Answer:
The last digit is estimated
Explanation:
the last digit of any measurement is estimated, and it is this estimated digit that reflects uncertainty. The more decimal places there are the less uncertainty there is.
The number of significant figures is uncertain in a number that ends with a zero to the left of the decimal point location. The zeros in the measurement 1,300 grams could be significant or they could simply indicate where the decimal point is located.
According to the concept of significant figures, the last digit is uncertain digit in a measurement.
What are significant figures?Significant figures are used for establishment of a number which is presented in the form of digits. These digits give a meaningful representation to the numbers.
The significant figures are the significant digits which convey the meaning according to the accuracy. These provide precision to the numbers and hence are called as significant numbers.There are rules for counting significant figures which are as follows:
1)All non-zero digits are significant .
2)All zeroes which occur between non-zero digits are significant.
3)All zeroes to the left and right of a non-zero digit are not significant.
4) All zeroes on right of decimal are significant if a non-zero number follows them.
5)All zeroes on right side of non-zero digit are significant.
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what is the percent by mass of a solution made by dissolving 0.396 moles of aluminum chloride into 150.0 ml of water?
As per the given question, the percent by mass of a solution made by dissolving 0.396 moles of aluminum chloride into 150.0 ml of water is 22.0%.
Given,
Number of moles of aluminum chloride = 0.396
Number of milliliters of water = 150.0
Density of water = 1 g/mL
Formula used to calculate the percent by mass of a solution:
Percent by mass of a solution = (mass of solute/mass of solution) × 100
In this case, we have to find the percent by mass of a solution made by dissolving 0.396 moles of aluminum chloride into 150.0 ml of water. In order to do that, we first need to find the mass of the aluminum chloride that has been dissolved.
Molar mass of aluminum chloride = Atomic mass of Al + (Atomic mass of Cl × 3)= 27 + (35.5 × 3)
= 106.5 g/mol
Mass of aluminum chloride = Number of moles × Molar mass
= 0.396 mol × 106.5 g/mol
= 42.294 g
So, the mass of aluminum chloride that has been dissolved is 42.294 g.The mass of the solution will be the sum of the mass of the solute and solvent i.e., water
.Mass of the solution = Mass of aluminum chloride + Mass of water
= 42.294 g + 150.0 g
= 192.294 g
Now, we can use the formula to find the percent by mass of the solution.
Percent by mass of a solution = (mass of solute/mass of solution) × 100
= (42.294 g/192.294 g) × 100
= 22.0%
Therefore, the percent by mass of a solution made by dissolving 0.396 moles of aluminum chloride into 150.0 ml of water is 22.0%.
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what are independant variables
Answer:
a variable (often denoted by x ) whose variation does not depend on that of another.
Explanation:
.Compare and contrast Thomson’s plum pudding atomic model with Rutherford’s nuclear atomic model.
Thomson's plum pudding atomic model and Rutherford's nuclear atomic model are two historical models proposed to describe the structure of the atom.
The key difference between these models lies in their understanding of the distribution of positive and negative charges within the atom. Thomson's model suggested that the atom was composed of a positively charged "pudding" with negatively charged electrons embedded throughout. In contrast, Rutherford's model proposed that the atom had a dense, positively charged nucleus at the center, surrounded by mostly empty space with electrons orbiting around it.
Thomson's plum pudding model, proposed in the late 19th century, envisioned the atom as a uniform, positively charged sphere with electrons scattered throughout like plums in a pudding. According to this model, the positive and negative charges were uniformly distributed throughout the atom. It explained the existence of negatively charged electrons but did not provide any insight into the presence of a dense, positively charged nucleus.
Rutherford's nuclear model, proposed in the early 20th century, came as a result of the famous gold foil experiment. Rutherford discovered that most of the alpha particles passed through the gold foil undeflected, while a few were deflected at large angles. From these observations, he concluded that the atom must have a concentrated positive charge at its center, which he called the nucleus. The electrons were then considered to be in orbit around the nucleus. This model explained the results of the gold foil experiment and introduced the concept of a small, dense, positively charged nucleus, which accounted for the deflection of alpha particles.
