Answer:
A
Explanation:
i had answer it and it was A
Show the calculation of the molality of a solution made by dissolving 15.9 grams of Ca3(PO4)2 in 400 grams of water.
The molality of a solution : 0.128 m
Further explanationGiven
15.9 g of Ca3(PO4)2 in 400 grams of water.
Required
The molality
Solution
molality = mol solute / kg solvent
solute= Ca3(PO4)2(MW=Molecular Weight: 310.2 g/mol)
mol solute :
[tex]\tt \dfrac{15.9}{310.2}=0.0512[/tex]
The molality :
[tex]\tt \dfrac{0.0512}{0.4~kg}=0.128~m[/tex]
Which statement describes a physical change? *
A. An iron bolt on a bridge rusts and weakens the bridge.
B. The surface of a silver cup turns black when it is exposed to air.
C. A sculptor casts a statue in molten bronze and allows it to harden.
D. Slivers of magnesium in fireworks form a bright glow as they burn.
The statement that describes a physical change is a sculptor casts a statue in molten bronze and allows it to harden. The correct option is C.
What are physical changes?"A physical change is one that simply affects the physical nature of the substance." Usually, increasing the temperature or applying pressure, both, will cause a physical change. In other words, physical changes are reversible.
All the other options like rusting of iron bolts on a bridge is a chemical change when iron reacts with oxygen in the air, it gets rust.
Similarly, silver cups exposed to air react with air is a chemical change, and option d, silver off magnesium that creates light, is also a chemical change.
Thus, the correct option is C. A sculptor casts a statue in molten bronze and allows it to harden.
To learn more about physical changes, refer to the below link:
https://brainly.com/question/21509240
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Q 16.1: Select the first step in the Wittig reaction. A : The alkyltriphenylphosphonium halide is deprotonated by a base to make a phosphorus ylide. B : The phosphorus ylide reacts with the aldehyde or ketone to make an oxaphosphetane. C : Triphenylphosphine attacks the alkyl halide to produce an alkyltriphenylphosphonium halide. D : The oxaphosphetane decomposes to form the alkene and triphenylphosphine oxide.
Answer:
The phosphorus ylide reacts with the aldehyde or ketone to make an oxaphosphetane.
Explanation:
The Wittig reaction is a reaction that occurs between a phosphorus ylide and an aldehyde or ketone. The final products are an alkene and triphenyl phosphine oxide.
The first step in the reaction is the attack of the phosphorus ylide on the aldehyde or ketone. This is followed by attack of oxygen on phosphorus to form a [2+2] cycloaddition product (oxaphosphetane) which decomposes to form the alkene and triphenylphosphine oxide.
how can use a BIPHASIC LIQUIDS
Answer:
BIPHASIC LIQUIDS are used ear cleaning, to softening the wax so that mild infections can be treated.
Explanation:
BIPHASIC LIQUIDS are liquids that contain two immiscible phases, one is suspension and the other is emulsion. In suspension, the finely solid are dispersed in a liquid or semi solidwhich is use for medicament
The emulsion consist of immiscible liquids, one is dispersed in globules.
They are used ear cleaning, to softening the wax so that mild infections can be treated.
explain the early theories of the atomic structure
Hi
i hope this helps
Answer:
The Greek atom theory
Explanation:
The concept of the Greek atomos theory is an indivisible particle of matter, goes back to ancient Greece and a man named Democritus held that all matter could be subdivided only until some finite particle was reached.
Experiment: Turn on Show electronegativity. Electronegativity (EN) describes how strongly an atom attracts a pair of shared electrons. The higher the EN value, the greater the tendency of an atom to hold onto electrons in a bond and become negatively charged. Electronegativity difference is found by subtracting the EN value of one atom from another. Choose two nonmetals with a small (or no) EN difference between them. Click Play. What happens to the shared electrons in this bond
Answer:
See explanation
Explanation:
If we take two nonmetals with little or no electronegativity difference between them, the shared electrons are not attracted greatly towards any of the bonding atoms. In other words, the shared electrons remain equidistant between the nuclei of the two bonding atoms.
