Answer:
The half-life of the radioactive isotope is 346 years.
Explanation:
The decay rate of the isotope is modelled after the following first-order linear ordinary differential equation:
[tex]\frac{dm}{dt} = -\frac{m}{\tau}[/tex]
Where:
[tex]m[/tex] - Current isotope mass, measured in kilograms.
[tex]t[/tex] - Time, measured in years.
[tex]\tau[/tex] - Time constant, measured in years.
The solution of this differential equation is:
[tex]m(t) = m_{o}\cdot e^{-\frac{t}{\tau} }[/tex]
Where [tex]m_{o}[/tex] is the initial mass of the isotope. It is known that radioactive isotope decays at a yearly rate of 0.2 % annually, then, the following relationship is obtained:
[tex]\%e = \frac{m(t)-m(t+1)}{m(t)}\times 100\,\% = 0.2\,\%[/tex]
[tex]1 - \frac{m(t+1)}{m(t)} = 0.002[/tex]
[tex]1 - \frac{m_{o}\cdot e^{-\frac{t+1}{\tau} }}{m_{o}\cdot e^{-\frac{t}{\tau} }}=0.002[/tex]
[tex]1 - e^{-\frac{1}{\tau} } = 0.002[/tex]
[tex]e^{-\frac{1}{\tau} } = 0.998[/tex]
[tex]-\frac{1}{\tau} = \ln 0.998[/tex]
The time constant associated to the decay is:
[tex]\tau = -\frac{1}{\ln 0.998}[/tex]
[tex]\tau \approx 499.500\,years[/tex]
Finally, the half-life of the isotope as a function of time constant is given by the expression described below:
[tex]t_{1/2} = \tau \cdot \ln 2[/tex]
If [tex]\tau \approx 499.500\,years[/tex], the half-life of the isotope is:
[tex]t_{1/2} = (499.500\,years)\cdot \ln 2[/tex]
[tex]t_{1/2}\approx 346.227\,years[/tex]
The half-life of the radioactive isotope is 346 years.
In which orbital does an electron in a cesium atom experience the greatest effective nuclear charge?
Answer:
The effective nuclear charge in a cesium atom is greatest in the 1s orbital
Explanation:
Effective nuclear charge (Zeff) is the positive nuclear charge that is experienced by an electron in an atom. It is affected by the shielding effect and penetration of electrons of the atoms.
The shielding effect is the decrease in attraction between an electron and the nucleus in any atom with more than one electron shell. Innermost electrons shield the outermost electrons from the positive charge of the nucleus. The more electron shells there are, the greater the shielding effect experienced by the outermost electrons. and the more electron shielding an electron has, the lower the Zeff value.
Penetration is the ability of an electron to approach the nucleus. The closer the electron is to the nucleus, the higher the penetration. Electrons with higher penetration will shield outer electrons from the nucleus more effectively. The s orbital being closest to the nucleus has the highest penetration while the f orbital has the lowest penetration.
Cesium has an atomic number of 55 as well as nuclear charge of +55. It has 54 electrons in its filled 1s²2s²2p⁶3s²3p⁶4s²3d¹⁰4p⁶5s²4d¹⁰5p⁶6s¹ shells and an outermost 6s electron. Based on the explanation above, the effective nuclear charge is greatest in the innermost 1s orbital and least in the outermost 6s orbital.
The electron in a cesium atom experience should be considered as the 1st orbital.
What is an Effective nuclear charge (Zeff)?It is considered to be the positive nuclear charge i.e. experienced via the electron in an atom. It should be impacted via the effect of shielding and the penetration of the electron with respect to the atoms.
The electronic configuration of cesium should be like
[tex]1s^2 2s^2 2p^6 3s^2 3p^6 3d^10 4s^2 4p^6 4d^10 5s^2 5p^6 6s^1[/tex]
Now
the electron which is in the innermost subshell will experience the highest effective nuclear charge and it should be 1s.
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Chemistry question. Image attached.
