Answer:
The ratio of half-lives for a reaction with starting concentrations of 0.05M and 0.01M, t1/2 (0.05M) / t1/2 (0.01M) = 1, if a reaction is known to be first order.
Explanation:
For a first- order reaction:the half-life of the reaction is constant and does not depend on the value of the initial concentration.
half-life (t1/2) = 0.693/k,
where, k is the rate constant of the reaction.
So, half;life of first-order reaction is constant whatever the initial concentration.
So the ratio of t1/2 (0.05M) / t1/2 (0.01M) = 1
Which of the following best describes the molecular orbital theory of bonding? Choose one: A. A theory of bonding based on the mixing of atomic orbitals of similar shapes and energies to form molecular orbitals that extend to two or more atoms B. A theory where the bonds and lone pairs of valence electrons in a molecule are represented in two-dimensions C. A theory that predicts the arrangement of valence electron pairs around a central atom minimizing their mutual repulsion to produce the lowest-energy orientations D. A theory of bonding that describes bonds as the electrostatic attraction between species of opposite charge E. A theory of bonding that assumes covalent bonds form when half-filled orbitals on different atoms overlap or occupy the same region in space
Final answer:
The molecular orbital theory of bonding involves the combination of atomic orbitals to form molecular orbitals that can extend over multiple atoms, leading to the formation of stabilized and destabilized regions in a molecule depending on the phase of orbital combinations. So the correct option is A.
Explanation:
The molecular orbital theory of bonding is best described by option A: A theory of bonding based on the mixing of atomic orbitals of similar shapes and energies to form molecular orbitals that extend over two or more atoms. This theory utilizes quantum mechanics to describe how electrons are distributed in a molecule, leading to the formation of bonding and antibonding molecular orbitals. Bonding molecular orbitals, which are in-phase combinations of atomic wave functions, stabilize a molecule, while antibonding molecular orbitals, resulting from out-of-phase combinations, make a molecule less stable. Molecular orbitals can incorporate atomic 's' and 'p' wave functions to form σ and π orbitals, respectively. A molecular orbital can hold up to two electrons with opposite spins, analogous to atomic orbitals in isolated atoms.
can anyone check my work/ help me figure out how to do this?
Determine the pH of the following solution.
A 4.5 x 10^-3 M HBr solution
My Work:
all I did was -log(4.5x10^-3) and got 2.35 but I am not sure at all how to do this
Answer:
2.35.
Explanation:
∵ pH = - log[H⁺].
[H⁺] = 4.5 x 10⁻³ M.
∴ pH = - log(4.5 x 10⁻³ M) = 2.346 ≅ 2.35.
Which is the basis of thin-layer chromatography?
A.) An electron beam excites atoms within the drug, which give off a characteristic X-ray spectrum.
B.) The drug gets carried through a stationary phase by a mobile phase and the retention time identifies the drug.
C.) The drug fragments have specific molecular weights that bind to the antibodies.
D.) The unknown amount of drug in a sample competes with a known amount of fluorescently labeled drug for binding to an antibody to that drug.
Answer:
B.) The drug gets carried through a stationary phase by a mobile phase and the retention time identifies the drug.
Explanation:
Chromatography is used in purifying complex mixtures of organic compounds. It uses the adsorption tendencies of compounds to seperate and identify them.
Chromatography is made up of two phases in contact, the stationary phase or non-mobile phase and the mobile phase. The movement of the mobile phase over the stationary phase causes the separation of a mixture into its constituents.
The stationary phase is made up of silica-gel or alumina in a solvent (an adsorbent) and the mobile phase or carrier is the organic solvent which is the drug.
Thin-layer chromatography is based on the separation of compounds as they move at different rates through a stationary phase under the influence of a mobile phase, due to their interactions with the stationary material.
Explanation:The basis of thin-layer chromatography (TLC) is the separation of compounds based on their differing rates of movement through a stationary phase, typically a slurry of solid beads of silica or a solid surface of these compounds, under the influence of a mobile phase. The substances are first dissolved in the mobile phase, and as the mobile phase moves through the stationary phase, the components of the mixture interact with the stationary phase to various extents. These interactions can result in different retention times, which are the times that solutes remain in the chromatography system before eluting. As a result, components with different chemical properties can be separated and identified.
TLC is characterized by its use of a stationary phase and a mobile phase, and relies on the physical and chemical interactions between the solute and these phases for separation. Compounds with different affinities for the stationary and mobile phases travel at different speeds, resulting in their separation.
