Answer:
Explanation:
in your case ,
Meaured value = 112.3
actual value = 119.5
Absolute error= measured value - actual value
Percent error = [measured value - actual value / actual value ] x 100
Hope this help you to find the answer
which element causes burning when me mix it with oxygen
Answer:
Hydrogen peroxide is ans
What is the predicted order of first ionization energies from highest to lowest for lithium (Li), sodium (Na), potassium (K), and rubidium (Rb)?
Rb > K > Na > Li
K > Rb > Na > Li
Li > Na > K > Rb
Rb > K > Li > Na
Answer:
Li>Na>K>Rb
Explanation:
Answer:
c. Li > Na > K > Rb
Explanation:
edge 2021
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1- A volumen constante un gas ejerce una presión de 880 mmHg a 20º Celsius dentro de una olla a presión ¿Qué temperatura habrá si el marcador de presión muestra un valor de 1050 mmHg?
Answer:
In this problem the correct thing would be to use the ideal gas equation.
Explanation:
Well in this exercise we will use the following equation:
(P x V) / T = (p x v) / t
On the right side of the equation we will find the initial values, that is, the values with which the reaction begins and in general they are always the first to write in the problems.
Instead on the left side of the equation, the letters that are in lowercase are the final values, that is to say at the end of the reaction that the values of pressure, temperature and volume are reached.
P is pressing, just like p, T and t are temperature, and V and v are volume.
We use this equation so we consider the behavior of said gas to be an IDEAL gas, a constant volume.
That is why the given pressures require an atmosphere to pass, which is another unit used to press the pressure ... Much needed in this equation! An atmosphere is equivalent to 760 millimeters of mercury ...
Then the final and initial pressures would be:
initial pressure: 1.15 atm
final pressure: 1.38 atm
In this way you already have the values to be able to solve in the equation your unknown that would be the final temperature:
Considering that the volume is constant, we cancel it from the equation, 1.15 atm would be in the value of P and 1.38 in the value of p ... In this way it considers that 20 degrees Celsius is the initial temperature or ses T, we would only have to clear the t.
1. Reaccionan 9.7 Kg de un mineral de níquel al 70% con 8L de una solución de ácido fosfórico al 60% y con una densidad de 1.36g/ml.
Answer:
The reaction produces 201.4 g of hydrogen gas and 12.2 kg of Nickel Phosphate.
Explanation:
English Translation
9.7 Kg of a 70% nickel mineral react with 8L of a 60% phosphoric acid solution and with a density of 1.36g / ml.
Solution
The problem doesn't seen to be complete as it doesn't ask a question in the end. But, we will just calculate the amount of each product expected to cover the grounds.
The balanced chemical reaction between Nickel and Phosphoric acid is given as
3Ni + 2H₃PO₄ → 3H₂ + Ni₃(PO₄)₂
We need to first obtain the limiting reagent, that is, the reagent that is used up during the reaction and is in short supply. This reagent determines the amount of products that will be formed.
Mass of nickel that is present at the start = 70% of 9.7 kg = 6.79 kg
Mass of Phosphoric acid present at the start of the reaction = 60% of (8000 mL × 1.36 g/mL) = 6528 g = 6.528 kg
Converting both of these to number of moles
Number of moles = (mass)/(Molar mass)
For nickel,
Mass = 6.79 kg = 6790 g
Molar mass = 58.6934 g/mol
Number of moles at the start = (6790/58.6934) = 115.7 moles
For Phosphoric acid
Mass = 6528 g
Molar mass = 97.994 g/mol
Number of moles = (6528/97.994) = 66.6 moles
3 moles of Ni reacts with 2 moles of H₃PO₄
From the number of moles present initially, shows that Phosphoric acid is in limited supply and is the limiting reagent.
From the stoichiometric balance of the reaction
2 moles of H₃PO₄ gives 3 moles of H₂
66.6 moles of H₃PO₄ will give (66.6×3/2) of H₂, that is, 99.9 moles of H₂.
Mass of H₂ liberated from the reaction = (Number of moles) × (molar mass) = 99.9 × 2.016 = 201.3984 g = 201.4 g
2 moles of H₃PO₄ gives 1 mole of Ni₃(PO₄)₂
66.6 moles of H₃PO₄ will give (66.6×1/2) of Ni₃(PO₄)₂, that is, 33.3 moles of Ni₃(PO₄)₂.
Mass of Ni₃(PO₄)₂ produced from the reaction = (Number of moles) × (molar mass) = 33.3 × 366.02 = 12,188.466 g = 12.2 kg
Hope this Helps!!!