Answer:
Pb(NO3)2(aq) + 2NaCl(aq) —> PbCl2(s) + 2NaNO3(aq)
Explanation:
When lead (II) nitrate, Pb(NO3)2 undergoes a double displacement reaction with aqueous sodium chloride, NaCl, the following products are obtained:
Pb(NO3)2(aq) + NaCl(aq) —>
Aqueous Pb(NO3)2 will dissociate in solution as follow:
Pb(NO3)2(aq) —> Pb2+(aq) + 2NO3-(aq)
On the other hand, aqueous NaCl will dissociate as follow:
NaCl(aq) —> Na+(aq) + Cl-(aq)
The double displacement reaction will take place as follow:
Pb(NO3)2(aq) + NaCl(aq) —>
Pb2+(aq) + 2NO3-(aq) + Na+(aq) + Cl-(aq) —> Pb2+(aq) Cl-(aq) + Na+(aq) 2NO3-(aq)
Pb(NO3)2(aq) + NaCl(aq) —> PbCl2(s) + NaNO3(aq)
We simply balance the equation by putting 2 in front of NaCl and 2 in front of NaNO3 as shown below:
Pb(NO3)2(aq) + 2NaCl(aq) —> PbCl2(s) + 2NaNO3(aq)
Given the information below, which is more favorable energetically, the oxidation of succinate to fumarate by NAD+ or by FAD? Fumarate + 2H+ + 2e- → Succinate E°´ = 0.031 V NAD+ + 2H+ + 2e- → NADH + H+ E°´ = -0.320 FAD + 2H+ + 2e- → FADH2 E°´ = -0.219
Answer:
Oxidation by FAD
Explanation:
1. Oxidation by NAD⁺
Succinate ⇌ Fumarate + 2H⁺ + 2e⁻; E°´ = -0.031 V
NAD⁺ + 2H⁺ + 2e⁻ ⇌ NADH + H⁺; E°´ = -0.320 V
Succinate + NAD⁺ ⇌ Fumarate + NADH + H⁺; E°' = -0.351 V
2. Oxidation by FAD
Succinate ⇌ Fumarate + 2H⁺ + 2e⁻; E°´ = -0.031 V
FAD + 2H⁺ + 2e⁻ ⇌ FADH₂; E°´ = -0.219 V
Succinate + FADH₂ ⇌ Fumarate + FAD; E°' = -0.250 V
Neither reaction is energetically favourable, but FAD has a more positive half-cell potential.
FAD is the stronger oxidizing agent.
The oxidation by FAD has a more positive cell potential, so it is more favourable energetically.
g If 1.00 mol of ethane gas and 5.00 mol of oxygen gas react, what is the limiting reactant and how many moles of water are produced from the reaction
Answer:
First, write a balanced equation of the reaction.
A hydrocarbon reacting with oxygen usually gives out carbon dioxide and water (combustion)
2C2H6 + 7O2 ---> 4CO2 + 6H2O
From the equation, we can see the mole ratio of ethane : oxygen is 2:7, meaning 2 moles of ethane reacts with 7 moles of oxygen.
If there's 1 mole of ethane gas, we need y moles of oxygen gas for complete reaction.
[tex]\frac{2}{7} =\frac{1}{y}[/tex]
y= 3.5 moles
Since 5 moles of oxygen is more than the required 3.5 moles, we can deduce oxygen gas is in excess, meaning ethane is limiting.
(You can get the same results too if you take y as ethane gas required).
The no. of moles of product produced ALWAYS depend on the no. of moles of the limiting reactant, since they are the ones which reacts completely.
So, from the equation, since the mole ratio of ethane : water = 2:6,
hence, (take the no. of moles of water produced as z),
[tex]\frac{2}{6} =\frac{1}{z} \\z= 3[/tex]
Therefore, 3 moles of water is produced.
Ethane is the limiting reagent in the given reaction. The number of moles of water produced from the reaction is 3 moles.
What is a limiting reagent?A limiting reagent can be defined as that reactant in the chemical reaction which is consumed first among the other reactants during the completion of a chemical reaction.
The limiting reagent is the reactant which decides the yield of the product when the quantity of the reactants is not taken in stoichiometry.
Given, chemical reaction of ethane and oxygen is:
[tex]C_2H_6 + \frac{7}{2} O_2 \longrightarrow 2CO_2 +3H_2O[/tex]
Given, the number of moles of ethane = 1 mol
The number of moles of oxygen = 5 mol
One more of ethane reacts with moles of oxygen = 3.5 mol
Therefore, ethane is the limiting reagent in this reaction as the oxygen is given in excess.
From the balanced equation, one mole of ethane produces moles of water equal to 3 moles.
