Search found 63 matches

by mcredi
Mon Mar 11, 2019 12:55 pm
Forum: First Order Reactions
Topic: concept
Replies: 2
Views: 53

Re: concept

A second order reaction is a reaction where x + y = 2. This can happen if one reactant is consumed at a rate proportional to the square of the reactant's concentration (rate = k[A]2) or both reactants are consumed linearly over time (rate = k[A][B]).
by mcredi
Mon Mar 11, 2019 12:54 pm
Forum: Zero Order Reactions
Topic: Zero Order Reaction
Replies: 5
Views: 118

Re: Zero Order Reaction

For example 10mg of a drug maybe eliminated per hour, this rate of elimination is constant and is independent of the total drug concentration in the plasma
by mcredi
Mon Mar 11, 2019 12:53 pm
Forum: Zero Order Reactions
Topic: Concept
Replies: 4
Views: 138

Re: Concept

Zero-order reactions are typically found when a material that is required for the reaction to proceed, such as a surface or a catalyst, is saturated by the reactants. For example a constant amount of drug is eliminated per unit time; 10mg a drug may be eliminated per hour, this rate of elimination i...
by mcredi
Mon Mar 11, 2019 12:51 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: pre-equilibrium
Replies: 1
Views: 30

Re: pre-equilibrium

yes we only need to know how to do this approach
by mcredi
Mon Mar 04, 2019 9:19 am
Forum: Method of Initial Rates (To Determine n and k)
Topic: Order of the reactant (n)
Replies: 4
Views: 86

Re: Order of the reactant (n)

The rate law or rate equation for a chemical reaction is an equation that links the reaction rate with the concentrations or pressures of the reactants and constant parameters. Basically it is a number that relates the rate of a chemical reaction with the concentrations of the reacting substances an...
by mcredi
Mon Mar 04, 2019 9:17 am
Forum: Zero Order Reactions
Topic: How to determine zero order rxts
Replies: 1
Views: 44

Re: How to determine zero order rxts

Zero-order reactions are typically found when a material that is required for the reaction to proceed, such as a surface or a catalyst, is saturated by the reactants. A reaction is zero-order if concentration data is plotted versus time and the result is a straight line; independent of the concentra...
by mcredi
Mon Mar 04, 2019 9:13 am
Forum: First Order Reactions
Topic: First Oder
Replies: 1
Views: 69

Re: First Oder

b/c it proceeds at a rate that depends linearly on only one reactant concentration, the rate of reaction is directly proportional to the concentration of the reacting substance
by mcredi
Wed Feb 27, 2019 10:09 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: draw galvanic cell
Replies: 3
Views: 62

Re: draw galvanic cell

I would know generally what it looks like and how it works, but for sure know how to draw a cell diagram
by mcredi
Wed Feb 27, 2019 10:09 am
Forum: Balancing Redox Reactions
Topic: salt bridge vs porous disk
Replies: 4
Views: 78

Re: salt bridge vs porous disk

Without the salt bridge, the solution in the anode compartment would become positively charged and the solution in the cathode compartment would become negatively charged,because of the charge imbalance,the electrode reaction would quickly come to a halt. The two basically have the same purpose
by mcredi
Wed Feb 27, 2019 10:07 am
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: flipping the sign of Ecell
Replies: 5
Views: 85

Re: flipping the sign of Ecell

yes, when the reaction is reversed you flip the sign
by mcredi
Thu Feb 21, 2019 10:21 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Pt as an electrode
Replies: 4
Views: 77

Re: Pt as an electrode

the mass of an inert electrode does not change during the oxidation-reduction reaction; inert electrodes are often made of platinum or gold because these metals are chemically unreactive.
by mcredi
Thu Feb 21, 2019 10:19 am
Forum: Balancing Redox Reactions
Topic: Number 6k.5 7th edition
Replies: 1
Views: 32

Re: Number 6k.5 7th edition

It doesn't seem to be asking for two half reactions, rather for you to balance the whole reaction by putting a 3 in front of O2 and O3
by mcredi
Thu Feb 21, 2019 10:06 am
Forum: Balancing Redox Reactions
Topic: Writing Half Reactions
Replies: 2
Views: 59

