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4 views

Measuring concentration of copper on a sample of tap water

Hi guys I need help with my uni assignment I would be ever so grateful if you could help thank you I need to measure the concentration if copper in a sample of tap water. So if you're provided with ...
-2
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0answers
12 views

concentrations and dilutions [on hold]

2) Make 250 mL of a 2.2% (m/v) NaCl solution.. Show all your work. A) How many grams of NaCl are needed to make 250 mL of a 2.2%(m/v) NaCl solution? B) 1 teaspoon contains approximately 11.0g ...
-2
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0answers
11 views

Solubility of Calcium [on hold]

The solubility of CaF(2) in a given temperature is : Ks= 3,2 . 10[-11] How many milligrams CaF(2) can be solved in 100 ml by this temperature.
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0answers
19 views

What is the electron configuration of the excited sulfur atom [on hold]

A valence electron in an atom of sulfur is excited by heating a sample. The electron jumps from the s orbital to the p orbital. What is the electron configuration of the excited sulfur atom, and what ...
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2answers
49 views

Can Henderson-Hasselbalch equation be used to determine the pH of a solution when a strong base and a strong salt of that base stay together?

The following problem I have stated was not given to me as a homework. I have found this one in my textbook. I have solved it in my own way, but I'm not sure about the correctness of my procedure. I ...
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0answers
13 views

Vapour pressure of water and ether [on hold]

At room temperature vapour pressure of water and ether are: a) different b) same c) zero d) none of these
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0answers
10 views

Crystallography - physical reason for ideal lattice approx

Why can we approximate a lattice as being infinite when we describe it as an ideal crystal? Is there any physical reason or is it just because the number of ions (/atoms) is so huge that we can treat ...
-3
votes
1answer
27 views

How to find the atomic mass of an element when the mass of the particular element is given? [on hold]

I would like know how to find the atomic mass of an element when the mass of the particular element is given. An example of such question would be An atom of an element weighs $5\times10^{-23}$. ...
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0answers
16 views

How can we explain the exceptions in the periodic table? [duplicate]

I notice that chromium, molybdenum, copper, silver, gold, and roentgenium have an incomplete $s$ sub-shell and I'm usually told that it's because of the energy levels. However, I know there's got to ...
-5
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0answers
27 views

Isotopes in mass spectrometer [on hold]

A sample of Chlorine gas has two isotopes, Cl-35 and Cl-37, in the approximate ratio of 3 atoms of Cl-35 to 1 atom of Cl-37, write the formulae of all the different ions/molecular ions produced in the ...
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0answers
23 views

Does 12 amu really equal the mass of one carbon-12 atom? [duplicate]

As I was studying chemistry, I encountered atomic mass units and based on some calculations, I realized that numbers don't work out: $$\text{12 amu= mass of a single carbon-12}$$ $$\text{atom = mass ...
-1
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0answers
15 views

chemical kinetics of TG analaysis [on hold]

Can some one help me figure out how to determine TG analysis Excel data for calculation activation energy?
2
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1answer
32 views

How many moles of sodium are there in 10mls of 30% sodium chloride?

How many moles of sodium are there in 10mls of 30% sodium chloride? 30% of 10mls is 3g NaCL. There is 3000mg of NaCl and would that be divided by the molecular weight of NaCl or of just Na? I ...
2
votes
0answers
48 views

Quadrupole moment of a molecule [on hold]

What is a quadrupole moment of a molecule and how does it arise? How is it measured for a particular molecule?
-1
votes
0answers
12 views

Dilution Factor [closed]

A laboratory has copper II sulfate solution S0 of molar concentration C0=1.0mol/L. The lab must prepare by diluting the solution S0, a solution S1 of volume V1=250mL and of molar concentration C1=0....
2
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0answers
15 views

Balancing by oxidation numbers method multiple atoms

In my Chemistry textbook, the rules for balancing a chemical equation using the Oxidation-Number method are as follows: Assign oxidation numbers to all atoms in the equation. Identify the atoms that ...
1
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0answers
23 views

Bond Energy of Ions of Molecular Oxygen

Three of the bond energies of $\ce{O2,\ O2^{-},\ O2^{2-},\ O2^+}$ have the values approximately $200, 490$ and $625\ \mathrm{kJ\ mol^{-1}}$. The value for one of the species is uncertain and, ...
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0answers
66 views

Paracetamol: does oxygen participate in the delocalization of p-orbitals

I'm analyzing the molecular structure of paracetamol and one of the things I have to do is to make a commentary about the delocalization of p-orbitals in this compound. Well I know that in the cyclic ...
0
votes
1answer
19 views

Why is it correct to assume a neutral amino acid is entered in this problem?

