what would be the final concentration if you added the two 2 l of distilled water to the 0.5 l of 12 m kcl?
The final concentration after adding 2L of water to a 0.50 L volume of 12 M KCl is 2.4 M.
The concentration of a solute in terms of molarity is expressed as the number of moles of solute per liter of solution. The problem is regarding the dilution process of KCl. The molarity can be calculated using the dilution formula, expressed as (initial concentration of 1st solution)(initial volume)=(final concentration)(final volume). This formula shows that the number of moles remained the same throughout the process.
(12 M KCl) * ( 0.50 L) = (final concentration) ( 0.50 L + 2.0 L)
final concentration = 2.4 M KCl
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Help! What role does lactase play in breaking apart the disaccharide lactose?
lactase provides a binding site for lactose to initiate chemical breakdown.
lactase lowers the activation energy needed to begin breaking down lactose.
lactase releases heat during the breakdown of lactose.
lactase prevents too many disaccharide molecules from clumping together during chemical reactions
The lactase enzyme lowers the activation energy required to begin breaking down lactose. Therefore, option (B) is correct.
What is lactase enzyme?The lactase enzyme is a part of the β-galactosidase family, found along the membrane of villi in the small intestine.
In the human body, the optimum temperature and pH for lactase are 37 ° C and 6 pH respectively. Lactase helps in the complete digestion of milk in the small intestine in the human body.
The lactase enzyme catalyzes the hydrolysis of the β-glycosidic bond of D-lactose. After the completion of the hydrolysis, D-glucose and D-galactose are obtained.
The lactase provides the path of low activation energy to initiate the breakdown of the lactose.
Therefore, option (B) is correct that lactase lowers the activation energy.
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Which of the following describes Bohr's model of the atom? (1 pt)
*
1 point
solid sphere like a marble but unique to the element it makes
numerous positive charges floating around in a sea of negative charge (plum pudding)
positive nucleus surrounded by a blob of negative charge
positive nucleus surrounded by electrons in circular orbits
positive nucleus surrounded by electron orbitals with complex 3-D shapes and assigned energies.
According to Bohr's concept of the atom, an atomic system with an orbiting system of electrons and a small, dense nucleus is drawn by electrostatic forces rather than gravity and has a structure similar to that of the solar system.
What is electrostatic force of attraction?Electrostatic forces, for example, pull or push on items without actually coming into touch with them.
Charge can be transferred from one surface to another when specific materials are rubbed together.
Charged objects pull uncharged ones, and other charged objects may push or pull against them.
According to Bohr's hypothesis, atoms have a tiny, positively charged nucleus that is around by negatively charged electrons.
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Can someone give me about 10 sentences about climate change pls i give the person 100
Explanation:
carbon dioxide is a green house gas among many others, human activities Increase the amount of co2 being released. Co2 acts as a global insulator, when the sun rays enter the atmosphere and then bounces back off the earth, the co2 creates a blanket that traps the sun rays. this therein causes the surface of the earth to "heat up" and cause global warming. the increased temperatures triggers another series of events; ice caps begin to melt and in already hot areas there are chances of forest fires etc. the melting of the ice then causes a rise in sea level and the potential release of diseases and other unknown material that was trapped in the ice from different ages ago. the rise in sea level can cause land area to decrease and small islands to be submerged. many habitats would be affected as the ice above the water acts as Insulation that keeps the water below at optimum conditions for sea creatures. on another note, the forest fires destroy habitats and property, this leads to many species becoming endangered and the environment to become inhabitable as the air is not breathable due to thick smoke etc. the fires also contribute back to the global warming and it will just get increasingly worse over a period of time if without interference. the seasons in many place will change to more rapid and serious conditions....
(hope this helps, I just went off lol)
Which 2 organelles make the protein needed for the cell?
Answer:
The endoplasmic reticulum
Explanation:
can either be smooth or rough, and in general its function is to produce proteins for the rest of the cell to function.
The structure of matter refers to its _____.
Select one:
a.
composition
b.
measurements
c.
behavior
d.
reactions
The structure of matter refers to its composition.
a. compositionWhich one of the following is insoluble in water
Answer:
The correct answer is Calcium Carbonate.
Explanation:
Please ask questions correctly
How much energy is required to raise the temperature of 2kg of iron from 20 c to 23 c?