Re: Writing Half Reactions

You can add water. Each equation is balanced by adjusting coefficients and adding H2O, H+, and e- in this order: Balance elements in the equation other than O and H then balance the oxygen atoms by adding the appropriate number of water (H2O) molecules to the opposite side of the equation.
by mcredi
Fri Feb 15, 2019 11:47 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7348
Views: 898407

Re: Post All Chemistry Jokes Here

Image
by mcredi
Tue Feb 12, 2019 7:52 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Irreversible Entropy Changes
Replies: 1
Views: 49

Irreversible Entropy Changes

When talking about entropy change due to temperature change when the process was done irreversibly, why do we use deltaS = nRln(t/t)
by mcredi
Tue Feb 12, 2019 11:34 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Equations for 2nd law
Replies: 1
Views: 48

Re: Equations for 2nd law

every energy transfer that takes place will increase the entropy of the universe and reduce the amount of usable energy available to do work
by mcredi
Tue Feb 12, 2019 11:29 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Reasons for Heat Capacity
Replies: 2
Views: 68

Re: Reasons for Heat Capacity

the transferred heat depends on three factors: (1) The change in temperature, (2) the mass of the system, and (3) the substance and phase of the substance.
by mcredi
Tue Feb 12, 2019 11:27 am
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Isochoric vs isometric
Replies: 4
Views: 129

Re: Isochoric vs isometric

An isochoric process, also called a constant-volume process, or an isometric process, is a thermodynamic process during which the volume of the closed system undergoing such a process remains constant.
by mcredi
Mon Feb 04, 2019 9:05 am
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: isothermal expansion
Replies: 2
Views: 79

Re: isothermal expansion

An isothermal process is a change of a system, in which the temperature remains constant: ΔT = 0. This typically occurs when a system is in contact with an outside thermal reservoir (heat bath), and the change in the system will occur slowly enough to allow the system to continue to adjust to the te...
by mcredi
Mon Feb 04, 2019 8:59 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Isolated System (Water bottle)
Replies: 6
Views: 115

Re: Isolated System (Water bottle)

An isolated system is a thermodynamic system that cannot exchange either energy or matter outside the boundaries of the system. Heat is not leaving and neither is the contents of the water bottle
by mcredi
Mon Feb 04, 2019 8:56 am
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Isothermic definition
Replies: 5
Views: 109

Re: Isothermic definition

There's the isothermal process where temperature is constant, internal energy is constant, and the quantity P x V, is also constant. There's the isometric process where the change in volume is 0, which means no work can be done.
by mcredi
Mon Jan 28, 2019 10:03 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: eq constants for acids
Replies: 4
Views: 90

Re: eq constants for acids

Strong acids do have Ka values, extremely large ones that, for the purpose of stoichiometry, the value is considered infinity. This is because strong acids will in theory dissolve completely
by mcredi
Mon Jan 28, 2019 10:02 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Salts
Replies: 1
Views: 52

Re: Salts

Salts do not chemically react with water. When they combination hit water, they break down into separate ions. The salt becomes soluble in the water, rather than reacting with it. The addition of salt causes the volume of the water to change. But since that salt does not release or bind to the water...
by mcredi
Mon Jan 28, 2019 10:00 am
Forum: Phase Changes & Related Calculations
Topic: Enthalpy and state property
Replies: 2
Views: 46

Re: Enthalpy and state property

Enthalpy is a state function because it depends only on two thermodynamic properties of the state the substance is at the moment (like temperature and pressure, or temperature and entropy, or any pair of other state functions). It does not depend on the path followed by the substance to get there. E...
by mcredi
Sat Jan 26, 2019 2:37 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Solids and Liquids for pressure change
Replies: 3
Views: 72

Re: Solids and Liquids for pressure change

Changes in presure have very little effect on the volume of a liquid. Liquids are relatively incompressible because any increase in pressure can only slightly reduce the distance between the closely packed molecules.
by mcredi
Fri Jan 25, 2019 3:04 pm
Forum: Phase Changes & Related Calculations
Topic: Enthalpy as a state property
Replies: 2
Views: 55

Re: Enthalpy as a state property

As represented by the solution to the integral, enthalpy is a state function because it only depends on the initial and final conditions, and not on the path taken to establish these conditions. Heat is bc the change in the internal energy of a system is equal to the sum of the heat and the work tra...
by mcredi
Fri Jan 25, 2019 3:01 pm
Forum: Phase Changes & Related Calculations
Topic: The qp symbol
Replies: 3
Views: 60