4-Methylphenol, CH3C6H4OH (pKa 10.26), is only slightly soluble in water, but its sodium salt, CH3C6H4O-Na , is quite soluble in water. Describe the solubility of 4-methylphenol in solutions of sodium hydroxide, sodium bicarbonate (NaHCO3), and sodium carbonate (Na2CO3). The pKa values for the conjugate acids of sodium hydroxide, sodium bicarbonate (NaHCO3), and sodium carbonate (Na2CO3) are 15.7, 6.36, and 10.33, respectively.
Explanation:
We know that more is the [tex]pK_{a}[/tex] value, weaker will be the acid. Also, an acid completely dissociates into ions in an aqueous base solution when [tex]pK_{a}[/tex] of conjugate acid of base is greater than acid.
4-methylphenol [tex](CH_{3}C_{6}H_{4}OH)[/tex] ([tex]pK_{a} = 10.26[/tex]) is quite soluble in its sodium salt. In NaOH, the dissociation will be as [tex]Na^{+}[/tex] and [tex]OH^{-}[/tex] ions as NaOH is a strong base.
Therefore, 4-methylphenol will readily dissolve in NaOH solution.
As, [tex]NaHCO_{3}[/tex] is not a strong base but as 4-Methylphenol forms a sodium salt hence, it will have a low solubility as compared to NaOH.
Whereas [tex]Na_{2}CO_{3}[/tex] is not a base but when dissolved in water it shows basic character as it produces NaOH (strong base) and [tex]H_{2}CO_{3}[/tex] (weak acid). As a result, the solution gets basic. Hence, 4-methylphenol will readily dissolve in [tex]Na_{2}CO_{3}[/tex].
Precision can be defined as the?
Answer:Precision can be defined as the. reproducibility of a measured value. Precision is how close the measured values are to each others. In contrast with accuracy, accuracy is the agreement between a measured value and an accepted value.
Explanation:
Why is tape attracted to my skin? Give explanation
Answer:
Since the tape has extra electrons, it has a negative charge. When you move your finger close to the tape, electrons in your skin are repelled and move away. This makes the skin on your finger tip have a slight positive charge. Since positive and negative attract, the tape moves toward your finger.
Hydrogen bonds can be found between molecules of which substance? NH3 H2 HI CH4
Answer:
All except ch4
Explanation:
NH3 N H 3 and HF can form hydrogen bonds as they have a hydrogen atom bonded to fluorine and nitrogen atoms.
Hydrogen bonds are formed between hydrogen and a highly electronegative atom such as oxygen, halogens etc. Among the given compounds HI form hydrogen bond.
What is hydrogen bond?Hydrogen bond a strong bond type formed between hydrogen and an electronegative atom. Water, hydrogen halides, hydrogen sulphide etc are formed by hydrogen bonds.
Hydrogen is an electropositive atom and will easily lose an electron to a electronegative atom. Thus hydrogen bonds with atoms by sharing electrons each other where, the shared pair of electrons are attractively pulled to the electronegative atom.
Therefore, all the hydrogen bonded compounds are polar in nature. Hydrogen bonds are strong bonds and it can be seen in proteins, DNA, and in other biomolecules.
HI or hydrogen iodide forms hydrogen bond because iodine is comparatively electronegative.
To find more on hydrogen bonds, refer here:
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when a car drives down a street, what evergy conversions are happening?
A new non-electrolyte molecule is discovered. When 241 mg of the molecule is dissolved in 250.0 mL of water, it has an osmotic pressure of 0.072 atm at 25 oC.What is the molar mass of the molecule
Answer:
327.89g/mol
Explanation:
Step 1:
The following data were obtained from the question:
Van 't Hoff factor (i) = 1 (since the molecule is non-electrolyte)
Temperature (T) = 25°C = 25°C + 273 = 298K
Gas constant (R) = 0.0821 atm.L/Kmol
Mass of molecule = 241mg
Volume of water = 250mL
Molarity (M) =?
Osmotic pressure (Π) = 0.072 atm
Step 2:
Determination of the molarity of the molecule.
This can be obtained as follow:
Π = iMRT
0.072 = 1 x M x 0.0821 x 298
Divide both side by 0.0821 x 298
M = 0.072 / (0.0821 x 298)
M = 2.94×10¯³ mol/L
Step 3:
Determination of the number of mole of the molecule. This can be obtained as follow:
Molarity = 2.94×10¯³ mol/L
Volume of water = 250mL = 250/1000 = 0.25L
Mole of molecule =..?