The questions is: $1.812\ \mathrm{g}$ of a crystallized α-amino acid ($\mathrm{p}K_\mathrm{a1} = 2.4, \mathrm{p}K_\mathrm{a2} = 9.7$) has a $\mathrm{pH}$ of $10.4$ when dissolved in $100\ \...
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0answers
16 views

Vapour Pressure related question [closed]

At 70°C, the vapour pressure of pure water is 39kPa. Which of the following is most likely vapour pressure for a 1.5M solution of Sucrose(aq) at the same temperature? A. 37kPa B. 39kPa C. 41kPa D. ...
3
votes
1answer
47 views

Haloform reaction in limited bromine

We were asked the reaction between 1 mole acetone and 1 mole $\ce{Br2}$ in basic medium. Since only a limited amount of bromine was given I got the final answer as 1-bromopropan-2-one (mono bromo ...
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2answers
60 views

Geometry of buta-1,3-dien-1-ol

Consider the molecular formula $\ce{CH2=CH-CH=CH-OH}$ $(\ce{C4H5OH})$. Tell the types of bond, hybridizations, bond angles and geometry of this compound. So I didn't have any trouble with the first ...
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0answers
45 views

Nature of Bond in Methylammonium lead Halide

I want to know about the nature of bond in Methylammonium Lead halide(CH3NH3PbX3),a perovskite compound.I went through wikipedia and many other sites and through certain research papers but I didn't ...
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votes
0answers
23 views

Empirical formula of a hydrate

I am trying to determine my unknown salt by looking at the percent of water. I'm thinking that I maybe did something wrong in the experiment but I ran two trials. Trial 1 mass hydrate in grams is 4....
2
votes
0answers
38 views

Which component decides what my pH will be in an aqeous solution?

I have an aqueous ammonium cinnamate solution of 0.5 M and want to know how I can calculate the pH of this solution. It is unclear to me which of the two components will have the upper hand as they ...
0
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0answers
40 views

What is the chemical formula of the compound manganic cyanide?

My teacher put this "manganic cyanide" on our nomenclature test, asking us to give the corresponding chemical formula. I do not know what it is even now, after the test. Please help, or assure me that ...
0
votes
1answer
30 views

Determine volume of Methane used to heat x water to x degrees?

I have 126.39L of water, what volume of methane gas would i need to combust to heat it (at room temp, 21 degrees Celsius) to 38 Degrees Celsius? How much CO2 gas would be produced? I calculated the ...
4
votes
1answer
45 views

Dissolving limestone in HCl and then neutralising the solution with NaOH

$15.0~\mathrm{mL}$ of $1.4~\mathrm{M}\ \ce{HCl}$ was mixed with $1.00~\mathrm{g}$ of limestone (impure $\ce{CaCO3}$) until all the solid had dissolved. The solution was then transferred to a conical ...
0
votes
1answer
26 views

How to find Mass fraction by given mass and density

I'm given the following details: $m$(salt) = 100g; $V$($\ce{H2O}$) = 500ml; $D$($\ce{H2O}$) = 1g/ml; The question is what is the mass fraction of salt in a mix of $\ce{H2O}$ and salt? In order to ...
0
votes
1answer
116 views

Explain why alumina-containing zeolites possess chemically active surfaces

I think zeolites possess acid sites that are catalytically active in many hydrocarbon reactions. The pore system only allows molecules that are small enough to enter, hence it affects the selectivity ...
3
votes
1answer
123 views

What is the mechanism for the reaction of an organic hydroperoxide with sulfuric acid?

The question asked to react the organic hydroperoxide substrate, $\ce{R-OOH}$, with dilute sulfuric acid, $\ce{H2SO4}$. In the last step, I removed a proton, making it act like a catalyst, along with ...
0
votes
1answer
29 views

Solubility of silver acetate in the presence of nitric acid

What will be the effect on the solubility of $0.1\ \mathrm{mol}$ of $\ce{CH3COOAg}$ in presence of $1\ \mathrm{l}$ of $0.1~\mathrm{M}\ \ce{HNO3}$ solution? $$K_\mathrm{sp} (\ce{CH3COOAg}) = 10^{-...
0
votes
1answer
62 views

Calculate the pH of Na2CO3

Given information: $K_\mathrm{a}(\ce{H2CO3}) = 4.3 \times 10^{-7}$, $K_\mathrm{a}(\ce{HCO3-}) = 4.8 \times 10^{-11}$, ${{\ce{[Na2CO3]}=0.20\ \mathrm{M}}}$ This was a question in an exam and I'm ...
0
votes
2answers
48 views

The reaction of copper(II) oxide and magnesium

Write an ionic equation for the reaction $$\ce{CuO + Mg -> Cu + MgO}$$ I know this a displacement reaction and I think the answer should be $$\ce{Cu + Mg^2+ -> Cu^2+ + Mg}$$ However, the ...
4
votes
0answers
94 views

Oxidation states of iron in Roussin's salts

For preservation of meat, sodium nitrite is usually added and as a result $\ce{NO}$ is, then,formed. Consequently, $\ce{NO}$ reacts with the sulphur and iron atoms from decomposition of proteins, ...
0
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1answer
43 views

Is aluminum nitrate a polyatomic?