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Mary smith obtained a density of 2.226g/ml for a metal sample. Using a different method, Joseph Henry obtained a value of 2.335g/mL for the same metal sample. Which student’s value is more accurate? Use the definition of accuracy to explain your answer. the true value is 2.300g/ml.
Answer:
Joseph Henry.
Explanation:
Hello,
In this case, we define the accuracy based on the degree of deviation a measure has regarding the the true or expected value. In this case, the lower the difference, the more accurate the procedure. In such a way, for the two students, we compute the difference between the expected value and the obtained value:
[tex]Mary=2.300g/mL-2.226g/mL=0.074g/mL[/tex][tex]Joseph=2.335g/mL-2.300mL=0.035g/mL[/tex]
In such a way, since the difference is lower in Joseph's measure, we can say he is the most accurate.
Best regards.
If a mixture of a given percentage or ratio strength is diluted to twice its original quantity, its active ingredient will be contained in twice as many parts of the whole, and its strength, therefore, will be?
Answer:
if a mixture of a given percentage or ratio strength is diluted to twice its original quantity, its active ingredient will be contained in twice as many parts of the whole, and its strength therefore will be reduced by one-half
How many grams of C are required to react with 64.6 g of Fe2O3 ?
Answer:
14.6 g
Explanation:
Fe₂O₃ + 3 C → 2 Fe + 3 CO₃
First, convert grams of Fe₂O₃ to moles. The molar mass is 159.69 g/mol.
(64.6 g)/(159.69 g/mol) = 0.4045 mol
Now, use stoichiometry to convert moles of Fe₂O₃ to moles of C. By looking at the chemical equation, you can see that for every 1 mole of Fe₂O₃, you need 3 moles of C. Use this relationship.
(0.4045 mol Fe₂O₃) × (3 mol C/1 mol Fe₂O₃) = 1.214 mol C
Now, convert moles of C to grams. The molar mass is 12.01 g/mol.
(1.214 mol C) × (12.01 g/mol) = 14.58 g
You need to use significant figures.
14.58 g ≈ 14.6 g
10. Show as many ways as you can think of: a) to make benzamide from benzene; b) to make cyclohexyl methyl ketone from bromocyclohexane;
Answer:
See explanation
Explanation:
a) Benzamide from benzene
For this synthesis, we have to start with the Friedel-Crafts reaction to produce Toluene. Then with a strong oxidant, we can produce benzoic acid. In the next step, we can use an esterification reaction to produce the methyl benzoate. Finally, we can use an acyl substitution reaction using ammonia to produce the benzamide.
b) From bromocyclohexane to cyclohexyl methyl ketone
In this case, we can start with a Grignard reaction. The first step is to produce the Grignard reagent with using magnesium. Then if we add acetaldehyde we can form an alcohol, 1-cyclohexylethan-1-ol. Finally, we can reduce the alcohol to produce cyclohexyl methyl ketone.
See figure 1
I hope it helps!
An adult rhino xan have a mass of 1400 kg the mass of a small egret is about 0.76kg. what is the radio of these two masses? how does this ratio compare to the ratio of the mass of a proton ti the mass of an electron?
Answer:
The ratio of the mass of an adult rhino to the mass of a small egret is
(1400 kg)/(0.76 kg) = 1842.11
The ratio of the mass of a proton to the mass of an electron is
1836.15
The two ratios are very similar, the ratio of the masses of the proton to the electron being slightly smaller.
What is the density of a gas with a molar mass of 28.26g/mol at 3.510atm and 237k?
Answer:
density = 5.1g/m³
Explanation:
use ideal gas equation
Pv=nRT
28.26 x 3.51 = m/v x 0.08206 x 237
m/v = (28.26 x3.51)/(237 x 0.08206) = 5.1g/m³
The pressure of the atmosphere on the surface of the planet Venus is about 88.8 atm. Compare that pressure in psi to the normal pressure on earth at sea level in psi.
Answer:
The pressure on Planet Venus is 88 times more that the pressure on earth at sea level.
Explanation:
Hello,
The pressure on the surface of planet Venus = 88.8atm.
The pressure at sea level on earth is 14.7psi.
To solve this question, we need to first convert the value of the pressure on the surface of Venus from atm to psi.
1 atm = 14.7psi
88atm = x psi
x = 1293.6psi
The pressure on the surface of planet Venus is 1293.6psi.
