Avogadro's law states that in every mole of a substance, there are [tex]6.022 \times 10^{23}[/tex] molecules.
This means that in 2.3 moles, there are [tex]2.3(6.022 \times 10^{23})=\boxed{1.4 \times 10^{24} \text{ (to 2 sf)}}[/tex]
Select the correct answer from each drop-down menu.
Scientific theories are always
testable
. A theory may be changed as a result of
.
Scientific theories are always testable. A theory may be changed as a result of new observations.
What are Scientific theories ?A scientific theory is a set of laws, facts and hypotheses that have a complete vision of an aspect of reality.
It is a proposed explanation for a set of observable phenomena.
It allows in this way to organize and understand the observations and to be able to predict or provoke other future observations.
Theories can be modified or improved as more information is collected.
That is, theories can continue to be tested indefinitely, and eventually rejected, if the tests lead to it.
Therefore, a scientific theory is testable by using a research method.
As mentioned, any theory can be tested or rejected as more information is collected.
This information to prove or reject theories are interpretations of observable facts, which generates new statements or allows to accept those already included in the theory.
Then, a theory may be changed as a result of new observations.
Finally, scientific theories are always testable. A theory may be changed as a result of new observations.
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Answer:
testable & new observations
Explanation:
An arrow is fired at a target on a high wall. How does the energy change between the moment the arrow is fired and the moment it hits the target?
o The potential energy and kinetic energy remain the same.
o The potential energy decreases as kinetic energy increases.
o The kinetic energy decreases as potential energy increases.
o The kinetic energy remains at zero, but potential energy increases.
The kinetic energy decreases as potential energy increases. Hence, option C is correct.
What is potential energy?Potential energy is stored energy that depends upon the relative position of various parts of a system.
As the target is fired high on the wall, the change in the energy that is observed as the arrow moves toward the target is kinetic energy starts to decrease as the arrow reaches nearer to the target and the potential energy is observed to increase.
So, in short, the energy transformation is from kinetic energy from a moving arrow to potential energy when the arrow hits the target.
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A chemical change Group of answer choices occurs when powdered lemonade is stirred into water. occurs when methane gas is burned. occurs when water is vaporized. occurs when salt is dissolved in water. occurs when paper is shredded.
A Chemical change occurs when methane gas is burned.
What is Chemical change ?A chemical change is a change of materials into another, new materials with different properties and one or more than one new substances are formed.
A chemical change occurs when matter undergoes a change to form a new substance with different chemical properties, and the reaction is usually not reversible.
In this case,burning of methane gas (CH₄) considered as chemical change.
Oxygen and methane are the reactants, while the new substance formed from the reaction are carbondioxide (CO₂) and water (H₂O) as ;
CH₄ + O₂ ---> CO₂ + H₂O
Hence, Chemical change occurs when methane gas is burned.
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How many moles is 25g of ammonia (NH3)?
Explanation:
Ammonia has a formula mass of 17.031 g/mol, so the top blank is 1 and the bottom blank is 17.031
Calculating the product, we get the answer to be 1.5 mol
A piece of lithium is added to a beaker of water. Will the solution formed be acidic, alkaline or neutral?
Answer:
alkaline
Explanation:
Lithium reacts intensely with water, forming lithium hydroxide and highly flammable hydrogen. The colorless solution is highly alkalic.
According to the chemical reaction between lithium and water, lithium hydroxide is formed which is a basic substance.
What are chemical reactions?Chemical reactions are defined as changes which occur when a substance combines with another substance to form a new substance.Alternatively, when a substance breaks down or decomposes to give new substances it is also considered to be a chemical reaction.
There are several characteristics of chemical reactions like change in color, change in state , change in odor and change in composition . During chemical reaction there is also formation of precipitate an insoluble mass of substance or even evolution of gases.
There are three types of chemical reactions:
1) inorganic reactions
2)organic reactions
3) biochemical reactions
During chemical reactions atoms are rearranged and changes are accompanied by an energy change as new substances are formed.
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Calculate the mass of slver n grams depostedwhen 10.920 coulombs of electrcty s passed through a soluton of slver salt. (Ag= 180, 1 faraday-96500C)
30 points!!!! Answer fast
EXPERIMENT: MAGNETISM Bar Magnet
1. Place the bar magnet on a table.
2. Put a sheet of glass or plastic over the magnet.
3. Sprinkle the iron filings over the sheet evenly.
4. On a separate paper, sketch the magnet. Show the lines made by the iron filings. Horseshoe Magnet
5. Place a horseshoe magnet on the table.
6. Put a sheet of glass or plastic over the magnet.
7. Sprinkle the iron filings over the sheet.
8. On a separate paper, sketch the magnet. Show the lines made by the iron filings. N Pole to N Pole
9. Place two bar magnets N pole to N pole with an inch between them.
10. Put a piece of glass or plastic over the magnets.
11. Sprinkle the iron filings over the glass or plastic.
12. On a separate paper sketch the magnets. Show the lines made by the iron filings. N Pole to S Pole
13. Turn one of the bar magnets around so the magnets are N pole to S pole with an inch between.
14. Sprinkle the iron filings over the glass or plastic.
15. On a separate paper sketch the magnets. Show the lines made by the iron filings.
From the information you have observed, determine the following:
What rule of magnetism is illustrated by the lines of the iron filings in Step 12?