20.7 kJ energy is required to raise the temperature of 2kg of iron from 20 c to 23 c.
Specific heat capacity refers to the amount of heat required to raise the temperature of a substance. Specific heat capacity is denoted by c.
The formula is Q = mcΔT
Given:
Mass = 2.00kgc = 449 J/ kg°CΔT = 23°CSolution:
Put the values in the formula given below
Q = mcΔT
Q = (2.00 kg) (449 J/ kg°C) ( 23°C)
Q = 20654 J or Q = 20.7 KJ
Approximately 20.7 kJ heat is required to raise the temperature of 2kg of iron from 20°C to 23°C.
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what type of bonding helps in stabilizing the alpha helix structure of a protein hydrogen bonds ionic bonds disulfide bonds hydrophobic interactions
Hydrogen bond are help in stabilizing the alpha helix structure of a protein.
Alpha helix structure is a structure whose inner section is tightly coiled main chain, its side chain extending outward in helical array. alpha helix structure is a element of secondary structure in which amino acid structure is arranged in spiral. alpha helix structure for proteins is stabilizing by intramolecular hydrogen bonding between C=O and N-H group of different peptide bond.
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explain why a s bond formed by overlap of an s orbital with an sp3 orbital of carbon is stronger than a s bond formed by overlap of an s orbital with a p orbital of carbon.
Overlapping of an sp³ orbital (which has high electron density) with an s orbital forms a stronger bond than that formed by overlapping of an s orbital with p orbital.
What is Orbital Overlapping?
an orbital overlapping is a merging of Orbital on adjacent Atom .Overlapping of orbitals results in the formation of Bond.This hybridized orbital is stable. it has lower energy than the atomic orbital.They are in Minimum Energy state.Single bonds contain one sigma bond. Double bonds contain one σ and one π bond. triple bonds consist of one σ and two π bonds.Positive Overlapping of Atomic Orbital –When two interacting orbitals are in same phase, then the overlapping is positive and this lead in the formation of bond.
2. Negative Overlapping of Atomic Orbital –
When two interacting orbitals are in opposite phase, then the overlapping is positive and bond is not formed.
3. Zero Overlapping of Atomic Orbital
When orbitals do not overlap each other then the overlapping is known as Zero overlapping orbital.
Now,
Overlapping of an sp³ orbital (which has high electron density) with an s orbital forms a stronger bond than that formed by overlapping of an s orbital with p orbital.
From the above conclusion we can say that , Overlapping of an sp³ orbital (which has high electron density) with an s orbital forms a stronger bond than that formed by overlapping of an s orbital with p orbital.
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you have a hot reservoir held at 30°c and a cold reservoir held at 0°c. if you move 400 j of heat from the hot reservoir to the cold reservoir, what is the total change in entropy? (1 point)
Entropy has been defined as the unavailable energy for the thermodynamic system. The total change in the entropy of the reservoir with 400 J energy is 0.15 J/K.
What is the entropy change?Entropy change has been the measure of the energy that got dispersed in the thermodynamic system. The change in energy and the change in temperature are used to give the entropy change.
Given,
Heat transferred (ΔQ) = 400 Joules
Temperature of hot reservoir (Th) = 30°C (30 +273) = 303K
The temperature of the cold reservoir (Tc) = 0°C (273K)
Using ΔS = Q ÷ T as:
For hot resorvoir:
ΔShot = - 400 ÷ 303
ΔShot = - 1.32 J/K
For cold reservoir:
ΔScold = 400 ÷ 273
ΔScold = 1.47 J/K
Total change in entropy (ΔStotal) is given as:
ΔStotal = ΔShot + ΔScold
= - 1.32 + 1.47
= 0.15 J/K
Therefore, 0.15 J/K is the change in the entropy of the reservoir when heat is transferred from hot to cold.
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Phosphoric acid can supply one, two, or three h3o ions in aqueous solution. Write balanced equations to show successive loss of hydrogen ions
Balanced equation for the first step of dissotiation:
H₃PO₄(aq) + H₂O(l) ⇄ H₂PO₄⁻(aq) + H₃O⁺(aq).
Balanced equations for the second step of dissotiation:
H₂PO₄⁻(aq) + H₂O(l) ⇄ HPO₄²⁻(aq) + H₃O⁺(aq).