However the pressure on earth at sea level on earth is 14.7psi
The pressure on the surface of planet venus is 88 times more than the pressure on earth at sea level.
Write a balanced equation depicting the formation of one mole of NaBr(s) from its elements in their standard states.
Express your answer as a chemical equation. Identify all of the phases in your answer.
Write a balanced equation depicting the formation of one mole of SO3(g) from its elements in their standard states.
Express your answer as a chemical equation. Identify all of the phases in your answer.
For SO3(g) find the value of ΔH∘f. (Use Appendix C in the textbook.)
Express your answer using four significant figures.
For NaBr(s) find the value of ΔH∘f. (Use Appendix C in the textbook.)
Express your answer using four significant figures.
Write a balanced equation depicting the formation of one mole of Pb(NO3)2(s) from its elements in their standard states.
Express your answer as a chemical equation. Identify all of the phases in your answer.
For Pb(NO3)2(s) find the value of ΔH∘f. (Use Appendix C in the textbook.)
Express your answer using four significant figures.
Answer:
Check Explanation.
Explanation:
Formation reactions are chemical reactions where one mole of a compound is produced from its constituent elements in their standard states.
NaBr (s)
The Standard formation reaction is
Na (s) + (1/2)Br₂ (g) → NaBr (s)
Using appendix C, the standard heat of formation of NaBr(s) is
ΔH∘f = -359.8 kJ/mol.
SO₃ (g)
The Standard formation reaction is
S (s) + (3/2) O₂ (g) → SO₃ (g)
Using appendix C, the standard heat of formation of SO₃(g) is
ΔH∘f = -395.2 kJ/mol.
Pb(NO₃)₂ (s)
The Standard formation reaction is
Pb (s) + N₂ (g) + 3O₂ (g) → Pb(NO₃)₂ (s)
Using appendix C, the standard heat of formation of Pb(NO₃)₂(s) is
ΔH∘f = -451.9 kJ/mol.
Hope this Helps!!!
Answer:
Explanation:
Formation reactions are chemical reactions where one mole of a compound is produced from its constituent elements in their standard states.
Choose the substance with the highest surface tension.
a. CH3CH2OH
b. CH3CH2Cl
c. CH3CH2CH3
d. CH2Br2
e. HOCH2CH2OH
Answer:
Hello
you're answer should be E.HOCH2CH2OH
hope this answer is correct
The substance with the highest surface tension - e. HOCH2CH2OH.
Surface tension is the elastic tendency of a fluid, caused by the attraction of particles in the surface which makes it acquire the least surface area.
it depends on intermolecular forces like hydrogen bonding, Vanderwall forces, ion-dipole, and ion-induced dipole interactions.The higher the intermolecular forces higher will be the surface tension.Among all these intermolecular forces, hydrogen bonding is the strongest.So from given options (a) and (e) have -OH functional group and forms H-bonding.Among these two options, option (e) has 2-OH groups so (e) will have more extensive H-bonding.Thus, The substance with the highest surface tension - e. HOCH2CH2OH.
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Of the following, only ________ has sp2 hybridization of the central atom. Of the following, only ________ has sp2 hybridization of the central atom. ICl3 PBr3 SiH2Br2 HCN BF3
Answer:
BF3
Explanation:
Hybridization can be defined as the mixing of two or more atomic pure orbitals. ( s, p , and d) to produce two or more hybrid atomic orbitals that are similar and identical in shape and energy e.g sp,sp²,sp³ ,sp³d, sp³d². Usually , the central atom of a covalent molecules or ion undergoes hybridization.
in BF3; Boron is the central atom. Here, A 2s electron is excited from the ground state of boron ( 1s²2s²2p¹) to one empty orbitals of 2p.
The 2s orbital is then mixed with two orbitals of 2p to form three sp² hybrid orbitals tat are trigonally arranged in the plane in order to minimize repulsion . Each of the three hybrid orbitals overlaps with p-orbital of fluorine atom to form three bonds of equal strength and with bond angles of 120⁰.
Energy
B ⇵ ║ ⇅ ║ ↑ -----------> *B ⇵ ║ ↑ ║ ↑ ║ ↑
1s 2s 2p 1s 2s 2p
Ground state Excited State
The above shows an illustrative example of how electrons move from the ground state to the excited state.