Thomson's plum pudding model proposed a uniform distribution of positive and negative charges throughout the atom, while Rutherford's nuclear model introduced the idea of a dense, positively charged nucleus at the center of the atom, with electrons orbiting around it. Rutherford's model provided a more accurate description of the atom's structure and paved the way for further advancements in atomic theory.
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a carboxylic acid is reacted with naoh in an organic solvent followed by a reaction with an acid chloride. what is the general structure of the carboxylic acid derivative formed in this reaction?
The carboxylic acid derivative formed in this reaction is an acid anhydride. The reaction starts with the carboxylic acid being reacted with NaOH in an organic solvent to form a salt that is water-soluble.
The salt is then reacted with an acid chloride which is a compound that has a chlorine atom bonded to an acyl group.
Carboxylic acids can react with bases to form salts, and with alcohols and acid chlorides to form esters and acid anhydrides, respectively. In this reaction, a carboxylic acid is first reacted with NaOH in an organic solvent to form a salt, which is water-soluble. This reaction is called neutralization, and it results in the formation of a carboxylate ion and a sodium ion. The general equation for this reaction is:RCOOH + NaOH → RCOONa + H2Owhere R is an alkyl group.The salt is then reacted with an acid chloride to form an acid anhydride. Acid chlorides are compounds that have a chlorine atom bonded to an acyl group. The general equation for this reaction is:RCOONa + R'COCl → RCOOCOR' + NaCl
where R and R' are alkyl or aryl groups.The carboxylic acid derivative formed in this reaction is an acid anhydride, which has the general structure:RCOOCOR'
The specific structure of the acid anhydride depends on the identity of the carboxylic acid and the acid chloride used in the reaction. Carboxylic acids are organic compounds that have a carboxyl functional group (-COOH) attached to a hydrocarbon chain. They are widely used in the production of pharmaceuticals, plastics, and other products. Carboxylic acids can react with bases to form salts, and with alcohols and acid chlorides to form esters and acid anhydrides, respectively.
Acid chlorides are compounds that have a chlorine atom bonded to an acyl group. The reaction is usually carried out in the presence of a Lewis acid catalyst, such as pyridine or triethylamine, to improve the yield of the product.The carboxylic acid derivative formed in this reaction is an acid anhydride, which has the general structure RCOOCOR'. The specific structure of the acid anhydride depends on the identity of the carboxylic acid and the acid chloride used in the reaction. Acid anhydrides are widely used in organic synthesis as acylating agents to form esters, amides, and other derivatives.
In conclusion, a carboxylic acid reacts with NaOH in an organic solvent to form a salt, which is water-soluble. The salt is then reacted with an acid chloride to form an acid anhydride. The carboxylic acid derivative formed in this reaction has the general structure RCOOCOR', and the specific structure depends on the identity of the carboxylic acid and the acid chloride used. Acid anhydrides are widely used in organic synthesis as acylating agents to form esters, amides, and other derivatives.
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The physical and chemical properties contribute to the function of the synthetic.products.wood
The physical and chemical properties of synthetic and natural jadeite for jewellery. The statement is correct.
What are the difference between chemical and physical property ?Chemical properties of an element can be defined as with the chemical changes where as Physical properties does not need any kind of changes.
All compounds are connected by different chemical bonds to show its chemical property while in Physical properties the compounds need to bonded to show its property.
chemical property of the element used to detect how substances react with each other and with other substances while physical property used in identify or describe the substance.
Chemical properties of a substance are Compressibility, flammability, toxicity, radioactivity where as physical properties of a substance are Molecular weight, melting point, length, color, odor, shape.
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Convert the following:
0.074 km
m.
The answer is 74 m
Yes the answer is 74
:)
that's correct
1. At 7 a.m., the science classroom had a temperature of 68°F. By 3 p.m., the temperature had
increased to 75°F. Calculate the rate of temperature change from 7 a.m. to 3 p.m.
