Answer: exchange both energy and matter with its surroundings.
Explanation:
An open system can exchange both energy and matter with its surroundings. The stovetop example would be an open system, because heat and water vapor can be lost to the air. A closed system, on the other hand, can exchange only energy with its surroundings, not matter.
Why does the rate of most reactions decrease over time?
A decrease in reactant concentration reduces the frequency of successful collisions.
A decrease in temperature reduces the average kinetic energy of the particles.
An increase in product concentration interferes with the effectiveness of the catalyst.
An increase in pressure of the system reduces the movement and energy of particles.
Answer:
A decrease in reactant concentration reduces the frequency of successful collisions.
Explanation:
The rate of any chemical reaction is the change in the concentration of the reactants with time.Rate = - d[Reactants]/d(time).
Also, the rate of a chemical reaction can be given by:Rate = k[Reactants]ˣ,
where, k is the rate constant of the reaction.
x is the no. of moles that the rate of the reaction depends on.
So, it is clear that the rate of the reaction is directly proportional to the concentration of the reactants.
The concentration of the reactants is at its maximum value at the time of the start of the reaction "mix up", so, the rate of the reaction is maximum at the start of the reaction.So, the rate of most reactions decrease over time due to there is a decrease in the concentration of the reactants with time and so, the chance for collision of the reactants decrease.So, the right choice is:
A decrease in reactant concentration reduces the frequency of successful collisions.
What is the solution to the problem expressed to the correct number of significant figures? (102,900 ÷ 12) + (170 × 1.27) = ? A. 8,790 B. 8,790.9 C. 8,791 D. 8,800
Answer:
The correct answer is option B.
Explanation:
Significant figures : The figures in a number which express the value -the magnitude of a quantity to a specific degree of accuracy is known as significant digits.
(102,900 ÷ 12) + (170 × 1.27)
= (8575)+ (215.9)
= 8790.9
There are 5 significant figures in 8790.9 which are ,'8','7','9','0' and '9'.
To solve the problem expressed to the correct number of significant figures, follow the rules for addition/subtraction and multiplication/division of significant figures.
Explanation:To solve the problem expressed to the correct number of significant figures, we need to follow the rules for significant figures:
Addition or subtraction: The final answer should have the same number of decimal places as the number with the fewest decimal places. In this case, (102,900 ÷ 12) has no decimal places and (170 × 1.27) has two decimal places. Therefore, the final answer should have two decimal places.Multiplication or division: The final answer should have the same number of significant figures as the number with the fewest significant figures. In this case, (102,900 ÷ 12) has five significant figures and (170 × 1.27) has three significant figures. Therefore, the final answer should have three significant figures.Using these rules, the solution to the problem expressed to the correct number of significant figures is 8,791 (option C).
The part of the electromagnetic spectrum that is necessary for the sense of sight in humans is__________
1.radio waves
2.gamma rays
3.infrared light
4.ultraviolet light
5.visible light
Answer:
visible light
Explanation:
Answer:
c
Explanation:
Generally, observed behavior that can be formulated into a statement, sometimes mathematical in nature, is called a(n):
A. observation.
B. measurement.
C. theory.
D. natural law.
E. experiment.
Answer:
Generally, observed behavior that can be formulated into a statement, sometimes mathematical in nature, is called a natural law- D.
The laws are universally accepted scientific statement and are not replaced and they are not explanations. A law can be a mathematical expression also. Hence, option D is correct.
What is a scientific law?Scientific laws are simple statements or mathematical expressions which describes what the nature does under certain conditions. Laws are very precise as well concise and they have to be universally accepted. Law are not replaceable.
Theories are scientific explanations that describes how nature goes. They can help predict future events as well. Theories are falsifiable and can be replaced.
Laws must be in harmony with other scientific laws and must not adhere to exceptions under favorable conditions. Unlike theories, Laws are concise statement or simply a mathematical expression.
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What is atom economy?
Answer:
The conversion efficiency of a chemical process.
Explanation:
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All matter in the Universe consists of many substances called elements.
True
False
All matter is composed of atoms that have specific properties and cannot be subdivided.
Explanation:All matter is composed of extremely small particles called atoms. Atoms of a given element are identical in size, mass, and other properties. Atoms of different elements differ in size, mass, and other properties. Atoms cannot be subdivided, created, or destroyed.
