The statement that accurately describes the origin & expansion of the universe is Cosmic background radiation is leftover thermal energy from the big bang.
What is the expansion of the universe?The expansion of the universe may be defined as the process of enlargement in space between any two given gravitationally untied parts of the detectable universe with duration.
Cosmic radiation extremely fills the universe more or less uniformly. These radiations are responsible for the splitting down of fossil remains and are considered as one of the factors which hypothesized the big bang theory at the origin of the universe.
The complete question is as follows:
As the universe continues to expand, it gradually gets warmer.Galaxies that are farther away are moving away more slowly.Cosmic background radiation is leftover thermal energy from the big bang. Stars and galaxies formed almost immediately after the big bang occurred.Therefore, the correct option is C.
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How many kilojoules of heat would be required to fully melt a 0.834 m³ block of ice , provided that the density of ice is 917 kg / m³ ? H₂O ( s ) → H₂O ( 1 ) AH = 6.01 kJ
2.54 × 10⁵ kJ of heat are required to fully melt a 0.834 m³ block of ice, with a density of 917 kg / m³.
What is melting?Melting is a physical change in which solids turn into liquids.
Step 1. Calculate the mass of ice.We have a block of 0.834 m³ of ice with a density of 917 kg/m³.
0.834 m³ × 917 kg/m³ = 765 kg = 7.65 × 10⁵ g
Step 2. Convert 7.65 × 10⁵ g to moles.We will use the molar mass of water.
7.65 × 10⁵ g × (1 mol/18,02 g) = 4.24 × 10⁴ mol
Step 3. Calculate the heat required to melt 4.24 × 10⁴ moles of water.According to the thermochemical equation, 6.01 kJ are required to melt 1 mol of water.
4.24 × 10⁴ mol × (6.01 kJ/mol) = 2.54 × 10⁵ kJ
2.54 × 10⁵ kJ of heat are required to fully melt a 0.834 m³ block of ice, with a density of 917 kg / m³.
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percent composition of Mg(OH)2
Answer:
The composition of Mg(OH)2 is
41.67 % Mg,
54.87 % O
3.457 % H
Explanation:
Thats the percent composition for each one in your question
Answer:
Hello! The answer to your question is:
Mg: 41.68%
O2: 54.86%
H2: 3.46%
Explanation:
We need to find the percent composition of each element, so first, we need to find the molar mass. This is calculated by using the number underneath the element. The "2" outside of the parentheses is distributed to Oxygen and Hydrogen as well-meaning that you multiply the number by 2:
Mg: 24.31 g/mol
O2: 16.00 × 2 = 32.00 g/mol
H2: 1.01 × 2 = 2.02 g/mol
Now, we have to add up the molar mass of each element:
24.31 g/mol + 32.00 g/mol + 2.02 g/mol = 58.33
To find the percent composition of each element, you have to divide the molar mass of each element by the total molar mass:
Mg: [tex]\frac{24.31 g/mol}{58.33 g/mol} \\= 41.68 percent[/tex]
O2: [tex]\frac{32.00 g/mol}{58.33 g/mol} \\= 54.86 percent[/tex]
H2: [tex]\frac{2.02 g/mol}{58.33 g/mol} \\= 3.46 percent[/tex]
The percent composition of each element is:
Mg: 41.68%
O2: 54.86%
H2: 3.46%
In a constant‑pressure calorimeter, 55.0 mL of 0.310 M Ba(OH)2 was added to 55.0 mL of 0.620 M HCl.
The reaction caused the temperature of the solution to rise from 24.25 ∘C to 28.47 ∘C. If the solution has the same density and specific heat as water ( 1.00 g/mL and 4.184J/g⋅°C,) respectively), what is Δ for this reaction (per mole H2O produced)? Assume that the total volume is the sum of the individual volumes.
