Answer:
The empirical formulae for the compound is CH3.
In a reversible reaction, the endothermic reaction absorbs ____________ the exothermic reaction releases. A. less energy than B. None of these, endothermic reactions release energy C. the same amount of energy as D. more energy than
Answer: C. the same amount of energy as
Explanation:
A reversible reaction is a chemical reaction where the reactants form products that, in turn, react together to give the reactants back.
Reversible reactions will reach an equilibrium point where the concentrations of the reactants and products will no longer change.
[tex]A+B\rightleftharpoons C+D[/tex]
Thus if forward reaction is exothermic i.e. the heat is released , the backward reaction will be endothermic i.e. the heat is absorbed and in same amount.
The amount of energy released will be equal and opposite in sign to the energy absorbed in that reaction.
Answer:
C.) the same amount of energy as
Explanation:
I got it correct on founders edtell
Assuming 100% dissociation, which of the following compounds is listed incorrectly with its van't Hoff factor i? Al2(SO4)3, i = 4 NH4NO3, i = 2 Mg(NO3)2, i = 3 Na2SO4, i = 3 Sucrose, i = 1
Answer:
- Aluminium sulfate Al2(SO4)3 dissociates in two aluminium ions and three sulfate ions, therefore, van't Hoff factor is 5 (incorrect).
Explanation:
Hello,
In this case, since the van't Hoff factor is related with the species that result from the ionization of a chemical compound, we can see that that
- Aluminium sulfate Al2(SO4)3 dissociates in two aluminium ions and three sulfate ions, therefore, van't Hoff factor is 5 (incorrect).
- Ammonium nitrate NH4NO3 dissociates in one ammonium ions and one nitrate ion, therefore, van't Hoff factor is 2 (correct).
- Sodium sulfate Na2SO4 dissociates in two sodium ions and one sulfate, therefore, van't Hoff factor is 3 (correct).
- Sucrose is not ionized, therefore, van't Hoff factor is 1 (correct).
Best regards.
Determine the oxidation state for each of the elements below. The oxidation state of ... silver ... in ... silver oxide Ag2O ... is ... ___ . The oxidation state of sulfur in sulfur dioxide SO2 is ___ . The oxidation state of iron in iron(
Answer:
The oxidation state of silver in [tex]\rm Ag_2O[/tex] is [tex]+1[/tex].
The oxidation state of sulfur in [tex]\rm SO_2[/tex] is [tex]+4[/tex].
Explanation:
The oxidation states of atoms in a compound should add up to zero.
Ag₂OThere are two silver [tex]\rm Ag[/tex] atoms and one oxygen [tex]\rm O[/tex] atom in one formula unit of [tex]\rm Ag_2O[/tex]. Therefore:
[tex]\begin{aligned}&\rm 2 \times \text{Oxidation state of $\rm Ag$}+ \rm 1 \times \text{Oxidation state of $\rm O$} = 0\end{aligned}[/tex].
The oxidation state of oxygen in most compounds (with the exception of peroxides and fluorides) is [tex]-2[/tex]. Silver oxide [tex]\rm Ag_2O[/tex] isn't an exception. Therefore:
[tex]\begin{aligned}&\rm 2 \times \text{Oxidation state of $\rm Ag$}+ \rm 1 \times \text{Oxidation state of $\rm O$} = 0\\ &\rm 2 \times \text{Oxidation state of $\rm Ag$}+ \rm 1 \times (-2) = 0\end{aligned}[/tex].
Solve this equation for the (average) oxidation state of [tex]\rm Ag[/tex]:
[tex]\text{Oxidation state of $\rm Ag$} = 1[/tex].
SO₂Similarly, because there are one sulfur [tex]\rm S[/tex] atom and two oxygen [tex]\rm O[/tex] atoms in each [tex]\rm SO_2[/tex] molecules:
[tex]\begin{aligned}&\rm 1\times \text{Oxidation state of $\rm S$}+ \rm 2 \times \text{Oxidation state of $\rm O$} = 0\end{aligned}[/tex].
The oxidation state of [tex]\rm O[/tex] in [tex]\rm SO_2[/tex] is also [tex]-2[/tex], not an exception, either.
Therefore:
[tex]\begin{aligned}&\rm 1 \times \text{Oxidation state of $\rm S$}+ \rm 2 \times \text{Oxidation state of $\rm O$} = 0\\ &\rm 1 \times \text{Oxidation state of $\rm S$}+ \rm 2 \times (-2) = 0\end{aligned}[/tex].