.Before using a solution of NaOH as titrant in a titration experiment, you should standardize the solution. Standardization is the process of titrating a solution prepared from ___________ accurately determine the concentration of the titrant. In particular, NaOH solutions need to be standardized because their concentrations ___________ due to the compound's Choose... Please put an answer in each box
Before using a solution of NaOH as a titrant in a titration experiment, you should standardize the solution. Standardization is the process of titrating a solution prepared from a primary standard to accurately determine the concentration of the titrant. In particular, NaOH solutions need to be standardized because their concentrations can vary over time due to the compound's hygroscopic nature.
Choose:
- Primary Standard: A primary standard is a highly pure compound with a known and stable concentration that can be used to accurately determine the concentration of a titrant.
- Vary over time: The concentration of NaOH solutions can change or fluctuate due to its hygroscopic nature, meaning it readily absorbs moisture from the atmosphere.
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Multiply the following measurement for wavelength and frequency of a wave
(4.8 x 10 4 ) (1.1 x 106 )
a. 3.2 x 106
b. 1.6 x 102
c. 5.3x 1010
d. 5.28x 1010
Answer : The correct option is, (d) 5.28 × 10¹⁰
Explanation :
As we are given the expression of wavelength and frequency. Now we have to determine the multiply the following measurement for wavelength and frequency of a wave.
The given expression is:
(4.8 × 10⁴) × (1.1 × 10⁶)
= (4.8 × 1.1) × (10⁴ × 10⁶)
= 5.28 × 10¹⁰
Therefore, the multiplication of wavelength and frequency of a wave is 5.28 × 10¹⁰
What is true about protons within an atom?
Determine where to dispose of each type of waste. broken flask Choose... unused solid reagent Choose... titrant solution Choose... syringe tips ✓ Choose... Box lined with puncture resistant bag Sharps container Nalgene bottle with cap Solid waste container
Broken flasks should be placed in a solid waste container, along with any unused solid reagents, titrant solutions should be disposed of as hazardous waste, and needle tips should be placed in a sharps container.
To maintain safety and environmental responsibility, it is crucial to adhere to the necessary standards and regulations while disposing of various forms of garbage. Here are the suggested disposal techniques for each of the previously stated waste types:
shattered flask Flasks and other broken glassware should be thrown away in a designated solid waste receptacle. The disposal of non-hazardous solid waste is intended for use with this particular container.
To protect waste handlers from harm, the shattered flask should be put in a bag that won't puncture or wrapped in several layers of newspaper before being put in the container.
Unused solid reagent: If the solid reagent is safe to use and is not contaminated, it can be thrown away in the previously indicated solid waste container.
If the reagent is dangerous or has the potential to be reactive, it should be handled and disposed of as hazardous waste. This can entail following particular norms or regulations that are local in nature.
Titrant solution: Hazardous titrant solutions are frequently utilised in analytical chemistry. Titratable solutions should be disposed of in accordance with local laws.
If neutralisation is required, it is typically advised to do so before treating the solution as hazardous waste. For correct disposal, this frequently entails getting in touch with a licenced trash management business.
Syringe tips: Syringe tips should be thrown away in a sharps container when they are used in laboratories. To stop inadvertent injury, sharps containers are made to safely store and discard things like needles and syringe tips.
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what percentage of the amino acids were in the favored or allowed regions of the ramachandran plots?
Explanation:
The Ramachandran plot is a way to visualize the allowed regions of protein backbone torsion angles, phi and psi. These angles determine the conformation of the peptide bond and are important for protein structure and function.
Typically, the allowed regions of the Ramachandran plot are divided into three regions: the most favored regions, the additionally allowed regions, and the generously allowed regions.
The percentage of amino acids found in the most favored and additionally allowed regions of the Ramachandran plot depends on the protein structure being analyzed. However, for a well-refined protein structure, the percentage of amino acids in the most favored regions can be around 98%, and the percentage of amino acids in the most favored and additionally allowed regions can be around 99.7%.
most bottled water in the united states does not contain fluoride. group of answer choices true false
The statement that most bottled water in the United States does not contain fluoride is true. Fluoride is a chemical that is added to water to prevent tooth decay.
