The average atomic mass of an element on the periodic table is a weighted average and not a whole number because it accounts for the different masses and abundances of each isotope, whereas the actual mass of an individual atom is approximately its mass number, a whole number.
You will never find an atom that has an actual atomic mass equal to the average atomic mass of the element because the atomic mass listed on the periodic table is a weighted average of all the naturally occurring isotopes of that element. Because each proton and each neutron has a mass of approximately one atomic mass unit (amu), and electrons contribute much less, the atomic mass of each isotope is approximately equal to its mass number, which is always a whole number. However, the average atomic mass is not a whole number because it is a calculation that includes the different masses of each isotope and their respective abundance percentages. This weighted average reflects the average mass of an atom if you could randomly pick one out of a sample containing all the isotopes of that element.
For example, carbon has two stable isotopes, 12C and 13C, with respective abundances of 98.89% and 1.11%. The average atomic mass of carbon is calculated by taking into account these abundances, leading to an average atomic mass that does not match exactly the mass of either isotope. In contrast, some elements have atomic masses in square brackets, like technetium (element 43) and promethium (element 61), which indicate the mass number of their most stable isotope because these elements do not have stable isotopes with an average atomic mass.
List three of Rutherford’s major achievements that helped earn him the title “Father of Nuclear Physics.”
help please:)
One of the ways that acid rain is harmful is _____.
it causes chemical burns on the skin of animals.
it increases the temperature of small bodies of water.
it leaches nutrients out of plants.
it creates holes in the leaves of plants.
The intrinsic solubility of sulfathiazole, an old antimicrobial, is 0.002 mol/l. it is a weak acid and its pka is 7.12. what is the ph of the saturated solution of sulfathiazole in pure water?
The formula we will use is:
pH = 0.5 (pKa – log C)
where C is the concentration of sulfathiazole in molarity or mol / L
Since all values are given, we can compute directly for pH:
pH = 0.5 (7.12 – log 0.002)
pH = 4.91
In the combustion chamber of an engine, the initial volume is 450 cm3 at a pressure of 1.0 atmosphere. If the piston displaces 402 cm3 of the total, what is the resulting pressure in the combustion chamber? (Assume negligible temperature change.) Hint: Calculate the new volume by subtracting the amount of space the piston takes up from the initial volume
Answer:
9.375 atm
Explanation:
Initial volume = 450 cm³
Volume displaced by the piston = 402 cm³
Final volume = Initial volume – displaced volume = 450 cm³ – 402 cm³ = 48 cm³
Initial pressure = 1.0 atm
According to Boyle’s Law,
P₁V₁ = P₂V₂
where P₁, P₂ are the initial and final pressure respectively, V₁ and V₂ are the initial and final volume respectively.
Substituting the given data we have,
450 cm³ x 1 atm = 48 cm³ x P₂
P₂ = (450 cm³ x 1 atm) / 48 cm³ = 9.375 atm
If the density of chloroform is 1.5g /cm3 what is the mass of 50.0cm of chloroform
Answer: The mass of chloroform is 75 grams.
Explanation:
To calculate density of a substance, we use the equation:
[tex]Density=\frac{Mass}{Volume}[/tex]
We are given:
Density of chloroform = [tex]1.5g/cm^3[/tex]
Volume of chloroform = [tex]50cm^3[/tex]
Putting values in above equation, we get:
[tex]1.5g/cm^3=\frac{\text{Mass of chloroform}}{50cm^3}\\\\\text{Mass of chloroform}=75g[/tex]
Hence, the mass of chloroform is 75 grams.
How are deltas and rivers similar?
Both are composed of ice.
Both feed into other bodies of water.
Both have high elevations.
Both travel in a north-south direction.
Answer:
Both feed into other bodies of water.
Explanation:
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Which step in the scientific method is conducted before a controlled experiment?
A. Form a hypothesis
B.Draw a conclusion
C.Communicate results
D.Analyze results
A certain ore yields an average of 64% iron. how much ore is needed to obtain 896 lb of iron?
Final answer:
To extract 896 lb of iron from an ore that contains 64% iron, 1400 lb of ore is needed.
Explanation:
The student asked how much ore is needed to obtain 896 lb of iron if the ore yields an average of 64% iron. To find the amount of ore required, we use the following mathematical relationship:
First, express 64% as a decimal, which is 0.64.
Next, divide the desired amount of iron by the percentage (as a decimal) of iron in the ore to find the total amount of ore needed. The equation for this is Total Ore Needed = Amount of Iron Required / Percentage of Iron in Ore.
Therefore, we divide 896 lb by 0.64 to find the total ore needed.
