Among the given substances, Ammonia, a compound, can be decomposed into Nitrogen and Hydrogen by a chemical change.
Explanation:The substance that can be decomposed by a chemical change among Sodium, Argon, Sulfur, and Ammonia is Ammonia. In a chemical change, one or more substances are converted into different substances. In this context, Sodium, Argon, and Sulfur are elements that exist in their most simplified form and cannot be broken further down by chemical change. On the other hand, Ammonia (NH3) is a compound and can be decomposed into Nitrogen and Hydrogen via chemical changes.
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After 252 days, a 12.0-g sample of the radioisotope scandium-46 contains only 1.5 g of the isotope. what is the half-life of scandium-46
The half-life of scandium-46 is determined by noting that after 252 days, the mass of the isotope reduces from 12.0 g to 1.5 g, which is 1/8 of the original mass, indicating that three half-lives have passed. Dividing the total time by 3 gives us a half-life of 84 days for scandium-46.
To determine the half-life of scandium-46, we use the fact that after a certain number of half-lives, the remaining mass of a radioactive substance is half of its initial mass after each half-life period. In the given problem, a 12.0-g sample of scandium-46 decays to 1.5 g after 252 days. This decay represents a reduction to 1/8 of the original mass, indicating that three half-lives have passed (since 12.0 / 2 / 2 / 2 = 1.5).
Initial mass of scandium-46: 12.0 gFinal mass of scandium-46 after 252 days: 1.5 gMass reduction to 1/8 indicates 3 half-lives.Since 3 half-lives are equivalent to 252 days, we can find the length of a single half-life by dividing the total time by 3:
252 days ÷ 3 = 84 days
Therefore, the half-life of scandium-46 is 84 days.
How many oxygen atoms are in 1.40 g of quartz?
Final answer:
To find the number of oxygen atoms in 1.40 g of quartz, calculate the number of moles of quartz and use Avogadro's number to convert to oxygen atoms, accounting for two oxygen atoms per mole of SiO₂.
Explanation:
To determine how many oxygen atoms are in 1.40 g of quartz (SiO₂), we need to perform a series of calculations using the molar mass of quartz and Avogadro's number. First, we find the molar mass of quartz by adding the molar mass of silicon (28.085 g/mol) and twice the molar mass of oxygen (2 × 15.999 g/mol), which equals 60.083 g/mol. Next, we calculate the number of moles of quartz in 1.40 g using the molar mass:
Number of moles of SiO₂ = 1.40 g / 60.083 g/mol
Finally, since each mole of SiO₂ contains two moles of oxygen atoms, we use Avogadro's number (6.022 × 10²³ atoms/mol) to find the total number of oxygen atoms:
Number of oxygen atoms = Number of moles of SiO₂ × 2 × Avogadro's number
Completing the calculations provides the answer to how many oxygen atoms are in 1.40 g of quartz.
Would a calcium ion (ca2+) and a chloride ion attract or repel each other?
Final answer:
A calcium ion (Ca²+) and a chloride ion (Cl-) attract each other due to their opposite charges, forming an ionic bond in the compound calcium chloride (CaCl²).
Explanation:
A calcium ion (Ca²+) and a chloride ion (Cl−) will attract each other due to the opposite charges they carry. Calcium donates two electrons to achieve a stable electron configuration, becoming a Ca²+ ion. Each electron is then accepted by a chlorine atom, which becomes a Cl− ion. This transfer leads to the formation of the ionic compound calcium chloride (CaCl²), where the attraction between the positively charged calcium ions and the negatively charged chloride ions results in a strong electrostatic force that holds the compound together in a lattice structure. The ionic bonding between Ca²+ and Cl− is a result of the coulombic attraction described by Coulomb's law, which states that opposite charges attract each other.
In the preparatory reaction which involves moving pyruvic acid into the mitochondrion
in the preceding information section there is a "bohr's diagram" of an atom. Which atom is it?
Bohr's Diagram primely illustrates an atom's unique arrangement of electrons, protons, and neutrons. Specifics of the diagram like the number and arrangement of electrons in the shells would let us identify which atom it refers to.
