# Questions tagged [homework]

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### 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 ...
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948 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. ...
13k 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 ...
136 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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### 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 ...
130 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)...
725 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 $\ce{Cl2CHCH2COOH}$ ?...
669 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 ...
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? ...
667 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 ...
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### 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,...
8k 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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### Mathematical form of four hybrid orbitals

The mathematical form of the four $\ce{sp^3}$ hybrid orbitals are given below. \begin{align} \ce{ \tag{a} sp^3 &= 1/2s + 1/2p_x + 1/2p_y + 1/2p_z\\ \tag{b} sp^3 &= 1/2s + 1/2p_x - 1/2p_y - 1/...
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### 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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### 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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### 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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$5.00~\mathrm{g}$ 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{... 1answer 11k 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) 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 ... 1answer 330 views ### What are the molecular orbitals of the hypothetical linear Hāāŗ 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). ... 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 ... 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 0Ā Ā°G and the boiling point of gallium as 1000Ā Ā°G. What is ... 1answer 25k 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 * ... 3answers 10k 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 ... 2answers 18k 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 ... 2answers 163 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} ... 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$$...
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\ \...