What rule of magnetism is illustrated by the lines of the iron filings in Step 15?
Why was glass or plastic used to separate the filings from the magnets in the experiments?
Did the glass or plastic stop the passage of the magnetic lines of force?
Did the iron filings almost or completely bridge the open end of the horseshoe magnet?
The magnetism is either created inside a given element by passing some number of charges,Q across it or it is due to the interaction with a permanent magnet.
What is Magnetism ?
A physical phenomenon produced by the motion of electric charge, which results in attractive and repulsive forces between objects.
The magnet consists the characteristics of having an optimum amount of energy (P.E inside it) inside it.
As, the energy lines are either directed outwards from the north pole of the magnet, the south pole of the magnet consumes or absorbs the magnetic rays(energy lines) originated from the north pole of the magnet.
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Q2:- Which branch of chemistry deal with the structure and properties of naturally occurring molecules?
Answer:
Explanation:
Organic ChemistryOrganic Chemistry It is often known as the 'Chemistry of Life' that deals with the structure, properties and reactions of organic compounds. A study of Organic Chemistry helps students to identify and classify the various naturally occurring compounds and to create one with desired properties and functions.
The branch of chemistry that deals with the structure and properties of naturally occurring molecules is Organic Chemistry.
What is Organic chemistry?Chemistry is divided into several branches in which we learn inorganic chemistry, Physical chemistry, analytical chemistry and also organic chemistry. Organic chemistry deals with natural compounds in which we learn about chemical and physical properties of natural compounds and then the structures of organic compounds as well. We study about the formation of different organic compounds and which kind of compounds will be useful in which field.
For example- Alcohols can be used in vehicles, as solvents, it can be used to form many other organic compounds as well.
Aldehydes, Ketones are the organic compounds which has medicinal use and helps in forming other compounds as well.
Therefore, The branch of chemistry that deals with the structure and properties of naturally occurring molecules is Organic Chemistry.
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How many moles of propane
react when 294 g of CO2 form?
C3H8 +502 → 3CO₂ + 4H₂O
2.23 moles of propane react when 294 g of CO₂ is formed .
What is moles ?Moles is a unit which is equal to the molar mass of an element.
A reaction is given
C₃H₈ +50₂ → 3CO₂ + 4H₂O
Grams of CO₂ formed = 294 gm
In moles = 294 /44 = 6.68 moles.
Let x be the moles of C₃H₈ is x
Mole ratio of CO₂ to C₃H₈ = 3 : 1
so
6.68 /x = 3/1
x = 6.68 /3 = 2.23 moles
Therefore 2.23 moles of propane react when 294 g of CO₂ is formed .
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The valence electrons found in metallic bonds are different from other bonds
because
A. their valance electrons are free-roaming
B.they allow conductivity of electricity
C.their valence electrons are immobile
D. They’re able to share electrons with other atoms
Answer:
their valence electrons are free roaming
calculate the amount of glucose required to prepare 250g of 5% sugar solution
Answer:
12.5g
Explanation:
1. Percentage of solution = 5.
2. Mass of solution = 250g.
3. = Mass of solute / 250 x 100.
4. = 5 x 250 / 100.
5. = 12.5g.
A 208.1 mL sample of gas exerts 574.6 mm Hg pressure at 44.4 ºC. What pressure does it exert at 68.1 ºC if the volume expands to 401.5 mL?
a. 320
b. 457
c. 190
d. 917
Answer:
a. P = 320 mmHg
Explanation:
For this problem, the pressure, volume, and temperature are changing, so we'll need to combine Boyle's Law and Charles' Law:
[tex]\dfrac{P_1V_1}{T_1}=\dfrac{P_2V_2}{T_2}[/tex]
For this equation, the temperatures must be measured in Kelvin. The rest of units in the equation only need to match between beginning and end conditions.
Recall that to convert from Celsius to Kelvin, add 273, or use the equation [tex]T_C+273=T_K[/tex].
So [tex]T_1=(44.4+273)[K]=317.4[K][/tex] and [tex]T_2=(68.1+273)[K]=341.1[K][/tex]
Substituting known values, we can solve for the unknown:
[tex]\dfrac{P_1V_1}{T_1}=\dfrac{P_2V_2}{T_2}[/tex]
[tex]\dfrac{(574.6[mmHg])(208.1[mL])}{(317.4[K])}=\dfrac{P_2(401.5[mL])}{(341.1[K])}[/tex]
[tex]\dfrac{(574.6[mmHg])(208.1[mL]\!\!\!\!\!\!\!\!\!\!{--} )}{317.4[K]\!\!\!\!\!\!{-}}*\dfrac{341.1[K] \!\!\!\!\!\!{-}}{401.5[mL] \!\!\!\!\!\!\!\!\!\!\!{--} }=\dfrac{P_2(401.5[mL] \!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!{-----})}{341.1[K] \!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!{----}}*\dfrac{341.1[K] \!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!{----}}{401.5[mL] \!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!{-----} }[/tex]
[tex]320.056719296[mmHg]=P_2[/tex]
Accounting for significant figures, [tex]P_2=320.1[mmHg][/tex].
The closest answer provided is 320, so "a".
Which of the following compounds would make a good electrolyte?
Select one:
O a. ethanol
O b. carbon dioxide
O c. sodium chloride
O d. water
Answer:
C. Sodium Chloride.
Explanation:
Because when NaCl dissolved in water, it will dissociate to produce 2 ions Na+ and Cl-.
IB Chemistry SL Question - Empirical/Molecular formulae
A 4.406g sample of a compound containing only C, H and O was burnt in excess oxygen. 8.802g of CO2 and 3.604g of H2O were produced.
i) Determine the empirical formula of the compound (section 6 of the data booklet)
ii) Determine the molecular formula of this compound if its molar mass is 88.12gmol-1
Answer:
(i)
Explanation:
is it right
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Hich statement about scientific consensus is true? a. it represents the beliefs of most scientists. b. it is the only way to prove a theory true. c. it is necessary to form a hypothesis. d. it is an assurance that the interpretations of a study are correct. e. it is necessary before research can be published in a science journal.
A compound has an empirical formula C₂H4S.
What is its molecular formula, if its molar
mass is 168 g/mol?
This means that the molar mass of [tex]\text{C}_{2}\text{H}_{4}\text{S}[/tex] is
[tex]2(12.011)+4(1.00794)+32.06=60.11376[/tex]
Dividing this by the given molar mass, we get [tex]\frac{168}{60.11376} \approx 3[/tex]
So, the molecular formula is about [tex]\boxed{\text{C}_{6}\text{H}_{12}\text{S}_{3}}[/tex]
if element X has two valence electrons and element Y has five valence electrons the formula for the compound is?
Answer:
the answer to the question is X3Y2
What molecule is shown below?
Answer: 3 methylhexane
Explanation: Attached is a picture of the molecule. Courtesy of the National Institute of Health, United States Government.
Answer: 3-methylhexane
Explanation:
The parent chain is six carbon atoms long, so there is the prefix 'hex'
There is a methyl branch on the third carbon atom, so it is 3-methylhexane.
If you take a 10.0 mL portion of a 14.8 M solution of NH3 and dilute it to a total solution volume of 0.500 L, what will be the concentration of the final solution
Answer:
no idea about this question sorry
A can of coke which is 12.0ml and is at a temperature of 18.0°C is placed into a refrigerator freezer. The
can was accidently left over night and the temperature dropped to -1.00°C. What would happen to the
volume of the coke can?
Answer:
See below
Explanation:
Volume would decrease to temp of approx 4 C then it would slightly increase to the 1 degree C point but it would still be a smaller volume than at 18 C .
( this assumes a freezing point of - 1.11 C for Coke )
Please select the word from the list that best fits the definition
Rock that is formed from the remains of older rocks and organisms
Super position
Radioactive dating
Sedimentary
Igneous
Metamorphic
Rock Cycle
Why do you need to combust benzoic acid before testing the "unknown" sample you are interested in? Why do you need to combust more than one sample of the "unknown" you are testing?
Various samples of the must be combusted in other to obtain a reliable result.
What is a bomb calorimeter?The bomb calorimeter is used to obtain the energy of a sample. This is called the energy equivalent or the energy value of the sample.
Now, we know that the bomb calorimeter is calibrated by the use of benzoic acid hence it must be combusted first to obtain the basic energy value of the calorimeter.
Various samples of the must be combusted in other to obtain a reliable result.
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What is the change in freezing
point, ATf, when the 0.195 m
aqueous solution of K2S dissolves
into 3 particles?
-1.09'C is the change in freezing point
“Freezing point depression” depends on the solvent and the molar concentration of the solute.
Sulfide is highly basic, consequently
K2S
completely and irreversibly hydrolyzes in water according to the following equation:
K2S+H2O→KOH+KSH
What is freezing?Freezing, also known as solidification, is a phase transition where a liquid turns into a solid when its temperature is lowered below its freezing point.
the temperature at which a liquid solidifies specifically : the temperature at which the liquid and solid states of the substance are in equilibrium at atmospheric pressure : melting point the freezing point of water is 0° Celsius or 32° Fahrenheit.
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Answer:1.0881
Explanation:
What mass of YCL3 forms when 10.0 grams of each reactant are combined?
The mass of [tex]YCl_3[/tex] that would be formed will be 18.22 grams
Stoichiometric calculationsLet us first look at the balanced equation of the reaction:
[tex]2Y + 3Cl_2 --- > 2YCl_3[/tex]
The mole ratio of Y to [tex]Cl_2[/tex] is 2:3.
Mole of 10.0 grams of Y = 10/88.9 = 0.11 moles
Mole of 10.0 grams [tex]Cl_2[/tex] = 10/71 = 0.14 moles
3/2 of 0.11 = 0.165. Thus, [tex]Cl_2[/tex] is limiting in availability.
Mole ratio of [tex]Cl_2[/tex] and [tex]YCl_3[/tex] = 3:2
Equivalent mole of [tex]YCl_3[/tex] = 2/3 x 0.14 = 0.093 moles.
Mass of 0.093 moles [tex]YCl_3[/tex] =0.093 x 195.26 = 18.22 grams
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The speed of light through space is
The speed of light through space is 300 million m/s .
What is the limit of the speed ?There was a time when everybody thought that there is no limit for the speed at which an object can travel , but Einstein gave the limit which is the speed of light.
The speed of the light in vacuum travels at a speed of 300 million m/s .
Therefore The speed of light through space is 300 million m/s .
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Most alkaline permanent waves have a pH between:
The alkaline permanent waves have a pH between 9.0 to 9.6.
What are Alkaline permanent waves?Alkaline permanent waves are chemical that is apply to the hair. The alkaline perm makes the hair curly or wavy.
The major ingredient is the ammonium thioglycolate and ammonium hydroxide.
The alkaline permanent wave is alkaline in nature and the pH scale for alkaline substances are higher.
pH of 7 depicts neutrality while pH of 7 and above depicts alkalinity.
Therefore, alkaline permanent waves have a pH between 9.0 to 9.6.
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How many grams of butane were in 1. 000 atm of gas at room temperature?
The mass in grams of butane at standard room temperature is 53.21 grams.
How can we determine the mass of an organic substance at room temperature?The gram of an organic substance at room temperature can be determined by using the ideal gas equation which can be expressed as:
PV = nRT
1 × 22.4 L = n × (0.0821 atm*L/mol*K× 298 K)
n = 22.4/24.4658 moles
n = 0.91556 moles
Recall that:
number of moles = mass(in grams)/molar massmass of butane = 0.91556 moles × 58.12 g/mole
mass of butane = 53.21 grams
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Which best describes two ways in which hydrogen is involved in photosynthesis?
O1-Hydrogen is stored in leaves of plants.
2-Hydrogen combines with carbon dioxide to make glucose.
O1-Hydrogen is stored in leaves of plants.
2- Hydrogen combines with oxygen to make water.
O 1-Hydrogen enters plants as a component of water.
2-Hydrogen combines with carbon dioxide to make glucose.
O1-Hydrogen enters plants as a component of water.
2- Hydrogen combines with oxygen to make carbon dioxide.
Answer:
1- Hydrogen enters plants as a component of water.
2-Hydrogen combines with carbon dioxide to make glucose.
Explanation:
Hydrogen enters the plant bonded with Oxygen as water (H2O).
The water molecule splits and the Hydrogen combines with carbon dioxide to make glucose.
Answer:
1 - Hydrogen enters plants as a component of water.
2 - Hydrogen combines with carbon dioxide to make glucose.
Explanation:
why do crystals form during crystallisation
Answer: Crystallization is a technique which chemists use to purify solid compounds. Crystals often form in nature when liquids cool and start to harden. Certain molecules in the liquid gather together as they attempt to become stable. They do this in a uniform and repeating pattern that forms the crystal. The process is based on the principles of solubility: compounds (solutes) tend to be more soluble in hot liquids (solvents) than they are in cold liquids. If a saturated hot solution is allowed to cool, the solute is no longer soluble in the solvent and forms crystals of pure compound. Impurities are excluded from the growing crystals and the pure solid crystals can be separated from the dissolved impurities by filtration.
For an example the salt we get from seawater can have many impurities in it. Hence, the process of crystallization is in use to remove these impurities.
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As the solution cools, the solvent can no longer hold all of the solute molecules, and they begin to leave the solution and form solid crystals.
During this cooling, each solute molecule in turn approaches a growing crystal and rests on the crystal surface.
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what is electron
and the unit