Solve this equation for the oxidation state of [tex]\rm S[/tex] here:
[tex]\text{Oxidation state of $\rm S$} = 4[/tex].
Using the following diagram, determine which of the statements below is true: The activation energy for the forward reaction is −60 J. The overall energy change for the forward reaction is −20 J. The activation energy for the reverse reaction is −80 J. The overall energy change for the reverse reaction is −40 J.
Answer:its saturated or unsaturaded
Explanation:
What type of chemist exclusively studies most carbon compounds?
-biochemist
-physical chemist
-organic chemist
-inorganic chemist
Answer:
Organic chemist? I do not know.
Explanation:
Thanks you.
The type of chemist exclusively studies most carbon compounds are organic chemist. Therefore, option C is correct.
What is an organic chemist ?The structure, characteristics, and reactivity of compounds containing carbon are studied by organic chemists. Additionally, they create novel organic materials with distinct features and uses.
Analytical capabilities, communication skills, and numeracy skills are three of the most important soft skills for an organic chemist.
Organic chemists often work in research and development in labs at universities, pharmaceutical, industrial, and biotechnology businesses, as well as government agencies, according to the American Chemical Society.
According to one assessment, organic chemistry is the hardest college course. According to certain statistics, almost one out of every two students in organic chemistry leave the course. The hopes of a medical career come tumbling down for those who fit this description. Organic chemistry is undoubtedly challenging.
Thus, option C is correct.
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Cite examples of how copper deposits occur. Choose one or more: A. as an agglomeration metal B. as a native metal C. in carbonate ore minerals D. in sulfide ore minerals
Answer:
A. as an agglomeration metal
B. as a native metal
D. in sulfide ore minerals
Explanation:
Copper is a metal with symbol Cu and atomic number 29. It has a pinkish-orange color and is malleable, ductile and has a high thermal and electrical conductivity. This is why it is often used in electrical appliances.
Copper exists as an agglomeration metal, as a native metal or in sulfide ore minerals such as Cu2S.
The examples of copper deposits are agglomeration metal, as a native metal or in sulfide ore minerals. Option A, B, and D are correct.
Copper is a metal with high thermal and electrical conductivity. hence, it is often used in electrical appliances.
Copper found as an agglomeration metal, as a native metal or in sulfide ore minerals such as [tex]\bold { Cu_2S.}[/tex]
Therefore, the examples of copper deposits are agglomeration metal, as a native metal or in sulfide ore minerals. Option A, B, and D are correct.
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The change in entropy for the surroundings in a situation where heat flows from a hotter system to a cooler surrounding is: ________
a. Greater than zero
b. Less than zero
c. Equal to zero
d. Impossible to predict
Answer:
A
Explanation:
The change in entropy for the surroundings in a situation where heat flows from a hotter system to a cooler surrounding is Greater than Zero.
Here the randomness of the molecules increase as the temperature of the surrounding increases.( it absorbs heat from the system).
Answer:
Option a (Greater than zero) is the correct answer.
Explanation:
The entropy transition can sometimes be due to something like the reconfiguration of atom or molecule through one sequence to the next. In the substances, there would be a corresponding increase throughout entropy mostly during response unless the compounds are still very much abnormal compared with the reaction mixture.Some other three choices don't apply to either the situations in question. And the correct approach will be Options A.
Please help, Which molecule is shown below
Answer:
Option B. 3–methylheptane.
Explanation:
To obtain the name of the compound given in the question above, we must
1. Determine the functional group of the compound.
2. Locate the longest continuous carbon chain. This gives the parent name of the compound.
3. Identify the substituent groups attached.
4. Locate the position of the substituent group attached by giving it the lowest possible count.
5. Combine the above to obtain the name.
Now let us name the compound given in the question above.
1. The compound is an alkane since it contains only single bond.
2. The longest continuous carbon chain is 7. Hence the parent name I the compound is heptane.
3. The substituent group attached is
—CH3 i.e methyl.
4. The substituent group attached is at carbon 3.
5. Therefore, the name of the compound is:
3–methylheptane.
volume of percentage =
formula??