Molarity = mole /Volume
2.94×10¯³ = mole / 0.25
Cross multiply
Mole of molecule = 2.94×10¯³ x 0.25
Mole of molecule = 7.35×10¯⁴ mole.
Step 4:
Determination of the molar mass of the molecule.
Mole of molecule = 7.35×10¯⁴ mole.
Mass of molecule = 241mg = 241×10¯³g
Molar mass of molecule =..?
Mole = Mass /Molar Mass
7.35×10¯⁴ = 241×10¯³/ Molar Mass
Cross multiply
7.35×10¯⁴ x molar mass = 241×10¯³
Divide both side by 7.35×10¯⁴
Molar Mass = 241×10¯³/7.35×10¯⁴
Molar Mass = 327.89g/mol
Therefore, the molar mass of the molecule is 327.89g/mol
What mass of salt would you need to add to 1.00kg of water to achieve a freezing point of -5 degrees C
Answer:
The type of salt to be added to the water is not known from the question but no worries, I will try to give you the step by step procedure to answer any type of question similar to this.
To answer this question, we should know some facts.
1. the molar freezing point depression constant of water (Kf) = 1.86 K kg/mol
2. the molar mass of the salt if NaCl = 58.5 g/mol ; KCl = 74.5 g/mol
3. since the salt can dissociate if NaCl or KCl into two ions, the Van't Hoff factor ( i )= 2
Note that: the change in freezing point, molarity, deepression constant and van't Hoff factor are related by this formula;
ΔTf = i Kf m
So lets take NaCl as the salt:
Molar mass = 58.5 g/mol
Van't Hoff factor = 2
1. calculate the number of moles
So we can calculate the molarity of the salt NaCl from the formula;
m = ΔTf / i Kf
m = 5 / 2 * 1.86
m = 5 / 3.72
m = 1.344 mol/kg
2. calculate the number of moles of the salt required
Next is to multiply the molarity by the mass of water. Density of water = 1kg/L
number of moles = 1.344 mol/kg * 1 Kg/L * 1 kg water
number of moles = 1.344 moles.
3. calculate the mass of the salt.
numner of moles = mass / molar mass
mass = number of moles * molar mass
mass = 1.344 * 58.5
mass = 78.624 g of NaCl salt.
You can follow these steps to solve for the type of salt you are given in the question.
Predict the order of elution if you were to attempt to separate using column chromatography on silica gel and with a gradient eluent system starting with petroleum ether and slowly increasing MTBE % over time.
Answer:
Follows this order: B=> A => C.
Explanation:
NB: kindly check the attachment for the diagram of compounds A, B and C.
Elution is a very important concept in chromatography separation techniques. It deals with the use of eluent in the removal of an adsobate from an adsorbent. The principle behind Elution is just about how polar the solvent is.
So, in this question Compound B will go with the Elution first because of its polarity. Compound B has lesser polarity as compared to Compounds A and B.
Compound A will then elutes second because of its polarity too as resonance increases its polarity.
Last, compound C elutes because it has the highest polarity which is caused by electronegative atoms.
Which of the following errors could cause your percent yield to be falsely high, or even over 100%?
Select ALL that apply.
A.) Heating the sample too vigorously.
B.) Handling the crucible directly with your hands.
C.) Failing to completely decompose the sodium bicarbonate sample.
D.) Taking the mass of the empty crucible without the lid, but including the lid in all other mass measurements.
E.) Taking the mass of all samples with the lid included.
Answer:
B.Handling the crucible directly with your hands.
D.Taking the mass of the empty crucible without the lid, but including the lid in all other mass measurements.
E.Taking the mass of all samples with the lid included.
Explanation:
When observed critically , the measures associated with the errors which could cause your percent yield to be falsely high, or even over 100% are those which increase the weight of the substance with the individual neglecting.
Handling the crucible directly with your hands,Taking the mass of the empty crucible without the lid, but including the lid in all other mass measurements and taking the mass of all samples with the lid included will all increase the weight of the substance. Instead the substance should be placed alone without any form of support or contamination.
Consider a cobalt-silver voltaic cell that is constructed such that one half-cell consists of the cobalt, Co, electrode immersed in a Co(NO3)3 solution, and the other half-cell consists of the silver, Ag, electrode immersed in a AgNO3 solution. The two electrodes are connected by a copper wire. The Co electrode acts as the anode, and the Ag electrode acts as the cathode. To maintain electric neutrality, you add a KNO3 salt bridge separating the two half-cells. Use this information to solve Parts B, C, and D.
