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How to calculate the mass of magnesium necessary to produce a certain volume of hydrogen gas?

How many grams of magnesium metal are required to produce 44.8 liters of hydrogen gas at STP according to the chemical equation shown below? (Answer: $48.6~\mathrm{g}$) $$\ce{Mg(s) + 2 HCl(aq) -> ...
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2answers
42k views

How to calculate the number of atoms of each element in a urea?

I have a stoichiometry question which I answered incorrectly and I am not sure where I went wrong. The question is as follows: Urea, $\ce{(NH2)2CO}$, is used for fertilizer and many other things. ...
2
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1answer
851 views

Equilibrium reaction ICE method to ideal gas law

The below equilibrium reaction takes place among the burnt exhaust gases still left inside the engine cylinder and being reused again for combustion. The author has specified the equilibrium between ...
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2answers
9k views

Air contain 20 % O2 by volume. How many cm³ of air will be required for oxidation of 100 cm³ of acetylene?

Air contain 20 % $\ce{O2}$ by volume. How many cm³ of air will be required for oxidation of 100 cm³ of acetylene? (a) 1064 cm³ (b) 212.8 cm³ (c) 500 cm³ (d) 1250 cm³ Answer: (d) My ...
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2answers
8k views

Is methyl orange acidic or basic?

It has been saying that if adding too much indicator in solution, the ph value of solution would be changed. From this, it can be saying that indicators have a pH value. Methyl orange is the indicator ...
3
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1answer
1k views

What is the standard heat of formation of the nitrate ion, based on the standard enthalpy of formation of silver nitrate?

Given the standard enthalpy of formation of $\ce{AgNO3(aq)} = -99 \text{ kJ/mol}$ and the standard enthalpy of formation of $\ce{Ag+(aq)} = +105 \text{ kJ/mol}$, what's the standard heat of formation ...
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3answers
4k views

Find the maximum temperature attained by the gas during the change

The main question is: 2 moles of an ideal gas is changed from its initial state $(16\ \mathrm{atm},\ 6\ \mathrm L)$ to final state $(4\ \mathrm{atm},\ 15\ \mathrm L)$ in such a way that this change ...
3
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2answers
17k views

How to calculate the percentage of calcium carbonate in sea shells in an experiment [closed]

We have a investigation in my chemistry class in which we must calculate the amount of calcium carbonate in sea shells. We can have as many sea shells as we wish, lab equipment, and hydrochloric acid ...
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2answers
1k views

Temperature Dependent Specific Heat of Nitrogen

Calculate the change in enthalpy as 1kg of nitrogen is heated from 1000K to 1500K, assuming the nitrogen is an ideal gas at a constant pressure. The tempreature dependent specific heat of nitrogen is ...
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2answers
2k views

Balancing a REDOX reaction using the oxidation number method, in acidic solution

I am trying to balance the REDOX equation shown below, but I got stuck after balancing the major atoms. Where can I go from here? I know I need to balance the H and O atoms, and make sure the charges ...
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4answers
60k views

How many valence electrons do elements in the d block have?

I just noticed that on the periodic table it doesn't say how many valence electrons there are for each column in the d block. How do I find out how many valence electrons elements in the d block have?...
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2answers
4k views

How to Prepare a Buffer Solution?

Problem I am given the task of preparing three buffer solutions at pH 10, 9.5, and 9.0. I have available concentrated ammonia and 3M hydrochloric acid. Attempt at Solving By adding HCl to a ...
3
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1answer
152 views

Nitration of aromatic compound with alkyl substituents

For 1,1,4,4-tetramethyl-1,2,3,4-tetrahydronaphthalene: What would be the products following a standard nitration with $\ce{NO2+}$? My reasoning is thus: Since the substituent group is alkyl then it ...
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3answers
3k views

Which of the compounds give the same SN1 and SN2 products?

I think answer (b) is correct but correct answer is (c). I think so as it is the only compound where C is not chiral. While in others racemic mixture in $\mathrm{S_N1}$ and enantiomer in $\mathrm{S_N2}...
4
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2answers
453 views

How does sugammadex (a modified cyclodextrin) draw rocuronium into its lipophilic cavity?

Sugammadex is a modified cyclodextrin: 8 member sugar ring with carboxyl thioether extensions. Rocuronium is an aminosteroid, 4 steroid rings and one protonated amine group. Sugammadex binds ...
3
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2answers
4k views

Ranking order of nucleophilicity

According to me the answer should be (c),(b),(a),(d). As we move left to right in a period the electronegativity increases and hence the tendency to donate electrons will decrease so nitrogen is ...
2
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2answers
29k views

Converting g/L to mol/L

I know I should divide $\mathrm{g~L^{-1}}$ by the molar mass of the substance, but I don't seem to find the specific answer on Google. So just to be sure: If I have $10^{-5}~\mathrm{g~L^{-1}}~\ce{Cu^...
3
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1answer
17k views

dsp3 and sp3d hybridization — what is the difference and which applies to square pyramidal?