Answer:
Volume percent is defined as: v/v % = [(volume of solute)/(volume of solution)] x 100%
Explanation:
A certain covalent compound is named sulfur hexafluoride. What's the chemical formula for this compound? A. F6S2 B. F6S C. S2F6 D. SF6
Answer: The sulphur hexafluoride will have a chemical formula of [tex]SF_6[/tex]
Explanation:
A covalent compound is a compound where the sharing of electrons takes place between two elements which are non-metals.
The naming of covalent compound is given by:
1. The less electronegative element is written first.
2. The more electronegative element is written second. Then a suffix is added with it. The suffix added is '-ide'.
3. If atoms of an element is greater than 1, then prefixes are added which are 'mono' for 1 atom, 'di' for 2 atoms, 'tri' for 3 atoms and so on.
Thus sulphur hexafluoride will have a chemical formula of [tex]SF_6[/tex]
Answer:
D. sf6
Explanation:
Please tell the answer
Answer:
see the photo
Explanation:
it was the answer
Match the words below to the appropriate blanks in the sentences. Make certain each sentence is complete before submitting your answerβ-1,4- and α-1,6-glycosidicβ-1,4-glycosidicgalactosean unbranchedglucosea branchedfructoseα-1,6-glycosidicAmylose is ......... polymer of ....... units joined by ........ bonds. Amylopectin is ....... polymer of .......units joined by ........ bonds.
The words given are not clear, so the clear question is as follows:
Match the words below to the appropriate blanks in the sentences. Make certain each sentence is complete before submitting your answer:
A. β-1,4- and α-1,6-glycosidic
B. α-1,4-glycosidic
C. α-1,4-galactose
D. an unbranched glucose
E. a branched fructose
F. α-1,6-glycosidic
Amylose is ......... polymer of ....... units joined by ........ bonds.
Amylopectin is ....... polymer of .......units joined by ........ bonds.
Answer:
D. an unbranched glucose
C. α-1,4-galactose
B. α-1,4-glycosidic
E. a branched fructose
A. β-1,4- and α-1,6-glycosidic
F. α-1,6-glycosidic
Explanation:
Amylose and amylopectin are two types of polysaccharides that can be found in starch granules.
Amylose is linear or unbranched glucose polymer of α-1,4-galactose units that are joined by α-1,4-glycosidic.
Amylopectin is a branched fructose polymer of β-1,4- and α-1,6-glycosidic units joined by α-1,6-glycosidic bonds.
Hence, the correct answers in the sequential order are:
Amylose:
D. an unbranched glucose
C. α-1,4-galactose
B. α-1,4-glycosidic
Amylopectin:
E. a branched fructose
A. β-1,4- and α-1,6-glycosidic
F. α-1,6-glycosidic
Chemistry
What is a chemical reaction
Answer:
A process that involves rearrangement
Explanation:
A chemical reaction is the process that involves rearrangement of the molecular or ironic structure of a substance, as a distinct from a change in physical form or a nuclear reaction.
Answer:
Explanation:
Chemistry
The chemical reaction H2(g) + ½ O2(g) → H2O(l) describes the formation of water from its elements.
The reaction between iron and sulfur to form iron(II) sulfide is another chemical reaction, represented by the chemical equation:
8 Fe + S8 → 8 FeS
Any process with a negative change in enthalpy and a positive change in entropy will be:_______.
a. spontaneous
b. nonspontaneous
c. spontaneous at high temperatures
d. spontanteous at low temperatures
Answer:
a. spontaneous
Explanation:
Hello,
In this case, since the Gibbs free energy is a metric that allows us to know whether a chemical reaction is spontaneous (Gibbs free energy less than 0) or nonspontaneous (Gibbs free energy greater than 0) we can mathematically define it as:
[tex]\Delta G=\Delta H-T\Delta S[/tex]
Thus, if the enthalpy is negative and the entropy is negative, the subtraction become always negative, for which the Gibbs free energy is negative as well, therefore, based on the aforementioned, any process with a negative change in enthalpy and a positive change in entropy will be: a. spontaneous.
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3. What is the mass of an object with a volume of 4 L and a density of 1.25 g/mL?
Answer:
5000g
Explanation:
mass= density × volume
Since the unit of density here is g/mL, we need to convert the volume to mL.