It is naturally present in some water sources, while it must be added to others. However, most bottled water in the United States does not contain fluoride. Many bottled water companies do not add fluoride to their products because they assume that people will get fluoride from other sources, such as toothpaste or tap water. Moreover, some bottled water brands come from natural springs that have fluoride levels that are lower than what is required for optimal dental health. In addition, not all bottled water products are created equal.
According to the FDA, bottled water that is sold in the United States must meet certain quality standards, but the regulations do not require that fluoride be added to the water. As a result, some bottled water brands do contain fluoride, but consumers must read the label to know for sure. The good news is that people who do not drink fluoridated water can still get fluoride from other sources. For example, they can use toothpaste that contains fluoride, eat foods that are high in fluoride, or take fluoride supplements. Overall, the statement that most bottled water in the United States does not contain fluoride is true. Consumers who want to know whether a particular brand of bottled water contains fluoride should read the label or contact the manufacturer for more information.
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calculate the free energy change for this reaction at 25 oc. is the reaction spontaneous? c3h8(g) 5 o2(g) 3 co2(g) 4h2o(g)
The Gibbs free energy temperature change (ΔG) ,The value of ΔG for the reaction is -1833.2 kJ/mol. The reaction is spontaneous.
The equation for the combustion of propane is:
C3H8(g) + 5O2(g) → 3CO2(g) + 4H2O(g)The values of the enthalpies of formation for each compound are:
C3H8(g) = -104.7 kJ/molO2(g)
= 0 kJ/molCO2(g)
= -393.5 kJ/molH2O(g)
= -241.8 kJ/mol
To determine the ΔH for the reaction, we subtract the sum of the enthalpies of formation of the reactants from the sum of the enthalpies of formation of the products:
ΔH = [3(-393.5) + 4(-241.8)] - [-104.7 + 5(0)]
ΔH = -2043.1 kJ/mol
To determine the ΔS for the reaction, we calculate the change in entropy between the products and reactants. We can use the standard entropy values for each compound spontaneous.
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3. Which can be decomposed by chemical change?
1) sodium
02) water
3) iron
O4) germanium
a strong lightning bolt transfers about 27.48 c to earth. how many electrons are transferred? the elemental charge is 1.602 × 10−19 c.
A strong lightning bolt that transfers about 27.48 C to Earth corresponds to approximately 1.716 × 10^20 electrons.
To calculate the number of electrons transferred, we need to divide the total charge transferred (27.48 C) by the elemental charge (1.602 × 10^(-19) C). This ratio will give us the number of elementary charges (electrons) involved.
Number of electrons = Total charge transferred / Elemental charge
Number of electrons = 27.48 C / (1.602 × 10^(-19) C)
Using this calculation, we find that the number of electrons transferred is approximately 1.716 × 10^20 electrons.
The elemental charge (1.602 × 10^(-19) C) represents the charge of a single electron. By dividing the total charge transferred by this value, we can determine how many electrons are involved in the process. In this case, the lightning bolt transfers 27.48 C of charge, which corresponds to a large number of electrons (1.716 × 10^20 electrons).
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Question 3: Spontaneous Reactions a) Write 2-3 sentences to describe how to determine if a reaction will be thermodynamically favorable. b) Write 2-3 sentences to describe what happens to the Gibbs Free Energy term when a chemical reaction is reversed. c) Write 3–4 sentences to describe how coupling reactions are used to drive an unfavorable chemical reaction.
a) ΔG determines if a reaction is thermodynamically favorable: negative ΔG means spontaneous. ΔH and ΔS influence ΔG. b) Reversing a reaction flips ΔG sign: positive forward reaction becomes negative in reverse, making it favorable.
c) Coupling reactions combine favorable reactions with unfavorable ones, using the energy released to drive the unfavorable reaction. Common in biology for energy-requiring processes.
