Questions tagged [homework]

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301 views

Isomers of co-ordination compounds

Does $\ce{[Co(H2O)3Br3]}$ show geometrical and optical isomerism? According to me $\ce{Co}$ should be $\mathrm{sp^3d^2}$ hybridised giving an octahedral geometry. It is of the form $\ce{Ma3b3}$ type. ...
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2answers
2k views

Plot Binary Eutectic from Temperature of Melting and Enthalpy

I'm a little confused about plotting a binary eutectic diagram (temperature vs mole fraction), and finding the eutectic point. I understand the eutectic point is the lowest temperature that a mixture ...
2
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1answer
8k views

Hybridization of tetraamminecopper(II) sulfate

$\ce{Cu^2+} $ has 9 electrons and a d-orbital and is almost completely filled (except 1 electron vacant) and $\ce{NH3}$ donates an electron eventually forming $\mathrm{sp^3}$ hybrid orbitals. But it ...
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2answers
26k views

How to calculate the concentration of all relevant species in a buffer of a given pH?

You prepare $1.0~\mathrm{L}$ of a $0.25~\mathrm{M}$ acetic acid solution with a final $\ce{pH}$ of $6.0$. What are the molar concentrations of all relevant acetic acid species ($[\ce{HA}]$ and $[\ce{A-...
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2answers
2k views

When is rotation around double bonds to form cis-trans isomers allowed?

The Rhodopsin molecules in the retain contain a derivative of vitamin A called cis-retinal (Figure 6). On exposure to light, cis-retinal becomes an isomer called trans-retinal (Textbook Question). ...
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2answers
370 views

Significant Figures in almost-scientific notation

For a homework assignment on significant digits, I have to find the number of significant digits in the number $0.40 \times 10^3$. I know that in scientific notation, the number of significant digits ...
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2answers
1k views

Using sigfigs when measuring with an instrument with marks other than powers of ten?

If an instrument does have markings that are powers of ten, then finding the precision of the instrument is easy. For example, if a graduated cylinder had markings for every 0.1mL, or every mL, or ...
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1answer
32k views

Calculating the molar mass of a solute from freezing point

A $\pu{4.305 g}$ sample of a nonelectrolyte is dissolved in $\pu{105 g}$ of water. The solution freezes at $\pu{-1.23^\circ C}$. Calculate the molar mass of the solute. $k_f$ for water is $\pu{1.86 C/...
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1answer
941 views

Molarity to Percent, Mole Fraction, Molality

I have a series of questions similar to the following. I want to make sure I do this correct before I do the others. I am in need of a hint. ...
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1answer
10k views

When Z>1 are repulsive forces dominant or are attractive forces dominant?

According to PVreal = ZRT If z >1 repulsive forces are dominant or are attractive forces? Different teachers are telling contradictory answers and after referring a few books, I have become more ...
2
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1answer
177 views

How is the Rate Law of a reaction measured?

What is Rate Law of the reaction below?$$\ce{4 HBr + O2 -> 2 H2O + 2 Br2}$$ How do we approach finding the rate law of reaction? Can this be found out only through experiments?
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1answer
3k views

Absolute configuration when hydrogen (lowest priority group) is in the plane of the page (and not a wedge or dash)

I have learnt that: Our absolute configuration is R(if clockwise) or S(if anticlockwise) when we rank the priorities, when the hydrogen (or other lowest priority group) is at the rear i.e. into the ...
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1answer
134 views

Finding moles of different compounds using balancing

$$\ce{K2Cr2O7 + $x$\,H2SO4 + $y$\,SO2 -> Cr2(SO4)3 + K2SO4 + $z$\,H2O}$$ For $\ce{Cr}$ change in oxidation number is: $+12$ becomes $+6$ For $\ce{S}$ change in oxidation number is: $+4y$ becomes ...
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1answer
126 views

How should I construct the orbitals of dilithium using only pen and paper?

For a week I have lessons about quantum chemistry and I have a trouble understanding how to arrive at the good answer for the drawing of the orbital $(\ce{III})$ for $\ce{Li2}$ (see the second picture)...
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1answer
3k views

What to do when there is an odd number of valence electrons left on the the central atom?

For example, I'm trying to write the formula for $\ce{NO}$, and $\ce{ClO2}$. The steps my teacher gave me always assume that the central atom has a full valence, or more than full, after the outer ...
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2answers
3k views

Volume change inside a balloon upon decreasing the the outer pressure

A balloon is filled with hydrogen at room temperature. It will burst if pressure exceeds 0.2 bar. If at 1 bar pressure the gas occupies 2.27 L volume, upto what volume can the balloon be expanded? ...
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2answers
702 views

Naming rules and acidity of Cl2CHCH2COOH

How do we name $\ce{Cl2CHCH2COOH}$ ? Is seeing branched chain our number 1 priority so we name it 1,1-dichloro-3-propanoic acid? also Which is more acidic $\ce{Cl2CHCOOH}$ or $\ce{Cl2CHCH2COOH}$ ?...
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1answer
663 views

ph & pOH - Autoionization of Water

So I was learning about pH and pOH and it made sense. I looked at strong, weak acids & bases and learned that they dissociate completely in water. So then I moved on to water and learned about the ...
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0answers
643 views

Precipitation of citric acid by CaCl2 and Ca(OH)2? [closed]

I need to precipitate citric acid from an aqueous solution in the form of calcium citrate. There are, to my knowledge, two different methods of doing this: using $\ce{CaCl2}$ and which will react ...
2
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1answer
276 views

Kinetics of an irreversible bimolecular reaction

Assume the reaction $$\ce{A + B ->} \text{Products}$$ is of second order kinetics and that the rate constant is $k$. The differential equation is given by $$\frac{\mathrm d}{\mathrm dt} [\ce{A}] = -...
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1answer
18k views

Calculating pH: Weak Acid, Strong Base

This is a question that had me puzzled for quite a while. I feel that information is missing. A weak acid, $\ce{HA}$, $K_a = 1.0$ x $10^{-4}$, is titrated with $\ce{NaOH}$. At the equivalence point,...
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1answer
819 views

Why can't electrons be transferred using hydrogen ions?