What is the difference between dsp3 and sp3d Hybridization? Are they one in the same? Also, I have a book that says that in compounds where the central atom is dsp3 hybridized, it's shape is square ...
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3answers
19k views

Filling a buret tip before an experiment

I have a question that asks if the buret tip is not filled before the experiment what would happen (effect on molarity for acid/base titration). The way I'm thinking about it, it's not like you're ...
2
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2answers
193 views

Redox reaction terminology

In the case of this redox reaction: $ \ce{ Cu SO_4 + Zn → Zn SO_4 + Cu} $ Is it correct to say that the sulfate reduces to the zinc? Or is it the whole molecule that is reducing? Or just the copper? ...
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2answers
15k views

How does equilibrium change when the products are solid and gas?

$$\ce{CaCO3(s) <=> CaO(s) + CO2(g)}$$ How will the amount of each element change if the pressure is increased? My guess is that the equilibrium will shift to the left, because the right side ...
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1answer
576 views

Effect of an inert gas on steam vapor pressure at equilibrium

Suppose we have a closed container with mobile walls, so it will change its volume in order to equal the external pressure(constant) to the internal pressure. This container has inside it a liquid ...
3
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2answers
571 views

Confusion about the oxidation state of copper in copper cyanide redissolved with excess cyanide

$\ce{CuSO4}$ when reacts with $\ce{KCN}$ forms $\ce{CuCN}$ while it is insoluble in $\ce{H2O}$. It is soluble in excess of $\ce{KCN}$ due to the formation of the following complex: a) $\ce{K2[Cu(...
2
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3answers
4k views

What is the pKa of the second ionizable group?

One compound contains an amino group with $\mathrm{p}K_\mathrm{a}$ of $8.8$, and one other ionizable group with a $\mathrm{p}K_\mathrm{a}$ of $5$ to $7$. To $100\ \mathrm{mL}$ of a $0.2\ \mathrm{M}$ ...
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4answers
1k views

Liquification of gas to liquid at critical temperature

The gas that liquifies first, when cooled from 500 K to its critical temperature given in parenthesis is a) $\ce{CO2}$ (304.1 K) b) $\ce{NH3}$ (405.5 K) c) $\ce{O2}$ (154.3 K) d) $\...
4
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1answer
87 views

Finding ppm getting too big of numbers

I have a question that is to find the concentration of magnesium ion in ppm for a $0.025\ \%$ solution of $\ce{MgCl2}$. I can use this formula: $$\text{concentration in ppm} = \frac{\text{mass solute}...
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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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2answers
83 views

Hydrolysis of Radiolabeled Esters

Hydrolysis of C$_6$H$_5$COO$^{18}$CH$_3$ with aqueous NaOH produces what final product. (a) CH$_3$$^{18}$OH (b) CH$_3$CO$^{18}$ONa (c) CH$_3$C$^{18}$OONa (d) CH$_3$$^{18}$ONa (e) CH$_3$OH The ...
1
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1answer
935 views

Determine the isotope half-life?

A sample of $\ce{^{41}Ar}$, a radioisotope used to measure the flow of gases from smokestacks, decays initially at a rate of 34,500 disintegrations/min, but the decay rate falls to 21,500 ...
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2answers
2k views

Magnesium powder mixed with CuSO4 solution

$\ce{Mg}$ powder is stirred into $\ce{CuSO4}$, what is the balanced molecular equation for this reaction ? I have $\ce{Mg + CuSO4 -> Mg2SO4 + Cu}$. Also, is the ionic equation the same as the net ...
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2answers
804 views

Understanding how electrons are counted for lone pairs vs. bonds especially when understanding resonance?

This is taken from the book Organic Chemistry as a Second Language from page 35. In the following image: It is seen that when the electrons from the double bond are pushed into the lone pair ...
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2answers
1k views

Distinguishing pentanol isomers in 13C DEPT NMR spectroscopy

Pentanol has eight isomers as shown below. The circles represent carbon atoms that I think are equivalent. Below there are eight DEPT-spectra that should represent these eight substances. As you can ...
3
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1answer
3k views

Elimination of bromide and acetate under reducing conditions

Here is the reaction that I didn't find the mechanism of; maybe you can help: The conditions is zinc dust, when the solvent is acetic acid at 110°C 1h. the reagents are Sodium acetate, 2,3,4,5-...
5
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3answers
5k views

Why do the trends in reactivity not apply for francium?