The bond is nonpolar since polarity is introduced into covalent bonds by a significant difference in electronegativity of the bonding atoms.
5x10-6 mol Na2C2O4 bileşiğinde kaç tane O atomu vardır?
How many oxygen atoms are present in 5x10-6 mol Na2C2O4 ?
There are 1.204 x 10¹⁹ atoms O
Further explanationThe empirical formula is the smallest comparison of atoms of compound forming elements.
A molecular formula is a formula that shows the number of atomic elements that make up a compound.
1 mol of molecule Na₂C₂O₄ :
There are 4 mol of O in 1 mol of molecule Na₂C₂O₄
So for 5 x 10⁻⁶ mol Na₂C₂O₄ :
[tex]\tt mol~O=4\times 5.10^{-6}=2.10^{-5}[/tex]
1 mole = 6.02.10²³ particles , so number of atoms O :
[tex]\tt 2\times 10^{-5}\times 6.02\times 10^{23}=1.204\times 10^{19}[/tex]
a) Calculate the standard reaction entropy for the combustion of methane to carbon dioxide and liquid water at 298 K. b) Calculate the standard reaction entropy for the hydrolysis of liquid water to form oxygen and hydrogen gas. c) Do your results in (a) and (b) agree with the general rule that reaction entropies are positive if there is a net formation of gas in a reaction, and negative if the is a net reduction of gas?
Answer: (a) [tex]\Delta S^{0}[/tex] = - 242.2J/K.mol
(b) [tex]\Delta S^{0}[/tex] = 163.34J/K.mol
(c) Yes
Explanation: Entropy is the measure of randomness or disorder of a system. Standard Entropy has the symbol [tex]S^{0}[/tex].
Mathematically, Entropy is defined as
[tex]\Delta S^{0}=\Sigma S^{0}(products)-\Sigma S^{0}(reagents)[/tex]
Each substance has its own entropy value.
(a) Combustion of Methane:
[tex]CH_{4}+2O_{2}[/tex] ⇒ [tex]CO_{2}+2H_{2}O[/tex]
Using standard entropy table, entropy will be:
[tex]\Sigma S^{0}(products)=214+2(69.91)[/tex] = 353.8
[tex]\Sigma S^{0}=186.264+2(205.138)[/tex] = 596.54
[tex]\Delta S^{0}=[/tex] 353.8 - 596.54
[tex]\Delta S^{0}=[/tex] - 242.2
Standard Entropy for combustion of methane is [tex]\Delta S^{0}=[/tex] - 242.2 J/K.mol.
(b) Hydrolysis of Water:
[tex]H_{2}O_{(l)}[/tex] ⇒ [tex]H_{2}_{(g)}+1/2O_{2}_{(g)}[/tex]
[tex]\Sigma S^{0}(products)=130.684+0.5(205.138)[/tex] = 233.253
[tex]\Sigma S^{0}(reagents)=69.91[/tex]
[tex]\Delta S^{0}=[/tex] 233.253 - 69.91
[tex]\Delta S^{0}=[/tex] +163.34
Standard Entropy for hydrolysis of water is [tex]\Delta S^{0}=[/tex] + 163.34 J/K.mol
(c) Yes, the results prove the general rule: Reactions Entropies are positive for net formation of gas and negative for net reduction of gas. This happens because, as entropy is the measure of disorder, the entropy for gases are greater than for liquids and solids. So, when there is formation of a gas, Entropy increases and when there isn't, entropy decreases.
What is the concentration of a solution made by diluting 35 mL of 6.0 M HCl to a final volume of 750 mL?
If 2.49g of CuNO3 is dissolved in water to make O.830M solution, what is the volume of the solution in milliliters?
How many moles of NaOH are present in 13.5mL of 0.17 M NaOH?
Answer:
1. 0.28M
2. 24mL
3. 0.002295moles of NaOH.
