The blank solution used to calibrate the spectrophotometer contains 0.2 M Fe(NO3)3 and 0.1 M HNO3 to reflect the composition of the actual samples and to maintain consistent ionic strength and acidity, leading to more accurate and reliable measurements.
Explanation:When calibrating a spectrophotometer, it is preferred to use a blank solution that is reflective of the matrix of the samples being measured. In this case, the blank solution contains not just de-ionized water but also 0.1 M HNO3 and 0.2 M Fe(NO3)3 diluted accordingly. This approach is preferred because it accounts for the absorption of the solvent and any potential interaction with the analyte.
The use of HNO3 in the calibration blank maintains a consistent ionic strength and acidity as in the samples, which can affect the absorbance readings. This method reduces background noise and leads to more accurate and reliable measurements when comparing the blank to the actual samples containing Fe³+ ions.
The blank solution for calibration includes Fe(NO₃)₃ and HNO₃ to match the sample matrix, reducing calibration errors caused by matrix effects. De-ionized water fails to replicate the sample's chemical environment.
The blank solution used to calibrate the spectrophotometer is 10.0 mL of 0.2 M Fe(NO₃)₃ diluted to 25.0 mL with 0.1 M HNO₃. This solution is preferred over de-ionized water because it closely matches the matrix of the actual samples being measured, ensuring that any absorbance readings due to the matrix itself are accounted for. This reduces the possibility of matrix effects, thus providing a more accurate calibration for the spectrophotometer. This ensures more accurate spectrophotometer readings.
De-ionized water lacks the chemical environment of the sample solutions, which could lead to calibration errors. By using a matrix-matched blank, the spectrophotometer can be properly calibrated, accounting for interactions between Fe(NO₃)₃ and HNO₃ that might affect absorbance.
Calculate the molality of a 27.0% (by mass) aqueous solution of nitric acid.
To calculate the molality of the aqueous solution of nitric acid, you first convert the mass of nitric acid to moles, then divide by the mass of water in kilograms. This gives a resulting molality of 5.86 mol/kg.
Explanation:The molality of a solution is calculated through the number of moles of solute per kilogram of solvent. To calculate the molality of a 27.0% (by mass) aqueous solution of nitric acid, we first need to determine the number of moles of Nitric acid and the mass of the water. Since the given information is in percantage by mass, we can assume a solution weight of 100g, therefore we have 27g of Nitric Acid and 73g(0.073 kg) of Water.
Step 1: Convert 27g of Nitric Acid to moles. Nitric Acid(HNO3) has a molar mass of about 63.01 g/mol, so that 27g/63.01 g/mol=0.428 mol of HNO3
Step 2: Calculate the molality using the formula molality=n(solute)/m(solvent in kg). So, our molality = 0.428 mol/0.073 kg = 5.86 mol/kg or simply 5.86m.
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To calculate the molality of a 27.0% nitric acid solution, determine the masses of solute and solvent, calculate the moles of [tex]HNO_3[/tex], convert the mass of the solvent to kilograms, and use the molality formula. The molality of this solution is 5.87 m.
Calculate the molality of a 27.0% (by mass) aqueous solution of nitric acid.
To calculate the molality of a 27.0% [tex]HNO_3[/tex]aqueous solution:
Determine the mass of solute ([tex]HNO_3[/tex]) and solvent (water). For a 100 g solution:
Mass of [tex]HNO_3[/tex]= 27.0 gMass of water = 100 g - 27.0 g = 73.0 gCalculate the moles of [tex]HNO_3[/tex]. Molar mass of [tex]HNO_3[/tex]= 1.01 g/mol (H) + 14.01 g/mol (N) + 3 x 16.00 g/mol (O) = 63.01 g/mol
Moles of HNO3 = 27.0 g / 63.01 g/mol = 0.4285 mol
Convert the mass of water to kilograms. Mass of water = 73.0 g = 0.073 kg
Calculate the molality. Molality (m) = moles of solute / mass of solvent in kg
Molality = 0.4285 mol / 0.073 kg = 5.87 m
The molality of the 27.0% aqueous solution of nitric acid is 5.87 m.