Re: The qp symbol

If q is positive, we say that the reaction is endothermic, that is, heat flows into the reaction from the outside surroundings. If q is negative, then the reaction is exothermic, that is, heat is given off to the external surroundings.
by mcredi
Thu Jan 17, 2019 9:22 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibrium Constants
Replies: 5
Views: 103

Re: Equilibrium Constants

Kc and Kp are the equilibrium constants of gaseous mixtures. However, the difference between the two constants is that Kc is defined by molar concentrations, whereas Kp is defined by the partial pressures of the gasses inside a closed system.
by mcredi
Thu Jan 17, 2019 9:20 am
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: difficulties recognizing weak acids and bases
Replies: 8
Views: 398

Re: difficulties recognizing weak acids and bases

Honestly, it is helpful to memorize them so the strong acids are hydrochloric acid, nitric acid, sulfuric acid, hydrobromic acid, hydroiodic acid, perchloric acid, and chloric acid. The only weak acid formed by the reaction between hydrogen and a halogen is hydrofluoric acid.
by mcredi
Thu Jan 17, 2019 9:13 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Why do stronger bases have conjugate acids with larger pKa values?
Replies: 4
Views: 67

Re: Why do stronger bases have conjugate acids with larger pKa values?

Strong acids include H3O+, HCl and HNO3. For example, in water, a strong acid like hydrochloric acid readily donates a proton to a water molecule and the equilibrium position lies so far to the right that we usually assume that the HCl molecule completely dissociates in water. This means that the re...
by mcredi
Sun Jan 13, 2019 6:23 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Aqueous Solutions [ENDORSED]
Replies: 2
Views: 48

Re: Aqueous Solutions [ENDORSED]

Pure solids or liquids are excluded from the equilibrium expression because their effective concentrations stay constant throughout the reaction. The density of a pure liquid or solid is the same, regardless of how much pure liquid or solid is present.
by mcredi
Sun Jan 13, 2019 6:21 pm
Forum: Ideal Gases
Topic: Units
Replies: 3
Views: 61

Re: Units

The torr is a unit of pressure and is defined as exactly of a standard atmosphere. A bar is a pressure unit defined as 100 kilopascals. This makes one atmosphere nearly equal to one bar. 1 bar = 750.06375541921 Torr
by mcredi
Sun Jan 13, 2019 6:18 pm
Forum: Ideal Gases
Topic: Definition of an Ideal Gas [ENDORSED]
Replies: 2
Views: 49

Re: Definition of an Ideal Gas [ENDORSED]

The ideal gas law is based on a series of assumptions on gas particles. 1. All gas particles are in constant motion and collisions between the gas molecules and the walls of the container cause the pressure of the gas. 2. The particles are so small that their volume is negligible compared with the v...
by mcredi
Sat Dec 08, 2018 11:05 pm
Forum: Conjugate Acids & Bases
Topic: Acceptor and Donor?
Replies: 3
Views: 146

Re: Acceptor and Donor?

A conjugate acid, within the Brønsted–Lowry acid–base theory, is a species formed by the reception of a proton (H+) by a base—in other words, it is a base with a hydrogen ion added to it. On the other hand, a conjugate base is what is left over after an acid has donated a proton during a chemical re...
by mcredi
Sat Dec 08, 2018 10:54 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Identifying Ligands
Replies: 1
Views: 71

Re: Identifying Ligands

en will be bidentate; dien will be tridentate; oxolato will be bidentate
by mcredi
Sat Dec 08, 2018 10:27 pm
Forum: Air Pollution & Acid Rain
Topic: acid rain
Replies: 1
Views: 123

Re: acid rain

It mentions it very briefly, like maybe a sentence in the 7th edition, so I would recommend google to help you out Layla
by mcredi
Thu Nov 29, 2018 5:45 pm
Forum: Hybridization
Topic: identifying hybridization of a central atom
Replies: 4
Views: 79

Re: identifying hybridization of a central atom

Polar molecules occur when two atoms do not share electrons equally in a covalent bond. If the electronegativity difference between the atoms is greater than 2.0, the bond is ionic. Ionic compounds are extremely polar molecules. But if the dipole moments cancel out on there molecule, its symmetrical...
by mcredi
Thu Nov 29, 2018 5:41 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Carbon monoxide
Replies: 1
Views: 43