Explanation:
1. The 6.0M HCl solution is diluted from 35mL to 750mL, that is:
750mL / 35mL = 21.43 times
The 6.0M HCl solution is diluted 21.43 times, the final concentration is:
6.0M / 21.43 = 0.28M
2. First, we need to convert grams of CuNO3 to moles and then, as molarity is moles per liter we can solve for volume of solution in liters and convert it to mililiters:
Moles CuNO3 -Molar mass 124.9g/mol:
2.49g * (1mol / 124.9g) = 0.020 moles of CuNO3
Volume is:
0.020 moles * (1L / 0.830mol) = 0.0240L * (1000mL / 1L) = 24mL
3. In 13.5mL = 0.0135L of 0.17M NaOH the moles are:
0.0135L * (0.17mol / L) = 0.002295moles of NaOH
Create an atom diagram using the Bohr model. Directions Choose three elements from the following list. Use a periodic table to determine the number of protons, neutrons, and electrons. Draw a diagram of each element you have selected. Use a separate piece of paper for each element. Be sure your drawing is neat, legible, and accurate. Use this data table to record information about each element. Element #1 Element #2 Element #3 Element #4
Answer:
Explanation:
proposed an early model of the atom as a central nucleus containing protons and neutrons being orbited by electrons in shells. As previously discussed, there is a connection between the number of protons in an element, the atomic number that distinguishes one element from another, and the number of electrons it has. In all electrically-neutral atoms, the number of electrons is the same as the number of protons. Each element, when electrically neutral, has a number of electrons equal to its atomic number.
Answer:
You can check diagram with number of proton neutron and electrons
Explanation:
Which compound would you expect to be soluble in the nonpolar solvent carbon disulfide?
Answer:
hexane C6H14
IS YOUR ANSWER
Explanation:
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When the volume of a gas is
changed from 3.6 L to 15.5 L, the
temperature will change from
°C to 87°C.
Assume that the number of moles and the
pressure remain constant.
Be sure to notice that temperatures are
given in °C!
Answer:
-189.55°C
Explanation:
Given data:
Initial volume of gas = 3.6 L
Final volume of gas = 15.5 L
Initial temperature = ?
Final temperature = 87°C (87+273 = 360 K)
Solution:
The given problem will be solve through the Charles Law.
According to this law, The volume of given amount of a gas is directly proportional to its temperature at constant number of moles and pressure.
Mathematical expression:
V₁/T₁ = V₂/T₂
V₁ = Initial volume
T₁ = Initial temperature
V₂ = Final volume
T₂ = Final temperature
Now we will put the values in formula.
V₁/T₁ = V₂/T₂
T₁ = V₁T₂ /V₂
T₁ = 3.6 L × 360 K / 15.5 L
T₁ = 1296 L.K / 15.5 L
T₁ = 83.6 K
Kelvin to °C:
83.6 K - 273.15 = -189.55°C
ANSWERS PLEASE HELP 20 MINUTES LEFT????!!!!?!!???
Answer:
Explanation:
b
PLEASE HELP WILL GIVE BRAINLIEST
Answer:
Coefficients represents no of moles while subscripts represent no of atoms.
Answer:
Coefficients came before formula . Example = 4CO means there are 4 molecules of carbonmonooxide.
Subscripts came after and below the formula . Example = Oxygen gas in which 2 is a subscript which means there are 2 atoms of Oxygen in 1 molecule of Oxygen i.e. oxygen gas
which event would most likely lead to a thunderstorm g i v i n g b r a i n l e s i t
Answer:
A
Explanation:
I took a test like this and my teacher said this was right so ye. hopefully I remembered correctly if its wrong im sorry ;C
Answer: A
Explanation: A thunderstorm forms when warm, moist air rises into cold air. Hope this helps. :)
Conservation of mass to balance the following reaction. Na2S+ KI= NaI+ K2S
Answer:
1+2=2+1 is the answer for the question
Which force keeps the planets from floating off into space?
Earth’s gravity
the Sun’s gravity
the moon’s gravity
Milky Way’s gravity
Answer:
Suns gravity
Explanation:
Answer: 2021
B
The Sun's gravity
Explanation: Just took the big test
Help me if you know this pleaseeee
Answer:
help you with what?