Balanced equations for the third step of dissotiation:
HPO₄²⁻(aq) + H₂O(l) ⇄ PO₄³⁻(aq) + H₃O⁺(aq).
A phosphoric acid or orthophosphoric acid (H₃PO₄) is three protic acid, which means that in water it releases three hydrogen ions. A phosphoric acid ionizes in three steps in water.
Species that are present: H₃PO₄, H₂PO₄⁻, HPO₄²⁻, PO₄³⁻ and H₃O⁺.
Hydronium ion (H₃O⁺ ) is the type of oxonium ion produced by protonation of water.
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Which statement best explains why the compound H2O is not toxic to drink, but H202 is toxic to drink?
Can someone help me please, anyone?!!!
Answer:
Compounds change properties when the number of atoms changes
The statement best explains the compound H₂O is not toxic to drink, but H₂O₂ is toxic to drink is compounds change properties when the number of atoms changes. The correct option is C.
What are H₂O and H₂O₂?H₂O is the chemical formula of water. It is made up of joining hydrogen and oxygen. Water is an essential compound of life. It is present in three forms on the earth.
H₂O₂ is the chemical formula of hydrogen peroxide. It is more viscous than water, and it is used as an antiseptic and used in cleaning cut areas and wounds.
When the atoms are more added to a compound. It changes its property because it becomes a new and different compound. Water and hydrogen peroxide are different compounds.
Thus, the correct option is C. compounds change properties when the number of atoms changes.
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How many significant figures are in 91010?
Answer:
4
Explanation:
Number--Scientific Notation--Significant Figures
9000 9.0×103 1
91010 9.101×104 4
956 9.56×102 3
9010.0 9.01×103 5
Answer:
Number; 91010
Scientific Notation; 9.101×10^4
Significant Figures; 4
Explanation:
Object a has a density of 10g/cm^3 and a mass of 9. object b has a density of 10g/cm^3 and a mass of 4g. which object has a greater volume and by how much?
Answer:
A has Larger volume by 0.5cm^3
Density = Mass/ Volume
Volume = Mass / Density
So, for A,
Volume = 9/10 = 0.9cm^3
For B, Volume = 4/10 = 0.4cm^3
Therefore Volume of A is larger.
Alternatively, since density of both objects are same, the object with greater mass will have larger volume.
Physical property of red color
Explanation:
Color is one of the nature of the substance, then is color a physical property?
For better understanding, let us assume that a band of the color spectrum falls on the material, absorbing the wavelength of 540 and 460 nm and reflecting the wavelength of 680nm. The resulting color of the material is red because red has a wavelength of 700-635nm. The absorbed colors are green and blue because the wavelength of green is 560-520nm and blue is 490-450nm. As the green and blue colors are absorbed by the material and red is reflected, the composition of the material does not alter; hence the color is the physical property of the material.
R
a student conducts an experiment to determine how the temperature of water affects the time for salt to dissolve in 100 ml of water. the student makes one measurement for each temperature.what is one way that the student could improve the experiment?perform multiple trials for each measurement instead of just oneperform multiple trials for each measurement instead of just oneuse a different type of salt for each temperature of wateruse a different type of salt for each temperature of waterperform one trial for each measurement but use a different volume of water for each testperform one trial for each measurement but use a different volume of water for each testuse a different timer for each temperature of water
"perform multipule trials for each measurment instead of just one" is the way that student can improve the experiment.
How is water's temperature determined?A thermistor, a metallic instrument that experiences a predictable change in resistance in response to temperature variations, can be used to monitor the temperature of water. A readout of the temperature in Celsius, Fahrenheit, or Kelvin is obtained by measuring and converting this resistance.Water should be consumed at room temperature (20°C/68°F) for optimum flavour or chilled to 6°C/43°F for maximum cooling.Why is water temperature important?Because it controls the sorts and types of aquatic life, limits the maximum dissolved oxygen concentration of the water, and affects the speed of chemical and biological reactions, temperature is a crucial water quality and environmental characteristic.
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A student is using a microscope to observe samples taken from pondwater. The student notices something
that she thinks may be a living thing. Which evidence would BEST support that the unknown sample is a
living thing?
A The sample is made of cells and is using energy.