Re: Carbon monoxide

By forming a triple bond, both C and O within carbon monoxide have a full valence shell.
by mcredi
Thu Nov 29, 2018 2:56 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Bond Strength
Replies: 2
Views: 59

Re: Bond Strength

Oxygen has a greater electronegativity than nitrogen so the non-bonded electron pair on a nitrogen atom is more available for sharing than a non-bonded electron pair on an oxygen atom.
by mcredi
Sun Nov 25, 2018 10:07 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: electron-deficient compounds
Replies: 1
Views: 47

Re: electron-deficient compounds

Electron deficiency occurs when a compound has too few valence electrons for the connections between atoms to be described as covalent bonds. I am not exactly sure if we have explicitly discussed them in class.
by mcredi
Sun Nov 25, 2018 10:05 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Nodal Planes
Replies: 3
Views: 55

Re: Nodal Planes

A nodal plane is a plane in which the probability of finding a electron is zero.
by mcredi
Sun Nov 25, 2018 10:03 pm
Forum: Bond Lengths & Energies
Topic: Bond Energy
Replies: 1
Views: 68

Re: Bond Energy

when you make a chemical bond between two atoms, the electrons go from higher energy atomic orbitals to lower energy molecular orbitals. The loss of energy by the electrons coincides with a simultaneous release of energy. Also if you didn't need energy to break a bond then combustion of wood could j...
by mcredi
Sun Nov 18, 2018 10:09 pm
Forum: Hybridization
Topic: Promotion
Replies: 3
Views: 73

Re: Promotion

electron promotion is when an electron absorbs a photon to jump from a low energy level orbital to a higher energy orbital. This can only happen if the photon energy matches the energy difference of the orbitals.
by mcredi
Sun Nov 18, 2018 10:04 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Polar/Nonpolar
Replies: 3
Views: 82

Re: Polar/Nonpolar

Although the bond arrangement around the C atom is symmetrical the different polarities of the C-Cl and C-H bonds means the effects of the bonds aren't canceled.
by mcredi
Sun Nov 18, 2018 9:54 pm
Forum: Bond Lengths & Energies
Topic: Electrostatic Energy and Energy Density
Replies: 1
Views: 71

Electrostatic Energy and Energy Density

What is electrostatic energy and energy density and how will we have to apply this information?
by mcredi
Sun Nov 11, 2018 3:10 pm
Forum: Ionic & Covalent Bonds
Topic: Metallic Bond
Replies: 7
Views: 117

Re: Metallic Bond

It is a type of chemical bonding that rises from the electrostatic attractive force between conduction electrons and positively charged metal ions
by mcredi
Sun Nov 11, 2018 3:09 pm
Forum: Properties of Electrons
Topic: Polar vs Non polar
Replies: 11
Views: 386

Re: Polar vs Non polar

If the electronegativity of two atoms is basically the same, a nonpolar covalent bond will form, and if the electronegativity is slightly different, a polar covalent bond will form.
by mcredi
Sun Nov 11, 2018 3:05 pm
Forum: Bond Lengths & Energies
Topic: Covalent Radius
Replies: 3
Views: 93

Re: Covalent Radius

Atomic radius applies to a single atom. It is the distance from the center of the nucleus to the boundary of its electron cloud. Covalent radius applies when two atoms of the same species are bonded. It is half of the distance between the two nuclei.
by mcredi
Wed Oct 31, 2018 12:04 am
Forum: Ionic & Covalent Bonds
Topic: Predicting which orbital an electron should be removed from to create 1+ ion
Replies: 2
Views: 64

Re: Predicting which orbital an electron should be removed from to create 1+ ion

The ground state of Cu is 3d^10 4s^1 because copper atoms have enough electrons to completely fill the 3d sub-shell, but only if one electron from the 4s sub-shell is used and this arrangement makes the atom more stable so it takes on this arrangement, so in order to get a +1 charge it would first l...
by mcredi
Wed Oct 31, 2018 12:01 am
Forum: Ionic & Covalent Bonds
Topic: Grounds states with f orbitals (2A.5)
Replies: 1
Views: 58

Re: Grounds states with f orbitals (2A.5)

The f orbital is introduced in periods 6 and 7 so in this case when Tl loses 3 electrons, one from the 6p orbital and two from the 6s orbital, the ground state is 4f^14 5d^10
by mcredi
Tue Oct 30, 2018 11:48 pm
Forum: Ionic & Covalent Bonds
Topic: Ground states (homework problem 2A.11)
Replies: 2
Views: 69

