The answer would be 25% remains left i.e., a radioactive substance has a half life of 5000 years, if the original sample contained 20 grams of the radioactive isotope, 25% will remains after 5000 years elapsed.
In this question (t1/2) is 5000 years , which refers that after 5000 years is half of the sample would have decayed and half would be left as it is.
Given , 20 g sample .
After 5000 years ( first half life) 20/2 = 10 g decays and 10 g remains left.
Two half lives or 5000 years 10 /2 = 5 g decays and 2.5 g remains left .
so we started with 20 g and after 5000 years 5 g of the sample will be left not decayed.
Percentage of sample left = mass of sample left x 100 / original mass of sample
Percentage of sample left = 5 g x 100 / 20g = 25 %
In conclusion, 25% remains after 5000 years have elapsed.
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a compound contains only c, h, and n. combustion of 35.0 mg of the compound produces 53.0 mg co2 and 32.6 mg h2o. what is the empirical formula of the compound?
Consequently, the compound and empirical formula will be:
Methanediamine, CH₃N.
How to determine the mass of Carbon
Mass of CO₂ = 53 mg
Molar mass of CO₂ = 44 g/mol
Molar of C = 12 g/mol
Mass of C =?
Mass of C = (12 / 44) × 53
Mass of C = 14.45 mg
How to determine the mass of H
Mass of H₂O = 32.6 mg
Molar mass of H₂O = 18 g/mol
Molar of H = 2 × 1 = 2 g/mol
Mass of H =?
Mass of H = (2 / 18) × 32.6
Mass of H = 3.62 mg
How to determine the mass of N
Mass of compound = 35 mg
Mass of C = 14.45 mg
Mass of H = 3.62 mg
Mass of N =?
Mass of N = (mass of compound) – (mass of C + mass of H)
Mass of N = 35 – (14.45 + 3.62)
Mass of N = 16.93 mg
How to determine the empirical formula
C = 14.45 mg
H = 3.62 mg
N = 16.93 mg
Empirical formula =?
Divide by their molar mass
C = 14.45 / 12 = 1.204
H = 3.62 / 1 = 3.62
N = 16.93 / 14 = 1.209
Divide by the smallest
C = 1.204 / 1.204 = 1
H = 3.62 / 1.204 = 3
N = 1.209 / 1.204 = 1
Thus, the empirical formula of the compound is CH₃N
What is empirical formula?An empirical formula is a compound's chemical formula that only specifies the ratios of the elements it contains and not the precise number or arrangement of atoms. The element in the compound with the lowest whole number ratio would be this one.
An empirical formula is used to indicate the simplest whole-number ratio of the various atoms in a molecule.
The precise number of various atom types present in a compound's molecule is indicated by the molecular formula.
Empirical formulae are beneficial since figuring out the molecular formula can be immensely aided by knowing the relative amounts of each constituent in a molecule.
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describe how private citizens have a voice in which projects the federal government will fund.
Explanation:
Two main ways, free elections, casting your vote for the candidate supporting your goals. Second, Lobbying the sitting gov.
Somebody pls help with theses questions??
3. Environmental chemistry
4. Biochemistry
5. Inorganic Chemistry
6. Organic chemistry
james chadwick discovered this particle, which was the last of the subatomic particles to be characterized.
James chadwick discovered this particle neutron also neutrino called as is last of the subatomic particles to be characterized.
In 1932 james chadwick announced that the core also contained a new uncharged particle, which he called the neutron. neutron is also called neutrino he proved the existence of neutrons elementary particles devoid of any electrical charge. james chadwick was an English physicist who was awarded the 1935 Nobel prize in physics for his discovery of the neutron in 1932.
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Which two phase transitions can liquid undergo? (2 answers)
A. melting
B. depostion
C. vaporization
D. freezing
E. sublimation
general chemistry fourth edition by mcquarrie, rock, and gallogly. university science books presented by macmillan learning. caffeine is the active ingredient in coffee, tea, and some carbonated beverages. add lone pairs, as needed, to the structure of caffeine. indicate the hybridization of the specified atoms. be sure to consider any lone pairs you added in the first part.