Explanation:Without the preceding information showing the Bohr's diagram, it's truly impossible to pinpoint which specific atom it represents. A Bohr's diagram typically includes a central nucleus, denoting protons and neutrons, with surrounding energy levels or shells that signify electrons. Each atom has a unique arrangement of electrons, so the specific makeup of the diagram would determine which atom it's representing. For instance, Hydrogen, the simplest atom, would have a diagram with 1 electron at its outermost shell whereas Carbon would have 6 electrons spread across two energy levels. Please provide the details of the diagram for more specific identification.
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An element has the electronic configuration 1s22s22p63s23p63d104s24p65s2. identify the element.
The electron configuration given corresponds to Strontium (Sr), which is element number 38 on the periodic table and ends with the 5s² subshell being filled after the noble gas krypton's (Kr) electron configuration.
The element with the electron configuration 1s2s²2p⁶3s²3p⁶3d¹⁰4s²4p⁶5s² is Strontium (Sr). It is identified by examining the electron configuration and matching it to the position on the periodic table. The electron configuration ends with 5s², following the noble gas krypton (Kr), and two additional electrons in the 5s orbital indicate that we move two places beyond krypton in the periodic table. This corresponds to the element with atomic number 38, which is Strontium (Sr).
Sunlight is slowed MOST when traveling through
Answer:
Diamond
Explanation:
The speed of sunlight depends upon the refractive index of the medium, Diamond has the highest refractive index.
When a sample of atoms is heated and releases light of certain wavelengths, it is called what?
The answer is emission spectrum. It is the range of frequencies of electromagnetic radiation produced because of an atom or molecule generating a transition from a high energy state to a lower energy state. The photon energy of the produced photon is equivalent to the energy change between the two states. There are many conceivable electron changes for each atom, and each change has a precise energy difference.
Potassium and bromine combine to make KBr. What is the name of this compound?
What state must a substance be in order to analyze it using uv vis spectroscopy?
During a flame test, a lithium salt produces a characteristic red flame. This red color is produced when electrons in excited lithium atoms
1. are lost by the atoms
2. are gained by the atoms
3. return to lower energy states within the atoms
4. move to higher energy states
The red color in a lithium salt flame test is due to electrons returning to lower energy states, emitting light at specific wavelengths. This is part of the atomic emission spectrum of lithium, with each metal displaying a unique flame color when heated.
The red color produced in a flame test when a lithium salt is subjected to heat is due to the electrons in the excited lithium atoms returning to lower energy states within the atoms. This phenomenon is a part of the atomic emission spectrum of lithium. When the lithium atoms in the flame are heated, their electrons are excited to higher energy levels. As the electrons fall back down to their original energy states, they emit light of specific wavelengths. The characteristic red color observed is due to this emission corresponding to the particular energy gap between the excited and ground states of the lithium electron.
Flame tests are commonly used to identify the presence of certain metal ions in compounds. Each metal emits a distinct color when burned, as the emission spectrum of each element is unique. For instance, sodium produces a bright yellow flame, and potassium produces a lilac color. In the context of lithium, the emission results in a bright, crimson flame, which is indicative of lithium's presence in the sample tested.
What natural method of separating mixtures happens in reservoirs over a long period of time?
A 25-ml sample of river water was titrated with 0.0010 m k2cr2o7 and required 8.3 ml to reach the end point. what is the chemical oxygen demand, in milligrams of o2 per liter, of the sample?
