, but what is the purpose of finding Q? Specifically why do we use the same formula and what does it mean?
Sat Dec 08, 2018 9:52 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: pH to salt solution
Replies: 1
Views: 100

### pH to salt solution

How do you calculate pH when you're given the molarity and volume of a basic solution like on Lyndon's review?
Sat Dec 08, 2018 5:35 pm
Forum: Calculating the pH of Salt Solutions
Topic: Ph to salt solution
Replies: 2
Views: 239

### Ph to salt solution

Given the formula and the final pH is it possible to do the formula backwards and find the original concentration?
Sun Dec 02, 2018 10:43 pm
Forum: Bronsted Acids & Bases
Topic: Strong Acids
Replies: 4
Views: 164

### Strong Acids

Why do strong acids produce more protons than a weak acid? The process.
Sun Dec 02, 2018 8:54 pm
Forum: Hybridization
Topic: Hybridization Application
Replies: 2
Views: 139

### Hybridization Application

Does every element need a hybridization formula when bonding? Or when are the circumstances when it is needed?
Sun Dec 02, 2018 8:52 pm
Forum: Hybridization
Topic: P orbital
Replies: 7
Views: 270

### P orbital

How do I know when to add the extra p orbital after the sp hybridization?
Tue Nov 27, 2018 10:03 am
Forum: Hybridization
Topic: Number
Replies: 2
Views: 129

### Number

Is hybridization based on bonds or electron regions? Do you include lone pairs?
Mon Nov 26, 2018 5:59 pm
Forum: Ionic & Covalent Bonds
Topic: Polar Molecule
Replies: 3
Views: 413

### Polar Molecule

Is a polar molecule any molecule with charges? If there is a net charge of 0 is it non polar (ex. central atom has +2 and two bonded atoms have -1 each)?
Mon Nov 26, 2018 5:57 pm
Forum: Hybridization
Topic: Pi bonds
Replies: 3
Views: 177

### Pi bonds

How would you draw a pi bond between two different molecules? Would lone pairs on one of the molecules affect it?
Sat Nov 24, 2018 3:41 pm
Forum: Octet Exceptions
Topic: Incomplete Octet
Replies: 2
Views: 383

### Incomplete Octet

For examples like BF3 where the central atom does not have a complete octet, what are the characteristic changes that occur? Bonding wise and attraction wise? Maybe even state wise?
Sun Nov 18, 2018 11:01 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles for H2O
Replies: 8
Views: 4898

### Re: Bond Angles for H2O

H20 has two lone pairs in order to complete the valence since 2 are being shared on each side with the hydrogens. These two lone pairs push the 2 hydrogens down because of electron repulsion. So the angle between the two hydrogens is less than 109.5. It is 104.5 because there are two lone pairs whic...
Sun Nov 18, 2018 10:58 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 2 Atoms
Replies: 1
Views: 63

### 2 Atoms

What is the correct reasoning on why 2 VSEPR models with 2 atoms of elements are not regarded? Can there be a lone pair between two bonded atoms? And would it always be linear?
Wed Nov 14, 2018 9:27 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 3D Structure
Replies: 2
Views: 83

### 3D Structure

When drawing a 3D structure of the VSEPR model and there is a double bond between two atoms would you draw two wedges/lines between the two atoms?
Wed Nov 14, 2018 9:23 pm
Forum: Ionic & Covalent Bonds
Topic: Hydrogen Bond
Replies: 7
Views: 469

### Hydrogen Bond

The textbook says that a hydrogen bond will dominate all other intermolecular forces, so first, is It possible for a molecule to have a covalent bond and a hydrogen bond? and second what would be the effect of that?
Sun Nov 11, 2018 7:11 pm
Forum: Ionic & Covalent Bonds
Topic: Bond Length
Replies: 3
Views: 154

### Bond Length

Is there a way to determine bond length or will it always be given?
Sun Nov 11, 2018 7:10 pm
Forum: Electronegativity
Replies: 13
Views: 787

How does electronegativity affect the radius of an atom? The process not just the trend.
Wed Nov 07, 2018 12:54 pm
Forum: Lewis Structures
Topic: Formal Charge
Replies: 14
Views: 518

### Formal Charge

Is it better for the central element of the outside elements to have a charge? Why?
Fri Nov 02, 2018 5:11 pm
Forum: Lewis Structures
Topic: How to decide central atom?
Replies: 6
Views: 351

### Re: How to decide central atom?

The central atom is the atom with the lowest ionization energy, so the atom that requires the lowest amount of energy to remove an electron. The element closest to the bottom left of the periodic table.
Fri Nov 02, 2018 5:06 pm
Forum: Octet Exceptions
Topic: s vs d orbital
Replies: 2
Views: 129

### s vs d orbital

Why are some elements written with a d^10 rather than s^2 and d^8?
Mon Oct 29, 2018 8:20 pm
Forum: Lewis Structures
Topic: Number of Electrons
Replies: 2
Views: 49

### Number of Electrons

Is the number of valence electrons based on the column the element is in? Is the proton number same as the total number of electrons?
Thu Oct 04, 2018 9:52 pm
Forum: Balancing Chemical Reactions
Topic: L.5 Mass
Replies: 3
Views: 128

### L.5 Mass

For part A where it gives you the mass of one reactant and asks you to find the other, do you just use the ratio, or do you have to change it to moles and use avogadros number?
Thu Oct 04, 2018 1:31 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Ed. 7 E.23D Equation
Replies: 3
Views: 132

### Ed. 7 E.23D Equation

What does the little multiplication seeming dot mean in the middle of Na2CO3*10H2O. Is it a solvent solute concept?
Wed Oct 03, 2018 9:33 pm
Forum: Significant Figures
Topic: E23C Sig Figs
Replies: 2
Views: 116

### E23C Sig Figs

How do I know how many significant figures do I add to my answer? Is it based on the 25.2kg in the question or the molar masses?