The enthalpy change (ΔH) for the reaction (per mole H₂O produced) is 56.96 KJ/mol
How to determine the mass of the solutionVolume = 55 + 55 = 110 mLDensity = 1 g/mLMass = ?Mass = density × volume
Mass = 1 × 110
Mass = 110 g
How to determine the heat Mass (M) = 110 gInitial temperature (T₁) = 24.25 °C Final temperature (T₂) = 28.47 °CChange in temperature (ΔT) = 28.47 – 24.25 = 4.22 °C Specific heat capacity (C) = 4.184 J/gºC Heat (Q) =?Q = MCΔT
Q = 110 × 4.184 × 4.22
Q = 1942.2128 J
How to determine the mole of H₂O producedBa(OH)₂ + 2HCl --> BaCl₂ + 2H₂O
Since the reaction occurs in a constant‑pressure calorimeter, it means both reactants are sufficient enough for the reaction.
Mole of Ba(OH)₂ = molarity × volume
Mole of Ba(OH)₂ = 0.310 × (55 / 1000)
Mole of Ba(OH)₂ = 0.01705 mole
From the balanced equation above,
1 mole of Ba(OH)₂ reacted to produce 2 moles of H₂O.
Therefore,
0.01705 mole of Ba(OH)₂ will react to produce = 0.01705 × 2 = 0.0341 mole of H₂O.
How to determine the enthalpy change ΔH per mole of H₂O producedHeat (Q) = 1942.2128 JMole of H₂O (n) = 0.0341 moleEnthalpy change (ΔH) =?ΔH = Q / n
ΔH = 1942.2128 / 0.0341
ΔH = 56956.29 J/mol
Divide by 1000 to express in KJ/mol
ΔH = 56956.29 / 1000
ΔH = 56.96 KJ/mol
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electronic configuration of organic compounds
The electronic configuration of organic compounds depends on the orbitals of their atoms and molecules.
What is electronic configuration?The expression 'electronic configuration' makes reference to the spacial arrangement of electrons in distinct energy orbitals of an atom/molecule.
The orbitals are designed with numbers and letters, whereas the amount of electrons in each orbital is expressed as superscripts (e.g., 1s² 2s² 2p² in the C atom that form glucose).
In conclusion, electronic configuration of organic compounds depends on the orbitals of their atoms and molecules.
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Please provide a synthesis for the following molecules with the provided starting material.
Answer:
Attached Below
Explanation:
Perform the calculation to the correct number of significant figures. (8.81 - 7.50)/0.0020
Answer:
655
Explanation:
using bodmas, (bracket first), 8.81-7.50=1.31
1.31÷0.0020=655
1. Balance the equation below: Fe(s) + Cl₂(g) → FeCl3(aq) 2. Calculate the moles of FeCl3 that will form if 2.0 moles of Fe react with sufficient Cl₂. 3. Calculate the moles of FeCl3 that will form if 1.0 moles of each reactant mix together. 4. How many grams of FeCl3 that will form if 1.0 g of each reactant mix?
Answer:
1.) 2 Fe (s) + 3 Cl₂ (g) ---> 2 FeCl₃ (aq)
2.) 2.0 moles FeCl₃
3.) 0.67 moles FeCl₃
4.) 1.5 g FeCl₃
Explanation:
1.)
The unbalanced reaction:
Fe (s) + Cl₂ (g) ---> FeCl₃ (aq)
Reactants: 1 iron, 2 chlorine
Products: 1 iron, 3 chlorine
The balanced reaction:
2 Fe (s) + 3 Cl₂ (g) ---> 2 FeCl₃ (aq)
Reactants: 2 iron, 6 chlorine
Products: 2 iron, 6 chlorine
2.)
To find moles FeCl₃, you need to multiply the given value by the mole-to-mole ratio of Fe to FeCl₃. This ratio is constructed via the coefficients from the balanced equation.
2.0 moles Fe 2 moles FeCl₃
--------------------- x ------------------------ = 2.0 moles FeCl₃
2 moles Fe
3.)
To determine how much FeCl₃ is produced, you need to identify the limiting reagent. To find it, you need to convert both reactants to the product then identify which reactant gives you the smallest amount of product. This reactant is the limiting reagent and will give you your actual answer.