a) To determine if a reaction will be thermodynamically favorable, calculate the change in Gibbs free energy (ΔG) using the equation ΔG = ΔH - TΔS. If ΔG is negative, the reaction is thermodynamically favorable as it indicates a spontaneous process. The enthalpy change (ΔH) and entropy change (ΔS) of the system play crucial roles in determining the sign and magnitude of ΔG.
b) When a chemical reaction is reversed, the sign of the Gibbs free energy (ΔG) term changes. If the forward reaction has a positive ΔG, indicating an unfavorable reaction, the reverse reaction will have a negative ΔG. Reversing the reaction flips the sign of ΔG, indicating that the reverse reaction becomes favorable, allowing it to occur spontaneously.
c) Coupling reactions are employed to drive unfavorable chemical reactions by combining them with highly favorable reactions. By connecting the two reactions, the energy released from the favorable reaction is utilized to provide the necessary energy for the unfavorable reaction to proceed. The favorable reaction acts as an energy source, effectively lowering the overall Gibbs free energy of the system, making the coupled reaction thermodynamically favorable and allowing the unfavorable reaction to occur. This coupling strategy is commonly used in biological systems to drive energy-requiring processes.
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How is a mixture different from a compound? 1. Particles of a mixture are combined chem2. Components of a mixture can be sepa- rated by physical means. 3. Composition of a mixture may be con- stant. 4. Components of a mixture can only be separated chemically.
Answer:
2. Components of a mixture can be separated by physical means
Explanation:
The Compound is defined as the substances that are chemically combined while mixtures are the substances in which two or more compounds are physically combined together.
The difference between compound and mixture from the given options is that mixture can be separated physically unlike compounds.
In a mixture, two or more compounds can be mixed in any proportion that can be separated by physical means. For example: salt from seawater (mixture) can be separated evaporation and nails from the mixture of sand and iron can be separated through magnetic separation.
Hence, the correct answer is "Components of a mixture can be separated by physical means".
Xef4 draw the single most stable lewis structure for the molecule. Show the formal charges of all atoms in the correct structure. Include all lone pairs of electrons
The central atom Xe is hybridized and bonded with four Fluorine atoms in XeF4. The single most stable Lewis structure of XeF4 is shown below:
The given molecule XeF4 is a halogen and belongs to the noble gas group. Since the central atom Xenon (Xe) has 8 valence electrons and each fluorine atom has 7 valence electrons, it makes a total of 8 + 4(7) = 36 electrons for the Lewis dot structure. The hybridization of the central atom is sp3d2.The single most stable Lewis structure of XeF4 is shown below. It is shown that all the Fluorine atoms are connected by a single bond with the central atom. The formal charges of each atom in the correct structure is 0. All the atoms have octets except for the central atom, which has two extra electrons. The extra electrons in the central atom act as a lone pair. Therefore, there are a total of 12 lone pair electrons in the molecule.
Thus, the central atom Xenon (Xe) is hybridized and bonded with four Fluorine atoms in XeF4. The single most stable Lewis structure of XeF4 is shown above with formal charges of 0 for all atoms.
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Suppose you are studying the kinetics of the iodine-catalyzed decomposition of hydrogen peroxide. 2H2O2⟶2H2O+O2 If you determine the initial rate is 7.50×10−4M/s when [H2O2]=0.455M and [KI]=0.280M, what is the rate constant? Assume that the order of both reactants is 1 .
The rate constant for the iodine-catalyzed decomposition of hydrogen peroxide is 5.43 M^(-2)·s^(-1).
The rate constant for the iodine-catalyzed decomposition of hydrogen peroxide can be determined using the initial rate and the concentrations of the reactants. Given that the initial rate is 7.50×10^(-4) M/s, [H2O2] = 0.455 M, and [KI] = 0.280 M, and assuming the order of both reactants is 1, we can use the rate equation: rate = k[H2O2][KI] to find the rate constant. The rate constant is calculated by dividing the initial rate by the product of the concentrations of the reactants. Substituting the given values, we get k = 7.50×10^(-4) M/s / (0.455 M * 0.280 M) = 5.43 M^(-2)·s^(-1).
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if a sample of pure x is a mixture of liquid and gas, which point marks the highest possible temperature and pressure of the sample?
