Search found 26 matches
- Sun Dec 10, 2017 10:44 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Final [ENDORSED]
- Replies: 4
- Views: 1400
Re: Final [ENDORSED]
Couldn’t we just say that since the products would be salt and water and salt is solid then the ph would equal the ph of water that is 7?
- Sun Dec 10, 2017 6:08 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Final [ENDORSED]
- Replies: 4
- Views: 1400
Final [ENDORSED]
Hi, Didn’t Dr lavelle mention that salts were not going to be included in our final due to the fire? Question 8a was asking for the PH of a solution containing both NaOH and HCl which produced nacl salt. Were we supposed to know how to solve this problem without the knowledge on salts? If so how cou...
- Sun Dec 10, 2017 3:12 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Exam HCl and NaOH question?
- Replies: 3
- Views: 802
Re: Exam HCl and NaOH question?
I had trouble with this question as well since we did not cover questions with 2 strong acid and base mixed together and their PH. It also wasn’t in our homeworks. Or at least I can’t remember it being discussed in the lectures.
- Sun Dec 10, 2017 8:30 am
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: 11.115 (f) equilibrium shift
- Replies: 1
- Views: 397
11.115 (f) equilibrium shift
In the online exercises, adding water is like adding a reactant and makes the equilibrium shift to the right. However in question 11.115, adding water has no effect on the equilibrium. Both equations have the same states. Liquid water and aq product. So how does water affect equilibrium?
- Sat Dec 09, 2017 1:25 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Homework 4.13
- Replies: 3
- Views: 491
Re: Homework 4.13
Why doesn’t the double bond in this question affect the bond angle?
- Sat Dec 09, 2017 8:11 am
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Coordination number [ENDORSED]
- Replies: 1
- Views: 336
Coordination number [ENDORSED]
Is the coordination number the number of bonds only in the coordination sphere? If the coordination compound is a cation or anion and is attached to an anion or cation, does that bond count in the coordination number if it is not in the sphere?
- Fri Dec 08, 2017 7:40 am
- Forum: Lewis Acids & Bases
- Topic: HF
- Replies: 4
- Views: 577
Re: HF
In our book it states that in these molecules as we go across a period we have to consider electronegativity but as we go down a group we have to consider bond length and the radius. So we compare HCL and HF based on their radius since they are in the same group. Cl has a larger radius and more acidic
- Wed Dec 06, 2017 3:21 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: 4.13 (b)
- Replies: 1
- Views: 373
4.13 (b)
The lewis structure of POCl3 is tetrahedral but p has an expanded octet and a double bond. Why doesn't the double bond affect the bond angles? I was thinking that because of the double bond the angle has to be less than 109.5 but in the solution manual the angles are 109.5. thanks
- Thu Nov 30, 2017 12:31 pm
- Forum: Hybridization
- Topic: 4.95
- Replies: 3
- Views: 509
Re: 4.95
The hybridization for oxygen is sp2 since it has 3 regions of electron density surrounding it. two regions of electron density are the lone pairs and the third region is the double bond. double bonds count as one region of electron density. we use 2sp2 when we want to specify the actual orbitals inv...
- Thu Nov 30, 2017 12:25 pm
- Forum: Ideal Gases
- Topic: Temperature in PV=nRT
- Replies: 9
- Views: 1088
Re: Temperature in PV=nRT
We have to use Kelvin temperature since in this formula T could be at the denominator. If we were using Celsius unit, then we would have had zero at the denominator at some point. Because a zero denominator does not give us a solution, we use kelvin. when kelvin is zero that suggests we have an abso...
- Thu Nov 23, 2017 3:41 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 11.43
- Replies: 1
- Views: 323
Re: 11.43
for this question, you have to draw the ICE table. the initial pressure of the reactant is 1. Its stoichiometry coefficient is 2 and if we consider the change of the products as X, the change NO undergoes would be -2X. so the pressure at equilibrium for NO would be (1-2x) and X for each of the produ...
- Thu Nov 23, 2017 3:34 pm
- Forum: Hybridization
- Topic: Valence/valency?
- Replies: 1
- Views: 462
Re: Valence/valency?
the valence number is the number of electrons located in the outer layer of the atom ( valence shell). These electrons can form bonds with other atoms, therefore they should not be paired. carbon has the electron configuration of (he)2s22p2 this means that there are 2 unpaired electrons in the outer...
- Thu Nov 16, 2017 5:42 pm
- Forum: Hybridization
- Topic: Significance of Hybridization
- Replies: 3
- Views: 6412
Re: Significance of Hybridization
Also, I think hybridization lowers the energy of the orbitals thus creating a compound that is more stable.
- Thu Nov 16, 2017 5:33 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: 4.25 lewis structure
- Replies: 4
- Views: 602
Re: 4.25 lewis structure
since F and Cl both belong to the same group and are both halogens the lewis structure would be the same.
- Wed Nov 08, 2017 11:20 pm
- Forum: Limiting Reactant Calculations
- Topic: Limiting Reactant
- Replies: 3
- Views: 629
Re: Limiting Reactant
Another strategy that seems to work when comparing moles is figuring out the number of moles for each compound and dividing it by its stoichiometric coefficient. At this point, we could compare the 2 numbers. The smaller number is the limiting reactant.