PLEASE HELP!
The freezing of water at 0⁰C can be represented as follows: H2O (l) ↔ H2O(s) The density of liquid water is 1.00 g/cm3. The density of ice is 0.92 g/cm3. In 3 – 4 sentences explain why applying pressure causes ice to melt.
The application of pressure makes ice to melt. This is because of the factor that externally applied pressure decreases or diminishes the melting point of ice, so it gets to transform into water readily. With the lowering of the melting point, it permits more solids to get transformed into water. Thus, leading to the melting of ice. This procedure is also known as regelation.
Which would melt more ice - a pot of hot water or a tub of warm water? explain your answer?
calculate the mass, in grams, of 0.433 mole of calcium nitrate
Taking into account the definition of molar mass, the mass of 0.433 moles of calcium nitrate is 71.012 grams.
Molar mass is the amount of mass that a mole of a substance contains, which can be an element or a compound.
Calcium nitrate is an inorganic compound with the formula Ca(NO₃)₂. The molar mass of a compound is the sum of the molar mass of the elements that make it up multiplied by the times they appear in the compound.
In this case, the molar mass of the elements is:
Ca: 40 g/moleN: 14 g/moleO: 16 g/moleSo, the molar mass of calcium nitrate is:
Ca(NO₃)₂= 40 g/mole + 2×(14 g/mole + 3×16 g/mole)
Ca(NO₃)₂= 164 g/mole
Then it is possible to apply the following rule of three: if by definition of molar mass 1 mole of calcium nitrate contains 164 g, 0.433 moles of the compound contains how much mass?
[tex]mass of calcium nitrate=\frac{0.433 molesx164 grams}{1 mole}[/tex]
mass of calcium nitrate= 71.012 grams
Finally, the mass of 0.433 moles of calcium nitrate is 71.012 grams.
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https://brainly.com/question/20423545?referrer=searchResultsWhat is the volume of this graduated cylinder to the correct degree of precision? 44.0 ml 44 ml 44 cc3 0.44?
Answer:
It is 44.
Explanation:
I just did it on odyssey
The volume of the graduated cylinder to the correct degree of precision is 44 ml.
What is graduated cylinder?The volume of a liquid is typically measured in a laboratory with a graduated cylinder, commonly referred to as a measuring cylinder or mixing cylinder. It is narrowly cylindrical in form. The amount of liquid that has been measured is shown by each marked line on the graduated cylinder.
The volume of a liquid is frequently measured using graduated cylinders. Graduated cylinders are typically more exact and precise than laboratory flasks and beakers, but they shouldn't be used for volumetric analysis since they are less accurate and precise.
Instead, volumetric glassware, like a volumetric flask or volumetric pipette, should be used. The volume of a solid can occasionally be determined indirectly by measuring the displacement of a liquid using graduated cylinders.
Therefore, The volume of the graduated cylinder to the correct degree of precision is 44 ml.
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Which choice is an example of a decomposer? Question 8 options: tree sun fungi bat
Answer:
fungi is the right answer
Explanation: took the test
which element would be a positive ion in a compound: Sr or Te
The element that would be a positive ion in a compound between Sr and Te would be Sr.
How to determine the charge on ionsElements form positive or negative ions based on the number of valence electrons their atoms contain and the tendency to either donate these electrons to form bonds or accept more electrons to form bonds.
The donation of acceptance of electrons will enable atoms to form an octet structure.
The number of valence electrons in Sr atoms is 2. In order to form an octet when bonding, these 2 electrons are readily donated rather than accepting more electrons. Thus, Sr ions are usually [tex]Sr^{2+[/tex].