A. The half-cell is a chamber in the voltaic cell where one half-cell is the site of the oxidation reaction and the other half-cell is the site of the reduction reaction.
Type the half-cell reaction that takes place at the anode for the cobalt-silver voltaic cell. Indicate the physical states using the abbreviation (s), (l), or (g) for solid, liquid, or gas, respectively. Use (aq) for an aqueous solution. Do not forget to add electrons in your reaction.
B. The half-cell is a chamber in the voltaic cell where one half-cell is the site of an oxidation reaction and the other half-cell is the site of a reduction reaction.
Type the half-cell reaction that takes place at the cathode for the cobalt-silver voltaic cell. Indicate physical states using the abbreviation (s), (l), or (g) for solid, liquid, or gas, respectively. Use (aq) for an aqueous solution. Do not forget to add electrons in your reaction.
Answer:
Anode half reaction;
Co(s) ----> Co^2+(aq) + 2e
Cathode half reaction;
2Ag^+(aq) + 2e-------> 2Ag(s)
Explanation:
A voltaic cell is an electrochemical cell that spontaneously produces electrical energy from chemical reactions. A voltaic cell comprises of an anode (where oxidation occurs) and a cathode (where reduction occurs). The both electrodes are connected with a wire . A salt bridge ensures charge neutrality in the anode and cathode compartments. Electrons flow from anode to cathode.
For the cell referred to in the question;
Anode half reaction;
Co(s) ----> Co^2+(aq) + 2e
Cathode half reaction;
2Ag^+(aq) + 2e-------> 2Ag(s)
Which best explains how heat plays a role in the movement of materials within Earth's interior?
Answer:
Hot material near the core is less dense and rises, when it cools, it becomes more dense and sinks.
Explanation:
This best explains how heat plays a role in the movement of materials within Earth's interior because it's how convection works. Convection is the circular motion that happens when warmer air or liquid which has faster moving molecules, making it less dense rises, while the cooler air or liquid drops down. Convection currents within the earth move layers of magma, and convection in the ocean creates currents.
Earth’s interior is like a closed chamber, hot material near Earth's surface is more denser and sinks, and when it cools, it becomes less dense and Rises.
What is Convection?Convection is the process of heat transfer by the bulk movement of molecules within fluids such as gases and liquids. The heat transfer take place from solid to no solid material. like air and water.
As we take example of home. In home heat take nearer the roof and cold air will be nearer to the flour. It is because of hot is less denser then the cold air. Hot air will become less denser and move towords upside. Cold air become denser move towards down.
Similarly, on earth. Nearer to earth hot materials are more dense and sinks. When it cools, it become less dense and rises.
To find more about Heat flow, refer the link below:
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Why don't we discuss the results during the results section of the project?
Answer: The result section of the project contains your findings while carrying out your research or study.
Explanation:
The Results section of a research or study usually contains only the findings of your study or research.The findings which usually include
1. Data presented in tables, charts, graphs, and other figures.
2. A contextual analysis of this data explaining its meanings. Usually in sentences.
Our result gotten is not discussed in result section because every project or research work has a discussion page where every results or findings are discussed. The result section is expected to carry what you found.
Choose the slope and Y intercept that correspond with the graph
y=3x + 4
Explanation:
Where 3 is the slope and 4 is the y-intercept
what is the equation for "acid dissociation constant" of "carbonic acid"
Answer:
H2CO3 = 2H+ + CO3-
Explanation:
It is simply what carbonic acid breaks down into when placed in water. Since carbonic acid is made up of H and CO3, these are the products.
A sample of 6.022 x 1023 particles of gas has a volume of 22.4 L at 0°C and a pressure of 1.000 atm. Although it may seem silly to contemplate, what volume would 1 particle of gas occupy?
pv=nRT
Answer:
1 particle of the gas would occupy a volume of 3.718*10⁻²³L
Explanation:
Hello,
1. The sample has a particle of 6.022×10²²particles
2. Volume of the sample = 22.4L
3. Temperature of the sample = 0°C = (0 +273.15)K = 273.15K
4. Pressure of the sample = 1.0atm
What volume would 1 particle of the gas occupy?
But we remember that 1 mole of any substance = 6.022×10²² molecules or particles or atoms
What would be the number of moles for 1 particule?
