Question a
Step 1
The average atomic mass of the element is calculated as:
[tex]Average\text{ atomic mass =}\frac{\sum_^(eachmass\text{ }x\text{ }\%abundance\rparen}{100}[/tex]--------------------
Step 2
Information provided:
Isotope 1:
10.0 % abundant and 23.8 amu.
Isotope 2:
40.0 % abundant and 24.6 amu.
Isotope 3:
25.8 amu, the % abundant = 100 % - 10.0 % - 40.0 % = 50.0 %
-----------------------
Step 3
Procedure:
Average atom mass = (10.0% x 23.8 amu + 40.0% x 24.6 amu + 50.0 % x 25.8 amu)/100 = 25.12 amu
Answer: 25.12 amu
Write the electron configuration (1s², 2s²,...) for the following:
Hydrogen
2
Fluorine
Boron - 1s²2s²2p¹
3 Aluminum
Draw the electron configuration with the correct atomic orbitals for the following:
4 Sodium
6
5 Sulfur
Boron-
Argon
15². 25
2p
that is for hydrogen, fluorine and aluminium
the reaction 2a → a2 was experimentally determined to be second order with a rate constant, k, equal to 0.0265 m–1min–1. if the initial concentration of a was 3.75 m, what was the concentration of a (in m) after 180.0 min?
Based on the integrated equation used for reactant concentration calculation in a second-order reaction and the data given (initial concentration, reaction rate constant, and time elapsed), the concentration of A after 180.0 min will be 0.20 M.
The integrated equation for the reactant concentration in a second-order reaction looks like this:
1/[A] = kt + 1/[A]₀
k - reaction rate constant (0.0265 min⁻¹M⁻¹)
[A]₀ - initial concentration (3.75 M)
t - time elapsed (180.0 min)
1/[A] = 0.0265 min⁻¹M⁻¹ * 180.0 min + 1/(3.75 M) = 4.77 M⁻¹ + 0.27 M⁻¹ = 5.04 M⁻¹
[A] = 1 / (5.04 M⁻¹) = 0.20 M
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Copper(II) oxide can be reduced by hydrogen:
CuO(s) + H2(g) → Cu(s) +H2O(g)
What mass of copper can be obtained from 15.9 g of copper(II) oxide?
Answer:
do that in calc
Explanation:
mass of cu = 63.55 ÷ 79.55 × 15.9
2. Explain the significance of the discovery of gallium (mass number 68) to Mendeleev periodic table
The significance of gallium is explained below
Describe gallium.The atomic number and symbol for the chemical element gallium are 31. The discovery was discovered in 1875 by French chemist Ga. Paul-Émile Lecoq de Boisbaudran. Gallium is a similar metal to the other elements in Group 13 of the Periodic Table (aluminium, indium, and thallium).
Under normal pressure and temperature, gallium is a soft and silvery element. When it's liquid, it takes on an icy white hue. Using too much force could cause gallium to shatter conchoidally. Since its discovery in 1875, gallium has been frequently used to produce alloys with low melting points. It is also used in semiconductors as a dopant on semiconductor substrates.
In 1875, a French chemist by the name of Paul Emile Francois Lecoq de Boisbaudran made a spectroscopic discovery of a new element while studying zinc blende. The properties of this freshly discovered element matched those of the eka-aluminum, which has an atomic weight of 69, as predicted by Mendeleev. The specific gravity of the element was later determined to be 5.9, as predicted by Mendeleev. The substance was then given the name gallium by Lepoq, who so elevated Mendeleev's periodic table and supported Mendeleev's theories.
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a student is running an experiment in which 42.0 grams of coso4 is needed, but the only jar of reagent in the lab is labelled cobalt(ii) sulfate hexahydrate. how many grams of the hydrate must the student weigh out in order to get the desired amount of the anhydrous compound?
A mass of 71.26g of [tex]CoSO_4.6H_2O[/tex] is required to get 42g of the anhydrous compound, i.e., [tex]CoSO_4[/tex].
A compound's molar mass indicates the mass of one mole of that substance. In other words, it informs you how many grams of a substance there are per mole. A covalent compound's formula mass is also known as its molecular mass. The mole is a useful quantity unit for representing very large quantities of atoms or molecules. A substance's molecular mass is the total of the atomic masses of all the atoms that comprise the molecule of the substance.