In the bicyclic structure of caffeine, two rings—one a six-membered ring and the other a five-membered ring—are fused together. Nitrogen, carbon, hydrogen, and oxygen are all components of the molecule.
What is carbonated beverages ?Drinks that have had carbon dioxide added to them are referred to as carbonated beverages. Carbon dioxide lacks both flavour and colour. Carbonated beverages often start with either carbonated water or soda water, both of which qualify as carbonated beverages in and of themselves.
Six valence electrons make up an oxygen atom, of which two are required to form bonds and the remaining four are found in lone pairs. Similar to oxygen, nitrogen possesses five valence electrons, three of which are employed to form bonds while the remaining two are present as a lone pair.
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If the solutions of nabr and hg(no3)2 are mixed, how many precipitation reactions will there be?
If the solutions of NaBr and Hg(NO₃)₂ are mixed, there will be one precipitation reaction.
What is a Precipitation Reaction?When dissolved substances react, one (or more) solid products are created, which is termed a precipitation reaction. These kinds of reactions, which are also occasionally known as double displacement, double replacement, or metathesis reactions, frequently involve the exchange of ions between ionic compounds in aqueous solutions.The development of a solid form residue known as the precipitate occurs during precipitation reactions, which are typically double displacement processes.Additionally, when two or more solutions containing various salts are mixed, these reactions take place, resulting in the creation of insoluble salts that precipitate out of the solution.The precipitation reaction of the given reaction is
NaBr + Hg(NO₃)₂ ⇒ HgBr₂ + NaNO₃.
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Ignoring the sign, which has a greater magnitude of charge?
A.) Electron
B.) Proton
C.) They have equal charges
D.) Not enough information
Answer:
C.) They both have equal charges.
Explanation:
Ignoring the signs, both a proton and electron have a charge of 1.
A proton has a greater magnitude of charge than an electron.
Both protons and electrons have charges, but the magnitudes of their charges are different. A proton carries a positive charge of +1 elementary charge, while an electron carries a negative charge of -1 elementary charge. The elementary charge is the fundamental unit of electric charge. Despite the opposite signs of their charges, the magnitudes are equal, and both charges have the same strength.
Therefore, when ignoring the sign of the charges and considering only their magnitudes, a proton has a greater magnitude of charge compared to an electron. The magnitude of the proton's charge is equal to that of the electron's charge. This is a fundamental property in the realm of electric charges, and it plays a critical role in various physical and chemical interactions, including the behavior of atoms, molecules, and electromagnetic forces.
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The moon diameter is about one quarter the diameter of the earth. If
Answer:
The Moon has a diameter of 2,159 miles (3,476 kilometers) and is about one-quarter the size of Earth. The Moon weighs about 80 times less than Earth.
Explanation:
Lauryn serves a volleyball with a mass of 2.1 kg. The ball leaves her hand with a speed of 30 m/s. Find the energy of the ball.
Answer: 1/2 X 2.1 kg X 30m/s^2 = 945 Joules
Explanation:
Some help me with this chem question
Answer:
C
Explanation:
because it is the only one that will give you an accurate answer.
arrange the following amines in order of decreasing water solubility, putting the most soluble amine first.
Amines in order of decreasing water solubility, putting the most soluble amine first is 2, 1, 3.
What is the solubility of amine in water?
Hydrogen bonding between water molecules and lower aliphatic amines are possible. These amines are therefore water soluble.
The molar mass of amines increases with an increase in the size of the hydrophobic alkyl component. Its solubility in water is often reduced as a result. Higher amines cannot be dissolved in water. Alcohol, benzene, and ether are examples of organic solvents that easily dissolve amines.
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round off the following numbers to three significant figures.