1 mole = 6.022×10²² particles
X moles = 1 particle
X = (1 × 1) / 6.022×10²² particles
X = 1.66×10⁻²⁴ moles
Therefore, 1 particle contains 1.66×10⁻²⁴ moles
Since we know our number of moles, we can proceed to use ideal gas equation,
Ideal gas equation holds for all ideal gas and is defined as
PV = nRT
P = pressure of the ideal gas
V = volume the gas occupies
n = number of moles of the gas
R = ideal gas constant = 0.082 L.atm / mol.K
T = temperature of the gas
PV = nRT
Solving for V,
V = nRT/ P
We can now plug in our values into the above
equation.
V = (1.66*10⁻²⁴ × 0.082 × 273.15) / 1
V = 3.718*10⁻²³L
Therefore, 1 particule of the gas would occupy a volume of 3.718*10⁻²³L.
An unknown compound, B, has the molecular formula C7H12. On catalytic hydrogenation 1 mol of B absorbs 2 mol of hydrogen and yields 2-methylhexane. B has significant IR absorption band at about 3300 and 2200 cm-1. Which compound best represents B?
Answer:
5-methylhex-1-yne//5-methylhex-2-yne//2-methylhex-3-yne
Explanation:
We have to start with the information on the IR spectrum. The signal at 3300 is due to a C-H bend sp carbon and the signal in 2200 is due to the stretch carbon-carbon. Therefore we will have an alkyne. Now if we have 2-methylhexane as the product of hydrogenation we have several options to put the triple bond. Between carbons 1 and 2 (5-methylhex-1-yne), between carbons 2 and 3 (5-methylhex-2-yne) and between carbons 3 and 4 (2-methylhex-3-yne). On carbon 5 we have a tertiary carbon therefore we dont have any other options.
See figure 1
I hope it helps!
Which process is a physical change
Answer:
a physical change is something that has not been modified chemically and can possibly be changed back to the state it was once before. A physical change keeps all the same atoms and none of them is modified.
Example:
When a block of clay is morphed into a giraffe statue, it can be morphed back to its original state. If someone burnt the block of clay, the atoms would be modified and it would be unable to go back to its previous state.
-----------------------------------------------------------------------------------------------------------------
(If you're referring to a question with these answers)
A. iron rusting
B. milk turning to curd
C. water boiling
D. paper burning
E. hard water staining pipes
-----------------------------------------------------------------------------------------------------------------
Answer:
C. Water Boiling
(If you are referring to a question with these answers I think this is the correct answer if not I do apologize)
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A scientist mixed 25.00 mL of 2.00 M KOH with 25.00 mL of 2.00 M HBr. The temperature of the mixed solution rose from 22.7 oC to 31.9 oC. Calculate the enthalpy change for the reaction in kJ/mol HBr, assuming that the calorimeter loses negligible heat, that the volumes are additive, and that the solution density is 1.00 g/mL, and that its specific heat is 4.184 J/g.oC.
Answer:
38.493 KJ/mol
Explanation:
Equation of reaction; HBr + KOH ---> KBr + H2O
Heat evolved = mass * specific heat capacity * temperature rise
Mass of solution = density * volume
Mass = 1.00 g/ml*50 ml = 50g
Temperature rise = 31.9 - 22.7 = 9.2 °C
Heat evolved = 50 * 4.184 * 9.2 = 1924.64 J
From the equation of reaction, 1 mole of HBr reacts with 1mole of KOH to produce 1 mole of H20
Number of moles of HBr involved in the reaction = molar concentration * volume (L)
Molar concentration = 2.0 M, volume = 25 ml = 0.025 L
Number of moles = 2.0 M * 0.025 L= 0.05 moles
Therefore, 0.05 moles of HBr reacts with 0.05 moles of KOH to produce 0.05 moles of H20
Enthalpy change per mole of HBr = 1924.64 J/0.05 moles = 38492.8 J/mol = 38.493 KJ/mol
Consider the reaction in a commercial heat pack: 4 Fe (s) + 3 O2(g) ® 2 Fe2O3 (s) DH = -1652 kJ a) How much heat is released when 1.00 g iron is reacted with excess O2? b) What mass of O2 must react with iron in order to generate 2150 kJ of heat?
Answer:
a) -7.395kJ of energy are released.
b) 125g of O₂ must react.
Explanation:
Based on the reaction:
4 Fe (s) + 3 O₂(g) → 2 Fe₂O₃ (s) ΔH = -1652 kJ
4 moles of iron with an excess of oxygen release -1652kJ of energy
a) The heat released is:
1.00g Fe (molar mass: 55.845g/mol)
1.00g × (1mol / 55.845g) = 0.0179 moles de Fe.