B The sample is responding to stimulus and is breathing oxygen.
C The sample is producing bubbles and is growing larger.
D The sample is green and is moving.
The evidence that would best support that the unknown sample is a living thing is that the sample is made of cells and is using energy (option A).
What are living things?Living things are classes of things that contains life in them.
According to this question, a student is using a microscope to observe samples taken from pond water. The student notices something that she thinks may be a living thing.
In order to confirm if this unknown sample is a living thing, it must conform to the cell theory, which states that all living things are made up of one or more cells.
Therefore, the evidence that would best support that the unknown sample is a living thing is that the sample is made of cells and is using energy.
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Which of the following statements about metals and nonmetals is correct? (1 pt)
*
1 point
A.Metals and nonmetals can both be found in any column of the periodic table.
B.Most metals are solid under normal room temperatures while most nonmetals are a liquid.
C.Metals can be hammered into thin sheets while nonmetals are brittle.
D.Metals tend to be poor conductors of electricity, while nonmetals are good conductors of electricity.
The statement metals can hammered into thin sheets and non metals are brittle is correct. Thus option C is true.
What are metals?Metals is defined as a substance with good conductor of electricity, luster and malleability, which are ready to lose electron to form a positive ion i.e. cation. Metals can also be defined according to their periodic table.
Non metals is defined as a substance which are poor conductor of electricity, luster and malleability which are ready to gain electron to form a negative ion i.e. anion. They can be gas, liquid or solid.
Thus, metals can hammered into thin sheets and non metals are brittle is correct. Thus option C is true.
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Write equations that show the process for (a) the first two ion- ization energies of lead and (b) the fourth ionization energy of zirconium.
The equation showing process for ionization energies -
a) For lead,
First Ionization energy : Pb (g) + IE₁ → Pb+ (g) + e-
Second Ionization energy: Pb+ (g) + IE₂ → Pb₂+ (g) + e-
b) Fourth ionization energy of zirconium -
Zr₃+(g) → Zr₄+(g)+e−
To remove an electron from a gaseous atom then the energy that is required is known as Ionization Energy.
Amount of energy required to remove the most loose bounded electrons form an isolated gaseous atom to form a gaseous ion, it is called the ionization enthalpy or ionization energy. It is usually represented in the units of kJ mol-1
The first two ionization energies of lead -
Lead is a heavy metal whose atomic number is 82. It has electronic configuration : [Xe] 4f14 5d10 6s2 6p2
Thee general formula to write the equation .
First : Pb (g) + IE1 → Pb+ (g) + e-
Second: Pb+ (g) + IE2 → Pb2+ (g) + e-
The first and second ionization energies of Lead, Pb is equal to =
First = 715.6 kJ mol⁻¹
Second = 1450.5 kJ mol⁻¹
The fourth ionization energy of zirconium is:
Zr₃+(g) → Zr₄+(g)+e−
The fourth ionization energy is 3313 kJ mol⁻¹
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How many atoms are there in 7.61 grams of arsenic?
Answer: 1.24 X 10-22 g. The atomic mass of arsenic is 74.92 amu, 1 mole of arsenic atom has 74.92g weight.
Explanation:
Mole measure the number of elementary entities of a given substance that are present in a given sample. Therefore, 0.602×10²³ atoms are there in 7.61 grams of arsenic.
What is mole?The SI unit of amount of substance in chemistry is mole. The mole is used to measure the quantity or amount of substance. We know one mole of any element contains 6.022×10²³ atoms which is also called Avogadro number.
Mathematically,
mole =given mass ÷ molar mass
given mass of arsenic= 7.61 grams
Molar mass of 1 mole of arsenic= 74.92g/mol
substituting the given values, we get
number of mole of arsenic =7.61 ÷ 74.92g
=0.10moles
number of atoms of arsenic= number of moles of arsenic× Avogadro number
=0.10× 6.022×10²³
=0.602×10²³ atoms
Therefore, 0.602×10²³ atoms are there in 7.61 grams of arsenic.
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In the electrolysis of aluminium ore, which is the positive ion? Give the name, not the symbol.
Positively charged aluminum ions gain electrons from the cathode and form molten aluminum. Electrolysis is used to perform the extraction. The aluminum oxide must let the ions to travel freely in order for electricity to flow through it.