1.) 4325
2.) 7.8939
Answer:
1) 433 (check screenshot)
2) 7.89
based on the graph witch data point is most likey to have experimental error?
what is the percent by weight (w/w%) of sugar in soda? assume the average mass of sugar in soda is 35.0 g and the total mass is 370.0 g.
The percent by weight (w/w%) of sugar in soda : 9.459 %
To find the percentage the given data's are:
mass of sugar = 35 g
total mass = 370 g
What is the percent weight?Percent by weight is also known as Mass percent composition.It is abbreviated as w/w%. For a solution, mass percent equals the mass of an element in one mole of the compound divided by the molar mass of the compound, multiplied by 100%.Solution for the given values are,
%weight = (mass of solute : mass of solution) x 100%
Mass of solute = Mass of sugar = 35 grams
Mass of solution = Mass of ( solvent + solute) = water + sugar = 370 grams
The percent weight of sugar in soda :
= (35 : 370) x 100%
= 0.0945945
= 9.459 %
Therefore, the percent by weight (w/w%) of sugar in soda : 9.459 %
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write and explain ten careers opportunity in chemistry
Chemistry careers range in nature, pay, and educational requirements;
Chemical analyst
An analytical chemist analyses the composition and quantity of substances as well as how these elements may behave and interact with one another.
Which nation offers the finest jobs in chemistry?Germany is the #1 destination for chemistry students looking to study abroad since it is known for its accommodating attitude toward foreign students. Due to Germany's dominance in Europe's chemical industry, several institutions there offer specialised courses designed for graduates who want to get into the workforce.
MSc. which the industries desire. For their senior scientist positions, most firms demand Ph.D. and post-doctoral fellows.
Engineer, Chemical
Designing and creating new goods from raw materials and changing materials' states are specialties.
as in the production of plastic from oil. Chemical engineers may work in practically any business, helping to create cutting-edge, high-end goods like biocompatible implants and ultra-strong materials.
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The density of steel is about 8.0g/cm³ and the density of water is 1.0 g/cm³ . If the mass of steel used for the ship is 50,000 kg, what would the volume need to be for the ship to float on water?
In order for the ship to float, the volume of the ship must be equal to or greater than 50,000,000 cm³.
What would be the volume of the ship in order for it to float on water?According to the principle of floatation, a body will float in a liquid if it displaces a weight of liquid equal to its own weight.
Therefore, for the ship to float in water, it must displace a weight of water at least equal or greater than its own weight.
Considering the data given:
The density of steel = 8.0g/cm³
the density of water is 1.0 g/cm³
the mass of steel used for the ship = 50,000 kg
Based on the principle of floatation, mass of water to be displaced is equal to the mass of the ship.
Mass of water to be displaced = 50000 kg
Mass of water to be displaced in g = 50,000,000 g
Volume of 50000000 g of water = 50,000,000 g * 1.0 g/cm³
Volume of 50000000 g of water = 50,000,000 cm³
Therefore, volume of the ship must be equal to or greater than 50,000,000 cm³ for the ship to float.
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Which is a chemical property that was used to separate your mixture
during the lab?
Solubility
Evaporation
Filtering
None of the above. Mixtures are separated through physical means.
None of the above.
Since none of the given option is a chemical property, rather all of them are physical method of separation and physical methods do not require a chemical change.
Solubility- It is a physical property because it is easily discernible through observation and does not alter the substance's chemical makeup. For instance, salt is still salt when it dissolves in water.
Evaporation - The chemical composition of a liquid does not change when it evaporates. The only alteration is a phase shift brought on by pressure and temperature. Evaporation, or the phase transition from liquid to gas, is a physical change as a result.
Filtration - Filtration is a physical separation procedure that uses a filter medium with a complicated structure that only allows fluid to pass through it to separate solid particles and liquid from a combination.