A 0.1-L unbuffered solution needs the pH adjusted from 3.5 to 1. How many microliters of a 6 molar HCl solution need to be added to adjust the pH
Answer:
1661μL of a 6M HCl you need to add
Explanation:
pH is defined as -log[H⁺] ([H⁺] =10^{-pH}), the initial and final concentrations of [H⁺] you need are:
Initial [H⁺] = 10^{-3.5} = 3.16x10⁻⁴M H⁺
Final [H⁺] = 10^{-1} = 0.1M H⁺
In moles, knowing volume of the solution is 0.1L:
Initial [H⁺] = 0.1L ₓ (3.16x10⁻⁴mol H⁺ / L) = 3.16x10⁻⁵moles H⁺
Final [H⁺] = 0.1L ₓ (0.1mol H⁺ / L) = 0.01 moles H⁺.
That means, moles of H⁺ you need to add to the solution is:
0.01mol - 3.16x10⁻⁵moles = 9.9684x10⁻³ moles of H⁺.
A solution of HCl dissociates in H⁺ and Cl⁻ ions, that means moles of HCl added are equal to moles of H⁺. As you need to add 9.9684x10⁻³ moles of H⁺ = 9.9684x10⁻³ moles of HCl:
9.9684x10⁻³ moles of HCl ₓ (1L / 6mol) = 1.6614x10⁻³L
In μL:
1.661x10⁻³L × (1x10⁶μL / 1L) =
1661μL of a 6M HCl you need to addOf the following species, ________ will have bond angles of 120°. A) PH3 B) ClF3 C) NCl3 D) BCl3 E) All of these will have bond angles of 120°.
Answer:
D. BCl₃
Explanation:
BCl₃ molecular geometry is trigonal planar and it has a bond angle of 120°.
Hope that helps.
According to the molecular geometry, BCl₃ has trigonal planar geometry and a bond angle of 120°.
What is molecular geometry?Molecular geometry can be defined as a three -dimensional arrangement of atoms which constitute the molecule.It includes parameters like bond length,bond angle and torsional angles.
It influences many properties of molecules like reactivity,polarity color,magnetism .The molecular geometry can be determined by various spectroscopic methods and diffraction methods , some of which are infrared,microwave and Raman spectroscopy.
They provide information about geometry by taking into considerations the vibrational and rotational absorbance of a substance.Neutron and electron diffraction techniques provide information about the distance between nuclei and electron density.
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Convert each compound name into its chemical formula, then balance the equation. mercury (II) oxide ⇒ mercury + oxygen
Answer:
HgO ⇒ Hg + 0.5 O₂
Explanation:
Let's consider the following equation corresponding to the decomposition of mercury (II) oxide.
mercury (II) oxide ⇒ mercury + oxygen
The corresponding compounds are:
mercury (II) oxide ⇒ HgOmercury ⇒ Hgoxygen ⇒ O₂The balanced chemical equation is:
HgO ⇒ Hg + 0.5 O₂
which element will have higher electronegativity
Convert each compound name into its chemical formula, then balance the equation. 1. aluminum chloride + calcium hydroxide aluminum hydroxide + calcium chloride
Answer:
2AlCl3 + 3Ca(OH)2 --> 2Al(OH)3 + 3CaCl2
Explanation:
aluminum chloride + calcium hydroxide --> aluminum hydroxide + calcium chloride
AlCl3 + Ca(OH)2 --> Al(OH)3 + CaCl2
Note: Al forms an ion of charge +3, Cl forms ion of charge -1, OH forms ion of -1, and Ca forms ions of charge +2. So when you combine 2 of these into ions, (must be one positive, one negative for ionic compounds), make sure the net charge at the end =0.
For example, Al ions have a charge of +3, so it needs 3 Cl- ions to eliminate the negative charge, so aluminium chloride is AlCl3.
Now balance the equation. make sure both sides have the equal no. of ions.
start with Cl. the reactant side has 3 Cl ions, while the product side has 2. So, the lowest common multiple is 6. Multiply AlCl3 by 2, and CaCl2 by 3 to get 6 Cl ions on each side.
2AlCl3 + Ca(OH)2 --> Al(OH)3 + 3CaCl2
Now the reactant side has 2 Al ions. So, multiply the Al(OH)3 on the product side by 2 to balance out Al ions.
2AlCl3 + Ca(OH)2 --> 2Al(OH)3 + 3CaCl2
Finally, the product side has 6 OH- ions, so multiply 3 on Ca(OH)2 from the reactant side to balance out the OH- ions.