Why is francium not included in the reactivity series? Why is potassium considered more reactive than francium? I know that reactivity increases down the group! But why does it not apply here?
3
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1answer
549 views

I am confused about the stability of carbanion III and IV in the image

I am confused about the stability of carbanion III and IV in the image, I think III is more unstable because of electron donating effect (+R) of -OCH3 group but my book says III is more stable than ...
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2answers
4k views

How to calculate the molar mass of a protein from its osmotic pressure?

I am unsure how to go about solving this question. I know how to get the osmotic pressure, but where do I go from there? I can't use the gas law since the protein is not a gas. $\pu{2.38 g}$ of a ...
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2answers
1k views

How are reactivity and dipole moment related?

Recently, I came across a question: which of the two compounds has a greater reactivity; $\ce{NH_{3}}$ or $\ce{NF_{3}}$? It is known that despite the same structure the dipole moment of $\ce{NH_{3}}$...
2
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2answers
3k views

Does 11.2 dm3 of nitrogen consist of 0.5 moles at STP?

Which of the following statements is true? $11.2~\mathrm{dm^{3}}$ of nitrogen at STP A: has a mass of $14\ \mathrm{g}$. B: consists of $0.5\ \mathrm{mol}$ atoms. My instinct was that the answer is ...
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2answers
2k views

Kinetic isotope effect in nitration of benzene

What is the effect of changing all the hydrogen atoms in benzene to deuterium? For example, which of the following reactions occurs at a faster rate?
2
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1answer
25k views

How to calculate the volume of a sodium hydroxide solution necessary to add to water, to raise the pH to a certain value?

What volume of 0.300N $\ce{NaOH}$ would be needed to bring $16.0~\mathrm{mL}$ of distilled water that has a pH of 7.00 to a new pH of 12.42? This is my attempt at a solution: $$\ce{NaOH + H2O-> ...
3
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2answers
12k views

Determining if reaction is endothermic or exothermic using equilbrium constant

For the following reaction: $$\ce{W_{(s)} + 4 Br_{(g)} <=> WBr4_{(g)}}$$ At 900 K, $K_\mathrm{p}=100$ and at 2800 K, $K_\mathrm{p}=5$. At higher temperatures, the equilibrium has shifted ...
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1answer
13k views

What does (heated) mean in a chemical equation?

I'm supposed to balance the following equation: $\text{Potassium chlorate (heated) --> Potassium chloride + Oxygen}$ But I don't understand what the (heated) means in front of the first element. ...
3
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2answers
10k views

What happens when C17H35COO-, a soap, reacts with an acidic solution?

My book says that in acidic water, the negative fatty acid ions become fatty acids. However, they did not include a chemical equation to demonstrate this, so I made my own: $$\ce{C17H35COO- (aq) + HCl ...
2
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1answer
66k views

How do I find the final temperature using specific heat?

What is the final temperature of water and iron if a $30~\mathrm{g}$ piece of iron at $144~\mathrm{°C}$ was dropped into a calorimeter with $40~\mathrm{g}$ of water at $20~\mathrm{°C}$? Specific heat ...
3
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1answer
7k views

Does solubility matter when measuring density with displacement method?

I thought I understood this, but I'm having some doubts now. My question is quite simple: Can the volume of a solid (specifically a granular crystal or powder) be accurately determined using the ...
2
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2answers
56k views

Calculate the pH of acetic acid for a 0.02 M solution

We have a solution $\ce{CH3COOH}$ (acetic acid) with $c=0.02~\mathrm{mol/L}$ and the of acetic acid, $K_A = 1.8\cdot10^{-5}$. Calculate the $\mathrm{pH}$ of this solution. I tried everything but I ...
3
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1answer
446 views

Reactivity and transport safety of substituted methyl benzoates

This was a practice question from an MCAT book whose answer I didn't really understand: The normal reactivity of methyl benzoate is affected by the presence of certain substituents. Which of the ...
0
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1answer
32k 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 ...
3
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1answer
541 views

What is the difference between these wave functions?

My chemistry textbook introduces the wave function as $$\psi(x)= A \sin\left(\frac{2\pi x}{\lambda}\right)$$ Therefore, the Schrödinger Equation is: $$\frac{d^2\psi(x)}{dx^2} = -~\left(\frac{...
4
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1answer
810 views

What is the structure of this molecule?

I need to find the Lewis structure of the ion $\ce{SCH^-}$. I think the Lewis structure should be: $\ce{S=C-H}$ with one lone pair on the carbon and two lone pairs surrounding the sulfur. Is this ...