I have a homework question that asks: Recognizing how oxidation and reduction occurs is essential for analyzing and understanding biochemical reactions. Which of the following methods would NOT be ...
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1answer
7k views

Solubility of calcium hydroxide determined by titration

For a lab I had to determine the solubility and $K_{sp}$ of $\ce{Ca(OH)2}$ by performing two different titrations. I am given the formula to find solubility in molarity it is as written below. ...
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4answers
426 views

Balancing the oxidative decomposition of FeS2

Doing some practice for the GRE next year. Please could you look at my working for this and tell me why I'm wrong? $$\ce{? FeS2 + ? O2 + ? H2O = ? Fe(OH)3 + ? H2SO4}$$ My working so far is: There ...
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1answer
7k views

Help balancing reaction between Iron (II) chloride and potassium phosphate

Very rusty with chemistry and looking to review some basics. Came across the following: Iron(II) chloride and potassium phosphate react. Write and balance the molecular, ionic, and net ionic ...
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4answers
7k views

How to find the empirical formula for an nitrogen oxygen compound from the given mass of nitrogen and the product?

$5.00~\mathrm{g}$ of nitrogen is completely converted into an oxide of nitrogen. The mass of the oxide formed is $19.3~\mathrm{g}$. The empirical formula of the oxide would be? My working: $$\ce{...
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1answer
264 views

What are the molecular orbitals of the hypothetical linear H₃⁺ molecule?

What would be the wave function of the lowest energy molecular orbital of a hypothetical linear H3+ molecule? According to the LCAO method, I feel the lowest energy MO will be 1s(A) + 1s(B) + 1s(C). ...
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1answer
10k views

Is glycerol/glycerin soluble in ethanol?

As titled, I wish to know if glycerol/glycerin is soluble in ethanol (not soluble, slightly soluble, very soluble)
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2answers
2k views

Why are more electronegative atoms better leaving groups?

My book says, "halide anions are electronegative and can easily stabilise negative charge, hence are good leaving groups." 1) what exactly does "stabilising negative charge" mean? I have read: " ...
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1answer
1k views

Equilibrium constants for parallel reactions

So, I am attempting to calculate the equilibrium constant for two separate reactions. A+B<--->C+D and A+B<--->C+E I have figured out the final pressures at equilibrium for A, B, C, D, and E. I ...
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2answers
2k views

Determining boiling point on a created temperature scale

1.Assume that you construct a thermometer using gallium as the fluid instead of mercury, and that you define the melting point of gallium as 0 °G and the boiling point of gallium as 1000 °G. What is ...
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2answers
22k views

How to write equations for dissociation of ionic compounds in water?

Please write a dissociation-in-water equation for the compounds $\ce{BeI2}$ and $\ce{LiI}$. Make sure to add the states of matter after each compound. Currently, for $\ce{BeI2}$ I have the equation $$...
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2answers
16k views

How does the polarity of the eluent and sample affect the Rf value in thin layer chromatography?

A three-component mixture (X, Y, Z) was separated using normal phase TLC. Three eluents of varying polarity were used. Select the TLC plate that was developed using the least polar eluent (click on ...
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2answers
155 views

Predicting rate equations from data

I am having trouble wit the following question on my problem sheet: "The reaction $\ce{Br- + ClO^- \to BrO^- + Cl^-}$ occurs with a rate constant of $\text{0.35 dm}^3 \text{mol}^{-1} \text{s}^{-1}$ ...
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1answer
35k views

Metal vs. Styrofoam cup calorimeter?

For a metal cup as opposed to a styrofoam cup calorimeter, do you expect the enthalpy of the reaction to be higher, lower, or the same? I think the enthalpy of the reaction would be the same in the ...
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1answer
6k views

UV-Visible Spectroscopy in the analysis of sodium chloride in potato chips

Here is the question and answer out of an exam paper: Firstly, I thought UV-Visible can also use radiation in the visible spectrum. Also when analyzing sodium chloride (a molecule), then UV-Visible ...
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1answer
24k views

How to calculate molality, molarity and mole fraction given density (g/mole)?

Calculate the molality, molarity and mole fraction of a $\ce{CuSO4}$ in a 17% m/m aqueous solution (density of the solution is 1.367 g/mole) I did .17 * 1.367 to find grams of $\ce{CuSO4}$ and .83 * ...
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1answer
1k views

How do I calculate the enthalpy change when a gas is being used to heat water?

The question I'm trying to answer is: Calculate the mass of butane gas that would be needed to heat $724\ \mathrm{cm^3}$ of water from an initial temperature of $7.44\ \mathrm{^\circ C}$ to $50.7\ \...
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3answers
9k views

How do I calculate the pressure of a known liquid in a sealed container heated above boiling point?

If I have water in a sealed container heated to say 150 degrees, how do I determine the amount of pressure being generated in the container? What about for other liquids? I have searched extensively ...