Explanation:
In a molecule of calcium sulfide, calcium has two valence electron bonds, and a sulfur atom has six valence electrons. How many lone pairs of electrons are present in the Lewis structure of calcium sulfide?
A. one
B. two
C. three
D. four
E. none
Also, state why.
Answer:
E
because it forms the ionic bond but not covalent.
what is a common use for electromagnets
Answer:
Electromagnets are widely used as components of other electrical devices, such as motors, generators, electromechanical solenoids, relays, loudspeakers, hard disks, MRI machines, scientific instruments, and magnetic separation equipment.
Explanation:
Hope this helps :)
(didn't get this from the internet)
Which chemical equation below is not balanced?
- 3 MgSO4 + 2 Nag PO4 → Mgs (PO4),+3 Na, S04
- 2 NaOH + HNO, → NaNO, + 2 H,0
- CH12 O6 4 6O2 → 6 CO, + 6 H,0
- HBr AGNO, → HNO, + AgBr
pic if needed ;)
Answer:
B
Explanation:
The second one is not balanced correctly.
2 NaOH + 2HNO3 → 2NaNO3 + 2 H20
I didn't notice this before but it can be balanced without the twos.
NaOH + HNO3 → NaNO3 + H20
It was still wrong. It needed to have the twos removed, not 2 more added. Adding two more isn't wrong, but it should be balanced without 2s if at all possible.
Suppose that all you know about a certain electron is that its principal quantum number is 3. What are the possible values for the other four quantum numbers
Answer:
Other possible quantum numbers would be.
A). When n = 3,
I = 0,
m1 = 0
ms = +1/2 or -1/2
B). When I = 1,
m1 = -1 or +1
ms = +1/2 or -1/2
C). When I = 2
m1 = -2,-1,0,1 or 2
ms = +1/2 or -1/2.
bond energy is the greatest for?. a: Ch4 b: O2 c: N2 d: Cl2
It's answer is c. N2
The maximum bond energy is of N2 because N2 molecule is formed by 3 covalent bonds and O2 molecule is formed by 2 covalent bonds.
Hope it helps :)
What happens to a rock formation that undergoes a repeated and frequent freeze and thaw cycle of water?
Answer:
Water from melting snow or rainfall infiltrates into cracks in rocks. ... As this process of freezing and thawing happens repeatedly, the rock begins to weaken and eventually breaks apart into angular fragments.
Explanation:
Water melting from snow or rainfall which infiltrates into cracks in rocks, this is repeated process of freezing and thawing, the rock begins to weaken and eventually breaks apart into angular fragments.
What are types of rock layers ?A rock can be formed due to the aggregation of mineral constituents in the earth’s crust and it can be classified is based on different factors like Geological classification, Physical classification, Chemical classification.
Geological classification can be either Sedimentary rock formed by the deposition of sediments by the weathering of pre-existing rocks and it can be carried out by various agents like water, wind, gravity, etc.
Igneous rocks formed by the solidification of magma below the earth’s surface which is held together below the earth’s surface and unable to descend, when these magma cools down and solidifies into igneous rocks.
Learn more about rock layer, here:
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Because of gravity, your weight
on the Moon
A. would be the same as it is on Earth
B. would be less than your weight on Earth
C. would be more than your weight on Earth
D. and your mass would be less than it is on Earth
Answer:
the answer is b
Explanation:
brcause the gravutational pull on the moon is lower than on earth...
At room temperature (20 °C), milk turns sour in about 64 hours. In a refrigerator at 3 °C, milk can be stored three times as long before it sours.
(a) Estimate the activation energy of the reaction that causes the souring of milk.
(b) How long should it take milk to sour at 40 °C?
Answer: Since k2 corresponds to 64 hours, the time for the milk to sour at 40 C is 64 h / 9.38 = 6.8 hours.
Explanation:
At temperature T1, the Arrhenius Equation is:
k1 = Ae^(-Ea/RT1).