As 4 moles release -1652kJ, 0.0179 moles release:
0.0179 mol Fe × (-1652kJ / 4mol Fe) = -7.395kJ of energy are released.
b) As 3 moles of oxygen produce -1652kJ, 2150kJ are released when react:
2150kJ × (3 mol O₂ / 1652kJ) = 3.9 moles of O₂
As molar mass of O₂ is 32g/mol, mass of 3.9 moles of O₂ is:
3.9 mol O₂ × (32g / mol) = 125g of O₂ must react.
Choose the INCORRECT statement. A. Temperatures of two bodies are equal when the average kinetic energies of the two bodies become the same. B. The heat capacity is the quantity of heat required to change the temperature of the system by one degree. C. The specific heat is the heat capacity for one mole of substance. D. Most metals have low specific heats, as metals can be heated quickly. E. The law of conservation of energy can be written: qsystem qsurroundings
Answer:
Option C
The specific heat is the heat capacity for one mole of a substance.
Explanation:
The incorrect statement is The specific heat is the heat capacity for one mole of a substance.
This is because the specific heat capacity is the amount of heat required to raise the temperature of 1 gramme of a substance by 1 degree Celcius.
Note that the unit in question here for the specific heat capacity of the substance is in grammes.
The definition given in the options is actually for the molar heat capacity of the substance, not the specific heat capacity.
g a solution is made by mixing 500.0 mL of 0.037980.03798 M Na2sO4 Na2sO4 with 500.0 mL of 0.034280.03428 M NaOH NaOH . Complete the mass balance expressions for the sodium and arsenate species in the final solution.
Answer:
The concentration of the sodium and arsenate ions at the end of the reaction in the final solution
[Na⁺] = 0.05512 M
[HAsO₄²⁻] = 0.00185 M
[AsO₄³⁻] = 0.01714 M
Explanation:
Complete Question
A solution is made by 500.0 mL of 0.03798 M Na₂HAsO₄ with 500.0 mL of 0.03428 M NaOH. Complete the mass balance expressions for the sodium and arsenate species in the final solution.
Na₂HAsO₄ + NaOH → Na₃AsO₄ + H₂O
From the information provided in this question, we can calculate the number of moles of each reactant at the start of the reaction and we then determine which reagent is in excess and which one is the limiting reagent (in short supply and determines the amount of products to be formed)
Concentration in mol/L = (Number of moles) ÷ (Volume in L)
Number of moles = (Concentration in mol/L) × (Number of moles)
For Na₂HAsO₄
Concentration in mol/L = 0.03798 M
Volume in L = (500/1000) = 0.50 L
Number of moles = 0.03798 × 0.5 = 0.01899 mole
For NaOH
Concentration in mol/L = 0.03428 M
Volume in L = (500/1000) = 0.50 L
Number of moles = 0.03428 × 0.5 = 0.01714 mole
Since the NaOH is in short supply, it is evident that it is the limiting reagent and Na₂HAsO₄ is in excess.
Na₂HAsO₄ + NaOH → Na₃AsO₄ + H₂O
0.01899 0.01714 0 0 (At time t=0)
(0.01899 - 0.1714) | 0 → 0.01714 0.01714 (end)
0.00185 | 0 → 0.01714 0.01714 (end)
Hence, at the end of the reaction, the following compounds have the following number of moles
Na₂HAsO₄ = 0.00185 mole
This means Na⁺ has (2×0.00185) = 0.0037 mole at the end of the reaction and (HAsO₄)²⁻ has 0.00185 mole at the end of the reaction
NaOH = 0 mole
Na₃AsO₄ = 0.01714 moles
This means Na⁺ has (3×0.01714) = 0.05142 mole at the end of the reaction and (AsO₄)³⁻ has 0.01714 mole at the end of the reaction
H₂O = 0.01714 moles
So, at the end of the reaction
Na⁺ has 0.0037 + 0.05142 = 0.05512 mole
(HAsO₄)²⁻ has 0.00185 mole
(AsO₄)³⁻ has 0.01714 mole.
And since the Total volume of the reaction setup is now 500 mL + 500 mL = 1000 mL = 1 L
Hence, the concentration of the sodium and arsenate ions at the end of the reaction is
[Na⁺] = 0.05512 M
[HAsO₄²⁻] = 0.00185 M
[AsO₄³⁻] = 0.01714 M
Hope this Helps!!!
Answer:
[tex]\rm [Na^{+}]= \text{0.055 12 mol/L}[/tex]
[tex]\rm [HAsO_{4}^{2-}] + [AsO_{4}^{3-}] + [H_{2}AsO_{4}^{-}] + [H_{3}AsO_{4}] = \text{0.018 99 mol/L}[/tex]
Explanation:
The overall equation for the reaction is
Na₂HAsO₄ + NaOH ⟶ Na₃AsO₄ + H₂O
1. Mass balance for Na
All the Na⁺ comes from the Na₂HAsO₄ and the NaOH.