Due to its extremely high melting point (about 2000°C), aluminum oxide would be expensive to melt. Although it doesn't dissolve in water, aluminum oxide does in molten cryolite. The melting point of this aluminum compound is lower than that of aluminum oxide. Cryolite utilization lowers some of the energy expenses associated with aluminum extraction. Carbon dioxide bubbles off once the oxygen and carbon in the electrodes react. The positive electrodes must consequently be replaced regularly since they lose carbon over time. This raises the price of the procedure.
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An oxide of iron is found to be 77. 75% iron by mass. Determine the empirical formula for this compound and name it.
In a sample of air at 25 °C, the molecules of oxygen, nitrogen and carbon dioxide all move with
different average speeds. Which of the following lists the molecules in order of decreasing average speed?
Order of decreasing average speed is Nitrogen>oxygen>carbon dioxide
According to Graham's law of diffusion, the rate of diffusion is inversely proportional to the vapour density of the molecule and therefore the smaller the weight of the molecule the faster the rate of diffusion.
Because of the above reason nitrogen has the lowest vapour density followed by oxygen and carbon dioxide with the highest and therefore nitrogen will possess the greatest speed than the others and the decreasing order are nitrogen>oxygen>carbon dioxide.
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What is scientific learning
Answer:
Scientific learning is the study methodology used through testing and experimentation.
Answer:
The Science of Learning is an approach that recognizes the value and importance of cross-fertilization across traditional fields of study, drawing on many different methods and techniques to understand how learning occurs— with the ultimate goal of optimizing learning for all.
Which best explains why a crystal is incompressible?
A.Its molecules remain in position without vibrating.
B.The molecules of a crystal behave like those of a gas.
C.There is little, if any, space left between its adjacent molecules.
D.Its molecules switch positions when they are compressed.
Answer:
its molecule remain in position without vibrating
Answer:
The Answer is C; There is little, if any, space left between its adjacent molecules.
Explanation:
Because it is so compact, it cannot be compressed any further. Imagine trying to press down on a piece of bread versus a brick. The bread would flatten because it is full of air, but the brick would not because it is compact.
I hope this helps, have a nice day! :)
Describe what happens when a lithium atom reacts with a chlorine atom.
Answer in terms of electrons.
vsepr theory predicts an identical shape for all of the following except: nh3 b. h3o c. bh3 d. ch3:- e. all have the same geometry
The following are all predicted to have an identical shape under the vsepr theory, with the exception of: BH 3
VSEPR theoryValence shell electron pair repulsion (VSEPR) is the name given to this idea. The total number of electron pairs (TEP) encircling the main atom of a species is calculated using the VSEPR theory. Bond pairs (BP) and lone pairs are the components of the TEP (LP). In this scenario, every pair of electrons will position themselves to reduce electrostatic attraction between them, just like a charge would. The covalent bonds' shapes around the main atom are determined by these repulsions.Except for BH 3, every molecule in the available possibilities has the same geometry. The reason for this is that the BH 3 compound doesn't have a lone pair.learn more about VSEPR theory here
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George used the apparatus below to find out what substances are produced when methanol burns.
As the methanol burned two different gases were produced.
A) One of these gases condensed in the u-Tube to give a colourless liquid. Give the name of this liquid.
B) The other gas turns the limewater cloudy. Give the name of this gas
The term combustion has to do with a situation in which a substance is burnt in oxygen. When we burn a substance in oxygen, we say that the substance is oxidized.
Methanol is a member of the alkanol series of organic compounds. The equation for the combustion of methanol is shown to be as follows;
[tex]CH_{3} OH + 3O_{2} ---- > 2O_{2}+ 4H_{2}O[/tex].
Looking at the set up as we can see it in the question, we can observe the following;
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Select all the correct answers. a scientist carried out several different procedures, each of which caused a change in matter. select each procedure that is likely a chemical change. salt crystals were crushed into a fine powder. bubbles were produced when iron was placed in acid. two liquids were combined, and a solid appeared. a piece of metal melted when it was heated. a white substance turned blue when water was added.
Answer:
-bubbles produced when iron placed in acid -two liquids combined and a solid appeared -white substance turned blue when water was added
Explanation:
all the other answers could be turned back into their previous state, or haven't really changed.