1.0 mole Fe 2 moles FeCl₃
------------------- x ----------------------- = 1.0 moles FeCl₃
2 moles Fe
1.0 mole Cl₂ 2 moles FeCl₃
------------------- x ------------------------ = 0.67 moles FeCl₃
3 moles Cl₂
4.)
Because Cl₂ is the limiting reagent, we need to convert grams Cl₂ to grams FeCl₃. This can be done using the molar masses of both compounds and the mole-to-mole ratio.
Molar Mass (Cl₂): 2(35.453 g/mol)
Molar Mass (Cl₂): 70.906 g/mol
Molar Mass (FeCl₃): 55.845 g/mol + 3(35.453 g/mol)
Molar Mass (FeCl₃): 162.204 g/mol
1.0 g Cl₂ 1 mole 2 moles FeCl₃ 162.204 g
------------- x ----------------- x ----------------------- x ------------------ = 1.5 g FeCl₃
70.906 g 3 moles Cl₂ 1 mole
Hello, please help tysmmmm!!
Answer:
2.07
Explanation:
1870=(20.01)(c)(45.2)
1870 = 904.452c
c = 2.07 J/g C (to 3 sf]
. Does the combustion reaction mentioned follow the model of the
combustion reactions?
. What do you think about the possibility of either ethanol or methanol to
fuel vehicles?
Do you or anyone in your family own a hybrid vehicle?
Do you have any other experience with a hybrid vehicle?
. As the technology improves, and the price comes down, do you think you
will be interested in purchasing an alternative fuel vehicle?
.
.
.
What role do you believe the government should play in influencing
consumers to purchase hybrid vehicles (should it be mandated, should tax
credits be offered, etc.)?
The combustion reaction mentioned follow the model of the combustion reactions as illustrated in the information about the hybrid vehicles.
How to explain hybrid vehicle?It should be noted that the comparison between the decrease in HC emissions and the blended fuels shows that methanol is more effective than ethanol.
The lowest emissions are obtained with methanol-blended fuel. When more combustion is complete, it will result in lower emissions.
Anyone in my family do not own a hybrid vehicle and I didn't have any other experience with a hybrid vehicle. Hybrid electric vehicles are powered by an internal combustion engine and one or more electric motors, that uses energy stored in batteries.
A hybrid electric vehicle cannot be plugged in to charge the battery but rather, the battery is charged through regenerative braking and by the internal combustion engine.
When the technology improves, and the price comes down, I will be interested in purchasing an alternative fuel vehicle.
The government should play in influencing consumers to purchase hybrid vehicles by offering tax credits and giving incentives.
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Find the solution to the question
Answer:
B
Explanation:
FUN is not building block of matter.
Discuss why the solubility of CaCO33(s) would be greater in distilled water than in tap water that contains 50 mg/L of calcium ions (Ksp CaCO3 = 8.7x10-9).
Answer:
mitxtitsixitdkgxgxmhhxlyfuldyooyddryodyoodyyodroydgodydout70r9ryiryogiustoydotsixulslysrluhsro6rh zpyrqujs7t7wiyidiey9ye9yd96d9ydoydoydodyoydoydoyydgkxyodigggoydyoydyyo
Explanation:
uodigdoydoydohhxoydoydodkgdyodisirs85ssto toutuset8itgxotteotsmvtieksititsgie8e85t8upfgtjwdujhftisnfvoyxuvfgkrtj57lhmdkhflfheogkhptufsjfxocljhflhfoydllbxoydoggsigxitieoyurreifosuuluprohgsjtgjzffgfhcpzfjchzjfcg gsjiggdoydogxlhd6oxhx9yfljf
The greater, the ionic property, the greater will be solubility. water is a covalent compound where calcium carbonate is ionic that's why the solubility of [tex]CaCO_{3}[/tex](s) would be greater.
What is solubility?The capability of a substance, the solvent, to combine with another substance, the solvent, has been known as solubility. Insolubility, or just the solute's inability to create that kind of a solution, would be the opposite attribute.