Performing the division, we get 896 lb divided by 0.64 equals 1400 lb of ore needed.
To summarize, 1400 lb of ore is needed to extract 896 lb of iron from an ore that contains 64% iron.
Which one of the following is the net ionic equation for the reaction of nitric acid with aluminum hydroxide
Option (a) 3H⁺(aq) + Al(OH)₃(s) → Al³⁺(aq) + 3H₂O(l) is the net ionic equation for the reaction between nitric acid and aluminum hydroxide. This equation represents the primary species undergoing chemical change. It excludes spectator ions to show only the substances involved in the actual chemical reaction.
Among the given options, the correct net ionic equation is:
(a) 3H⁺(aq) + Al(OH)₃ (s) → Al³⁺(aq) + 3H₂O(l)
Here is the explanation:
The complete molecular equation is:3HNO₃(aq) + Al(OH)₃(s) → Al(NO₃)₃(aq) + 3H₂O(l)This equation shows that nitric acid (HNO₃) reacts with aluminum hydroxide (Al(OH)₃) to form aluminum nitrate (Al(NO₃)₃) and water (H₂O).To find the net ionic equation, we focus on the species that actually participate in the reaction, excluding spectator ions:H⁺(aq) and OH⁻(aq) ions form water:3H⁺(aq) + Al(OH)₃ (s) → Al³⁺(aq) + 3H₂O(l)Thus, option (a) is the net ionic equation for this reaction.
Complete Question:
Which one of the following is the net ionic equation for the reaction of nitric acid with aluminum hydroxide?
(a) 3H⁺(aq) + Al(OH)₃ (s) → Al³⁺(aq) + 3H₂O(l)
(b) 3HNO₃ (aq) + Al(OH)₃ (s) → 3Al(NO₃)₃ (aq) + 3H₂O(C)
(c) 2H⁺(aq) + Al(OH)₂ (s) → Al²⁺ (aq) + 2H₂O(l)
(d) H⁺(aq) + OH⁻(aq) → H₂O(l)
(e) 3NO₃⁻(aq) + Al³⁺(aq) → Al(NO₃)₃ (aq)
A sample of n2 effuses in 255 s. how long will the same size sample of cl2 take to effuse?
Apply Graham's law of effusion to compare the rates of effusion of Nitrogen gas (N₂) and Chlorine gas (Cl₂) and calculate the time it would take for the same volume of Cl₂ as N₂ to effuse.
Explanation:The question is asking about the concept of effusion from the field of Chemistry, which refers to how quickly gases escape through a small hole. The rate of effusion for gases can be calculated using Graham's law of effusion, which states that the rate of effusion of a gas is inversely proportional to the square root of its molar mass.
In this case, the student is asking how long it would take for the same volume of Cl₂ as N₂ to effuse. Given that the molar mass of nitrogen (N₂) is approximately 28 g/mol and that of chlorine (Cl₂) is approximately 70 g/mol, we can use these values in the relation (Rate of N₂ / Rate of Cl₂) = sqrt(Molar mass of Cl₂ / Molar mass of N₂). We're told that the rate of N₂ is 255s. Hence, by inserting these values into the relation, we can find the effusion rate of Cl₂.
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Which option is an example of a physical property?
Flammability
pH
toxicity
freezing point
Answer: freezing point
Explanation:
Chemical property is defined as the property of a substance which is observed during a reaction where the chemical composition identity of the substance gets changed.
Physical property is defined as the property which can be measured and whose value describes the state of physical system. For Example: State, density etc.
Flammability is a chemical property as it alters the chemical composition of substance.
pH is a chemical property as it alters the chemical composition of substance.
Toxicity is a chemical property as it alters the chemical composition of substance.
Freezing point is a physical property as it deals only with phase changes.
How many significant figures are used in expressing a measurement as 0.2503 l?
Which best describes stellar equilibrium?
The balance between pressure cause heat and gravity caused by the stars mass
what is latent heat?
Answer :
Latent heat : Latent heat is defined as the amount of heat required to convert the solid into liquid or vapor and a liquid into a vapor without changing the temperature.
As there are two types of latent heat which are :
(1) Latent heat of fusion
(2) Latent heat of vaporization
Latent heat of fusion : Latent heat of fusion is defined as the amount of heat energy released or absorbed when the solid converted to liquid at atmospheric pressure at its melting point.
Latent heat of vaporization : Latent heat of vaporization is defined as the amount of heat energy released or absorbed when the liquid converted to vapor at atmospheric pressure at its boiling point.