The mass balance equation for Na is
[tex]\rm c_{Na^{+}} = 2[Na^{+}]_{Na_{2}HAsO_{4}} + [Na^{+}]_{NaOH}[/tex]
At the moment of mixing and before the reaction started, the total volume had doubled, so the concentrations of each component were halved.
[Na₂HAsO₄] = ½ × 0.037 98 =0.018 99 mol·L⁻¹
[NaOH] = ½ × 0.034 28 = 0.017 14 mol·L⁻¹
[tex]\rm c_{Na^{+}} = 2\times 0.01899 + 0.01714 = 0.03798 + 0.01714\\c_{Na^{+}}= \textbf{0.055 12 mol/L}[/tex]
2. Mass balance for arsenate species
All the arsenate species come from the Na₂HAsO₄.
The reactions involved are
HAsO₄²⁻+ OH⁻ ⇌ AsO₄³⁻ + H₂O
HAsO₄²⁻ + H₂O ⇌ H₂AsO₄⁻ + OH⁻
H₂AsO₄⁻ + H₂O ⇌ H₃AsO₄ + OH⁻
The mass balance equation for arsenate species is
[tex]\rm c_{\text{arsenate}} = [HAsO_{4}^{2-}] + [AsO_{4}^{3-}] + [H_{2}AsO_{4}^{-}] + [H_{3}AsO_{4}][/tex]
At the moment of mixing, the concentration of Na₂HAsO₄ had halved.
[Na₂HAsO₄] = ½ × 0.039 78 = 0.018 99 mol·L⁻¹
[tex]\rm [HAsO_{4}^{2-}] + [AsO_{4}^{3-}] + [H_{2}AsO_{4}^{-}] + [H_{3}AsO_{4}] = \textbf{0.018 99 mol/L}[/tex]
If a jet’s cruising altitude is 32,200ft(to three significant figures),the distance in km is :(1 mile=1.61km;1 mile=5280 ft)
Answer:
9.82 km.
Explanation:
Hello,
In this case, given the conversion factors from miles to kilometres and from miles to feet, we can directly compute the jet’s cruising altitude in kilometres as shown below:
[tex]32,200ft\times \frac{1mile}{5280ft}\times \frac{1.61km}{1mile} \\\\=9.82km[/tex]
Best regards.
To determine the absolute age of rocks and fossils, geologists use _____.
Answer:
The rates of decay of radioactive elements
Explanation:
The age of a rock in years is called its absolute age. Geologists find absolute ages by measuring the amount of certain radioactive elements in the rock. When rocks are formed, small amounts of radioactive elements usually get included.
A researcher placed 25.0 g of silver chloride, AgCl, in sunlight and allowed the substance to decompose completely to form silver, Ag, with the release of chlorine gas, Cl2. The gas was collected in a container during the decomposition. The researcher determined that the mass of the silver formed was 18.8 g, and the mass of the chlorine gas formed was 6.2 g. The equation for the reaction is:
Answer:
A. The law of definite proportions states that all pure samples of a particular chemical compound contain the same elements combines in the same proportion by mass.
B. The law of conservation of mass states that during ordinary chemical reactions, matter can neither be created or destroyed.
Note: The full question is as follows;
A researcher placed 25.0 g of silver chloride, AgCl, in sunlight and allowed the substance to decompose completely to form silver, Ag, with the release of chlorine gas, Cl2. The gas was collected in a container during the decomposition. The researcher determined that the mass of the silver formed was 18.8 g, and the mass of the chlorine gas formed was 6.2 g. The equation for the reaction is:
2AgCl ----> 2Ag + Cl2
a. State the law of definite proportions. Then use the researcher's data to confirm the law of definite proportions. Show your calculations.
b. State the law of conservation of matter. Then use the researcher's data to confirm the conservation of matter. Show your calculations.
Explanation:
A. Mass of silver obtained from AgCl = 18.8g.
Percentage mass of silver in the chloride = (18.8/25.0) * 100 = 75.2 %
Mass of chlorine obtained from AgCl = 6.2
Percentage mass of chlorine = (6.2/25) * 100 = 24.8 %
In one mole of AgCl with a molar mass of 143.3 g/mol; mass of silver = 107.8, mass of Cl = 35.5
Percentage mass of Ag = (107.8/143.3) * 100 = 75.2%
Percentage mass of Cl = (35.5/143.3) * 100 = 24.8%
Since the percentages by mass of Ag and AgCl obtained from the sample is the same to that obtained from a mole of AgCl, the law of definite proportions which states that all pure samples of a particular chemical compound contain the same elements combined in the same proportion by mass is verified.