How does solubility depend on the ionic compound?Ionic chemicals dissolve readily in just about any liquid that has the ability to rupture the ionic link present in them. Since water itself has a stronger ionic bond and is still polar in nature, water disrupts the ionic link by hydrogen bonding. Several other solvents, like kerosene and gasoline, are unable to dissolve the ionic bond.
The greater, the ionic property, the greater will be solubility. water is a covalent compound where calcium carbonate is ionic that's why the solubility of [tex]CaCO_{3}[/tex](s) would be greater in distilled water than in tap water that contains 50 mg/L of calcium ions
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Consider the reaction below.
Upper N a superscript plus, plus upper C subscript 2 upper H subscript 3 upper O subscript 2 superscript minus (a q) plus upper H superscript plus, plus upper C l superscript minus right arrow upper N a superscript plus, plus upper C l superscript minus plus upper H upper subscript 2 upper H subscript 3 upper O subscript 2.
Which is the net ionic equation for the reaction?
Answer:
D.) C₂H₃O₂⁻ (aq) + H⁺ ---> HC₂H₃O₂
Explanation:
The net ionic equation shows the compounds/elements that directly involved in the reaction. These substances can be determined depending on where and how many times they appear in the equation. If the compounds/elements appear on both the reactants and products side of the equation, they will not be found it the net ionic equation.
Expanded Equation:
Na⁺ + C₂H₃O₂⁻ (aq) + H⁺ + Cl⁻ ---> Na⁺ + Cl⁻ + HC₂H₃O₂
Net Ionic Equation:
C₂H₃O₂⁻ (aq) + H⁺ ---> HC₂H₃O₂
Therefore, since Na⁺ and Cl⁻ are located on both sides, they are eliminated. This leaves only the C₂H₃O₂⁻ (aq), H⁺, and HC₂H₃O₂ left in the net ionic equation.
Which of the following equations is correct for coffee-cup calorimeter?
q reaction = q calorimeter
q reaction = -q calorimeter
The equation that is correct for coffee-cup calorimeter is q reaction = -q calorimeter. Details about coffee-cup calorimeter.
What is a calorimeter?A calorimeter is an apparatus for measuring the heat generated or absorbed by either a chemical reaction, change of phase or some other physical change.
A coffee-cup calorimeter is a specific type of calorimeter that involves the absorption of heat of a reaction by water when a reaction occurs.
The enthalpy change of the reaction is equal in magnitude but opposite in sign to the heat flow for the water:
qreaction = -(qwater)
Therefore, the equation that is correct for coffee-cup calorimeter is q reaction = -q calorimeter.
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a compound with a molar mass of 92g/mol contains 0.3955g of nitrogen and 0.904g of oxygen. Determine the empirical and molecular formula
Answer:
Empirical: NO2. Molecular: N2O4
Explanation:
In order to determine the empirical formula, we divide each element's mass by their respective molar mass:
N: 0.3955g/14.01 g/mol = 0.02823 mol
O: 0.904g/16.00 g/mol = 0.0565 mol
Next, we take the smallest value and multiply it till it is close enough to an integer:
0.02823 x 40 = 1.12 Close enough to 1.
0.0565 x 40 = 2.26. Close enough to 2.
Therefore, the Empirical Formula is: NO2
Next, we determine how much the Empirical formula weighs and see if it matches 92g/mol:
14.01 g/mol + 2(16.00 g/mol) = 46.01 g/mol
We can assume this is roughly half of 92 g/mol so we can multiply each subscript by 2 to match the weight.
Therefore, the Molecular formula is N2O4
Hope this helped!
How much does 2.3 moles of Mg(NO2)2 weigh?
Answer:
mass = 266.8 g
Explanation:
mass = no. of moles x molar mass ([tex]M_r[/tex])
[tex]M_r \space\ \space\ of[/tex] [tex]Mg(NO_2)_2[/tex] = 24 + 2[14 + 2(16)]
= 116
∴ mass = 2.3 x 116
= 266.8 g
what is the frequency of a photon with an energy of 4.56 x 10-19J?