1L= 1000mL
4L= 4 ×1000 = 4000 mL
Mass of object
= 1.25 ×4000
= 5000g
Answer:
5,000 grams
Explanation:
The mass of an object can be found by multiplying the volume by the density.
mass= volume * density
The density is 1.25 g/mL and the volume is 4 L.
First, we must convert the volume to mL. The density is given in grams per milliliter, but the volume is given in liters.
There are 1,000 mL per L. The volume is 4 L. Therefore, we can multiply 4 and 1,000.
4 * 1,000 = 4,000
The volume is 4,000 mL.
Now, find the mass of the object.
mass= volume * density
volume = 4,000
density= 1.25
mass= 4,000 * 1.25 = 5,000
Add the appropriate units for mass, in this case, grams, or g.
mass= 5,000 g
The mass of the object is 5,000 grams.
Heterocyclic aromatic compounds undergo electrophilic aromatic substitution in a similar fashion to that undergone by benzene with the formation of a resonance-stabilized intermediate. Draw all of the resonance contributors expected when the above compound undergoes bromination
Answer:
See explanation
Explanation:
When we talk about electrophilic substitution, we are talking about a substitution reaction in which the attacking agent is an electrophile. The electrophile attacks an electron rich area of a compound during the reaction.
The five membered furan ring is aromatic just as benzene. This aromatic structure is maintained during electrophilic substitution reaction. The attack of the electrophile generates a resonance stabilized intermediate whose canonical structures have been shown in the image attached.
(a) Identify the name of the method used below for the separation.
(b) Give one more application of this method of separation.
(c) What is the name for the line at position B ?
(d) what conclusions can you draw about the colours present in sweets C and D ?
Answer:
(a) Chromatography
(b) DNA fingerprinting
(c) Origin
(d) Sweet C consists of more colours than sweet D.
ii. The speed of colours in sweet C are proportional to one another, while that of colours in D is not.
Explanation:
Chromatography is one of the physical method of separating mixtures. This process composed of the ability of the constituents in a mixture to separate by virtue of rate of movement through a medium, thus separates into constituents.
It can be used to determine the soluble constituents of a given mixture. And for purification purpose.
g A chemist combines 59.9 mL of 0.282 M potassium bromide with 15.4 mL of 0.512 M silver nitrate. (a) How many grams of silver bromide will precipitate
Answer:
[tex]m_{AgBr}=1.48gAgBr[/tex]
Explanation:
Hello,
In this case, the undergoing chemical reaction is:
[tex]KBr(aq)+AgNO_3(aq)\rightarrow AgBr(s)+KNO_3(aq)[/tex]
Thus, since the potassium bromide and silver nitrate are in a 1:1 mole ratio, the first step is to identify the limiting reactant, by considering the reacting volumes of reactants in order to compute the available moles of potassium bromide and the moles of potassium bromide consumed by the 15.4 mL of 0.512-M solution of silver nitrate:
[tex]n_{KBr}=0.0599L*0.282\frac{molKBr}{L} =0.0169molKBr\\\\n_{KBr}^{consumed}=0.0154L*0.512\frac{molAgNO_3}{L} *\frac{1molKBr}{1molAgNO_3}=0.00788molKBr[/tex]
In such a way, since less moles are consumed than available, we infer that silver nitrate is the limiting reactant, for which the resulting grams of silver bromide (molar mass 187.8 g/mol) result:
[tex]m_{AgBr}=0.00788molAgNO_3*\frac{1molAgBr}{1molAgNO_3} *\frac{187.8gAgBr}{1molAgBr} \\\\m_{AgBr}=1.48gAgBr[/tex]
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Account for the change when NO2Cl is added using the reaction quotient Qc. Match the words in the left column to the appropriate blanks in the sentences on the right.
1. decreases
2. loss
3. Increases
4. greater
A. Disturbing the equilibrium by adding NO2Cl______Qc to a value_____than Kc.
B. To reach a new state of equilibrium, Qc therefore______which means that the denominator of the expression for Qc______.
C. To accomplish this, the concentration of reagents______, and the concentration of products_______.
Answer:
A. Disturbing the equilibrium by adding NO2Cl decreases Qc to a value less than Kc.
B. To reach a new state of equilibrium, Qc therefore increases which means that the denominator of the expression for Qc decreases.