In my book it talks about aluminum nitrate and copper (II) perchlorate. It is stated that: "In the chemical formula for aluminum nitrate and copper perchlorate, parenthesis followed by the ...
0
votes
1answer
43 views

How to determine the percentage of iron(II) and iron(III) in a solution?

Outline a plan of an experiment to determine the percentage of iron present as iron(III) in a solution containing $\ce{Fe^3+(aq)}$ and $\ce{Fe^2+(aq)}$ ions. You are provided with zinc, a standard ...
4
votes
1answer
26 views

Calculating Ratio of Stability Constants

Solution I contains a mixture of $\ce{FeCl2}$ and $\ce{FeCl3}$, and solution II contains a mixture of $\ce{K4Fe(CN)6}$ and $\ce{K3Fe(CN)6}$. The concentrations of iron-containing species satisfy the ...
0
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2answers
34 views

Good acids for removing rust for experiments

I'm planning to conduct an experiment in which I test how fast rusting occurs with changes to the concentration of NaCl in the solution. I want to measure that by finding the change in mass of an ...
0
votes
0answers
64 views

Decomposition of CaCO3 in a sealed vessel

For the equilibrium $$\ce{CaCO3(s) <=> CaO(s) + CO2(g)}$$ $\Delta H^\ominus = 178\ \mathrm{kJ\ mol^{-1}}$ and $\Delta S^\ominus = 160\ \mathrm{J\ mol^{-1}}$. I'm asked to suppose that $1\ \...
0
votes
1answer
35 views

NH3 : HNO3 - Titration problem

I am stuck with this question I am doing: To determine the ammonia ($\ce{NH3}$) concentration in a cleaning product, a chemist diluted 20 mL of the product to 500 mL. Of the 500 mL solution, 25 mL ...
3
votes
2answers
154 views

Titration problem

I am doing this titration question and am getting a different concentration to what it says in the answers. This is the question: $5.267~\mathrm{g}$ of $\ce{Na2CO3}$ was dissolved in $250.00\ \...
2
votes
2answers
51 views

Is the reaction of silver nitrate and copper endothermic or exothermic?

Is the following reaction endothermic or exothermic and why? $$\ce{2 AgNO3 + Cu -> Cu(NO3)2 + 2 Ag}$$ EDIT: I have a feeling that it is exothermic due to the fact that it is spontaneous and will ...
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0answers
15 views

Coagulation with Ferric Chloride

I'm having a hard time understanding the use of coagulation wastewater treatment. I have read in literature that ferric chloride is used as a coagulant to remove COD, TSS and Ammonia from landfill ...
1
vote
1answer
39 views

Finding pH using the -log, why does my calculation differ from the book's answer?

An aqueous solution containing 0.0020 mol/L barium hydroxide, what is the pH? I do the following: 14-(-log(0.0020))=11.3pH. The answer is 11.6. 2.0*10^-3 mol/L sodium hydroxide solution, what is the ...
0
votes
1answer
21 views

Does conductivity change in a solution due to rust?

I plan on conducting an experiment in which I place an iron nail in water and analyze its rate of corrosion into rust with different concentrations of NaCl. My original plan was to cover the water in ...
0
votes
1answer
14 views

Find molar concentration of sodium carbonate dissolved in water

The question is A solution of $\ce{Na2CO3}$ is made by dissolving $5.3~\mathrm{g}$ of the powder in enough water to make $250~\mathrm{mL}$ of solution. Find the molar concentration. I have done ...
0
votes
1answer
98 views

Is this reaction SN1, SN2, E1, or E2?

In the following question, which I tried to solve, I became confused by which way I should proceed. Here is my thought process: SN1: If Cl detaches and forms a secondary carbocation, then there's no ...
0
votes
1answer
41 views

Why is the production of aspirin considered a synthesis?

In chemistry, a synthesis reaction is a reaction in which multiple reactants combine to make one main product. However, when aspirin is produced, this is also considered a synthesis reaction even ...