Answer:
The wavelength of a photon with an energy of 4.56×10⁻¹⁹ J is 463nm (nanometer)
Define the wavelength of a photon.
Each photon has a wavelength and a frequency. The wavelength is defined as the distance between two peaks of the electric field with the same vector.
A photon is the smallest element of electromagnetic radiation. You can think of a photon as a packet of energy travelling at the speed of light. There is no constant wavelength of a photon, it is dependent on how much energy the photon carries.
The mathematical relationship can be written as
E=hc/ λ
In terms of wavelength,
λ=hc/E
- h is planks constant
- c is the speed of light
- E is the energy of the photon
Where h = 6.626×10⁻³⁴ J⋅s is Planck’s constant and c = 3×10⁸ m/s is the speed of light.
If E = 4.56×10⁻¹⁹ J then λ = 463nm (nano meter)
Hence, the wavelength of a photon with an energy of 4.56×10⁻¹⁹ J is 463nm(nanometer)
Hope its helpful!
Answer:
The wavelength of a photon with an energy of 4.56×10⁻¹⁹ J is 463nm (nanometer)
Define the wavelength of a photon.
Each photon has a wavelength and a frequency. The wavelength is defined as the distance between two peaks of the electric field with the same vector.
A photon is the smallest element of electromagnetic radiation. You can think of a photon as a packet of energy travelling at the speed of light. There is no constant wavelength of a photon, it is dependent on how much energy the photon carries.
The mathematical relationship can be written as
E=hc/ λ
In terms of wavelength,
λ=hc/E
- h is planks constant
- c is the speed of light
- E is the energy of the photon
Where h = 6.626×10⁻³⁴ J⋅s is Planck’s constant and c = 3×10⁸ m/s is the speed of light.
If E = 4.56×10⁻¹⁹ J then λ = 463nm (nano meter)
Hence, the wavelength of a photon with an energy of 4.56×10⁻¹⁹ J is 463nm(nanometer)
A sample of helium gas inside a closed but flexible container occupies a volume of 355mL at 23°C. If the pressure is held constant, to what temperature must the He be raised to cause the container to expand to a final volume of 1.50 L?
Answer:
978.19° C
Explanation:
P1V1/T1 =P2V2/T2 Since the pressure is constant, this can be written as
V1/T1 = V2/T2 RE-ARRANGE TO
V2 * T1/V1 = T2 Note: T must be in Kelvin!!
1.5 L * (273.15 + 23) / (.355 L ) = T2 = 1251.338 K =978.19 C
The compound HgO can be decomposed to form Hg and O2. This can be represented at the atomic level by a chemical equation:
2HgO 2Hg + O2
According to the law of conservation of mass, if 23.5 grams of HgO decomposes and 21.8 grams of Hg is formed, how many grams of O2 must simultaneously be formed?
According to the law of conservation of mass 1.7 grams of [tex]O_2[/tex] will be formed.
What are moles?A mole is defined as 6.02214076 × 1[tex]0^{23}[/tex]of some chemical unit, be it atoms, molecules, ions, or others. The mole is a convenient unit to use because of the great number of atoms, molecules, or others in any substance.
[tex]2HgO[/tex]→ [tex]2Hg + O_2[/tex]
According to the laws of conservation mass of reactants should be equal to the mass of products.
23.5 grams - 21.8 grams
1.7 grams of [tex]O_2[/tex] will be formed.
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Identify the nitrogen compound represented by the formula NO2.
Nitrous oxide
Nitrite
ammonia
nitrate
Answer:
Nitrite
Explanation:
Nitrous Oxide = N₂O
Nitrite = NO₂
Ammonia = NH₃
Nitrate = NO₃⁻
Solve this whole experiment,
I'll be so glad . thanks
●do the above experiment
●give detailed answers
THANKS
The table shows the thermodynamic data for a reaction.