C. To accomplish this, the concentration of reagents decreases, and the concentration of products increases.
Explanation:
Hello,
In this case, for the equilibrium reaction:
[tex]NO_2Cl(g)+NO(g)\rightleftharpoons NOCl(g)+NO_2(g)[/tex]
Whose equilibrium expression is:
[tex]Kc=\frac{[NO_2][NOCl]}{[NO_2Cl][NO]}[/tex]
The proper matching is:
A. Disturbing the equilibrium by adding NO2Cl decreases Qc to a value less than Kc, since the denominator becomes greater, therefore, Qc decreases.
B. To reach a new state of equilibrium, Qc therefore increases which means that the denominator of the expression for Qc decreases, since the lower the denominator, the higher Qc as it has the concentration of reactants.
C. To accomplish this, the concentration of reagents decreases, and the concentration of products increases, since the reactants must be consumed in order to reestablish equilibrium by shifting the reaction towards the products.
Best regards.
There are 2.4g of calcium hydroxide reacted with nitric acid. Calculate the number of moles of calcium hydroxide used. Write your answer using proper significant digits and units. Show all your work.
Answer:
0.032 moles
Explanation:
no of moles =
[tex] \frac{mass \: in \: grams}{relative \: molecular \: mass} [/tex]
=
[tex] \frac{2.4}{40 + 32 + 2} [/tex]
= 0.032
Calcium hydroxide reacted with nitric acid the total number of moles will be 0.032 moles.
What is a mole?
A mole is Avogadro's number of particles, which is exactly 6.02214076×1023.
The mole is widely used in chemistry as a convenient way to express amounts of reactants and products of chemical reactions. For example, the chemical equation 2H2 + O2 → 2H2O can be interpreted to mean that for each 2 mol dihydrogen (H2) and 1 mol dioxygen (O2) that react 2 mol of water (H2O) form.
Number of moles = Mass of substance / Mass of one mole Number of moles
mass of substance = 2.4g
molar mass of calcium hydroxide is (1 ×40.078g/mol Ca) +(2 × 15.999g/mol O) + (2 × 1.008g/mol H) = 74.092 g/mol Ca (OH)2
substituting the value,
number of moles = 2.4 / 74.029
= 0.032 moles
Therefore, moles of calcium hydroxide will be 0.032 moles
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A 10.00-mL aliquot of vinegar requires 16.95 mL of the 0.4874 M standardized NaOH solution to reach the end point of the titration. Demonstrate how to calculate the molarity of the vinegar solution (HC2H3O2). Show complete work below. Answer: 0.8261 M.
Answer:
0.8261 M.
Explanation:
We'll begin by writing the balanced equation for the reaction. This is given below:
HC2H3O2 + NaOH —> NaC2H3O2 + H2O
From the balanced equation above, we obtained the following:
Mole ratio of the acid, HC2H3O2 (nA) = 1
Mole ratio of the base, NaOH (nB) = 1
Data obtained from the question include the following:
Volume of acid, HC2H3O2 (Va) = 10 mL
Molarity of acid, HC2H3O2 (Ma) =..?
Volume of base, NaOH (Vb) = 16.95 mL Molarity of base, NaOH (Mb) = 0.4874 M
Finally, we shall determine the molarity of the acid solution, as follow:
MaVa/MbVb = nA/nB
Ma x 10 / 0.4874 x 16.95 = 1
Cross multiply
Ma x 10 = 0.4874 x 16.95
Divide both side by 10
Ma = (0.4874 x 16.95) /10
Ma = 0.8261 M.
Therefore, the molarity of the vinegar solution (HC2H3O2) is 0.8261 M.
Lead ions are toxic when absorbed into the body and can interfere with the neurological development of children. Based on what you learned in this lab activity, what substance might be added to an IV solution to remove Pb2 ions from the blood of a contaminated person
Answer:
The interpretation of the particular subject is covered in the subsection below in detail.
Explanation:
Large quantities of heavy substances like Lead ions become extremely poisonous when provided by a human. The administration of the medications recognized as "chelators" will eliminate these harmful chemicals from an infected individual's blood.However, here law enforcers calcium sodium polyacrylate seems to be the safest chelator in radiation sickness. It could be administered intravenously and attaches throughout the blood system with either the lead ions and afterward, removes the metal-chelator complicated from urine.The heat of vaporization of water is 40.66 kJ/mol. How much heat is absorbed when 3.11 g of water boils at atmospheric pressure?