First let us calculate the moles of K2Cr2O7 that was supplied.
moles K2Cr2O7 = 0.0010 M * 0.0083 L = 8.3x10^-6 mol
From the chemical formula itself, we see that there are 7 O for every mole of K2Cr2O7 or 3.5 O2. Therefore:
moles O2 = 8.3x10^-6 mol K2Cr2O7 * (3.5 mol O2 / 1 mol K2Cr2O7)
moles O2 = 2.905x10^-5 mol O2
Calculating for the mass of O2 in mg:
mass O2 = 2.905x10^-5 mol O2 * (32 g / mol) * (1000 mg / g)
mass O2 = 0.9296 mg
Therefore the chemical oxygen demand (COD) is:
COD = 0.9296 mg / (0.025 L)
COD = 37.184 mg/L
The Chemical Oxygen Demand (COD) for the given sample is calculated based on the amount of K2Cr2O7 used in the analysis. Considering this calculation, the COD of the analyzed sample comes around 63,744 mg/L or approximately 63.744 g/L.
Explanation:The Chemical Oxygen Demand (COD) can be determined using the titrated volume of potassium dichromate (K2Cr2O7) required to reach the endpoint of the titration. In this case, the dichromate ion (Cr2O7) is reduced by any present organic matter in the water sample, while being oxidized to Cr, and each Cr2O7 ion utilizes 6 moles of oxygen in the process.
In this scenario, the volume of K2Cr2O7 used is 8.3 ml with a molarity of 0.0010 M. Hence, the total moles of oxygen used can be calculated as 8.3 ml x 0.0010 moles/ml x 6 moles O2/ mole Cr2O7 = 0.0498 moles O2.
As the question requires the answer in milligrams per liter (mg/L), we have to convert moles of O2 to mg and the sample volume to L. This gives us 0.0498 moles x 32 g/mole x1000 mg/g = 1593.6 mg O2 in the original 0.025 L sample. Thus, the Chemical Oxygen Demand (COD) of the sample is 1593.6 mg /0.025 L = 63,744 mg/L or approximately 63.744 g/L.
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Because the core of the sun is so hot, what heavier element is created when hydrogen atoms fuse together in the sun's core?
Answer is: helium.
Nuclear reaction is in the inner core of the Sun and hydrogen is conveted into helium.
The inner core is the central region of the Sun and all solar energy is produced in the core by nuclear fusion.
The Sun interior is divided into three regions: the inner core, the radiative zone and the convection zone.
Helium (symbol: He) is an element with atomic number 2 (2 protons) and mass number 4 (2 neutrons; n° = 4 - 2 = 2).
How does dalton's atomic theory support the law of conservation of mass?
Final answer:
Dalton's atomic theory supports the law of conservation of mass by positing that atoms, the indivisible units of matter, are neither created nor destroyed during chemical reactions, ensuring mass remains constant in a closed system.
Explanation:
How does Dalton's atomic theory support the law of conservation of mass? John Dalton's atomic theory re-introduced the idea of atomism, which suggests that all matter is composed of small, indestructible units known as atoms. This theory aligns closely with the law of conservation of mass, established by Antoine Lavoisier, which states that mass in an isolated system is neither created nor destroyed by chemical reactions or physical transformations.
Dalton proposed that chemical reactions involve the rearrangement of atoms that are combined, separated, or rearranged, but never created or destroyed. Therefore, the total mass of reactants in a chemical reaction equals the total mass of the products. This agreement with the law of conservation of mass is a fundamental principle showing that during any chemical process in a closed system, the mass remains constant. Dalton's theory provides a microscopic explanation of this macroscopic observation, illustrating that the mass conservation is due to the conservation of atoms in chemical processes.
If an element like copper consists of only one kind of atom, it means it cannot be broken down into simpler substances. This implies that atoms, the fundamental building blocks of matter, are neither created nor destroyed during a chemical change, reinforcing the concept of mass conservation. This understanding marks a pivotal development in the field of chemistry, allowing for the quantitative study of chemical reactions and the advancement of chemical science.
What particles in an atom can increase or decrease without changing the identity of the element?
For the angular momentum quantum number l=2 , how many possible values are there for the magnetic quantum number (m subscript l)?
1
3
5
8
The angular momentum quantum number l = 2 corresponds to 5 possible values for the magnetic quantum number m, which are -2, -1, 0, 1, and 2.
For the angular momentum quantum number,
l = 2, the number of possible values for the magnetic quantum number (m) is given by the formula 2l + 1. Plugging in
l = 2, we get 2(2) + 1 = 5 possible values.