Thermodynamic Data
Energy of the Reactants Energy of the Products Activation Energy
−420 kJ −240 kJ −310 kJ
Which of the following statements explains if the reaction is endothermic or exothermic?
The true statement about this chemical reaction is that: D. the change in enthalpy is +180 kJ, so it is an endothermic reaction.
How to determine the type of reaction?In order to determine whether this chemical reaction is endothermic or exothermic, we would determine the change in enthalpy as follows:
The change in enthalpy = The energy of products - the energy of reactants
Substituting the given parameters into the formula, we have;
The change in enthalpy = -240 - (-420)
The change in enthalpy = -240 + 420
The change in enthalpy = 180 kJ.
Since the change in enthalpy for this chemical reaction, we can infer and logically conclude that it is an endothermic reaction because heat is absorbed.
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Complete Question:
The table shows the thermodynamic data for a reaction.
Thermodynamic Data:
Energy of the Reactants: -420 kJ
Energy of the Products: -240 kJ
Activation Energy: -310 kJ
Which of the following statements explains if the reaction is endothermic or exothermic?
The activation energy is lower than the change in enthalpy, so it is an exothermic reaction.
B. The activation energy is higher than the change in enthalpy, so it is an endothermic reaction.
C. The change in enthalpy is -180 kJ, so it is an exothermic reaction.
D. The change in enthalpy is +180 kJ, so it is an endothermic reaction.
How much would a 55 kg person weigh on venus
Answer:
109.988623 Pounds or 49.89kg
Explanation:
the identities of substances are the same before and after which type of change
Answer:
change of state
Explanation:
Change of state .... like ice changing state to water ....or water chaging state to steam
The hydronium ion concentration of a solution is 2.4 x 10-4.
a. Calculate the pH of the solution.
b. Calculate the pOH of the solution.
c. Calculate the hydroxide ion concentration of the solution
Answer:
a.) pH = 3.62
b.) pOH = 10.38
c.) [OH⁻] = 4.17 x 10⁻¹¹
Explanation:
The hydronium ion concentration can be represented by the symbol: [H₃O⁺]. The hydroxide ion concentration can be represented by the symbol: [OH⁻].
a.) The pH of a solution represents the hydrogen (hydronium) ion concentration. It can be calculated using the following formula:
pH = -log[H₃O⁺]
Since you have been given the hydronium concentration, you can easily find the pH.
[H₃O⁺] = 2.4 x 10⁻⁴
pH = -log[2.4 x 10⁻⁴]
pH = 3.62
b.) The pOH of a solution represents the hydroxide concentration. It measures the opposite of the pH measurement. Since the pH range goes up to 14, you can find the pOH using the following formula:
pOH + pH = 14
Since you now know the value of the pH, you can plug it into the formula to find the pOH.
pOH + 3.62 = 14
pOH = 10.38
c.) You can find the hydroxide concentration using the following formula:
[OH⁻] = 10^-pOH
Since you now know the value of the pOH, you can plug it into the formula to find the hydroxide concentration.
[OH⁻] = 10⁻¹⁰°³⁸
[OH⁻] = 4.17 x 10⁻¹¹
what is the frequency of a wavelength if its wavelength is 3.6 x 10^-9m and its velocity is 3.o x 10^8 m/s
Answer:
Frequency of the wave = 8.33 × 10¹⁶ Hz
Explanation:
• We can use the wave equation to solve this problem:
v = f λ
where:
v = velocity of wave (3.0 × 10⁸ m/s)
f = frequency of wave (?)
λ = wavelength of wave (3.6 × 10⁻⁹ m)
• Substituting these values into the equation:
3.0 × 10⁸ = f × 3.6 × 10⁻⁹
f = (3.0 × 10⁸) ÷ (3.6 × 10⁻⁹)
f = 8.33 × 10¹⁶ Hz
when 1 mol of glucose is burned, 2802.5kj of energy is released. calculate rhe quantity of energy released to a person by eating 5.00g of glucose in a candy
77.78 kJ of energy is released when 1 mol of glucose is burned, 2802.5 kJ of energy is released.