The number of valence electrons in Te atoms is 6. Hence, instead of donating these electrons to form an octet, it will rather accept 2 more electrons. Thus, Te ions are usually [tex]Te^2^-[/tex].
In other words, Sr would be the positive ion in a compound.
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Final answer:
Strontium (Sr) would form a positive ion in a compound since it is an alkaline earth metal that readily loses electrons to become a cation, whereas tellurium (Te) tends to gain electrons to form an anion.
Explanation:
Between the elements strontium (Sr) and tellurium (Te), Sr would typically form a positive ion in a compound. This is because Sr is an alkaline earth metal and is found in Group 2 of the periodic table, where elements readily lose electrons to form cations with a +2 charge. On the other hand, Te is a metalloid in Group 16, known for gaining electrons to form anions with a -2 charge. Compounds are neutral, which means that the total number of positive charges must balance the total number of negative charges.
Additionally, Sr is lower down in its group than Ca, making it easier to remove an electron from Sr than from Ca. Hence, Ca has the higher ionization energy (IE) compared to Sr. When considering a potassium ion (K+), it would also be harder to remove an electron because it already has a positive charge. Therefore, the IE of K+ is significantly higher, especially since the next electron to be removed would come from a different electron shell.
The equation 2c3h7oh(g) + 9o2(g)→6co2(g) + 8h2o(g) is an example of which type of reaction?
the answer is combustion
The given equation represents a combustion reaction. The organic gas combines with atmospheric oxygen to form carbon dioxide and water .
What is combustion?Combustion is a type of reaction, in which gaseous reactants combines with atmospheric oxygen to form carbon dioxide and water. In combustion reaction heat energy is released by the reaction system.
The reaction from which a heat energy is released is called an exothermic reaction. Thus, combustion is an exothermic reaction. The reaction in which heat is absorbed the system is called endothermic reaction.
In the given reaction, 2 moles of propanol reacts with 9 moles of oxygen forming 6 moles of carbon dioxide and 8 moles of water. This reaction is an example of combustion.
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__________ is the editor enzyme for DNA replication. It checks to make sure that the bases were added correctly. Question 1 options:
What is the Lewis dot structure of BeO
Please help with a chem question thank you!
Radioactivity was discovered around:
1600
1700
1800
1900
All chemical reactions involve a transfer of energy true or false
Answer:
true
Explanation:
Which gas law has assumptions of a fixed amount and temperature of a gas
Find the half-life of an element which decays by 3.415% each day.
The half-life of an element that decays by 3.415% each day is approximately 20.27 days.
Explanation:The half-life of an element can be calculated using the formula:
half-life = (ln(2)) / (decay constant)
where the decay constant is the rate at which the element decays per time period. In this case, the element decays by 3.415% each day. To find the decay constant, we convert the percentage to a decimal by dividing it by 100:
decay constant = 0.03415
Now we can calculate the half-life:
half-life = (ln(2)) / (0.03415)
A calculator can be used to find the value of ln(2), which is approximately 0.693:
half-life = 0.693 / 0.03415 = 20.27 days
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Which of the following gases will diffuse most quickly at a given temperature?
Gas A; MW = 14.28 g/mol
Gas B; MW = 26.92 g/mol
Gas C; MW = 39.95 g/mol
Gas D; MW = 108.60 g/mol
The gas that is having lowest density will diffuse faster than other gases. As lesser denser will diffuse more quickly than the one which is more denser. Density is directly proportional to mass of the substance that is more mass of the substance is , more denser it will be. So here the Gas A is having lesser molecular weight than the other gases so it will diffuse more quickly than the other gases.
Gas A; MW = 14.28 g/mol
which describes the force between two magnets winter south poles are almost touching
What limitation is placed on electrons in the bohr model of the atom?
Bohr's model of the atom places a limitation on electrons by assuming they move in discrete orbits, but this model is not accurate and does not account for electron-electron interactions.