Therefore, neither new nor broken chemical bonds are created or broken during the separation. During the separation, bonds are severed or strengthened.
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which of the following statements are true about the properties of both molecular and ionic compounds? select all that apply.
They are neutrally charged
They typically do not conduct electricity in solid state
Molecular compounds are formed when elements share electrons in a covalent bond to form molecules.Ionic compounds are formed by the strong electrostatic interactions between the ions.Ionic compounds have high boiling and meltin point and electrical conductivity than covalent compounds.Eventhough,the molecular compounds and ionic compounds have some similarities in their properties.They both are electrically neutral.The molecules formed due to both molecular and ionic compound are electrically neutral.In ionic bonding,the two charges join and cancel each other out,and in covalent bonding,two electrically neutral components come together.So,both the compounds are electrically neutral.Ionic compounds conducts electricity in aqueous or molten solution,it is because of their ions are very free to move.Ionic compounds do not conduct electricity in solid state.Molecular or covalent compounds do not conduct electricity either in pure form or when dissolved in water.Molecular compounds do not conduct electricity because they do not transfer electrons unless they reacts.To know more about molecular compounds visit : https://brainly.com/question/23088724
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Why is the petroleum ether placed in an ice water bath prior to washing the product on the filter?
Before washing the substance on the filter, petroleum ether is poured into an ice water bath to assist stop the product from dissolving.
Re-crystallization procedures only work based on the solubility properties of the compound of interest. The re-crystallization experiment cannot be performed using a solvent if the compound of interest is not soluble in it. For example, if I chose petroleum ether as my solvent instead of water, my recrystallization experiment will not work because acetanilide is not at all soluble in petroleum ether. In order for my recrystallization experiment to be successful, I need an efficient solvent for acetanilide. Acetanilide should only be dissolved by this solvent at temperatures above room temperature. Additionally, my solvent for acetanilide should be soluble for the impurities species at all temperatures. Since petroleum ether does not meet these requirements, the experiment will not be successful with petroleum ether.
Petroleum ether may not react with the product on the filter, however, the majority of organic molecules are generally non-polar and soluble in petroleum ether. Temperature lowers solubility Petroleum ether is cooled in an ice water bath to stop the product from dissolving in the solvent.
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you use 25% ethyl acetate (an ester) in hexane to run a tlc and obtain a single round spot with an rf of 0.9 for the main compound. what would you do?
Try 25% ethyl acetate to see the results, this is because adding more ethyl acetate will increase the polarity and the compounds get easily separated.
In TLC, the polarity between the stationary phase and mobile phase is the basis for mixture separation. In accordance with the "like dissolves like" principle, polar substances can only dissolve in other polar substances, while non-polar substances may only dissolve in other non-polar substances.
Consequently, when two compounds with different levels of polarity are present, the more polar molecule interacts with silica more strongly and is, therefore, better able to displace the mobile phase from the accessible binding sites. The less polar compound thus travels higher up the plate (resulting in a higher Rf value).
However, changing the mobile phase to a more polar solvent or a mixture of solvents improves binding to the polar plate and thereby displaces solutes from it, causing all compounds on the TLC plate to rise higher up the plate. It is a prevalent belief that although "weak" eluents hardly move the examined compounds, "strong" eluents drive them up the plate.
Therefore, all compounds move longer and have a larger Rf when a mobile phase is made more polar than it was originally.
Since hexane has a non-polar property while ethyl acetate has a polar property. As a result, adding 35% ethyl acetate will enhance the polarity, making it easier to separate the compounds.
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Sf3 , has a tetrahedral electron-pair geometry and a trigonal-pyramidal molecular geometry. the hybridization of the central sulfur atom is ________.
Sf3 , has a tetrahedral electron-pair geometry and a trigonal-pyramidal molecular geometry. the hybridization of the central sulfur atom is 5.