If a sample of pure X is a mixture of liquid and gas, then the highest possible temperature and pressure of the sample are marked at the critical point. A critical point is defined as the point at which the liquid and gas states of a substance become indistinguishable from each other.
At this point, the substance exhibits its maximum density, and the heat of vaporization goes to zero. The critical point is also the point where the main answer lies.A sample of pure X that is a mixture of liquid and gas has different boiling and melting points than those of a pure substance. Instead, its boiling and melting points will be a range of temperatures and pressures over which the substance is in a liquid and gas phase. When the temperature and pressure exceed the critical point of the sample, the substance can no longer exist in the gas or liquid state, and it instead exists in the supercritical state. At this state, the substance exhibits properties that are intermediate between those of a liquid and a gas.
The highest possible temperature and pressure of the sample lie at the critical point, which is the point at which the liquid and gas states of a substance become indistinguishable from each other. A sample of pure X that is a mixture of liquid and gas has different boiling and melting points than those of a pure substance.
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The Henry's Law constant (Kh) for O2 in water at 20 degrees C is 1.28 x 10-3 mol/(L*atm).
How many grams of O2 will dissolve in 2.25 L of H2O that is in contact with pure O2 at 1.00 atm? ............. g O2
How many grams of O2 will dissolve in 2.25 L of H2O that is in contact with air where the partial pressure of O2 is 0.209 atm? .............. g O2
The grams of O2 dissolved in 2.25 L of H2O under pure O2 (1.00 atm) and air (0.209 atm) are approximately 2.88 g and 0.603 g, respectively, according to Henry's Law.
1. According to Henry's Law, the amount of gas dissolved in a liquid is directly proportional to the partial pressure of the gas above the liquid. The equation for Henry's Law is given as:
C = Kh * P
Where C is the concentration of the gas in moles per liter (mol/L), Kh is the Henry's Law constant, and P is the partial pressure of the gas in atmospheres (atm).
For the first case, we are considering pure O2 at a pressure of 1.00 atm. Given that the Henry's Law constant (Kh) for O2 in water is 1.28 x 10^-3 mol/(L*atm), we can calculate the concentration of O2 in the water as follows:
C = Kh * P
C = (1.28 x 10^-3 mol/(L*atm)) * 1.00 atm
C = 1.28 x 10^-3 mol/L
To convert the concentration to grams, we need to multiply it by the molar mass of O2 (32 g/mol) and the volume of water (2.25 L):
Mass of O2 = (1.28 x 10^-3 mol/L) * (32 g/mol) * (2.25 L)
Mass of O2 = 2.88 grams of O2
Therefore, approximately 2.88 grams of O2 will dissolve in 2.25 L of H2O in contact with pure O2 at 1.00 atm.
2. For the second case, the partial pressure of O2 in air is given as 0.209 atm. Using the same equation, we can calculate the concentration of O2 in the water:
C = Kh * P
C = (1.28 x 10^-3 mol/(L*atm)) * 0.209 atm
C = 2.67 x 10^-4 mol/L
To calculate the mass of O2, we multiply the concentration by the molar mass of O2 and the volume of water:
Mass of O2 = (2.67 x 10^-4 mol/L) * (32 g/mol) * (2.25 L)
Mass of O2 = 0.603 grams of O2
Therefore, approximately 0.603 grams of O2 will dissolve in 2.25 L of H2O in contact with air, where the partial pressure of O2 is 0.209 atm.
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2. If the mixture separates upon standing, the mixture
is a
Answer: suspension
Explanation:
what does kinetic molecular theory tell us about temperature and motion of molecules, collisions, space between molecules, density, and phase
The kinetic molecular theory is a scientific model that describes the behavior of matter on a molecular level. It tells us that molecules of matter are always in constant motion, and this motion is directly related to temperature.
