Nodes
What is the minimum number of nodes that a binary tree can have?
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Acid-Base Theories
Hello, could someone explain the different acid-base theories and their uses?
I heard about a few theories, including the arrehenius acid base theory, bronsted-lowry theory, and lewis theory, and was wondering about their different aspects and significances.
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----v3=1.59·10-2
S=Ksp43=1.59·10-2
S is the concentration of ions in mol/L above which begins the formation of the precipitate. Knowing this, what should I do?
What is the concentration of 2% starch?
I am doing a lab report that asks what the concentration of 2% starch is and I do not know how to answer. please help. I think it was a 5ml solution if that helps. I do not know how to solve so I cannot provide any work. I measured the weight of one drop of starch (0.038g)
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 compounds may react with bromine but it will only require Chemistry that I've been taught). It doesn't contain a halogen or sulfur for the same reason. It burns with a smoky flame and is insoluble in water and HCl but dissolves in NaOH and forms bubbles (I haven't had time to set up lime water to check it's CO2) on addition to NaHCO3 so it's acidic.
It melts at approximately 132 degrees C.
I can't think of any compounds which fit the bill. I considered fumaric or maleic acid but my teacher made it clear that's wrong. He's also suggested there's a benzene ring, which fits with the smoky flame.
Any ideas??
Electrolysis of KBr
Use the standard reduction potentials to determine what is
observed at the cathode during the electrolysis of a 1.0 M
solution of KBr that contains phenolphthalein. What
observation(s) is(are) made?
O2(g) + 4 H+(aq) + 4 e– :rarrow: 2 H2O(l) E° = 1.23 V
Br2(l) + 2e– :rarrow: 2 Br–(aq) E° = 1.07 V
2 H2O(l) + 2 e– :rarrow: H2(g) + 2 OH– E° = –0.80 V
K+(aq) + e– :rarrow: K(s) E° = –2.92 V
(A) Solid metal forms.
(B) Bubbles form and a pink color appears.
(C) Dark red Br2(aq) forms.
(D) Bubbles form and the solution remains colorless.
The answer is (B). So I know that H2 gas and OH- are formed at the cathode, so that's where the pink color comes from. But what exactly forms at the anode? Is it Br2 gas? Why wouldn't it be Br2 liquid?
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 giving me headache, or I'am not confident with some of my answers, so any help is appreciated.
Questions:
1) When asked about how many particles of Hydrogen are in 1 gram of Hydrogen, one student said 6.02 × 1026, but another student said 5.97258 × 1026. Explain the difference of opinion and say who is correct (if any).
2) A lump of Iron weighing 111.7 grams was left in the rain and rusted to make Iron (III) Oxide. When it was weighed again it weighed 150 grams. Calculate how much of the iron reacted with oxygen. Show your working.
3) Given that HCl reacts with NaOH to make NaCl and H2O, what mass of HCl was used to make 29.22 grams of NaCl? Show your working. HCl + NaOH ? NaCl + H2O
4) Calculate the mass of CuSO4 needed to make 25 cm3 of a 0.1 mol dm-3 solution.
5) g) A 0.50g sample of potassium (V) iodate, KlO3 is dissolved in water and made up to 250cm3, a 25.0cm3 sample of this solution is added to an excess of Potassium Iodide in Sulphuric acid solution. The reaction is:
1O3- + 5l- + 6H+ ? 3l2 + 3H2O
The Iodine formed requires 20.0cm3 of Sodium thiosulphate solution for titration, the reaction is:
2Na2S2O3 + I2 ? Na2S4O6 + 2Nal
What is the concentration of the Sodium thiosulphate solution and how many molecules of Sodium thiosulphate is there in 20 cm3 of solution? Explain your answer.
I know it is unethical to just ask for answers, So I'am more than happy with any hints tips you have to set me in the right direction (And if you do answer them, can you explain how you got your answer so I can understand and learn, the assignment will be followed by an open book exam)
Methane Stoichiometry
Methane is a very powerful greenhouse gas. One pound of methane traps 25 times more heat in the atmosphere than a pound of carbon dioxide. Methane is also the main ingredient in natural gas. Because methane can be captured from landfills, it can be burned to produce electricity, heat buildings, or power garbage trucks. What volume of oxygen is necessary to completely react with 8.46 x 1019 molecules of methane gas, CH4 during combustion?
So I started with balancing the equation, which is CH4 + 2O2 :rarrow: CO2 + 2H2O
I think next I'm supposed to go from 8.46 x 1019 particles of methane gas (CH4) to moles of (CH4) to moles of oxygen to volume of oxygen. What I'm confused about is how I'm supposed to set the equation up and I would appreciate any help in doing so
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 complete this assignment (at school internet is free at home I have none so I need to use the library which is very far from home).
Some of the organic families have been done by me. Please help me out, you don't have to go out of your way to do this, just remembering some interesting molecule that belongs to one of the families mentioned below and posting it's name would be great.
Here is what I need:
Alkyl Halides: two molecule names and why they are unique/their application (cannot be Tetrafluoroethylene)
Aldehydes: three molecule names and why they are unique/their application
Esters: three molecule names and why they are unique/their application
Ethers: two molecule names and why they are unique/their application (not diethyl ether)
Amines: three molecule names and why they are unique/their application
Amides: three molecule names and why they are unique/their application
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 saturated solution all the salt(s) ,here PbSO4 5*10-4M, is dissociated...
Thanks!!!!!!