1. Electronegativity is:
A) how strongly an atom pulls electrons to itself when it is bonded to other atoms
B) how much energy is needed to take an electron away from an atom
C) how large an atom is
D) the energy needed to add an electron to an atom
2. Which element has the highest electronegativity?
A) Si
B) P
C) S
D) Cl
3.Which element has the lowest electronegativity?
A) Be
B) Sr
C) Ca
D) Mg
4.Order the following elements from lowest to highest electronegativity?
F, Li, C, N, O
A) F, Li, O, N, C
B) N, C, Li, F, O
C) Li, C, N, O, F
D) Li, C, O, N, F
5.On the periodic table, electronegativity increases going down a group and decreases going across a period.
A) True
B) False
1) Electronegativity is A) how strongly an atom pulls electrons to itself when it is bonded to other atoms. 2) D. Cl has the highest electronegativity. 3) B. Sr has the lowest electronegativity.
4) C) Li, C, N, O, F is the correct order of elements from lowest to highest electronegativity. 5) B. False, Electronegativity increases from left to right across a period and decreases from top to bottom of a group.
Understanding Electronegativity in Chemistry
1. Electronegativity is the ability of an atom to attract electrons in a bond. 2.Chlorine (Cl) has the highest electronegativity among the given options because it is located further to the right on the periodic table and higher up compared to other options.3.Strontium (Sr) has the lowest electronegativity among the given options because it is located further down the group in the periodic table.4. The correct order from lowest to highest electronegativity is Li then C, followed by N, then O, and F. This sequence shows how electronegativity increases across a period from left to right.5. Electronegativity actually decreases going down a group and increases going across a period.How is 6.3 written in scientific notation
True Or FALSE EASY 15 POINTS Pure substances are made up of single elements or compounds.
True
False
Answer: The given statement is true.
Explanation:
A pure substance is defined as the substance which is formed by same or different type of atoms which are chemically combined in a fixed ratio by mass.
Compounds and elements are considered as pure substances.
For Example: Sodium and sodium chloride are both considered as pure substances because sodium is entirely made up of sodium atoms and sodium chloride is entirely made up of sodium chloride molecules.
Hence, the given statement is true.
What type of bond is shown by the Lewis dot structure?
Final answer:
Lewis electron-dot structures show the bonding in covalent molecules. Covalent bonds between atoms can be indicated either with dots (:) or a dash (-). The Lewis structure or Lewis formula shows all the bonding electron pairs as lines (bonds) and lone pairs (non-bonding electron pairs) as pairs of dots around each atom in a molecule.
Explanation:
Lewis electron-dot structures show the bonding in covalent molecules. Covalent bonds between atoms can be indicated either with dots (:) or a dash (-).
The Lewis structure or Lewis formula shows all the bonding electron pairs as lines (bonds) and lone pairs (non-bonding electron pairs) as pairs of dots around each atom in a molecule. Lewis dot symbols can be used to predict the number of bonds formed by elements in a compound.
Is mixing sodium chloride and silver nitrate a chemical or physical change?
How do thermal energy and intermolecular forces behave with each other?
What is the percent by mass of water in iron (ii) sulfate heptahydrate, feso4•7h2o (or what percent of the molar mass of feso4•7h2o is due to the waters of crystallization)?
The percent by mass of water in iron (II) sulfate heptahydrate, FeSO4·7H2O, is 51.00%.
Explanation:To calculate the percent by mass of water in iron (II) sulfate heptahydrate, FeSO4·7H2O, we need to determine the molar mass of the compound and the molar mass of water. The molar mass of iron (II) sulfate heptahydrate is calculated as follows:
The molar mass of Fe is 55.85 g/mol.The molar mass of S is 32.07 g/mol.The molar mass of O is 16.00 g/mol.The molar mass of H is 1.01 g/mol.The molar mass of FeSO4 is equal to (55.85 g/mol + 32.07 g/mol + (4 * 16.00 g/mol)) = 151.91 g/mol.The molar mass of FeSO4·7H2O, including the waters of crystallization, is equal to (151.91 g/mol + (7 * 18.02 g/mol)) = 247.14 g/mol.Next, we determine the molar mass of the waters of crystallization:
The molar mass of water (H2O) is 18.02 g/mol.The molar mass of the waters of crystallization (7H2O) is equal to (7 * 18.02 g/mol) = 126.14 g/mol.Finally, we calculate the percent by mass of water in iron (II) sulfate heptahydrate:
(126.14 g/mol / 247.14 g/mol) x 100% = 51.00%
The basic principle in balancing a chemical equation is to ______. hints
Answer is: obey the Law of conservation of mass.
For example, balanced chemical reaction:
Pb(NO₃)₂(aq) + Li₂SO₄(aq) → PbSO₄(s) + 2LiNO₃(aq).