In addition, the theory tells us about the collisions between molecules, the space between them, their density, and the phase they are in. Kinetic molecular theory and temperature:The kinetic molecular theory tells us that as the temperature of a substance increases, the motion of its molecules also increases. This means that hotter substances have faster-moving molecules compared to colder substances
The theory tells us that when a substance is heated, its molecules gain kinetic energy and move faster. If this kinetic energy is great enough, the substance will change phases (solid to liquid to gas).In conclusion, the kinetic molecular theory explains the behavior of matter on a molecular level, including the relationship between temperature and molecular motion, the collisions between molecules, the space between them, their density, and the phase they are in.
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what is the ground-state electron configuration of the sulfide ion s2− ?
The ground-state electron configuration of sulfide ion S²⁻ is 1s² 2s² 2p⁶ 3s² 3p⁶.
Sulfide ion S²⁻ consists of 16 electrons. A ground-state electron configuration refers to the lowest energy level configuration, and it can be determined by arranging electrons into various orbitals in the increasing order of their principal quantum numbers. For finding the electron configuration of an atom or ion, we use the following rules:
1. Aufbau principle- The Aufbau principle states that electrons will first occupy the lowest energy level orbitals before occupying the higher ones.
2. Pauli Exclusion principle- Pauli exclusion principle states that no two electrons can have the same set of four quantum numbers.
3. Hund’s rule- Hund’s rule states that for orbitals with the same energy, each orbital is filled with an electron before any orbital is doubly occupied.
For finding the electron configuration of the S²⁻ ion, we first need to identify the number of electrons that it contains. Sulfur (S) has an atomic number of 16. It has a total of 16 electrons in its neutral state. However, the S²⁻ ion has an additional two electrons, which means it has a total of 16+2 = 18 electrons. Now we can fill these electrons into various orbitals in the increasing order of their principal quantum numbers. The electron configuration is given below:1s² 2s² 2p⁶ 3s² 3p⁶
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calculate the ph of a buffer solution made from equal amounts of 0.30 m hydrofluoric acid and 0.70 m sodium fluoride. ka
As per the given question, the pH of the buffer solution made from equal amounts of 0.30 M hydrofluoric acid and 0.70 M sodium fluoride is 3.14.
A buffer solution is formed when a weak acid or base is mixed with its salt or a strong acid or base. Buffer solutions help maintain pH and resist pH changes upon the addition of acid or base.
To calculate the pH of a buffer solution made from equal amounts of 0.30 M hydrofluoric acid and 0.70 M sodium fluoride with a Ka value, follow these steps:
Step 1: Write down the chemical reaction that occurs in the buffer solution.HF + NaF ↔ Na+ + F- + H2O
Step 2: Calculate the concentration of the conjugate base. The concentration of the conjugate base (F-) can be determined by subtracting the concentration of hydrofluoric acid used (0.30 M) from the concentration of sodium fluoride used (0.70 M). [F-]
= [NaF] - [HF][F-]
= 0.70 - 0.30[F-]
= 0.40 M
Step 3: Calculate the Ka of hydrofluoric acid.
Ka = [H+][F-]/[HF]
= x2/0.30x
= 6.76 × 10-4
Step 4: Calculate the pH of the buffer solution.pH = pKa + log([conjugate base]/[weak acid])
pH = -log(6.76 × 10-4) + log(0.40/0.30)
pH = 3.14
Therefore, the pH of the buffer solution made from equal amounts of 0.30 M hydrofluoric acid and 0.70 M sodium fluoride is 3.14.
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a scientist measures the speed of sound in a monatomic gas to be 449
The molar mass of the monatomic gas is approximately 0.029 kg/mol. To calculate the molar mass of the monatomic gas, we can use the equation derived from the kinetic theory of gases:
Molar mass (M) = (speed of sound)^2 × molar mass of air / (speed of sound of air)^2
Given that the speed of sound in the monatomic gas is 449 m/s at 20°C, we need to know the speed of sound of air at the same temperature. The speed of sound in air at 20°C is approximately 343 m/s.
Plugging the values into the equation, we have:
M = (449 m/s)^2 × 0.029 kg/mol / (343 m/s)^2 ≈ 0.029 kg/mol
Therefore, the molar mass of the monatomic gas is approximately 0.029 kg/mol.