Answer:
The amount of heat that is absorbed when 3.11 g of water boils at atmospheric pressure is 7.026 kJ.
Explanation:
A molar heat of vaporization of 40.66 kJ / mol means that 40.66 kJ of heat needs to be supplied to boil 1 mol of water at its normal boiling point.
To know the amount of heat that is absorbed when 3.11 g of water boils at atmospheric pressure, the number of moles represented by 3.11 g of water is necessary. Being:
H: 1 g/moleO: 16 g/molethe molar mass of water is:
H₂O= 2* 1 g/mole + 16 g/mole= 18 g/mole
So: if 18 grams of water are contained in 1 mole, 3.11 grams of water in how many moles are present?
[tex]moles of water=\frac{3.11 grams*1 mole}{18 gramos}[/tex]
moles of water= 0.1728
Finally, the following rule of three can be applied: if to boil 1 mole of water at its boiling point it is necessary to supply 40.66 kJ of heat, to boil 0.1728 moles of water, how much heat is necessary to supply?
[tex]heat=\frac{0.1728 moles*40.66 kJ}{1 mole}[/tex]
heat= 7.026 kJ
The amount of heat that is absorbed when 3.11 g of water boils at atmospheric pressure is 7.026 kJ.
Which of the following happens to a molecule of an object when the object is heated? (1 point)
Answer:
They get more energy, so they vibrate!
Explanation:
Which of these species would you expect to have the lowest standard entropy (S°)?
a. CH4(g)
b. H2O(g)
c. NH3(g)
d. HF(g)
Answer:
d. HF(g)
Explanation:
Hello,
In this case, the standard entropy S° could be predicted by looking at the amount of bonds the compound has, thus, the fewer the number bonds, the lower the standard entropy, it means that d. HF(g) has lowest value as it has one bond only whereas methane has four bonds, water two bonds and ammonia three bonds.
Best regards.
The formula of complex ion formed when aluminum hydroxide dissolves in sodium hydroxide will be: Select the correct answer below: [AlOH]2+
Answer:
Al(OH)₃ + OH⁻ → Al(OH)₄⁻
The compound is called hydroxoaluminate.
Explanation:
Aluminiun Hydroxide → Al(OH)₃
NaOH → Sodium hydroxide.
The Al(OH)₃ is an amphoteric compound, while the NaOH is a strong base. When they react, we may think that, fist of all, the base can dissociate: NaOH → Na⁺ + OH⁻
So the Al(OH)₃ will be a Lewis acid, as it can donate a pair of e⁻
Al(OH)₃ + OH⁻ → Al(OH)₄⁻
Please help, Which type of molecule is shown below?
Answer:
Carbohydrate
Explanation:
A.pex
A hypothetical metal crystallizes with the face-centered cubic unit cell. The radius of the metal atom is 198 picometers and its molar mass is 195.08 g/mol. Calculate the density of the metal in g/cm3.
Answer:
7.38 g/cm³ is the density of the metal
Explanation:
In a Face-centered cubic unit cell you have 4 atoms. Also, the edge length is √8×r (r is radius of the atom).
To solve this problem, we need first to calculate the volume of the unit cell and then, with molar mass calculate the mass of 4 atoms. As density is the ratio between mass and volume we can obtain this value.
Volume of the unit cellVolume = a³
a = √8×r
(r = 198x10⁻¹²m)
a = 5.6x10⁻¹⁰ m
Volume = 1.756x10⁻²⁸ m³
1m = 100cm → 1m³ = (100cm)³:
1.756x10⁻²⁸ m³× ((100cm)³ / 1m³) =
1.756x10⁻²² cm³ → Volume of the unit cell in cm³Mass of the unit cell:There are 4 atoms of gold:
4 atoms × (1mol / 6.022x10²³ atoms) = 6.64x10⁻²⁴ moles of gold
As 1 mole weighs 195.08g:
6.64x10⁻²⁴ moles of gold × (195.08g / mol) =
1.296x10⁻²¹g is the mass of the unit cellDensity of the metal:1.296x10⁻²¹g / 1.756x10⁻²² cm³ =
7.38 g/cm³ is the density of the metalThe density of the metal is 7.40 g/cm³
In cubic crystal system, face-centered cubic FFC is the name given to sort of atom arrangement observed in which structure is made up of atoms organized in a cube with a portion of an atom in each corner and six extra atoms in the center of each cube face.