What are moles?A mole is defined as 6.02214076 ×[tex]10^{23}[/tex] of some chemical unit, be it atoms, molecules, ions, or others. The mole is a convenient unit to use because of the great number of atoms, molecules, or others in any substance.
Calculate the moles of 5.00g of glucose.
Given mass = 5.00g
The molar mass of glucose = 180.156 g/mol
[tex]Moles = \frac{mass}{molar \;mass}[/tex]
[tex]Moles = \frac{5.00g}{180.156 g/mol}[/tex]
Moles =0.02775372455
The quantity of energy released to a person by eating 5.00g of glucose in a candy.
0.02775372455 x 2802.5 kJ
77.77981305 kJ =77.78 kJ
Hence, 777.78 kJ of energy is released.
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Uric acid can collect in joints, giving rise to a medical condition known as gout. If the pKa of uric acid is 3.89, what is the pH of a 0.0140 M solution of uric acid?
Answer:
The pH of the solution is 2.873
Explanation:
Given:
Pka = 3.89pH of a 0.0140 MLet the solution of the uric acid be HA. We have to set up the ICE table as follows;
HA(aq) + H20(l) ⇄ H3O^+(aq) + A^-
I 0.0140 0 0
C -x +x +x
E 0.0140 - x x x
Ka = 10^-(pka)
= 10^-3.89
= 1.28 x 10^-4
Ka = [H+] * [A-]/[HA]
=> 1.28 x 10^-4 = [H+]^2 / 0.0140
=>[H+]^2 = 1.28 x 10^-4 x 0.014
=> [ H+] = 1.338656 x 10^-3
so pH = - log [ H+ ] = - log 1.338656 x 10^-3
= 3 - log 1.338656
= 2.87333101111
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What is hypotheses
?
Answer:
is an assumption , in an idea that is proposed for the sake of argument so that it can be tested to see if it might be true.
아 이거 끝이 없어
How many atoms are there in 65.89 g of lead?
Answer:
1.915 x 10²³ atoms Pb
Explanation:
To find the amount of atoms, you need to (1) convert grams to moles (via atomic mass of lead) and then (2) convert moles to atoms (via Avogadro's Number). It is important to arrange the conversions in a way that allows for the cancellation of units (the desired unit should be in the numerator). The final answer should have 4 sig figs to match the given value (65.89 g).
Atomic Mass (Pb): 207.20 g/mol
Avogadro's Number:
6.022 x 10²³ atoms = 1 mole
65.89 g Pb 1 mole 6.022 x 10²³ atoms
------------------ x ---------------- x ------------------------------- = 1.915 x 10²³ atoms Pb
207.20 g 1 mole
In the preparation of the soap above, a student dissolved 5 g of NaOH in 25 mL water and added 10 mL palm kernel oil (density: 0.997 g/cm3). The mixture was heated and boiled with 20 mL of water, followed by addition of NaCl to the soap solution. At the end of the experiment, the student obtained 6.2 g of soap What is the percentage yield of the soap?
The Percent yield of soap is 17.8%
What is the percent yield of soap?Percent yield is given as follows:
Percent yield = actual yield/expected yield * 100%The actual yield of soap = 6.2 g
The expected yield is determined from the equation of the reaction.
The equation of the reaction is given as follows:
NaOH + CH₃(CH₂)₁₄COOH ----> CH₃(CH₂)₁₄COONa + H₂O
Molar mass of (palm kernel oil) CH₃(CH₂)₁₄COOH = 256 g/mol
Molar mass of NaOH = 40 g/mol
Molar mass of (soap) CH₃(CH₂)₁₄COONa = 278 g/mol
Mass of palm kernel oil = 9.9 g
Expected mass of soap = 5/40 * 278 = 34.75 g
Percent yield = 6.2/34.75 * 100 = 17.8%
Therefore, the Percent yield of soap is 17.8%
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