Re: Ground states (homework problem 2A.11)

Since the ion lost 3 electrons, therefore becoming +3, you need to find the element that can lose its two 4s electrons and one 3d electron and have the groundstate of 3d^6 and cobalt can lose its two 4s electrons and one of its 3d^7 electrons to become 3d^6
by mcredi
Sun Oct 28, 2018 9:02 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Degeneracy
Replies: 7
Views: 108

Re: Degeneracy

Electron orbitals that have the same energy levels are called degenerate orbitals.
by mcredi
Sun Oct 28, 2018 8:58 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Ionization energy
Replies: 2
Views: 36

Re: Ionization energy

The ionization energy is defined as the minimum amount of energy required to remove the most loosely bound electron, the valence electron. As the atomic radius decreases, it becomes harder to remove an electron that is closer to a more positively charged nucleus
by mcredi
Sun Oct 28, 2018 8:54 pm
Forum: Properties of Electrons
Topic: Energy of Electrons
Replies: 1
Views: 140

Re: Energy of Electrons

Yes, it does! The order of the electron orbital energy levels, starting from least to greatest, is as follows: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p. Except in hydrogen atoms, in hydrogen, all orbitals with the same principal quantum number n are degenerate
by mcredi
Sun Oct 21, 2018 9:54 pm
Forum: Properties of Electrons
Topic: Schrodinger question
Replies: 3
Views: 215

Re: Schrodinger question

The Schrodinger equation is used to find the allowed energy levels of quantum mechanical systems
by mcredi
Sun Oct 21, 2018 9:50 pm
Forum: Properties of Electrons
Topic: Wave Properties
Replies: 4
Views: 97

Re: Wave Properties

Everything exhibits wave-particle duality, everything from electrons to baseballs. The behavior of relatively large objects, like baseballs, is dominated by their particle nature so we don't/can't detect their wave like properties.
by mcredi
Sun Oct 21, 2018 9:47 pm
Forum: Properties of Light
Topic: Photoelectric Effect
Replies: 8
Views: 236

Re: Photoelectric Effect

When light shines on a metal, electrons can be ejected from the surface of the metal in a phenomenon known as the photoelectric effect. The photoelectric effect did not produce the results they expected but rather supports the view that radiation consists of photons that behave like particles. Basic...
by mcredi
Sat Oct 13, 2018 6:13 pm
Forum: Photoelectric Effect
Topic: Threshold energy [ENDORSED]
Replies: 17
Views: 388

Re: Threshold energy [ENDORSED]

Threshold energy is associated with the amount of energy required to remove an electron from a solid, like in the photoelectric effect, but is not used in the calculation of the energy of a photon
by mcredi
Sat Oct 13, 2018 6:03 pm
Forum: Properties of Light
Topic: C=Wavelength*Frequency
Replies: 11
Views: 215

Re: C=Wavelength*Frequency

C is the the speed of light = 3.0 x 10^8 m/s
by mcredi
Sat Oct 13, 2018 5:59 pm
Forum: Photoelectric Effect
Topic: Units for the Work Function of a Metal
Replies: 1
Views: 84

Re: Units for the Work Function of a Metal

Yes, you do need to convert to joules beforehand but based on on decimal points your answer seems correct
by mcredi
Sat Oct 06, 2018 8:34 pm
Forum: Limiting Reactant Calculations
Topic: theoretical yield
Replies: 1
Views: 61

theoretical yield

Hello, could someone please explain to me how to calculate theoretical yield for example in the problem in m1 when 35.0 g of ammonia reacted with an excess of hypochlorite ion, 25.2 g of hydrazine was produced; what is the percentage yield of hydrazine?
by mcredi
Sat Oct 06, 2018 8:25 pm
Forum: Molarity, Solutions, Dilutions
Topic: dilutions? [ENDORSED]
Replies: 5
Views: 121

dilutions? [ENDORSED]

Could someone please explain to me the general steps for how to complete a dilution problem?
by mcredi
Sat Oct 06, 2018 8:14 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: MOLARITY
Replies: 13
Views: 468

Re: MOLARITY

Molarity is the number of moles of solute per liter of solution and can be calculated by Molarity= mol solute/L of solution

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