What do you mean by hybridization?Hybridization in Chemistry is defined as concept of mixing two atomic orbitals to give rise to a new type of hybridized orbitals. This intermixing usually results in formation of hybrid orbitals having entirely different energies, shapes, etc. The atomic orbitals of same energy level mainly take part in hybridization. However, both the fully filled and half-filled orbitals can also take part in this process, provided they have equal energy.
On the other hand, we can say that concept of hybridization is an extension of the valence bond theory and it helps us to understand the formation of bonds, bond energies and bond lengths.
Redistribution of energy of orbitals of individual atoms to give orbitals of equivalent energy happens when two atomic orbitals combine to form a hybrid orbital in a molecule. This process is called hybridization. During process of hybridization, atomic orbitals of comparable energies are mixed together and mostly involves the merging of two ‘s’ orbitals or two ‘p’ orbitals or mixing of an ‘s’ orbital with a ‘p’ orbital as well as ‘s’ orbital with a ‘d’ orbital. The new orbitals thus formed are known as the hybrid orbitals. More significantly, hybrid orbitals are quite useful in the explaining atomic bonding properties and molecular geometry.
Here is a formula to find the hybridization:
(V+M-C+A)/2
(6+3–0+1)/2 = 5
Hybridization: sp3d
Geometry: Trigonal Bipyramidal
Shape: T-shaped
V is the valence electrons of the central atom.
M is the number of monovalent atom (which makes single bond with central atom).
C and A are number of the cation and the anion.
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According to the kinetic molecular theory, where does the pressure exerted by a gas in a container come from?
collisions between the gas particles and the walls of the container.
What is kinetic molecular theory?
The assumption that matter is made up of microscopic particles that are always in motion forms the foundation of the kinetic-molecular theory, which explains the states of matter. The observable characteristics and behaviours of solids, liquids, and gases are explained by this theory. We can better comprehend why matter exists in different stages (such as solid, liquid, and gas) and how it can transition from one stage to another thanks to the kinetic theory of matter. One may also think about various properties of matter using the kinetic theory of matter.
Therefore,
According to the kinetic molecular theory, where does the pressure exerted by a gas in a container come from collisions between the gas particles and the walls of the container.
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What discoveries were made by j. j. thomson, henri becquerel, and lord rutherford? how did dalton's model of the atom have to be modified to account for these discoveries?
Discoveries were made by j. j. thomson, henri becquerel, and lord rutherford.
What is Dalton's atomic model?
John Dalton, an English physicist and chemist, proposed the atomic hypothesis in 1808 as a scientific theory about the composition of matter. It claimed that tiny, indivisible particles called "atoms" make up all substance.
Almost all of chemistry at the time could be explained by Dalton's atomic model, a relatively straightforward combinatorial concept that paved the way for later advancements and advances in this and many other scientific domains. Postulates of the Dalton Model
Modern atomic theory and the discovery of the electron and proton were made possible by Thomson's cathode ray discharge experiment and Rutherford's scattering experiment.
Dalton's concept was groundbreaking at the time and provided a wealth of information for young chemists to study. Many people contributed to the modification of the Atomic theory following Dalton, including Chadwick, JJ Thompson, Ernest Rutherford, Niels Bohr, and others. Later, Rutherford worked on the model to find the nucleus while JJ Thompson made the electron discovery.
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Consider two samples of water of equal mass; one that is at 20. 0 °c and the other is at 30. 0 °c. Please compare the volume of these two water samples, and explain how you determined this conclusion.
The volume of water at 30°C will be more than the volume of water at 20 °C because of the property of thermal expansion.
We generally observe that objects around us expand on heating.
Expansion due to heating is known as thermal expansion. It is of the following 3 types-
Increase in Length - Linear ExpansionIncrease in Area - Area ExpansionIncrease in Volume - Volume ExpansionWhen a liquid like water is heated from a lower temperature to a higher temperature its volume expands which means that it undergoes volume expansion.
Thus, The volume of water at 30°C will be more than the volume of water at 20°C because of the property of thermal expansion.