Explanation:Bohr's model of the atom places a limitation on electrons in that it assumes they move in discrete orbits around the nucleus, with each orbit having a certain energy level. However, this model does not account for electron-electron interactions in atoms with more than one electron and does not accurately represent the true behavior of electrons in atoms. As quantum mechanics was developed, it revealed that electrons do not have well-defined orbits but instead exist as clouds of probability around the nucleus. This limitation of Bohr's model was an important step toward developing a more accurate understanding of atomic physics.
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What mass of KBr (in grams) should you use to make 150.0 mL of a 1.70 M solution of KBr?
Final answer:
To make 150.0 mL of a 1.70 M KBr solution, you need 30.33 grams of KBr. This is calculated by multiplying the molarity (1.70 M), the volume in liters (0.150 L), and the molar mass of KBr (119.00 g/mol).
Explanation:
To calculate the mass of KBr needed to make 150.0 mL of a 1.70 M solution, we need to use the formula:
Mass (g) = Molarity (M) × Volume (L) × Molar Mass (g/mol)
First, convert the volume from milliliters to liters by dividing by 1000:
150.0 mL = 0.150 L
Next, find the molar mass of KBr, which is the sum of the atomic masses of potassium (K) and bromine (Br). Potassium has an atomic mass of 39.10 g/mol, and bromine has an atomic mass of 79.90 g/mol:
Molar Mass of KBr = 39.10 g/mol + 79.90 g/mol = 119.00 g/mol
Now, we can calculate the mass of KBr:
Mass of KBr = 1.70 M × 0.150 L × 119.00 g/mol = 30.33 grams
Therefore, you should use 30.33 grams of KBr to make the solution.
HELP I DON'T HAVE MUCH TIME PLZ HELP ME IF YOU ARE REALLY GOOD AT SCIENCE COME TO MY QUESTION PLEASEEEE Which fossil fuel creates the least amount of pollution when it is burned? A. bituminous coal B. petroleum C. natural gas D. anthracite
Answer:
The other guy is right. It's C
Explanation:
12.03 Quiz: Nonrenewable Energy - Fossil Fuels Part 2
XD
If the half-life of a radioactive isotope is 5,000 years, how much of the radioactive isotope in a specimen will be left after 10,000 years?
Final answer:
After two half-lives of 5,000 years each, only 25% of the original radioactive isotope would remain.
Explanation:
If the half-life of a radioactive isotope is 5,000 years, after 10,000 years, two half-lives will have passed. According to exponential decay, after the first half-life, 50% of the original isotope remains. After the second half-life, another half of this remaining amount will have decayed, leaving only 25% of the original isotope. We can use the expression (1/2)n, where 'n' is the number of half-lives, to calculate the remaining amount of the isotope. In this case, it would be (1/2)2 = 1/4 or 25%.
A 250 mL sample of a .125 M solution of NaOH contains _____g of NaOH
Sodium chloride is formed when the metal sodium bonds to the nonmetal chlorine. the atoms are hold together by a
Answer:
abbylittle is correct. When Metals and Nonmetals bond, they are held together by ionic bonds.
Explanation:
Which of the following is the last step in performing a titration? finding out which pH indicator works determining the concentration of an unknown base finding the number of moles of product produced in a reaction determining the molecular masses of the products in the reaction
Answer: Determining the concentration of an unknown base
Explanation: While performing a titration,below mentioned steps are followed in the written order -
a) Finding out which pH indicator works - this is the important and the initial step
b) After that , one will determine the molecular masses of the products formed in the reaction.
c) After determining the molecular mass, number of moles of the product are calculated in order to reach to the conclusion.
d) Thus the final step would be the determiation of the concentration of the unknown base.
Explain why phospholipids spontaneously form a bilayer when mixed with water?
Phospholipids form a bilayer when mixed with water, since the hydrophilic head is attracted to water, while the hydrophobic tails reject water and tend to aggregate with other hydrophobic molecules, this conflict is resolved with the formation of a lipid bilayer , which satisfies both parties.