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Complete question: A scientist measures the speed of sound in a monatomic gas to be 449 m/s at 20∘C. What is the molar mass of this gas?
Heavier objects are harder to move than lighter ones. Based on this, which of
the following measures inertia?
Answer:
mass
Explanation:
the mass of a body is directly proportional to imteria
HI decomposes to H2 and I2 by the following equation:
2HI(g) → H2(g) + I2 (g);
Kc = 1.6 103 at 25°C
If 1.0 M HI is placed into a closed container and the reaction is allowed to reach equilibrium at 25°C, what is the equilibrium concentration of H2 (g)?
0.076 M
0.924 M
0.0017 M
0.038 M
The equilibrium concentration of H2 (g) is approximately 0.038 M.
The equilibrium concentration of H2 (g) can be determined using the equilibrium constant (Kc) and the initial concentration of HI.
In this case, the equilibrium constant (Kc) is given as 1.6 × 10^3, and the initial concentration of HI is 1.0 M. By using the stoichiometric coefficients from the balanced equation, we can calculate the equilibrium concentration of H2 (g) to be approximately 0.038 M.
The equilibrium constant expression for the given reaction is:
Kc = [H2] × [I2] / [HI]^2
Given that Kc = 1.6 × 10^3, we can set up the equation:
1.6 × 10^3 = [H2] × [I2] / [HI]^2
Since the initial concentration of HI is 1.0 M, we substitute this value into the equation:
1.6 × 10^3 = [H2] × [I2] / (1.0)^2
1.6 × 10^3 = [H2] × [I2]
Since the reaction stoichiometry states that the ratio of H2 to HI is 1:2, we can assume that the equilibrium concentration of H2 is also equal to x (in M). Therefore, the equilibrium concentration of I2 will also be equal to x.
1.6 × 10^3 = x × x
x^2 = 1.6 × 10^3
x ≈ 40
Thus, the equilibrium concentration of H2 (g) is approximately 0.038 M.
Therefore, the correct answer is 0.038 M.
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approximately how many grams of nacl can dissolve in 100 g h2o at 70oc? 38 approximately how many grams of cacl2 can dissolve in 200 ml h2o at 10oc? 130
38 grams of NaCl can dissolve in 100 grams of H2O at 70oC, while 130 grams of CaCl2 can dissolve in 200 ml of H2O at 10oC. Solubility is defined as the amount of solute that can be dissolved in a given amount of solvent at a specific temperature and pressure.
As a result, when calculating solubility, it is important to consider the temperature and amount of solvent used.NaCl is the solute, while H2O is the solvent, in the first scenario. The question asks for the quantity of NaCl that can dissolve in 100 g of H2O at 70oC. The solubility of NaCl in water varies with temperature.
As the temperature increases, the solubility of NaCl in water also increases, allowing more NaCl to dissolve in the same amount of water.At 70oC, the solubility of NaCl in H2O is 38 g/100g of water.
As a result, 38 grams of NaCl can dissolve in 100 grams of H2O at 70oC.In the second scenario, CaCl2 is the solute, and 200 ml of H2O is the solvent. At 10oC, the solubility of CaCl2 in H2O is 74.5 g/100 ml.
As a result, the maximum quantity of CaCl2 that can dissolve in 200 ml of H2O at 10oC is 2 x 74.5 g, which is 149 grams.
However, the question asks for the maximum amount of CaCl2 that can dissolve in 200 ml of H2O at 10oC, which is 130 grams. As a result, this quantity is lower than the maximum solubility of CaCl2 in H2O at 10oC, which is 149 grams. Therefore, 130 grams of CaCl2 can dissolve in 200 ml of H2O at 10oC.
To summarise, 38 grams of NaCl can dissolve in 100 grams of H2O at 70oC, while 130 grams of CaCl2 can dissolve in 200 ml of H2O at 10oC. The quantity of solute that can dissolve in a given amount of solvent is defined as solubility, which varies with temperature. As the temperature rises, the solubility of most substances in water increases, allowing more of them to dissolve in the same amount of water.
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