What is an ethical vacuum?
A. A scientific idea that lacks ethics.
B. A philosophy that ethics cannot exist in a vacuum, but need specific examples to be valid.
C. When technology has created something for which we do not have an ethical framework yet.
D. The situation of being without ethics.
An ethical vacuum is when technology has created something for which we do not have an ethical framework yet. That is option C.
What is an ethical vacuum?An ethical vacuum can be defined as the development of a structure by technology which lacks ethical framework backup.
Before a new innovation is approved in the society, it needs to be given an ethical backup to be fully assimilated into the society at large.
Therefore, an ethical vacuum is can be defined as when technology has created something for which we do not have an ethical framework yet.
Learn more about ethics here:
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How much fluorine (in grams) did the second sample produce? ?Upon decomposition, one sample of magnesium fluoride produced 1.66 of magnesium and 2.56 of fluorine. A second sample produced 1.31 of magnesium.
Answer:
[tex]\boxed{\text{2.02 g F}}[/tex]
Explanation:
You get 2.56 g of F with 1.66 g of Mg.
[tex]\text{Mass of F} = \text{ 1.31 g Mg} \times \dfrac{\text{2.56 g F}} {\text{1.66 g Mg}} = \boxed{\textbf{2.02 g F}}[/tex]
Answer: The mass of fluorine produced in sample 2 will be 2.02 grams
Explanation:
The chemical formula of magnesium fluoride is [tex]MgF_2[/tex]
We are given:
Mass of magnesium in sample 1 = 1.66 grams
Mass of fluorine in sample 1 = 2.56 grams
Mass of magnesium in sample 2 = 1.31 grams
Applying unitary method:
When 1.66 grams of magnesium is produced, the mass of fluorine produced is 2.56 grams
So, when 1.31 grams of magnesium will be produce, the mass of fluorine produced will be = [tex]\frac{2.56}{1.66}\times 1.31=2.02g[/tex]
Hence, the mass of fluorine produced in sample 2 will be 2.02 grams
If I have 3.5 moles of C, and excess Fe2O3 , how many moles of Fe can I produce?
2Fe2O3 + C → Fe + 300,
7 moles Fe
1.17 moles Fe
1.75 moles Fe
3.5 moles Fe
Answer:
3.5 moles Fe
Explanation:
From the equation, Reaction of 2 moles of Fe₂O₃ with 1 mole of C produces 1 mole of Fe. When excess Fe₂O₃ is used, the only liming factor is C.
The ratio of amount of C used to the amount of Fe produced is 1:1
Therefore, if 3.5 moles of C are used, 3.5 moles of Fe are also produced.
the amount of water on Earth is _______but the form and location of the water _______ as it moves through the hydrologic cycle
Hey there!
I can't be sure my answers are the exact words, but it should be something along the lines of...
The amount of water on Earth is constant, but the form and location of the water changes as it moves through the water cycle.
This means that Earth has always had the same amount of water within in, along with it being the same water the whole time. No new water was introduced to our planet. Some of our water is liquid, some is solid, and some is gas. Some is deep in the soil and some is high up in the atmosphere. Some is in rain and some is in snow.
I hope this helps!
When table salt (NaCl) is dissolved into water, it breaks into 2 ions, Na+ and Cl-. The water molecules are attracted to them because water is polar. Which of the following is true:
A. Negatively charged oxygen atoms are attracted to positively charged sodium atoms.
B. Positively charged oxygen atoms are attracted to positively charged sodium atoms.
C. Negatively charged hydrogen atoms are attracted to positively charged sodium atoms.
D. Positively charged hydrogen atoms are attracted to positively charged sodium atoms.
Answer:
A
Explanation:
According to Coulomb's Law, like charges repel each other, whereas unlike charges attract each other. This applies to all charged particles.
When NaCl dissociates into its ions in water, we observe the following ions in the system:
Na+ (positive)
Cl - (negative)
H+ (positive)
OH- (negative)
The only correct option is A where the negatively charged oxygen atoms are attracted to the positively charged sodium atoms.
In option B the charge of the oxygen atom is incorrectly mentioned as positive. In option C, the charge of hydrogen atoms is incorrectly mentioned as negative, and in option D the charges of the atoms are correct, but the pairing is incorrect as like charges repel each other.
Hope this helpsAnswer:
D. Positively charged hydrogen atoms are attracted to positively charged sodium atoms.
Explanation:
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