According to principle of mass conservation, number of atoms must be equal on both side of balanced chemical reaction.
There are two lithium atoms, one lead atom, one sulfur atom, ten oxygen atoms and two nitrogen atoms on both side of reaction.
Is pizza a element compound homogeneous mixture or heterogeneous mixture?
Pizza is a heterogeneous mixture because the different components are not evenly distributed throughout the mixture.
Pizza is a heterogeneous mixture. A heterogeneous mixture is a mixture in which the components are not evenly distributed throughout the mixture. This means that the different components of pizza, such as the sauce, cheese, and toppings, can be easily distinguished from each other.
Pizza is not an element, because an element is a pure substance that cannot be broken down into simpler substances by chemical means. Pizza is also not a compound, because a compound is a substance that is made up of two or more elements that are chemically bonded together.
The components of pizza are not chemically bonded together, so they can be easily separated. For example, the cheese can be removed from the pizza, and the sauce can be removed from the pizza. This shows that pizza is a heterogeneous mixture.
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Which elements make up the compound that helps give carbonated beverages their "fizz"?
Unstable isotopes undergo radioactive decay. what occurs during radioactive decay?
Radioactive decay occurs when an unstable isotope emits radiation to transform into a more stable nuclide. This process releases energy, and possibly mass, and it involves various types of emissions such as alpha, beta, and gamma decay. Each isotope has a specific half-life, the period needed for half of the isotope's atoms to decay.
Explanation:During radioactive decay, an unstable isotope, also known as a radioisotope, changes spontaneously into another nuclide. This process occurs because the nuclei that are not within the band of stability are unstable and tend to achieve a more stable state. The transformation involves the release of energy and sometimes mass, as the atom's nucleus emits radiation to become more stable.
There are various types of radioactive decay, such as alpha, beta, and gamma decay. Each of these changes the composition of the original nucleus, known as the parent nuclide, resulting in a daughter nuclide. The daughter nuclide could be stable or might further decay if it is still outside the band of stability. An example of this decay process is Carbon-14, which decays into Nitrogen-14, a stable product.
In nuclear reactions, significant amounts of energy are released, which are much greater than the energies involved in chemical reactions. Furthermore, nuclear reactions, and thus radioactive decay, occur regardless of environmental conditions such as temperature and pressure. Each radioisotope has a characteristic half-life, the time required for half of its atoms to decay.
Is you splashed strong acid on your face, how would get rid of it?
Final answer:
In the event of a strong acid splash on the face, immediately rinse with water for at least 15 to 20 minutes, remove any contaminated clothing, and seek medical attention without delay. Do not apply any substances to the affected area before consulting a professional.
Explanation:
If you splash strong acid on your face, it is crucial to act quickly to prevent severe burns and further injury. The first step is to immediately rinse the affected area with a large amount of water for at least 15 to 20 minutes. It is essential to use lukewarm water and avoid rubbing the area, which can further damage the skin. If available, you can also use special neutralizing solutions designed for chemical burns, but water should be your first choice.
After rinsing, it is critical to seek professional medical help immediately. Do not apply any creams, ointments, or other substances to the affected area before getting medical advice. While waiting for medical help, you should remove any contaminated clothing carefully and avoid touching the burn to reduce the risk of infection and further irritation. Always be careful when handling chemicals and wear appropriate protective gear to prevent such accidents.
The process that changes the identity and number of protons in a nucleus is
Enthalpy change depends on the rate at which a substance is heated or cooled true or false
Compounds that have the same chemical formula but a different arrangement of atoms are called
How many kilocalories are released by the combustion of 18.5 g of c8h18 ?
Without the exact heat of combustion per gram of octane (C8H18), it is impossible to calculate the specific number of kilocalories released by the combustion of 18.5 g of octane. The process would involve multiplying the heat of combustion per gram by the amount of substance burned and converting the energy from kilojoules to kilocalories if necessary.
Explanation:The student is asking about the enthalpy change associated with the combustion of octane (C8H18). To answer this, we first need the heat of combustion per gram or per mole of octane, which can be found in a given table or chemistry reference. However, since this value is not provided in the information given, we can't calculate the specific number of kilocalories released without it.
To find the heat released by combustion, once the heat of combustion per gram is known, you would multiply this value by the mass of the substance burned (in this case, 18.5 g of octane). Remember to convert kilojoules to kilocalories if necessary, as there are 0.239006 kilocalories in one kilojoule.
For example, if we knew that the combustion of 1 gram of octane released X kJ, then the heat released by burning 18.5 grams would be 18.5 * X kJ, which could then be converted to kilocalories.
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