## Search found 10 matches

Tue Mar 14, 2017 5:40 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: 2014 Final 1C
Replies: 3
Views: 546

### Re: 2014 Final 1C

I believe there are 3 sig figs in the answer because at one point in the equation, there is adding/subtracting, which has different sig fig rules from multiplying/dividing. When dealing with addition/subtracting, you take the smallest number of decimal places which will be 3 sig figs, so when you di...
Mon Mar 13, 2017 11:41 pm
Forum: Balancing Redox Reactions
Topic: Final 2013 Q3A
Replies: 3
Views: 573

### Re: Final 2013 Q3A

That makes it so clear! Thank you
Mon Mar 13, 2017 11:26 pm
Forum: Balancing Redox Reactions
Topic: Final 2013 Q3A
Replies: 3
Views: 573

### Final 2013 Q3A

Given the redox reaction: HClO_2(aq) + Cr^+3 _(aq) \rightarrow HClO_(aq) + Cr_2O_7 ^-2 _(aq) We are asked to write the two half reactions and balanced equation for the above redox reaction. Just to be sure, do we balance the equation after writing the half reactions b...
Thu Mar 02, 2017 12:16 pm
Forum: *Alkanes
Topic: Naming with dimethyl groups
Replies: 1
Views: 336

### Re: Naming with dimethyl groups

I believe so yes, since the 2,3 indicate on which carbon the methyl groups are attached.
Sun Feb 19, 2017 10:47 pm
Forum: First Order Reactions
Topic: Homework 15.23
Replies: 1
Views: 390

### Re: Homework 15.23

Hi Bridget! The solution uses the equation [A] t =.153(mol A)L^-1 - [(2 mol B/1 mol A)(0.034 mol B/1)] to find the concentration of t after the 115 seconds. This method works because it uses the the value of B after the 115 seconds. Using stoichiometry, it converts the amount that B rises after the ...
Sun Feb 12, 2017 9:31 pm
Forum: Balancing Redox Reactions
Topic: Half Reactions
Replies: 2
Views: 350

### Re: Half Reactions

To add onto the previous answer, there are also other trends that I've seen that help to find the oxidation number. For example, for elements in compounds, Group 1 have +1 charge, group 2 +2, group 17 -1, group 16 -2. Transition metals are usually the elements that have varying oxidation numbers, an...
Sun Feb 05, 2017 7:57 pm
Forum: Balancing Redox Reactions
Topic: What is the purpose of a salt bridge?
Replies: 3
Views: 4839

### Re: What is the purpose of a salt bridge?

You can refer to Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams > Salt Bridge ( https://lavelle.chem.ucla.edu/forum/viewtopic.php?f=140&t=18869&sid=6884801e75457b00373c75298282c157 ) since chem_mod gave a detailed explanation of it. But basically, a salt bridge a...
Sun Jan 29, 2017 11:00 pm
Forum: Phase Changes & Related Calculations
Topic: Significance of State Functions
Replies: 1
Views: 271

### Significance of State Functions

Apologies if this was asked before, but what is the importance of something being a state function? I know that for a state function like enthalpy or Gibbs free energy the path to get where it is doesn't matter, but why does that matter? Is it because these functions are state functions that we can ...
Sun Jan 22, 2017 7:47 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 8.75b HOMEWORK PROBLEM
Replies: 2
Views: 327

### Re: 8.75b HOMEWORK PROBLEM

It might be easier to understand/visualize the breaking/bonding aspects of the question by drawing out the lewis structures for the problem. When you draw the lewis structures for the reaction, you can see where new bonds form in the product and where bonds break in the reactants. Like the previous ...
Sat Jan 14, 2017 11:55 pm
Forum: Calculating Work of Expansion
Topic: Reversible and Irreversible Processes
Replies: 2
Views: 300

### Reversible and Irreversible Processes

Can someone clarify the importance of reversible processes in chemistry and work? I understand the difference of reversible and irreversible processes in that the former can be reversed by a infinitely small change in a variable but I can't see the connection to its significance in work.