Atomic Composition
The concept that all matter is composed of atoms was first proposed by the ancient Greek philosopher Democritus around 400 BCE. He suggested that these atoms were indivisible and indestructible. However, it was not until the early 20th century that experimental evidence confirmed the existence of atoms as the fundamental units of matter.
Subatomic Particles
Protons, neutrons, and electrons are the three primary subatomic particles that constitute an atom. Protons carry a positive charge, neutrons have no charge (they are neutral), and electrons carry a negative charge. The number of protons in an atom determines its atomic number, which in turn defines the element’s identity. Neutrons contribute to the mass of the atom, while electrons are involved in chemical bonding and determining the atom’s reactivity.
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Arrange the elements TELLURIUM, RUBIDIUM, POTASSIUM & BROMINE in order of increasing second energy (IE2) and in decreasing atomic size.
Answer:
IE2: Te < Br < Rb < K
Atomic size: Rb > K > Te > Br
Explanation:
2nd Ionization energy
Ions with only one valence electron (K and Rb) should have the highest second ionization energies. Once the first electron has been removed, the next one would have to come from a filled valence shell.
Atoms lower down in the Periodic Table should have lower ionization energies, because their valence electrons are further from the nucleus and are less tightly held.
Br and Te each have a nearly complete subshell, so both electrons can come from the same level. Te is further down the Periodic Table, so Te < Br
The order of second ionization energies is Te < Br < Rb < K.
Atomic Size
Atomic size increases from right to left and from top to bottom of the Periodic Table. Thus, the biggest atoms are at the lower left and the smallest atoms are at the upper left.
Rb: Left of Row 5. ∴ Biggest atom.
Te: Right of Row 5. ∴ Rb > Te. Also, Br is in Row 4, so Te > Br
K: Left of Row 4. ∴ Rb > K
Br: Right of Row 4 ∴ K > Br
So far, we have Rb > K and K > Br, so Rb > K > Br .
We also have Rb > Te and Te > Br, but is Te > K or is K > Te?
In going from K to Te, the effect of adding 33 more protons to the nucleus outweighs the effect of adding one more shell, so K > Te.
The final order is Rb > K > Te > Br.
Adam wants to work in the field of forensic science and follow the rules for handling evidence. Which organization can he join to fulfill this aspiration?
International Academy of Forensic Science
National Academy of Sciences
National Academy of Forensic Science
National Science Academy
Answer:
I would say its c . National Academy of Forensic Science
Explanation:
I would say its c . National Academy of Forensic Science
Answer:
National Academy of Forensic Science
Explanation:
Science with forensic application is a branch of scientific disciplines that allows them to help the police and justice to determine the circumstances in the commission of an infraction and allow the identification of the perpetrators. Criminalistics applies knowledge, methods and techniques for the examination of material related to a criminal act to determine, and administer justice.
Calculate the mass percent composition of carbon in C3H10N4O4. Enter your answer as a number to 1
decimal place.
Answer:
Explanation:
I'm using approximate molecular masses.
3 * C = 3 * 12 = 36
10*H = 10* 1 = 10
4*N = 4 *14 = 56
4*O = 4 * 16 = 64
================
Total = 166
Molecular Mass = 166
% Carbon = 36/166 * 100 = 21.7
Carbon = 21.7%
My atomic masses are approximate because all periodic tables are different. Re do the problem using the numbers off your periodic table.
I need help please:(
Answer: B) Each oxygen atom has an atomic number of 8.
Explanation:
According to the periodic table, oxygen has the atomic number of 8. Also, the oxygens share their characteristics and do not differ just because they are in a compound.
What is the strongest intermolecular force between an NaCl unit and an H2O molecule together in a solution?
Covalent bonding
Dipole-dipole force
Hydrogen bonding
Ion-dipole force
Answer:
Ion-dipole force
Explanation:
Dipoles are found in the polar molecule. A polar molecule is formed when one atom in the molecule attracts most of the electron cloud (due to its higher atomic number) hence making this side of the molecule partially negative. The other part of the molecule becomes partially positive (forming dipoles). Ionic compound (because they are charged) dissociate in polar solvents and the ions form ion-dipole bonds.
Answer:
Ion-Dipole Force
Explanation:
Guy above was correct and explained to the greatest detail.
How is the nitrogen cycle important to humans
Answer:
Explanation:
Nitrogen cycle is one of the important biochemical cycle in nature. The element nitrogen is fixed by the soil bacteria which is available in nature in the form of atmospheric nitrogen. The atmospheric nitrogen is absorbed by the soil bacteria which converts it into forms like nitrates and nitrites which are easily absorbed by the plants. The plants use these forms for the synthesis of amino acids. These amino acids are used by the plants to synthesize their proteins.
The plants and their products are the source of proteins which are the building blocks of human body. The proteins are necessary for building up the muscle mass, renew of hair and skin, repair of injured tissues, defense against the injury, foetal development and others. Hence, nitrogen cycle is important for humans.
Answer:The nitrogen cycle, or n cycle, on Earth, is very important as it provides every living thing with what they need to grow. Humans, animals, even plants. Nitrogen is the most abundant source in the atmosphere. It is also the building block of proteins, nucleic acids like DNA, and a very important component of all life.
Explanation:
Typical room temperature is 23°C. In a classroom at sea level, the atmospheric pressure is 1.00 atm,
Would the gas in a balloon held in this classroom be at STP?
Answer: No the given gas is not at STP.
Explanation:
According to avogadro's law, 1 mole of every substance occupies 22.4 L at STP and contains avogadro's number [tex]6.023\times 10^{23}[/tex] of particles.
Standard condition of temperature (STP) is 273 K and atmospheric pressure is 1 atmosphere respectively.
Given temperature :[tex]23^C=(23+273)K=296K[/tex]
1 mole of every gas occupy volume at STP = 22.4 L
Thus at STP, the temperature is 273 K and pressure is 1 atmosphere and the given gas is not at STP.
Answer:
no
Explanation:
What is common about the elements of a period? Select all that apply. They have the same number of electron energy levels. They have similar chemical characteristics. They have similar physical characteristics. They transition from a metal to noble gas.
Answer:
They have the same number of electron energy levels.
They transition from a metal to noble gas.
Explanation:
Periods in the periodic table of elements refer to elements in the same row. All the elements in a certain row of the periodic table;
have the same number of electron energy levels.
transition from a metal to noble gas.
Which of the following is an endothermic process?
A. rusting a nail in water
B. mixing strong hydrochloric acid and strong ammonium hydroxide
C. a heat pack
D. a cold pack, cooling
Hello There!
A Heat Pack is An Example Of A Endothermic Process.
An Endothermic Reaction Is A Reaction That Requires Energy To Move Forward.
An endothermic process is D. a cold pack, cooling.
Explanation:Endothermic reaction is that type of chemical reaction that requires heat from the surrounding for the reaction to occur. It basically draws heat from the environment to imitate the reaction. The process of using a cool pack for cooling is also an example of endothermic reaction as the heat is absorbed from the surrounding object by the cool pack.
Due to this heat, the ice in the cool pack begins to melt. This process is considered endothermic because the physical change in state of ice into water is not possible without the heat from the surrounding.
V1 T2 = V2 T1 is an expression of
Answer:
Charles' Law
Explanation:
Charles' law gives the relationship between the the volume of a fixed mass of a gas and the absolute temperature.
It states that, Provided the pressure of a fixed mass of a gas remains constant, the volume of a fixed mass of a gas is directly proportional to the absolute temperature.
V/T= constant
When one of the conditions either temperature of volume changes under the same pressure, then the relationship.
V1T2= V2T1 is true
A chemist runs a reaction and has a percent yield of only 30%. Which of the following would NOT explain the low percent yield?
The reaction was stopped too soon, and some of the reactant had not yet been converted to product.
One of the products was a gas that was not contained and weighed.
The product still had moisture in it when the mass was recorded.
Some of the product was spilled before the mass was recorded.
Answer:
the moisture
Explanation:
A low percent yield indicates less product formed than expected. Moisture in the product would not cause a low yield but an inaccurately high yield if anything. The correct percent yield calculation requires a pure product and accounts for less than perfect recovery due to various physical and chemical losses.
Explanation:When a chemist runs a reaction and obtains a percent yield of only 30%, it indicates that there was less product formed than the calculated theoretical yield. Various factors can contribute to a low percent yield, including experimental errors, incomplete reactions, and losses due to product recovery issues. The options given all indicate potential reasons for a low percent yield except for the option where the product still had moisture in it when the mass was recorded. If the product was weighed with moisture, that would generally result in a higher mass and potentially a percent yield greater than 100%, not lower. So, this would not be a reason for a low percent yield, but rather for an inaccurately high yield.
Many reactions, especially on a laboratory scale, will not achieve a 100% yield due to the law of conservation of mass. Even in industry, achieving yields close to 100% is challenging. The chemist must always take care to purify the products to obtain as accurate a percent yield as possible, reflecting the amount of desired product actually formed compared to the theoretical prediction. The percent yield is calculated using the formula: (actual yield / theoretical yield) x 100%.
15. Which of the following is not human-caused groundwater pollution?
A. Water in an aquifer dissolves elements such as arsenic and mercury from surrounding rock.
B. Water in an aquifer is contaminated by leachate that seeps into the ground from a landfill.
C. Water in an aquifer becomes polluted with chemicals used in hydraulic fracturing, or fracking.
D. Water in an aquifer absorbs harmful bacteria from the drainage field of a septic tank.
Answer:
A. Water in an aquifer dissolves elements such as arsenic and mercury from surrounding rock
Explanation:
The aquifers are large natural reservoirs of water bellow the surface of the Earth. With all of the human activity, the aquifers have became badly damaged, especially when it comes to polluting them, thus making the water unusable. But not all pollution of the water in the aquifers comes from the human activities, as there are natural processes that pollute it and make it very dangerous. One way in which the water is getting polluted is by the chemical reactions between the water and the surrounding rocks. Some rocks have mercury and arsenic in them, and both of them are extremely toxic. If the rocks containing them are dissolved by the water, they will make the water very toxic, so anyone using it will probably end up dead.
Answer:
A. Water in an aquifer dissolves elements such as arsenic and mercury from surrounding rock.
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Which of the following gases is the best choice for inflating a balloon that must remain inflated for a long period of time?
Argon is the preferred choice over helium for inflating a balloon to ensure it remains inflated longer due to its heavier molecular weight, resulting in slower effusion through the balloon material.
When choosing the best gas for inflating a balloon that must remain inflated for a long period of time, argon would be a better choice than helium. This is because helium is a lighter gas with a molar mass of 4.00 g/mol, which effuses rapidly through the microscopic pores of the balloon. Conversely, argon is a heavier inert gas and molecules of heavier gases effuse more slowly through porous material, meaning the balloon will remain inflated longer. Additionally, if we were to prepare a balloon with an inert gas like argon and ensure a proper seal with a rubber stopper, the balloon would likely retain its shape and volume for an extended period compared to a helium-filled balloon.
What did Ernest Rutherford’s gold foil experiment demonstrate about atoms?
Answer:
Ernest Rutherford's gold foil experiment consisted in shooting positive particles called α particles, which are nuclei of helium atoms (2 protons and 2 neutrons), to a thin gold film.
Explanation:
Rutherford's Gold Foil Experiment proved the existance of a small massive center to atoms, which would later be known as the nucleus of an atom. Ernest Rutherford, Hans Geiger and Ernest Marsden carried out their Gold Foil Experiment to observe the effect of alpha particles on matter.
Ernest Rutherford’s gold foil experiment demonstrates that the positive charge of an atom is located in the nucleus, the small region that contributes most to the mass of the atom.
What did Ernest Rutherford’s gold foil experiment demonstrate about atoms?Rutherford proposed that the atom is mostly empty space. The electrons revolve in circular orbits about a massive positive charge at the center. His model explained why most of the α particles passed straight through the foil.The gold foil experiment by Ernest Rutherford proved that the positive charge of an atom is located in the nucleus, the small region that contributes most to the mass of the atom. Most of the atom is empty space, but the nucleus, however small, dictates the mass of the atom.To learn more about Ernest Rutherford’s gold foil experiment, refer to: https://brainly.com/question/1471810
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If you compress (volume) a gas, what happens to the temperature if pressure is constant
Answer:
The temperature decreases.
Explanation:
Per Charles' Law, the volume of a gas is directly proportional to the kelvin temperature if other factors remain constant
[tex]V \propto T \text{ or } T \propto V[/tex]
Thus, if V decreases, the temperature decreases.
c. What are the characteristics of an old river?
Answer:
Explanation:
An old river occurs at the plain course and it is at its lower stage.
Here:
The river gradient is very gentle as it is on a plain. An old river would be at its depositional phase where all the sediments its carries are being laid down. It has a low velocity and a very sluggish flow. Lateral erosion is very active at this stage. The volume of the river increases substantially as more river tributaries joins. Some of the river features are flood plains, leeves, ox-bow lakes, delta e.tc.What is the charge of the hydride ion?
Answer:
Negative 1.
Explanation:
Negative 1:- H-.
Examples of Hydrides are KH, NaH and LiAlH4.
Which statement about a solid-liquid solution is true?
The solution and the solvent are liquid; the solute is a solid.
The solute is a liquid, the solvent is a solid, and the solution will vary.
The solution and the solute are liquid; the solvent is a solid.
The solvent is a liquid, the solute is a solid, and the solution will vary.
Answer:
The solution and the solute are liquid; the solvent is a solid.
Explanation:
Answer: The correct answer is the solution and the solvent are liquid; the solute is a solid.
Explanation:
Solute is defined as the substance which is present in smaller proportion in a solution.
Solvent is defined as the substance which is present in larger proportion in a solution.
Solution is the combination of solute and solvent.
For a given solid-liquid solution, the solution has a large proportion of liquid in it. Thus, liquid is considered as solvent and the solution.
Solid particles are present in smaller proportion in a solution and is considered as solute.
Thus, the correct answer is the solution and the solvent are liquid; the solute is a solid.
Consider the following system at equilibrium.
CaCO3(s) = Ca2+(aq) + CO32-(aq)
The addition of which compound will cause a shift in equilibrium because of a common ion effect?
OCCIA
CO2
CuSO4
Na2CO3
Answer:
Na₂CO₃.
Explanation:
Le Châtelier's principle states that when there is an dynamic equilibrium, and this equilibrium is disturbed by an external factor, the equilibrium will be shifted in the direction that can cancel the effect of the external factor to reattain the equilibrium.The compound that has a common ion effect is Na₂CO₃.
When it is added to the solution, it is dissolved to produce Na⁺ and CO₃²⁻ which increases the concentration of CO₃²⁻ that will increase the concentration of the products side, so the reaction will be shifted to the left side to suppress the increase in the concentration of CO₃²⁻.
Answer:
D. eez Nutz
Explanation:
Na2Co3
In which phase(s) of matter are the atoms closely packed but still able to slide past each other?
Gas
Liquid
solid and gas
Liquid and solid
Answer:
Liquid.
Explanation:
In a solid the atoms are closely packed , vibrate but remain in a fixed position. In a gas the atoms are moving fast and fill any space they are contained in.
Perform the following operation.
Express your answer in scientific
notation.
3.120 x 10-7 x 3.075 x 104
Answer:
9.594 * 10^-3.
Explanation:
3.120 x 10-7 x 3.075 x 104
= 3.120 * 3.075 * 10^-7 x 10^4
= 9.594 * 10^(-7+4)
= 9.594 * 10^-3.
Which contribution added to Rutherford's discovery of a positive nucleus?
A: Electrons are scattered in an atom.
B: Neutrons are inside the nucleus of an atom.
C: Atoms of the same element have the same properties.
D: Atoms are indivisible.
Answer:
A: Electrons are scattered in an atom.
Explanation:
Ernest Rutherford performed the gold foil experiment which gave a deeper perspective into what an atom really is. In his experiment, he bombarded a thin gold foil with an alpha particle source.
From the behavior of the alpha particles that associated with the gold foil, a number of conclusions were drawn:
He suggested that an atom has a small positively charged nucleus where the bulk of the atomic mass is concentrated. Surrounding the nucleus is a large space which contains the electrons.Which of the following is a pure substance?
Air
Blood
Copper
Wood
Answer:
copper
Explanation:
its an element, its not mixed with anything else
The answer is "Copper" or option C. Air, and blood aren't pure substances but mixtures, wood is also a mixture which means the answer is copper. Pure Substances are is matter with composition and distinct chemical properties.
Hope this helps.
Working with SI (metric) Units
For each of the following commonly used measurements, indicate its symbol.
liter
gram
milliliter
kilogram
meter
centigram
milligram
centimeter
kilometer
second
millimeter
milliseconds
The symbols for commonly used metric measurements include L for liter, g for gram, mL for milliliter, kg for kilogram, m for meter, and cm for centimeter.
Explanation:The symbol for liter is L.
The symbol for gram is g.
The symbol for milliliter is mL.
The symbol for kilogram is kg.
The symbol for meter is m.
The symbol for centigram is cg.
The symbol for milligram is mg.
The symbol for centimeter is cm.
The symbol for kilometer is km.
The symbol for second is s.
The symbol for millisecond is ms.
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