What are phospholipids?They are those that have phosphoric acid in their composition, they are usually amphipathic: their molecules have a part that is soluble in water (that is, hydrophilic) and another that is not (hydrophobic).
Characteristics of phospholipidsWhen they come into contact with water, the phospholipid molecules organize themselves to form bilayers, which are macromolecular groups with a large amount of lipids. In bilayers, hydrophobic fatty acid chains align with each other, interacting with each other and leaving their hydrophilic ends in contact with water.Therefore, we can conclude that phospholipids are found in the active membranes of cells whose distinctive feature is they are usually amphipathic.
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Final answer:
Phospholipids form a bilayer in water due to their amphipathic properties, with hydrophilic heads facing the water and hydrophobic tails facing inward, creating a structure critical to cellular membranes.
Explanation:
Phospholipids spontaneously form a bilayer when mixed with water due to their amphipathic nature. Each phospholipid molecule has a hydrophilic (water-attracting) head and two hydrophobic (water-avoiding) tails.
In an aqueous solution, phospholipid molecules arrange themselves so that their hydrophilic heads are exposed to water, while their hydrophobic tails face each other inside the bilayer, away from the water.
This results in the formation of a lipid bilayer, a structure that is fundamental to the plasma membrane of cells. In this bilayer, the hydrophobic tails interact only with each other, forming a barrier that separates the water and other materials on one side from those on the other side.
Furthermore, when phospholipids are heated in aqueous solutions, they tend to form small spherical structures called liposomes or micelles, with the hydrophilic heads outside and the hydrophobic tails inside, underscoring their self-assembling properties.
Kasterville is a rapidly growing city. Which of the following situations will most likely have a positive impact on the resources available to Kasterville? A. Factories dump wastewater directly into nearby rivers. B. Builders cut down trees to build homes without replanting new ones. C. Most people water their lawns every day to keep them green. D. Most people are careful to recycle all glass, metal, and plastic.
Answer: D
Explanation:
What is the experimental molar heat of combustion?
Explanation:
Molar heat combustion:
Molar heat of combustion is defined as heat released when 1 mole of substance is burnt under the action of oxygen gas to give water and carbon-dioxide.It is measured in kiloJoules (kJ) per mole.This heat of energy can be positive or negative.
If the enthalpy is positive than the reaction is said to be an endothermic reaction.If the enthalpy is negative than the reaction is said to be an exothermic reaction.The molar heat of combustion is illustrated as the heat discharged when one mole of the component is burnt by reacting with oxygen gas to provide carbon dioxide and water. It is determined in kJ per mole. This heat of energy can be negative or positive. In case if the enthalpy is negative than the reaction is considered as an exothermic reaction, and if the enthalpy is positive than the reaction is considered as an endothermic reaction.
When ammonium nitrate is dissolved in water, energy is absorbed from the surroundings, causing a decrease in the resulting solution's temperature. Which of the following best describes this type of reaction?
Determine the number of protons and neutrons in plutonium-239 and enter its symbol in the form azx.
Plutonium-239 has 94 protons and 145 neutrons in its nucleus, represented by the symbol 239Pu.
Plutonium-239 has 94 protons and a mass number of 239. To find the number of neutrons, you subtract the number of protons from the mass number: 239 - 94 = 145 neutrons. The symbol for Plutonium-239 is 239Pu.
1. Protons (Z): The atomic number (Z) for plutonium (Pu) is 94. Hence, plutonium-239 has 94 protons.
2. Neutrons (N): The mass number (A) for plutonium-239 is 239. The number of neutrons (N) is calculated by subtracting the number of protons (Z) from the mass number (A), i.e., N = A - Z. Therefore, N = 239 - 94 = 145. Thus, plutonium-239 has 145 neutrons.
What mineral has the least hardness according to the scale?