Moles
————-
Coefficient
Moles
————-
Coefficient
- Wed Nov 08, 2017 10:32 pm
- Forum: Balancing Chemical Reactions
- Topic: Net Moles of Gas
- Replies: 5
- Views: 563
Re: Net Moles of Gas
If we have 4 moles of C4H10 that would result in 26 moles o2, 16 moles co2 and 20 moles H2o.
4+26=30
16+20=36
The difference in the gases which is the net gas produced is 36-30=6
In this equation we consider all of the states as gas since the temperature is very high and the water evaporates.
4+26=30
16+20=36
The difference in the gases which is the net gas produced is 36-30=6
In this equation we consider all of the states as gas since the temperature is very high and the water evaporates.
- Thu Nov 02, 2017 10:43 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Writing Electron Configurations for ions
- Replies: 2
- Views: 450
Re: Writing Electron Configurations for ions
if you start by writing the electron configuration of Cu in its ground state, you will have [Ar]3d104s1
now if you take one electron away from the outer shell to get the ion, you will have [Ar]3d10.
now if you take one electron away from the outer shell to get the ion, you will have [Ar]3d10.
- Thu Nov 02, 2017 8:48 pm
- Forum: Trends in The Periodic Table
- Topic: Carbon vs. Nitrogen Ionization Trend
- Replies: 3
- Views: 3025
Re: Carbon vs. Nitrogen Ionization Trend
nitrogen has an ionization energy of 1400 kJ/mol while carbon has an energy of 1086 kJ/mol. Therefore as expected, nitrogen has higher energy than carbon. There is an irregularity in their electron affinity.
- Thu Oct 26, 2017 10:05 am
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: s- electrons vs p- electrons [ENDORSED]
- Replies: 7
- Views: 1596
Re: s- electrons vs p- electrons [ENDORSED]
Basically, the s orbitals have fewer electrons standing between them and the nucleus, therefore, they are less shielded. The p orbitals are more shielded than the s orbitals of the same shell.that is why p orbitals have higher energy.
- Thu Oct 26, 2017 9:23 am
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: 2.1
- Replies: 2
- Views: 432
Re: 2.1
Hi
You need to look at each separately
a) energy of electron increases as we increase n from 1 to 2
b) we are going from 1s to 2p so n is increasing
c) the s orbital has l=0 and the p orbital has l=1 so it is increasing
d) radius of atom increases when n increases
You need to look at each separately
a) energy of electron increases as we increase n from 1 to 2
b) we are going from 1s to 2p so n is increasing
c) the s orbital has l=0 and the p orbital has l=1 so it is increasing
d) radius of atom increases when n increases
- Wed Oct 18, 2017 2:34 pm
- Forum: Properties of Electrons
- Topic: Energy Levels
- Replies: 3
- Views: 553
Re: Energy Levels
the electron could absorb energy and go to a higher level or emit energy and go to a lower level. The equation En=-hR/n2 simply calculates the energy of the specific level and it has nothing to do with the previous energy level. the difference between energy levels is calculated with deltaE= Efinal-...
- Wed Oct 18, 2017 2:22 pm
- Forum: DeBroglie Equation
- Topic: 1.37 [ENDORSED]
- Replies: 5
- Views: 751
Re: 1.37 [ENDORSED]
Hi
I think their masses would be given on a separate sheet attached to the exam paper.
I think their masses would be given on a separate sheet attached to the exam paper.
- Thu Oct 12, 2017 4:18 pm
- Forum: Einstein Equation
- Topic: Einstein
- Replies: 4
- Views: 584
Re: Einstein
Hi
Einstein discovered the concept of the photon however Gilbert Lewis, an american chemist, named it photon.
Einstein discovered the concept of the photon however Gilbert Lewis, an american chemist, named it photon.
- Thu Oct 12, 2017 4:01 pm
- Forum: Properties of Light
- Topic: Prefix Conversion
- Replies: 12
- Views: 1310
Re: Prefix Conversion
Hi
I tend to convert all the units into SI units or to common chemistry units ( s , m, g) before trying to solve the problem. After the problem has been solved, I convert them back to the desired units in the problem.
I tend to convert all the units into SI units or to common chemistry units ( s , m, g) before trying to solve the problem. After the problem has been solved, I convert them back to the desired units in the problem.
- Thu Oct 05, 2017 9:11 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: E. 23
- Replies: 5
- Views: 1804
Re: E. 23
you have 3.00 grams of CuBr2 with the molar mass of 223.35. by dividing them you get the moles of CuBr2 available. each mole of CuBr2 has 1 mole of Cu ions.
therefore the number of moles of CuBr2 equal the number of moles of Cu ions .
therefore the number of moles of CuBr2 equal the number of moles of Cu ions .
- Thu Oct 05, 2017 9:00 pm
- Forum: Limiting Reactant Calculations
- Topic: L39 .. I don't understand it. May someone please explain it to me?! Thank You.
- Replies: 2
- Views: 1636
Re: L39 .. I don't understand it. May someone please explain it to me?! Thank You.
By subtracting 26.45 from 28.35 ( 28.35-26.45=1.90) you will have the actual grams of product formed. you already know that the product is made of tin ( Sn) and Oxygen. with the initial amount of tin available ( 1.50g) you can determine the moles of tin available and produced. we have 1.90 grams of ...