Search found 17 matches

by George
Fri Mar 10, 2017 1:59 pm
Forum: Introduction
Topic: Hello
Replies: 0
Views: 3738

Hello

Hello, I will be taking the California Civil Surveying exam in the spring.

I am just starting to study and sure I will have many questions to bounce off you all in the coming months.
by George
Thu Mar 09, 2017 10:54 am
Forum: Chemical Projects
Topic: Ksp problem
Replies: 0
Views: 1978

Ksp problem

How many mL of HCl 0.3M I must add to 5 mL di Pb(NO3)2 0.3M to start the precipitation of PbCl2, knowing that its Ksp is 1.62·10-5? From Ksp formula Ksp=[Pb2+]⋅[Cl−]2 Ksp=[Pb2+]⋅[Cl−]2 S=Ksp4−−−−√3=1.59⋅10−2 S=Ksp43=1.59⋅10−2 S is the concentration of ions in mol/L above which begins the formation o...
by George
Thu Mar 09, 2017 10:53 am
Forum: Chemical Projects
Topic: Unknown organic compound
Replies: 0
Views: 1717

Unknown organic compound

For my Advanced Higher Chemistry project (a piece of coursework in the last year of school) I'm trying to determine experimentally the identity of an unknown organic compound chosen by my teacher. It's a white odourless crystal. It decolourises bromine so it's unsaturated (I know some saturated comp...
by George
Thu Mar 09, 2017 10:49 am
Forum: Chemical Projects
Topic: Moles and Substances
Replies: 0
Views: 1848

Moles and Substances

Evening guys, I'am doing an independent assignment at the moment and could use some guidance on a few questions. We have had zero help in class, so we have to do our own research and seek help elsewhere. I'am just looking for help/advice and to be pointed in the right direction, a few questions are ...
by George
Thu Mar 09, 2017 10:46 am
Forum: Chemical Projects
Topic: Organic Molecules and Their Application
Replies: 0
Views: 1769

Organic Molecules and Their Application

Here is a chance to share some of your knowledge about certain types of organic molecules. Story: My partner decided to bail on me and leave this whole assignment to do by myself. I really need help because with the internet resource I have at my disposal is very limited and I was given one day to c...
by George
Thu Mar 09, 2017 10:43 am
Forum: Chemical Projects
Topic: saturated solution
Replies: 0
Views: 1705

saturated solution

I don't understand its meaning.... A saturated solution is a solution with also a precipitate?? Or only a solution without precipitate and with Q = ks ?? For example if I know that I have a saturated solutuion of PbSO4 5*10-4 M , can i say that [Pb2+] is 5*10^-4 ?? (that is equal to say that in a sa...
by George
Thu Mar 09, 2017 10:42 am
Forum: Chemical Projects
Topic: Free Energy Question
Replies: 0
Views: 1872

Free Energy Question

Hi, Hydrogen peroxide can be prepared in several ways. One method is the reaction between hydrogen and oxygen, another method is the reaction between water and oxygen. Given the ΔG°rxn values for each reaction, which method (reaction 1 or 2) requires less energy under standard conditions? 1. H2(gas)...
by George
Thu Mar 09, 2017 10:39 am
Forum: Chemical Projects
Topic: Precipitate with Si
Replies: 0
Views: 1858

Precipitate with Si

Elemental silicon is oxidized by O2 to give a compound which dissolves in molten Na2CO3. When this solution is treated with aqueous hydrochloric acid, a precipitate forms. What is the precipitate? (A) SiH4 (B) SiCO3 (C) SiO2 (D) SiCl4 The answer is (C). I'm just very confused about what happens here...
by George
Thu Mar 09, 2017 10:32 am
Forum: Chemical Projects
Topic: Conetration/Percent by mass
Replies: 0
Views: 1919

Conetration/Percent by mass

A solution is mad containing 22.8g of magnesium nitrate per 325g of water. What is the weight/weight % or percent by mass of the solute? I have tried twice to answer this and I don't seem to be getting it right. I know that for weight weight % you divide the two weights and then multiply by 100 to g...
by George
Thu Mar 09, 2017 10:09 am
Forum: Chemical Projects
Topic: Chemical Equilibrium: Position Shifts and Concentration Changes
Replies: 0
Views: 1764

Chemical Equilibrium: Position Shifts and Concentration Changes

Hi there, My questions are in relation to the following system: NaOH(s) <> Na (aq) + OH (aq) + energy When NaCl (or just Na) is added: i) Does the equilibrium shift to the left still despite the reactants being a solid? ii) Does the concentration of OH reduce as a result of the equilibrium shifting ...