It is expressed by using the formula:
[tex]\mathbf{\rho = \dfrac{Z \times M}{N_A\times a^}}[/tex]
where;
[tex]\rho[/tex] = density of the metalZ = atoms coordination no = 4 (for FCC)Molar mass (M) = 195.8 g/molAvogadro's constant (NA) = 6.022 × 10²³ /mola = edge lengthFor face-centered cubic FFC;
The edge length [tex]\mathbf{a =2 \sqrt{2}\times r }[/tex]
[tex]\mathbf{a =2 \sqrt{2}\times 198 \ pm }[/tex]
[tex]\mathbf{a =560.0285 \ pm }[/tex]
a = 5.60 × 10⁻⁸ cm
Replacing it into the previous equation, we have:
[tex]\mathbf{\rho = \dfrac{4 \times 195.8}{6.022 \times 10^{23} \times( 5.60 \times 10^{-8} )^3}}[/tex]
[tex]\mathbf{\rho = 7.40\ g/cm^3 }[/tex]
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For the following set of pressure/volume data, calculate the new volume of the gas sample after the pressure change is made. Assume that the temperature and the amount of gas remain constant.
a. 125 mL at 755 mm Hg; V =2mL at 780 mm Hg
b. 223 mL at 1.08 atm; V =2mL at 0.951 atm
c. 3.02 L at 103 kPa; V= 2Lat 121 kPa
Answer:
a. 121 ml, b. 253 ml and c. 2.57 L.
Explanation:
The new volume can be calculated by using the Boyle's law equation:
P1V1 = P2V2
In the equation, P1 and P2 are the initial and final pressures and V1 and V2 are the initial and final volumes for a real gas at constant temperature.
a) Based on the given information, P1 = 755 mmHg, V1 = 125 ml, P2 = 780 mm Hg and V2 will be,
V2 = P1V1/P2
V2 = 755 mmHg × 125 ml/780 mmHg
V2 = 121 ml
b) Based on the given information, P1 = 1.08 atm, V1 = 223 ml, P2 = 0.951 atm and V2 will be,
V2 = P1V1/P2
V2 = 1.08 atm × 223 ml/0.951 atm
V2 = 253 ml
c) Based on the given information, P1 = 103 kPa, V1 = 3.02 L, P2 = 121 kPa and V2 will be,
V2 = P1V1/P2
V2 = 103 kPa × 3.02 L/121kPa
V2 = 2.57 L
How many moles of NaF must be dissolved in 1.00 liter of a saturated solution of PbF 2 at 25°C to reduce the [Pb 2+] to 1.0 × 10 –6 M? The K sp for PbF 2 at 25 °C is 4.0 × 10 –8.
Answer:
0.1957 moles of NaF
Explanation:
The Pb²⁺ and F⁻ are in equilibrium with PbF₂ as follows:
PbF₂(s) ⇄ Pb²⁺(aq) + 2F⁻(aq)
Where Ksp expression is:
Ksp = 4.0x10⁻⁸ = [Pb²⁺] [F⁻]²
A saturated solution contains the maximum possible amount of Pb²⁺ and F⁻. That is:
PbF₂(s) ⇄ Pb²⁺(aq) + 2F⁻(aq)
PbF₂(s) ⇄ X + 2X
Where X is amount of ions presents in solution
4.0x10⁻⁸ = [Pb²⁺] [F⁻]²
4.0x10⁻⁸ = [X] [2X]²
4.0x10⁻⁸ = 4X³
4.0x10⁻⁸/4 = X³
1.0x10⁻⁸ = X³
2.15x10⁻³M = X
That means initial concentration of Pb²⁺ is = X = 2.15x10⁻³M and [F⁻] = 2X = 4.30x10⁻³M
Now, using again Ksp, if you want a [Pb²⁺] = 1.0x10⁻⁶M, the [F⁻] you need is:
4.0x10⁻⁸ = [Pb²⁺] [F⁻]²
4.0x10⁻⁸ = [1.0x10⁻⁶M] [F⁻]²
0.04M = [F⁻]²
0.2M = [F⁻]
You need a final concentration of 0.2M of F⁻. As initial concentration was 4.30x10⁻³M and volume of the buffer is 1.00L, the moles of F⁻ = moles of NaF you must add are:
0.2M - 4.30x10⁻³M =
0.1957 moles of NaF