The term anhydrous means "without water." Anhydrous chemicals are compounds that do not contain water or do not contain water. An anhydrate is formed when water is removed from a hydrate. Suction or high-temperature heating of the chemical removes the water molecules. An anhydrous salt, for example, has had water driven out of its crystals.
Given:
Mass of [tex]CoSO_4[/tex] needed = 42g
To find:
Mass of [tex]CoSO_4.6H_2O[/tex] = ?
Formula:
Mass of [tex]CoSO_4.6H_2O[/tex] = (Mol. Wt. of [tex]CoSO_4.6H_2O[/tex] / Mol. Wt. of [tex]CoSO_4[/tex]) x Mass of [tex]CoSO_4[/tex]
Calculations:
Mol. Wt. of [tex]CoSO_4[/tex] = 155g/mol
Mol. Wt. of [tex]CoSO_4.6H_2O[/tex] = 155 + 6 x 18 = 263g/mol
Mass of [tex]CoSO_4.6H_2O[/tex] = (263 / 155) x 42
Mass of [tex]CoSO_4.6H_2O[/tex] = 71.26g
Result:
71.26g of [tex]CoSO_4.6H_2O[/tex] is required to get 42g of the anhydrous compound.
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Match the structural formulas given to you below with the correct chemical formula from the bank above. (Image provided)
1) C3H6O because there are 6 hydrogen in formula and one oxygen. 2) H2So4 sulphric acid.
What three categories exist for chemical formulas?Chemical formulas can be divided into three categories: empirical, molecular, and structural. Molecular formulas display the quantity of each type of atom in a molecule, while structural formulas display the simplest whole-number relationship between the atoms in a compound. Empirical formulas display the simplest whole-number relationship between the atoms in a compound.
3) C2H2 ethyne where carbons have triple bond.
4) CO carbon monoxide where C and O have triple bond between them .
5) HNO3 is nitric acid .
6) CH2F2
7) Ch2O
8) C2H4 is ethene in which carbon carbon have double bonds.
9) SO3 sulphur trioxide.
10) CH3F
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you have two test tubes. one test tube contains fe 3(aq) solution and the other test tube contains ni 2(aq). predict what will happen when naoh(aq) is added to both test tubes. if a reaction occurs, what is the new chemical formula?
The new chemical formula is [tex] Fe(OH)_{3}[/tex] or ferric hydroxide.
Ion [tex] {Fe}^{3 + } [/tex] will react with NaOH while [tex] {Ni}^{2 + } [/tex] will not. The chemical reaction is as follows -
Chemical reaction stating reaction between [tex] {Fe}^{3 + } [/tex] and NaOH.
[tex] {Fe}^{3 + } [/tex] + NaOH → [tex] Fe(OH)_{3}[/tex] + Na
In the reaction, [tex] {Fe}^{3 + } [/tex] represents ferric ions, NaOH is the chemical formula of sodium hydroxide, [tex] Fe(OH)_{3}[/tex] is the chemical formula of ferric hydroxide and Na represents sodium. The ferric hydroxide precipitates as reddish brown. It does not dissolve in excess is sodium hydroxide.
Chemical reaction stating reaction between [tex] {Ni}^{2 + } [/tex] and NaOH
Nickel does not react with sodium hydroxide due to its basic nature. The reason can be owed to electron donating characteristic of both the metal and base.
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If a substance conducts electricity when dissolved in water, turns litmus from blue to red, and tastes sour, would you expect it to be acidic, basic, or neutral? Justify your answer.
Answer:
The substance is acidic.
Explanation:
When a substance is able to dissolve in water, it means that it is ionic. This just means that the polarity of the water and the polarity of the substance will attract each other to their positive and negative ends respectively. (Positive attracts negative and negative attracts positive).
Litmus paper that is blue and then turns red when introduced to a substance, is known to be acidic.
The opposite can be said when red litmus paper turns blue when introduced to a substance; this means the substance is basic.
Also, if it is sour, then that means it is acidic! Some examples of sour things that are acidic are soft drinks, apples and lemons/limes.