Therefore, the values of m that are possible for
l = 2 are -2, -1, 0, 1, and 2, which confirms that there are 5 possible values for the magnetic quantum number when l is 2.
What are the final or new substances (molecule) in a chemical equation called?
Use the given figure to complete the statement below.
∠2 and ∠4 are angles. supplementary adjacent vertical complementary
Easy, its vertical :3
Answer: ∠2 and ∠4 are vertical angles.
Explanation: We are given two linear lines that intersect each other and forms angles.
Theorem: When two lines intersect, the vertical angle are congruent to each other which means that the two angles are equal. Vertical angles are the angles that are opposite to each other.
In the given figure, ∠2 and ∠4 are opposite to each other, hence they are considered as vertical angles.
∠2 = ∠4 (From above theorem)
Which of these factors make hydrogen fuel cells a better option than burning fossil fuels?
Hydrogen fuel cells have a higher energy efficiency.
Hydrogen fuel cells create less pollution.
Burning fossil fuels relies on outdated devices and technology.
Pure hydrogen is more readily available than fossil fuels.
Hydrogen fuel cells are more expensive than fossil fuels.
Answer:
Hydrogen fuel cells have a higher energy efficiency.
Hydrogen fuel cells create less pollution.
Explanation:
Hydrogen fuel cell is an electrochemical cell which employs hydrogen gas to produce electricity and water.In this cell chemical energy of hydrogen gas is converted into electrical energy.
Advantages of hydrogen fuel cell:
It directly converts chemical energy into electrical energy.Only emission of water and little heat that is it creates less pollution.Much more reliable source of energy.Highly efficient energy resource.Extraction of hydrogen can be done without harming an environment than the extraction of other fossil fuels and oil which causes damage.When an oxygen atom is attached to a carbon atom the carbon atom becomes more?
Answer: Reduced
Explanation: When an oxygen atom is attached to a carbon atom, the carbon atom becomes reduced.
Is electron affinity the opposite of ionization energy?
When comparing the activation energy between different exothermic reactions, as the activation energy decreases at a given temperature, the reaction rate increases because the _______?
Answer:
number of successful effective collisions is higher
A glass of cold milk sometimes forms a coat of water on the outside of the glass (often referred to as ‘sweat'). how does most of the water get there?
What is a major source of calcium and sodium in oceans?
A) air pollutants
B) gases from active volcanoes
C) minerals dissolved in aquifers
D) weathering and erosion of rocks
The answer is D. weathering and erosion of rocks
how many moles of copper must react to form 0.854 mol ag
How many moles of copper must react to form 0.854 mol Ag? =0.427
Is rain turning to snow a physical or chemical change?
Ionization energy and electron affinity both express the general attraction of an atom for
Ionization energy is the energy required to remove an electron from an atom. Meanwhile, Electron affinity is the energy required to add an electron to an atom. So we can see that the two are opposite variables. However, they both refers to general attraction of an atom for “electron”.
Which would make the best primary material for a new coin: a metal, nonmetal, metalloid? Explain please! I’ll give Brianliest answer!
Answer:
best primary material for a new coin: a metal,
Explanation:
As metal has the capacity to be molded and melted to a solid object to take the shape of a new coin and from the rounded shape as compared to the non- metal the material must be of a high-grade quality or otherwise it cannot withstand the pressure and durability for making the new coin. While a metalloid is a type of chemical element which is a mix of metal and a non-metal as boron, silicon, germanium, arsenic and does not show the best properties for the formation into a new coin. These have various elements and mineral properties involved in their formation.Heat is so closely related to _____, the same units are used to measure both.
Answer:
I am pretty sure temperature is wrong. It is actually work.
Explanation:
Scientists use the term joule(s) for heat. Temperature is measured in celcius, kelvin, fahrenheit. Work also uses the same term for measuring; joules. I am pretty sure the right answer is actually work, even though temperature sounds more correct. I learned this in science so I think I am right.