2AlCl3 + 3Ca(OH)2 --> 2Al(OH)3 + 3CaCl2
Recount the ions to make sure it is correctly balanced! :)
Ethylene glycol, C2H6O2, is infinitely miscible (soluble) in water. It is a nonelectrolyte that is used as antifreeze. What is the lowest possible melting point for engine coolant that is 26.1% ethylene glycol
Answer: The lowest possible melting point for engine coolant that is 26.1% ethylene glycol is [tex]-7.83^0C[/tex]
Explanation:
Depression in freezing point or melting point is given by:
[tex]\Delta T_f=i\times K_f\times m[/tex]
[tex]\Delta T_f=T_f^0-T_f=(0-T_f)^0C[/tex] = Depression in freezing point
i= vant hoff factor = ( 1 for non electrolyte)
[tex]K_f[/tex] = freezing point constant for water= [tex]1.86^0C/m[/tex]
m= molality
[tex]\Delta T_f=i\times K_f\times \frac{\text{mass of solute}}{\text{molar mass of solute}\times \text{weight of solvent in kg}}[/tex]
Given : 26.1 g of ethylene glycol in 100 g of water
Weight of solvent (water)= 100 g = 0.1 kg (1kg=1000g)
Molar mass of solute (ethylene glycol) = 62 g/mol
Mass of solute (ethylene glycol) added = 26.1 g
[tex](0-T_f)^0C=1\times 1.86\times \frac{26.1g}{62g/mol\times 0.1kg}[/tex]
[tex](0-T_f)^0C=7.83[/tex]
[tex]T_f=-7.83^0C[/tex]
Thus the lowest possible melting point for engine coolant that is 26.1% ethylene glycol is [tex]-7.83^0C[/tex]
Calculate Ecell at 80 ºC for a voltaic cell based on the following redox reaction: H2(g, 1.25 atm) + 2AgCl(s) → 2Ag(s) + 2H+(aq, 0.10 M) + 2Cl–(aq, 1.5 M) The standard cell potential Eºcell = +0.18 V at this temperature.
Answer:
Ecell = +0.25V
Explanation:
the half-cell reactions for a voltanic cell
cathode(reduction): 2H⁺(aq) + 2e⁻ ------- H₂(g)
anode(oxidation): 2AgCl(s) ------- 2Ag⁺(aq) + 2Cl⁻ + 2e⁻
we have the standard cell potential E⁺cell = 0.18V at 80C respectively
Q = [H⁺]/[Cl⁻]
sub for [H+] = 0.10M and [Cl-] = 1.5M
Q= 0.1M/1.5M
Q = 0.067
Ecell = E⁺cell - [tex]\frac{0.059}{n}[/tex] logQ
= 0.18 - [tex]\frac{0.056}{1}[/tex] log 0.067
0.18- 0.059(-1.174)
Ecell = +0.25V
Begin by writing formulas for the reactants and products, including physical states. When necessary use coefficients to balance the equation.
A) When solid sodium hydride, NaH, is added to water, hydrogen gas is released and aqueous sodium hydroxide forms.
B) Aluminum metal reacts with chlorine gas to form solid aluminum chloride.
Answer:
NaH(s) + H₂O(aq) ⇒ NaOH (aq) + H₂ (g)
Al(s) + Cl₂(g) ⇒ AlCl₃(s)
Explanation:
NaH - sodium hydride
H₂O - water
NaOH - sodium hydroxide
Al - aluminium
Cl₂ - Chlorine
AlCl₃ - aluminium chloride
If the particles of matter that make up a substance are relatively far apart and can move freely, the substance is in what state?
gaseous
liquid
solid
Answer:
Gaseous
Explanation:
Gasses can move freely and do not form the shape of their containers
Liquids are more free than solids, but they conform to the shape of their container
Solids are not free
The gas evolved in the metal carbonate reaction with acid turns limewater milky The milky substance formed is
Answer:
The gas evolved because of reaction of acid with metal carbonate or metal hydrogen carbonate turns lime water milky. This shows that the gas is carbon dioxide gas. This happens because of formation of white precipitate of calcium carbonate.
Hope it helps you!
The milky substance formed is CO₂ gas.