A student measures 25ml of acid into the flask and adds the 3 drops of the indicator. if the student then adds 20ml of water to the flask, will this change to amount of base needed to reach the endpoint?
The addition of water to the acid solution will change the molarity of the solution, but not the amount of base needed to reach the titration endpoint because the total amount of acid hasn't changed.
During this titration, a solution of the base will be added to a solution of the acid, and when the endpoint is reached, the indicator will change color. The titration endpoint is reached when the acid in the sample solution has been completely neutralized, and an excess base is now appearing.
The amount of base required for neutralization is determined by the amount (number of moles) of acid in the starting solution. Although the starting solution would become more dilute (lowering its molarity) upon the addition of water, the total amount of acid will not be reduced, thus requiring the same amount of base.
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When sodium hydroxide reacts with sulfuric acid a solution of sodium sulfate is produced.
a.) Describe how crystals of sodium sulfate can be obtained from a solution of sodium sulfate.
When an acid and a base react, the base balances the acid, creating salt and water as a result..
2NaoH+ H2SO4----> Na2SO4 + H2O
Both sulfuric acid H2SO4 and sodium hydroxide NaOH are powerful acids and bases, respectively.
This reaction is exothermic in nature and is referred to as the neutralizing reaction (since heat is released during the reaction as there is formation of new bonds).
a). If you left your aqueous sodium sulfite solution open on the side, air oxygen would catalyze the chemical shift, the water would hydrate the new compound, and the slow evaporation of water would give you wonderful huge crystals of Na2SO4 without you having to do anything.
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cheggin the experiment to determine which mechanism was used by restriction endonucleases, what evidence ruled out the formation of a covalent intermediate?
The covalent phosphodiester bonds of DNA are hydrolyzed by restriction enzymes, leaving either "sticky/cohesive" ends or "blunt" ends.
By incubating the target DNA molecule with restriction enzymes, which detect and bind certain DNA sequences and cleave at specified nucleotides either inside or outside of the recognition sequence, restriction digestion is carried out.
An isolated bacterial protein known as a restriction enzyme cleaves DNA at sequence-specific locations to create DNA fragments with a known sequence at either end. Restrictions enzymes are crucial for numerous laboratory processes, including recombinant DNA technology and genetic engineering.
At the particular restriction site, DNA bonds between the 3′ OH of one nucleotide and the 5′ phosphate of the following one are cleaved by restriction enzymes.
In order to prevent the plasmid vector from ligating with itself and to verify that the inserted gene is oriented correctly, two separate restriction enzyme sites might be used.
A) #1 5′ - CGTGATCTCGATTCGCTAGTAACGTT - 3′
3′ - GCACTAGAGCTAAGCGATCATTGCAA - 5′
#2 5′ - TCATGAATTCCTGGAATCAGCAAATGCA - 3′
3′ - AGTACTTAAGGACCTTAGTCGTTTACGT - 5′
B) Recognition sites:
#1 5′ - GAATTC - 3′
3′ - CTTAAG - 5′
#2 5′ - GAATTC - 3′
3′ - CTTAAG - 5′
C) Cleavage sites:
#1 5′ - G AATTC - 3′
3′ - CTTAA G - 5′
#2 5′ - G AATTC - 3′
3′ - CTTAA G - 5′
The correct and complete question is in the image.
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Help, how to solve? - The question underneath, why is it Option C (4.8*10^23 ions) and not option B (1.2*10^23 ions). How do we solve and approach the question?
Option C (4.8 × 10²³ ions) is correct not option B (1.2 × 10²³ ions) as one molecule of (NH₄)₃PO₄ contains four ions, three NH₄⁺, and one PO₄⁻³.
To calculate ions, first, we have to calculate number of molecules of (NH₄)₃PO₄ in 0.20 moles.
To calculate number of molecules, the number is moles is multiplied by Avogadro number (6 × 10²³).
So, the number of molecules of (NH₄)₃PO₄ in 0.20 moles is,
Number of molecules = 0.20 × 6 ×10²³ = 1.2 × 10²³
One molecule of (NH₄)₃PO₄ contains three ions of NH₄⁺, and one ion of PO₄⁻³. So, number of ions in 0.20 moles of (NH₄)₃PO₄ are
Number of ions = 4 × 1.2 × 10²³ =4.8 × 10²³
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What scientific principle do bulletproof vests worn by law enforcement officers best illustrate when they protect personnel from impact injury in the line of duty?
Answer:
Ballistic vests use layers of very strong fibers to "catch" and deform a bullet, mushrooming it into a dish shape, and spreading its force over a larger portion of the vest fiber. The vest absorbs the energy from the deforming bullet, bringing it to a stop before it can completely penetrate the textile matrix.
In a parallel circuit with identical light bulbs, which of these is true?
A
A battery is not the source of voltage.
B
There is only one resistor, such as a light bulb.
C
The circuit is left open so that current cannot flow.
D
Adding more identical light bulbs will not change their brightness.
In a parallel circuit with identical light bulbs, the true statement is option D Adding more identical light bulbs will not change their brightness.
Two bulbs in a simple parallel circuit every experience the overall voltage of the battery. that is why the bulbs in the parallel circuit might be brighter than the ones within the series circuit. some other gain to the parallel circuit is that if one loop is disconnected, then the other stays powered.
While batteries are connected in parallel, the voltage remains the same, but the contemporary which could float in the circuit will increase. when bulbs have equal power, then their resistance is likewise the same. while the 2d bulb connected in parallel to the first bulb is switched on, the effective resistance of the circuit turns into half of, and the present-day circuit becomes double. due to it, this double modern-day divides itself equally into bulbs.
The voltage across every resistor inside a parallel aggregate is precisely equal however the currents flowing through them are not the same as that is determined by their resistance fee and Ohms regulation.
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how to identify oxides that don't dissolve in water?
Answer: The oxides of hard metal or the transition metals oxides like oxides of copper, zinc, iron, and chromium do not dissolve in water due to their limited basicity. Alkaline earth metal oxides also form hydroxides in water but these hydroxides themselves give slaked solutions and are not completely soluble.
Explanation: The oxides of hard metal or the transition metals oxides like oxides of copper, zinc, iron, and chromium do not dissolve in water due to their limited basicity. Alkaline earth metal oxides also form hydroxides in water but these hydroxides themselves give slaked solutions and are not completely soluble.
This long unit of measurement can be used to measure great distances. It *
is equal to 1000 meters.
Omillimeter
O centimeter
O meter
O kilometer
Odecimeter
1. using your titration data, calculate the %na2co3 for each trial, the average %na2co3 and standard deviation. 2. describe how to obtain a second derivative plot. 3. why is potentiometry used to detect the endpoints for this titration? could color indicators have been used?
Simply subtract the differences in the first derivative values from the differences in the midpoint volumes to obtain the second derivative, and then plot this value at the intersection of the two midpoint volumes.
Potentiometric titration is a laboratory method to determine the concentration of a given analyte.
Na2CO3 and NaHCO3 concentration in a mixture can be determined by accurately weighing 2.0 g of the mixture and making a distilled water solution in a 250 ml standard flask. Use phenolphthalein as an indicator while you gradually titrate 25 ml of this solution against regular hydrochloric acid. To concord, repeat (Vp ml).
In order to locate the equivalency more precisely, a second derivative plot is also generated. point—where the extrapolated line intersects the x-axis (graph 4). A highly precise value for the volume of titrant can be acquired because the x-axis indicates the volume of titrant utilized.
Potentiometric titration is one of the chemical methods of analysis, and it involves adding a titrant with a known concentration and measuring the endpoint of the titration with an indicator electrode that records the change in potential as a function of the amount (often the volume) added.
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What is the lithosphere? ) (25 pts)
What is the speed of a car that travels 45 miles in 45 minutes? Answer in miles per hour.
Answer:60 miles in one hour
Explanation:
Describe these three experiments which have been used to support the atomic theory: Cathode Ray Tube, Gold Foil Experiment, and Atomic Emission Spectra.
The atomic theory developed along the experiments of the Cathode Ray Tube, Gold Foil and Atomic Emission Spectra.
What is the atomic theory?The term atomic theory has to do with the arrangement of the particles that compose the atom. Let us look at the development of the atomic theory chronologically.
Cathode Ray Tube - In the cathode ray tube, J.J Thompson was able to pass an electric discharge through the tube and a color was observed that corresponds to the gas in the tube.
Gold foil experiment - Here, thin gold foils were bombarded with alpha particles and the movement of the alpha particles were tracked.
Atomic emission spectra - Here, electrons were excited to different wavelengths and the corresponding spectra was observed.
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Which of the following samples can be considered as a concentrated
solution of Povidone Iodine, an antiseptic for minor wounds ?
A. 3 drops of Povidone Iodine dissolved in 100 ml of water.
B. 5 drops of Povidone Iodine dissolved in 100 ml of water.
C. 10 drops of Povidone Iodine dissolved in 100 ml of water.
D. 50 drops of Povidone Iodine dissolved in 100 ml of water.
The sample that should be considered concentrated solution of Povidone Iodine is 50 drops of Povidone Iodine dissolved in 100 ml of water. That is option D
What is a concentrated solution?A concentrated solution is defined as the type of solution that contains more dissolved solute with less solvent when compared with other solutions.
A solute is defined as the part of a solution that dissolves in a solvent while the solvent is part of the solution that is the dissolving medium.
From the options listed, the most concentrated solution is the solution that contains more of the povidone iodine which is 50 drops of Povidone Iodine dissolved in 100 ml of water.
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Here is my question on Electron Configurations. There are 5 parts: a to e.
Answer:
too lendi to answer the question
What is the volume of 2.00 moles of an unknown gas at STP?
O2.00 L
0 11.2L
0 44.8L
O 22.4L
If [H+] = 1.0 x 10-11 M, what is the pH of the solution?
Answer:
use the pH equation :
pH: -log [H+]
pH: -log 1×10^-11
pH: 11.00
the pH of the solution is 11.00 and the solution is basic.
and make sure to remember :pH does not have a value .
a solution merely has pH(11.00)
Look at the two waves shown. What is the speed of each wave?
The speed of all electromagnetic waves is equal to the speed of light that is 3 × 10⁸ m/s.
What is an electromagnetic wave?An electromagnetic wave is a wave of certain wavelength of an electromagnetic radiation of the electromagnetic spectrum. There are different types of waves in the spectrum like IR, radio waves etc.
The speed of c of the wave is the product of its frequency and wavelength. The speed of all electromagnetic waves are equal to the speed of visible light.
Hence, the speed of both waves is 3 × 10⁸ m/s.
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Why are race cars and bicycles made of lightweight materials?
What mass of HCI is needed to
generate 45.2 g of AICI3?
2AI + 6HCI → 2AlCl3 + 3H₂
AICI3: 133.33 g/mol
HCI: 36.46 g/mol
Answer:
37.1g of HCl
Explanation:
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a hydrogen atom emits a photon. you are given the wavelength of the photon. what sign will the energy of the photon be calculated as?
The energy of the photon to will be calculated by using E=hv.
Photons are fundamental subatomic particles that carry electromagnetic force — or, to put it another way, they are light particles. The energy of a photon is calculated by determining the wavelength of the photon. To do this, we need to know the frequency of the light and its speed in a vacuum.
A hydrogen atom emits a photon with a frequency of about 6.6x1014 Hz and a speed in a vacuum of 3.0x108 m/s.
The value for E = hν is:
E = hν
= Planck's Constant × Frequency × Wavelength
= hc/(2π×frequency × wavelength)
The unit of energy is given by Joules(J).
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why do you like homo and heterogen mixtures?
Homogeneous are hard to seperate but heterogeneous are easy to seperate.
What role does heterogeneous mixture have in daily life?Every day, humans employ heterogeneous mixes that can be found all around them. Particles in heterogeneous mixtures can be recognized after mixing and still maintain their chemical characteristics. Filtration and chemical processes can be used to separate the components of heterogeneous mixes.
All substances exist in one state of matter, which is a homogenous mixture. Solids can combine uniformly with other solids, liquids can combine with other liquids, and so on.
On the other hand, a heterogeneous mixture (derived from the Greek word "hetero" for dissimilar) has a non-uniform composition, which means that different parts may contain more or less of a given component. A heterogeneous mixture allows for the simultaneous existence of solid, liquid, and gas phases as well as other states of matter.
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A river flows at a rate of 57.3m/sec, what is the rate when it is converted to km/day? Please answer fast!!!