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Calculate the maximum concentration (in m) of silver ions (ag ) in a solution that contains of co32-. the ksp of ag2co3 is
Acetylcholinesterase equilibrium equation is Ag2CO3(s) <---> 2 Ag+(aq) + CO32-(aq)
What is Acetylcholinesterase ?Following the transmission of information between two nerve cells or neurons, the neurotransmitter acetylcholine is hydrolyzed by the enzyme acetylcholine esterase. Choline and acetate result from the breakdown of acetylcholine (also called acetic acid). Acetate will permeate the presynaptic cell's membrane and choline will travel through it to allow for the reuse of the components.
In order for a muscle cell to contract, acetylcholine transmits a signal from a nerve cell to its receptors. A breakdown of the acetylcholine is then performed to prevent misunderstanding with brand-new neurotransmitters.
Due to their potent acetylcholinesterase inhibitory properties (see parasympathomimetic), many nerve agents and neurotoxins have the ability to constantly induce the contraction of muscle cells. This can cause death when consumed in big numbers.
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What is the concentration of bromide ion in a 25.0 ml sample of water if the addition of excess silver nitrate results in the precipitation of 361 mg silver bromide (fm = 187.777)?
The concentration or Molarity of bromide ion in the sample solution is 0.077 M.
What is molarity ?A substance's molarity (M) is the volume of solution in which it is present. The amount of a solute in moles per liter of a solution is known as molarity. A solution's molar concentration is another name for molarity.The secret to determining molarity is to keep in mind that it is measured in moles per liter (M).Molarity is determined by:Count the moles of solute dissolved in the solution.Calculate the solution's volume in liters, and.Divide liters of solution by moles of the solute.In the given question,
0.361 g AgBr × (1 mol AgBr/187.77 g AgBr) × (1 mol Br⁻/1 mol AgBr) × (80.0 g Br⁻/1 mol Br⁻) = 0.1536 g Br⁻
0.1536 × (1 mol Br⁻/80.0 g Br⁻) = 0.00192 mol
Molarity = 0.00192 mol/0.025 L = 0.077 M
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6. Makes sure that oxygen is absorbed into
the blood.
a. Circulatory System
b. Digestive System
c. Respiratory System
d. Excretory System
A water skier has a mass of 79 kg and accelerates at 1.4 m/s/s what is the net force acting on him ?
The net force acting on water skier is 110.6N.
Equation :To find net force on a water skier we can use the formula,
net force = mass x acceleration
F = m x a
Given in equation,
F = ?
m = 79 kg
a = 1.4 m/s²
Putting the values,
F = 79 kg x 1.4 m/s²
F = 110.6N
Net Force :The overall forces acting on an object is known as the net force. A mass can accelerate due to net force. A body is subject to another force whether it is at rest or in motion. When there are a lot of forces acting on a system, the term "net force" is used.
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Manganese is composed of two stable isotopes: Mn-54 and Mn-57. Use the periodic table
and predict which of these isotopes is more abundant. Explain your prediction.
Why is the mass in amu of a carbon atom reported as 12.011 in the periodic table of the
elements?
The more abundant isotope of manganese is Mn-54 because the average atomic mass of manganese is 54.938 amu.
What are isotopes?The term isotopes refers to the fact that atoms of an element are not exactly alike. The atoms of an element has the same atomic number (which is the signature of the element) but not the same mass number. The mass number of the element has to do with the number of neutrons.
Now we know that the atomic mass of elements is not a whole number because of the existence of isotopes. The relative atomic masses is obtained as the sum of the products of the atomic mass and the relative abundance of each isotope.
The more abundant isotope of manganese is Mn-54 because the average atomic mass of manganese is 54.938 amu.
The reason why the relative atomic mass of the carbon atom is 12.011 in the periodic table of the elements is because this is the weighted average of the masses of all the isotopes of carbon,
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