B. Mass of reactant; AgCl sample = 25.0
Mass of products; At = 18.8 g; Cl = 6.2 g
Sum of products masses = 18.8 + 6.2 = 25.0 g
Therefore mass of reactant = mass of products.
This is in accordance with the law of conservation of mass which states that during ordinary chemical reactions, matter is neither created nor destroyed.
Describe, in detail, to a freshman undergraduate how to make 1 liter of LB + Kan (100 μg/ml final concentration) + Amp (50 μg /ml final concentration) liquid media. [Include things like how many grams of each component that you use, how much antibiotic (in ml) to add (stock solutions – 100 mg/ml ampicillin, 25 mg/ml kanamycin), and in what type of container you perform the sterilization step.] Show your calculations.
Answer:
Explanation:
The objective here is to prepare 1 liter of LB + Kan (100 μg/ml final concentration) + Amp (50 μg /ml final concentration) liquid media.
Given that :
the Stock concentration of Amp: 100 mg/ml (since 1 mg/ml = 1000 μg/ml)
it is required that we convert stock concentration in μg/ml since 100 mg/ml = 100000 μg/ml
However, using formula C₁V₁=C₂V₂ (Ampicilin),
where:
C₁ = 100000 μg/ml,
V₁=?,
C₂= 50 μg/ml,
V₂=1000 ml
100000 μg/ml × V₁ = 50 μg/ml × 1000 ml
V₁ = 50 μg/ml × 1000 ml/100000 μg/ml
V₁ = 0.5 ml
Given that:
the Stock concentration of Kan: 25 mg/ml (since 1 mg/ml = 1000 μg/ml)
it is required that we convert stock concentration in μg/ml , 25 mg/ml = 25000 μg/ml
Now by using formula C₁V₁=C₂V₂ (Kanamycin),
C₁ = 25000 μg/ml,
V₁=?,
C₂= 100 μg/ml,
V₂=1000 ml
25000 μg/ml × V₁ = 100 μg/ml × 1000 ml
V₁ = 100 μg/ml × 1000 ml/25000 μg/ml
V₁ = 4 ml
Thus; in 1 lite of Lb+ Kan+Amp preparation;
0.5 ml of Amp & 4 ml of kanamycin is used for their stock preparation.
Finally;
Sterilization step should be carried out in flask (Clean dry glass wares) for media in an autoclave, the container size should be twice the volume of media which is prepared.
Calculate Keq for these reactions and predict if the equilibrium will lie to the right or to the left as written. (You may enter your answer in scientific notation, e.g. 1.0*10^-9. Enter your answer to two significant figures.) Reaction 1: + + pKa = 9 pKa = 38 Keq = Equilibrium position = _______ Reaction 2: + + pKa = 35 pKa = 25 Keq = Equilibrium position = _______
Complete Question
The complete question is shown on the first uploaded image
Answer:
For reaction 1
[tex]K_{eq} = 10^{29}[/tex]
The equilibrium position is to the right
For reaction 2
[tex]K_{eq} = 10^{-6.66}[/tex]The equilibrium position is to the left
Explanation:
Generally [tex]pKa[/tex] is mathematically evaluated as
[tex]pKa = pKa _ \ {left }} - pKa _ \ {right }}[/tex]
And equilibrium position [tex]K_a[/tex] is mathematically evaluated as [tex]K_{eq} = 10^\ {-pK_a}[/tex]
From the question we are told that
For reaction 1
[tex]pKa_\ {left}} \ = 9[/tex]
[tex]pKa_\ {right }} \ = 38[/tex]
So
[tex]pKa = 9-38[/tex]
[tex]pKa =-29[/tex]
So [tex]K_{eq} = 10^{-(-29)}[/tex]
[tex]K_a = 10^{29}[/tex]
This implies that the equilibrium position is to the right
For reaction 2
[tex]pKa_\ {left}} \ = 15.9[/tex]
[tex]pKa_\ {right }} \ = 9.24[/tex]
So
[tex]pKa = 15.9-9.24[/tex]
[tex]pKa = 6.66[/tex]
So [tex]K_{eq} = 10^{-(6.66)}[/tex]
[tex]K_{eq} = 10^{-6.66}[/tex]
This implies that the equilibrium position is to the left