What leads to the formation of white precipitate of calcium carbonate ?The gas evolved because of reaction of acid with metal carbonate or metal hydrogen carbonate turns lime water milky. This shows that the gas is carbon dioxide gas.
This happens because of formation of white precipitate of calcium carbonate.
Lime water turns milky when the gas liberated from an acidified carbonate solution is passed into it.
The liberated CO₂ reacts with lime water to give calcium bicarbonate as the precipitate.
Hence, the milky substance formed is CO₂ gas.
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Calculate the pH in titration of a weak acid: What is the pH in titration of formic acid (HCHO2, 0.200 M, 100.0 mL) after the addition of 300.0 mL NaOH (0.120 M)? The Ka of formic acid is 1.799 x 10-4.
Answer:
pH = 12.61
Explanation:
First of all, we determine, the milimoles of base:
0.120 M = mmoles / 300 mL
mmoles = 300 mL . 0120 M = 36 mmoles
Now, we determine the milimoles of acid:
0.200 M = mmoles / 100 mL
mmoles = 100 mL . 0.200M = 20 mmoles
This is the neutralization:
HCOOH + OH⁻ ⇄ HCOO⁻ + H₂O
20 mmol 36 mmol 20 mmol
16 mmol
We have an excess of OH⁻, the ones from the NaOH and the ones that formed the salt NaHCOO, because this salt has this hydrolisis:
NaHCOO → Na⁺ + HCOO⁻
HCOO⁻ + H₂O ⇄ HCOOH + OH⁻ Kb → Kw / Ka = 5.55×10⁻¹¹
These contribution of OH⁻ to the solution is insignificant because the Kb is very small
So: [OH⁻] = 16 mmol / 400 mL → 0.04 M
- log [OH⁻] = pOH → 1.39
pH = 14 - pOH → 12.61
What is the name of the compound Br8P4? A. Bromine tetraphosphate B. Octaboron tetrapotassium C. Boron tetraphosphide D. Octabromine tetraphosphide
Answer:
Option D.
Explanation:
This compound has in its formula:
- Eight bromines
- Four phosphorous
8 → octa prefix
4 → tetra prefix
Right answer is Octabromine tetraphosphide
It can not be option A, tetraphosphate is P4O7
It can not be B and C, we do not have B (boron)
Answer:
Octabromine tetraphosphide
Explanation:
Answer via Educere/ Founder's Education
A 5.00 gram sample of an oxide of lead PbxOy contains 4.33 g of lead. Determine simplest formula for the compund
Answer: The empirical formula is [tex]PbO_2[/tex]
Explanation:
Mass of Pb = 4.33 g
Mass of O = (5.00-4.33) g = 0.67 g
Step 1 : convert given masses into moles
Moles of Pb =[tex]\frac{\text{ given mass of Pb}}{\text{ molar mass of Pb}}= \frac{4.33g}{207g/mole}=0.021moles[/tex]
Moles of O =[tex]\frac{\text{ given mass of O}}{\text{ molar mass of O}}= \frac{0.67g}{16g/mole}=0.042moles[/tex]
Step 2 : For the mole ratio, divide each value of moles by the smallest number of moles calculated.
For Pb = [tex]\frac{0.021}{0.021}=1[/tex]
For O = [tex]\frac{0.042}{0.021}=2[/tex]
The ratio of Pb O= 1: 2
Hence the empirical formula is [tex]PbO_2[/tex]
what is the chemical formula for deionized water?
Answer:
Formula: H2O Formula Weight: 18.02 CAS No.: 7732-18-5 Density: 1.000 g/mL at 3.98 °C(lit.)
Explanation:
Name the compound Ga S3
Answer:
Gallium(III) sulfideAccording to Le Châtelier's principle, how would a change in pressure affect a
gaseous system in equilibrium?
Answer:
Le Châtelier's principle states that when a chemical system at equilibrium is distributed by a change in conditions, the equilibrium position will shift in a direction that tends to counteract the change.
Therefore, when there is a change in pressure, the equilibrium will counteract the change by reducing/increasing the pressure through adjusting the no. of moles of gas.
Note: At constant temperature and volume the pressure of a gas is directly proportional to the number of moles of gas.
For example, when there's an increase in total pressure, the equilibrium position will shift to the side with a smaller no. of moles of gas so as to reduce the pressure.
Answer:
The equilibrium would shift to reduce the pressure change
Explanation: