Final answer:
The change from liquid water to water vapor is actually a physical change, not a chemical change, because the molecular structure of water remains unchanged in both states. Physical changes only affect the form, not the composition, whereas chemical changes involve new substances being created.
Explanation:
Dear Friend,
I understand why you might think that the change from liquid water to water vapor is a chemical change, but in fact, it's a physical change. When water boils and becomes steam, it's simply undergoing a phase change; the molecular structure of water (H₂O) remains the same in both its liquid and gas states. This means that it's still water even when it's in the form of steam.
The difference between physical and chemical changes is that physical changes only affect the form of a substance, not its chemical composition. For instance, when we see ice melting into water or water evaporating into steam, the arrangement of the molecules changes, but the molecules themselves remain intact. In contrast, chemical changes involve making or breaking chemical bonds to create new substances, like when gasoline burns or milk sours.
So, when we consider a phase change like vaporization of liquid water to steam (H₂O(l) → H₂O(g)), it is a reversible process that does not alter the composition of the substance. If you cool the water vapor, it will condense back into liquid water. The same molecule, just a different phase.
Warm regards,
Your Chemistry Friend
Which of the following statements is FALSE? A. Air temperatures over the ocean remain fairly constant throughout a 24-hour cycle. B. Air temperatures over the land can vary significantly throughout the day. C. Air temperatures over land reach their highest values in the mid-afternoon. D. Air temperatures over land are always higher than air temperatures over the ocean.
Answer:
d
Explanation:
Air temperatures over land are always higher than air temperatures over the ocean. This statement is false.
What is temperature ?The physical concept of temperature indicates in numerical form how hot or cold something is. A thermometer is used to determine temperature. Thermometers are calibrated using a variety of temperature scales, which historically defined distinct reference points and thermometric substances.
Above the course of a 24-hour cycle, air temperatures over the ocean remain largely unchanged. Throughout the day, there can be large variations in the air temperature over the land. Mid-afternoon is when land-based air temperatures are at their maximum. Always higher than air over the ocean are air temperatures over land.
Water has a heat capacity that is around four times more than that of land, meaning it requires more energy to heat it up and reacts more slowly to temperature
Thus, option D is correct.
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What is the pressure of nitrogen in atmospheres of a sample that is at 745 mmHg?
balance the following reaction. CH4+O2==>CO2+H20
Answer:
[tex]\huge \boxed{\mathrm{CH_4+ 2O_2 \Rightarrow CO_2 +2 H_2O}}[/tex]
[tex]\rule[225]{225}{2}[/tex]
Explanation:
[tex]\sf CH_4+ O_2 \Rightarrow CO_2 + H_2O[/tex]
Balancing the Hydrogen atoms on the right side,
[tex]\sf CH_4+ O_2 \Rightarrow CO_2 +2 H_2O[/tex]
Balancing the Oxygen atoms on the left side,
[tex]\sf CH_4+ 2O_2 \Rightarrow CO_2 +2 H_2O[/tex]
[tex]\rule[225]{225}{2}[/tex]
Critical Thinking:
Suppose you need to build a raft. Write a paragraph describing the physical and chemical properties of the raft that would be important to ensure your safety.
To ensure safety when building a raft, one must evaluate physical properties such as buoyancy, water-resistance, stability, and balance, as well as chemical properties that dictate material inertness and resistance to degradation.
In building a raft to ensure safety, one must consider both physical and chemical properties. It is crucial that the materials selected are buoyant to keep the raft afloat. The materials should also be water-resistant to minimize water absorption, which could lead to deterioration or increased weight causing the raft to sink. Stability and balance are also critical physical properties, as they help prevent the raft from flipping over in water.
From a chemical standpoint, the materials should be inert and non-reactive with water or the substances in it to prevent the raft from breaking down over time. Chemical treatments may be applied to enhance water resistance or prevent biological growth such as algae or bacteria on the raft which can weaken materials or make the surface slippery. Selection based on quality and construction is more practical for safety than aesthetics like color or superficial measures such as size.
Furthermore, when considering the construction method, one must ensure that all parts of the raft are securely bound to avoid disintegration under stress. A sensible selection process is paramount, involving critical evaluation of each raft's potential problems and considering how these could impact safety and performance during river crossing.
Which is the most accurate description of compounds?
a. They are formed by elements that join in any given mass ratio.
b. They have the same properties as the elements that make them up.
c.They have a unique set of properties that can be used as identifiers.
d. They cannot be broken down into the elements that form them through chemical changes.
Answer: c.They have a unique set of properties that can be used as identifiers.
Explanation:
Compound is a pure substance which is made from atoms of different elements combined together in a fixed ratio by mass.
Compounds can be decomposed into simpler constituents using chemical reactions.
Example: Water [tex](H_2O)[/tex]
[tex]2H_2O\rightarrow 2H_2+O_2[/tex]
Compounds have different properties than the elements it is made up of.
Thus the most accurate description of compounds is that they have a unique set of properties that can be used as identifiers.
Which of these substances are molecules
The standard unit of mass is the: gram kilogram pound cubic centimeter
Answer:
The standard unit of mass is the kilogram.
Explanation:
The kilogram is the basic unit of mass in the International System of Units. Among the seven basic units of the International System of Units, kilograms are the only basic unit with a prefix.
The XXVI General Conference on Weights and Measures of 2018 approved the definition of a kilogram based on fixing the numerical value of the Planck constant. The decision entered into force on May 20, 2019.
dust mites are microscopic bugs that are too small to see with the dissecting microscope. to see the details of a dust mite's skin, which of the following microscopes would you use? Please help fast with make brainiest
A.dissecting microscope
B.compound microscope
C.transmission electron microscope
D.scanning electron microscope
I know the answer is not A.
Nevermind got the answer it is D.
The scanning electron microscope is used to see the details of a dust mite's skin. Thus option D is correct.
What is microscope?Microscope is defined as an optical equipment that magnifies an object by using a lens or a combination of lenses.
It can also be defined as an optical equipment consisting of a lens or group of lenses used to magnify images of small things.
There are five types of microscopes.
Simple microscopeCompound microscopeElectron microscopeStereomicroscopeScanning electron microscopeThus, the scanning electron microscope is used to see the details of a dust mite's skin. Thus option D is correct.
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Yttrium -90 has a half life of 64 hours . How much of a 120g sample will remain after 128 hours ?
how small do you think an individual atom is
Which of the following is designed to convert energy into mechanical energy?
A.Blender
B.Kerosene heater
C.Flashlight
D.Baking oven
In this chemical reaction a very reactive metal, sodium, combines with a poisonous gas and results in the formation of ordinary table salt. In the chemical reaction ______________ is the product.A)NaB)NaClC)Cl2EliminateD)a reactive metalDescribe the mass of the reactants and products given the balanced chemical reaction. A) The mass of the products is 2 3 that of the reactants. B) The mass of the reactants equals the mass of the products. C) The mass of the reactants is less than the mass of the products. Eliminate D) The mass of the reactants is greater than the mass of the products.
Antoine Lavoisier found that mass was conserved in chemical reactions when he saw thatA)heat was released in chemical reactions.B)the products differed greatly from the reactants.C)the mass of the products was the same as that of the reactants.EliminateD)the mass of the products were heavier than the mass of the reactants.
A copper sheet is heated in a furnace until it melts. The hot liquid copper is then cooled until it becomes solid again. Compare the mass of the copper before and after melting.A)The new solid copper is lighter than the original sheet.B)The new solid copper is heavier than the original sheet.C)The new solid copper is the same weight as the original sheet.EliminateD)The molten copper was lighter than the sheet or the new solid.
A newly discovered element, Y, has two naturally occurring isotopes. 87.8 percent of the sample is an isotope with a mass of 267.8 u, and 12.2 percent of the sample is an isotope with a mass of 269.9 u. What is the weighted average atomic mass for this element? 267.9 u 268.1 u 268.9 u 269.1 u
Answer : The average atomic mass of this element is, 268.1 u
Explanation :
Average atomic mass of an element is defined as the sum of masses of each isotope each multiplied by their natural fractional abundance.
Formula used to calculate average atomic mass follows:
[tex]\text{Average atomic mass }=\sum_{i=1}^n\text{(Atomic mass of an isotopes)}_i\times \text{(Fractional abundance})_i[/tex]
For isotope-1 :
Mass of isotope-1 = 267.8 amu
Fractional abundance of isotope-1 = 87.8 % = 0.878
For isotope-2 :
Mass of isotope-2 = 269.9 amu
Fractional abundance of isotope-2 = 12.2 % = 0.122
Putting values in equation 1, we get:
[tex]\text{Average atomic mass }=[(267.8\times 0.878)+(269.9\times 0.122)][/tex]
[tex]\text{Average atomic mass }=268.1u[/tex]
Thus, the average atomic mass of this element is, 268.1 u
At room temperature, which of these are oxide minerals? Select all that apply.
A.H2OB.CO2C.Al2O3D.Fe3O4
Answer: C.[tex]Al_{2}O_{3}[/tex] and D.[tex]Fe_{3}O_{4}[/tex]
Explanation: Oxide minerals are the minerals in which the oxide anion is bonded to the central metal atom. These are useful for industrial purposes.
Out of the given options, only two of them can be categorized as the oxide minerals.
H2O and CO2 will not be considered as oxide minerals.
If a system has 425 kcal of work done to it, and releases 5.00 × 102 kJ of heat into its surroundings, what is the change in internal energy of the system?
Using the first law of thermodynamics, the change in internal energy of the system, given the work done on the system and the heat released by the system, was calculated to be -2.28 × 10^6 Joules.
Explanation:The subject of this problem is a classic concept in thermodynamics: the conservation of energy. According to the first law of thermodynamics, the change in the internal energy (ΔU) of a system is the sum of the heat (Q) added to the system and the work (W) done on the system, expressed in the equation ΔU = Q - W.
In this case, the work is performed on the system, amounting to 425 kcal. To convert this into a common unit like Joules, use the conversion factor 1 kcal = 4.184 × 10^3 J. Therefore, the work done on the system (W) is 425 kcal × (4.184 × 10^3 J/kcal) = 1.78 × 10^6 J.
The heat released by the system (Q) is - 5.00 × 10^2 kJ (the negative sign indicates heat is lost from the system). Converting into Joules gives -5.00 × 10^2 kJ × (10^3 J/kJ) = -5.00 × 10^5 J.
Substituting Q and W into the equation gives ΔU = (-5.00 × 10^5 J) - (1.78 × 10^6 J) = -2.28 × 10^6 J. Hence, the change in internal energy of the system is -2.28 × 10^6 J.
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The change in internal energy of the system is -1277.4 kJ.
Explanation:The change in internal energy of a system can be calculated using the equation:
Change in internal energy = heat transfer - work done
In the given scenario, the system receives 425 kcal of work and releases 5.00 × 102 kJ of heat. To calculate the change in internal energy, we need to convert the units to a consistent format. 1 kcal = 4.184 kJ, so the work done is 425 kcal x 4.184 kJ/kcal = 1777.4 kJ.
Using the formula, the change in internal energy is:
Change in internal energy = 5.00 × 102 kJ - 3 kJ = -1277.4 kJ
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what is the percent composition of the u.s quarter, which has the mass of 5.670g
and contains 5.198g Cu and 0.472g Ni
Final answer:
The percent composition of Cu in the US quarter is approximately 91.72%.
Explanation:
The percent composition of an element in a compound is the percentage of the total mass of the compound that is due to that element.
To calculate the percent composition of Cu in the US quarter, we need to divide the mass of Cu by the total mass of the quarter and multiply by 100.
Percent composition of Cu = (Mass of Cu / Mass of quarter) x 100
Mass of quarter = Mass of Cu + Mass of Ni = 5.198g + 0.472g = 5.670g
Percent composition of Cu = (5.198g / 5.670g) x 100 = 91.72%
Final answer:
The U.S. quarter, with a mass of 5.670g, is composed of approximately 91.67% copper and 8.32% nickel, calculated using the mass of the individual elements and the total mass of the coin.
Explanation:
To find the percent composition of the U.S. quarter with a mass of 5.670g, which contains 5.198g of copper (Cu) and 0.472g of nickel (Ni), you can use the formula:
Percent Composition = (mass of element/mass of compound) × 100%.For copper (Cu): Percent Composition of Cu = (5.198g / 5.670g) × 100% = 91.67%.For nickel (Ni):
Percent Composition of Ni = (0.472g / 5.670g) × 100% = 8.32%.Therefore, the U.S. quarter is composed of approximately 91.67% copper and 8.32% nickel.
very reactive nonmetal element has most protons in the halogen group
Which example provides a complete scientific description of an object in motion? Question 3 options: The marble changed position quickly. The car traveled north. The marble moved 30 cm north in 6 seconds. The ball rolled 20 cm in 5 seconds.
Answer:
The marble moved 30 cm north in 6 seconds. is correct
Explanation:
according to K12
100% sure
Define prediction and explain how it is used to formulate a hypothesis.
Answer:a prediction is a scientific guess that’s solely based on known knowledge
Explanation:
A prediction is used to make a hypothesis because it goes in hand of guessing an outcome that can be tested
A prediction is a scientific guess that is based on knowledge which is known.
What is knowledge?Scientific knowledge is defined as a systemic explanation of phenomenon or behavior of interest that are obtained using the scientific method. The principal on which scientific knowledge depends is the test of knowledge.
The fact which makes scientific knowledge different from other knowledge is that it depends upon fact and scientific resources as well as data. Scientific knowledge helps us to improve and develop new technology find solution of practical problems and make informed decisions.
The procedure of aquaring scientific knowledge is a result of practice of the several method such as observation, filtering hypothesis, deduction of test for hypothesis following testing and experimentation which lead to confirmation or failure of the hypothesis.
Therefore, A prediction is a scientific guess that is based on knowledge which is known.
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Can an element with eight valence electrons still be reactive?
Copper is more reactive than calcium. True or false?
Answer;
The above statement is false
Explanation;
Copper is less reactive than Calcium.
This is because Calcium is higher in the reactivity series of metals compared to copper and thus reacts more than copper.
The reactivity series of metals is vital tool that is used in determining the products of displacement reactions and the reactivity of metals in other reactions. The higher the metal is in the reactivity series, the more reactive it is and conversely the lower the metal in the reactivity series the less reactive it is.
In this case, calcium is higher in the reactivity series than copper thus more reactive.
Answer: The given statement is false.
Explanation:
Electronic configuration of calcium is [tex]1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}[/tex], that is, there are two extra electrons. So, in order to attain stability calcium loses two electrons readily.
Whereas electronic configuration of copper is [tex][Ar]4s^{1}3d^{10}[/tex]. Since, it has completely filled d-orbital so, it is stable in nature and thus, does not react readily.
Therefore, we can conclude that reactivity of calcium is more than copper. That is why, the given statement is false.
Magma is made up of melted or *blank* materials.
A. Intrusive
B. Molten
C. Extrusive
D. Cooled
if a hill or Mountain has a high gradient (slope) what happens to the speed of a river flowing downward and the rate of erosion?
A 20.0 % by mass solution of phosphoric acid (H3PO4) in water has a density of 1.114 g/mL at 20°C. What is the molarity of this solution?
Answer:
Molarity is 2.272M
Explanation:
The mass % of phosphoric acid is 20.0%
It means in 100 g of solution there is 20g of phosphoric acid in it.
Molarity = moles of solute dissolved per litre of solution.
So we need volume of solution
Volume can be calculated from mass and density as
Volume = mass / Density = 100/1.114 = 89.77 mL = 0.08977 L
Moles of solute = mass of solute / molar mass of solute
moles of solute = 20g / 98 = 0.204
molarity = [tex]\frac{moles}{volume}=\frac{0.204}{0.08977} =2.272M[/tex]
The equation below shows the products formed when a solution of silver nitrate (AgNO3) reacts with a solution of sodium chloride (NaCl).
AgNO3 + NaCl → NaNO3 + AgCl
(Reactants) → (Products)
In this equation, the total mass of the reactants is
A) equal to the mass of AgCl.
B) less than the mass of AgCl.
C) equal to the total mass of the products.
D) greater than the total mass of the products.
In the given equation, the total mass of the reactants is equal to the total mass of the products. Therefore, option (C) is correct.
What is the balanced chemical equation?A chemical equation can be defined as the representation of a chemical reaction in terms of symbols of the substances. A balanced equation consists of reactants, formed products, and an arrow representing the direction of the chemical reaction.
The chemical equation in which the number of atoms of each element participated in the reaction is equal on either side of the equation is called a balanced chemical equation.
The law of conservation of mass must obey by a balancing of a chemical equation. According to this law, in a chemical reaction, the mass can neither be created nor destroyed.
The total mass on the reactant side should be equal to the total mass on the product side in a balanced chemical equation.
For the given chemical equation total mass of AgNO₃ and NaCl is equal to the total mass of NaNO and AgCl.
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Match the scientist with his discovery or contribution.
Match
Term
Definition
J. J. Thomson A) Protons
John Dalton B) Atoms
Ernest Rutherford C) Electrons
James Chadwick D) Neutrons
I NEED THIS IN 5 MINUTS MAX
Thomson - Electrons
Dalton - Atoms
Rutherford - Protons
Chadwick - Neutrons
will be the answer
The correct match of the scientists with their discovery are:
A. J. J. Thomson - Electrons
B. John Dalton - Atoms
C. Ernst Rutherford - Protons
D. James Chadwick - Neutrons
What are subatomic particles?An atom is made up of subatomic particles. Electron, proton, and neutron are the particles that form an atom.
Electron was discovered in 1898 and proton was discovered in 1908 and neutron was discovered in 1932.
Thus, the correct options are, A. J. J. Thomson - Electrons
B. John Dalton - Atoms
C. Ernst Rutherford - Protons
D. James Chadwick - Neutrons
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Which two structures would provide a positive identification of a plant cell under a microscope? A. cytoskeleton, cell wall B. endoplasmic reticulum, chloroplasts C. chloroplast, large central vacuole D. large central vacuole, flagellum
You see a burning candle. You feel heat above the flame, you see black smoke rising from the wick, and wax melts. List each of the changes that occurred and tell the type of change that caused it.
A burning candle undergoes several changes: heat production, smoke emission, and wax melting. The forming of water vapor and carbon dioxide during heat production and the generation of soot particles during smoke emission are chemical changes. The melting of the wax is a physical change.
Explanation:Three changes occur when you see a burning candle: the production of heat, the emission of smoke, and the melting of wax.
Production of Heat: When you light a candle, the heat of the flame melts the wax near the wick. This liquid wax is drawn up the wick towards the flame. The heat of the flame vaporizes the liquid wax (turns it into a hot gas) and starts to break down the hydrocarbons into molecules of hydrogen and carbon. These vaporized molecules are drawn up into the flame, where they react with oxygen from the air to create heat, water vapor, and carbon dioxide. This process is an example of a chemical change because new substances (water vapor, carbon dioxide) are formed. Emission of Smoke: This is also a chemical change resulting from incomplete combustion. When the flame doesn't get enough oxygen, it can't totally break the hydrocarbons, resulting in small soot particles that scatter light (black residue). Melting of Wax: The wax near the wick melts due to the heat of the flame. This is a physical change since it involves a change of state (solid wax to liquid), but the chemical composition of the wax stays the same. Learn more about Candle Burning here:
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Radioactive isotopes of an atom are?
Radioactive isotope, also called radioisotope, radionuclide, or radioactive nuclide, any of several species of the same chemical element with different masses whose nuclei are unstable and dissipate excess energy by spontaneously emitting radiation in the form of alpha, beta, and gamma rays.
Answer:
Less stable
Explanation:
I took the K12 test
The table below shows the average temperatures of the crust, the mantle, and the outer and inner core of Earth arranged randomly:
Average Temperature of Layers Unknown Layer
Average Temperature (°C) A 4,500 B 1,300 to 2,500 C 5,000 D 0 to 1,300 Which layer is most likely the mantle?
someone please help 10 points science
B is most likely to be the mantle 1,300-2,500 YOUR WELCOME
Average temperature of layers unknown layer average temperature is 1,300 to 2,500. The crust's temperature is between 200° Celsius and 400° Celsius close to the Moho.
What is average temperature ?The average air temperature throughout a specific time period, often a day, a month, or a year, as measured by a thermometer that has been properly exposed. The mean temperature is often calculated for the year and for each month in climatological tables.
Normal and average temperatures have different connotations according to meteorologists than they do in regular language. A normal temperature is higher than the mathematical average of an average temperature.
The combined temperatures of all the hot regions, all the cold places, and all the in-between locations make up the global average temperature. It is a crucial indicator of how the Earth's system is changing.
Thus, option B is correct.
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