An equivalent equation can be written at T2:
k2 = Ae^(-Ea/RT2).
If these equations are divided, then A cancels:
k1/k2 = e^(-Ea/RT1)/e^(-Ea/RT2)
Taking the natural log:
ln(k1/k2) = (Ea/RT2)-(Ea/RT1);
or:
ln(k1/k2) = (Ea/R)(1/T2 - 1/T1)
We can infer from the question that the milk sours 3 times as fast at the higher temperature (let's call it T1), so we can arbitrarily call k2 = 1 and k1 = 3.
a) Substitute:
ln(3) = (Ea/R)(1/276.15 K - 1/293.15 K).
We get Ea/R = 5231.6. Multiply this by whatever value of R you choose to get Ea in your favorite energy unit. Remember the sig figs.
b) Again, let's let the lower temperature = T2, since we have defined k2 = 1:
ln(k1) = (5231.6)(1/276.15 K - 1/313.15);
ln(k1) = 2.24, so k1 = 9.38.
Since k2 corresponds to 64 hours, the time for the milk to sour at 40 C is 64 h / 9.38 = 6.8 hours.
4. Kendrick drags his bat out to play baseball. which statement best describes the science of what he did?
O Kendrick would use less energy if he dragged the bat faster.
Kendrick did not have to work to move the bat because he dragged it.
Kindrick gave the bat potential energy.
Kindrick gave the bat kinetic energy.
Explanation:
Kendrick gave the bat potential Energy
How many grams of oxygen, O2 are produced if 52.0g of potassium chlorate, KClO3, decomposes? (The molar mass of O2 = 32 g/mol and the molar mass of KClO3 = 122.4 g/mol).
Answer:
20.39 g of O2.
Explanation:
We'll begin by writing the balanced equation for the reaction. This is illustrated below:
2KClO3 —> 2KCl + 3O2
Next, we shall determine the mass of KClO3 that decomposed and the mass of O2 produced from the balanced equation. This is illustrated below:
Molar mass of KClO3 = 122.4 g/mol
Mass of KClO3 from the balanced equation = 2 × 122.4 = 244.8 g
Molar mass of O2 = 32 g/mol
Mass of O2 from the balanced equation = 3 × 32 = 96 g
Summary:
From the balanced equation above,
244.8 g of KClO3 decomposed to produce 96 g of O2.
Finally, we shall determine the mass of O2 produced from the decomposition of 52 g of KClO3. This can be obtained as follow:
From the balanced equation above,
244.8 g of KClO3 decomposed to produce 96 g of O2.
Therefore, 52 g of KClO3 will decompose to produce =
(52 × 96)/244.8 = 20.39 g of O2.
Thus, 20.39 g of O2 is produced.
The table shows four reactions.
Reactions
Reaction Equation
C₃ H8+ 50₂ 3C02 + 4H20
2Ca + O2- 2CaO
AgNO3 + NaCl
AGCI + NaNO3
CH3COOH + 202 - 2CO2 + 2H20
4
Which of the above reactions is an example of combustion of an Inorganic substance? (5 points)
Answer: 2
Explanation:
A combustion reaction must include O2 as a reactant.
An inorganic substance almost never includes carbon.
So, by process of elimination:
1. Carbon is a reactant = probably not
2. Has O2, no carbon = yes
3. O2 is not a reactant = no
4. Carbon is a reactant = probably not
An example of the combustion of an inorganic substance is:
2 Ca + O₂ ⇒ 2 CaO
We have 4 reactions and we want to determine which is an example of combustion of an inorganic substance.
What is combustion?A combustion reaction is a reaction in which a substance reacts with oxygen gas, releasing energy in the form of light and heat.
What is the difference between organic and inorganic substances?Organic substances always contain carbon while most inorganic substances do not contain carbon.
Let's consider the following reactions.
C₃H₈ + 5 O₂ ⇒ 3 CO₂ + 4 H₂OThis is a combustion reaction but C₃H₈ is an organic substance.
2 Ca + O₂ ⇒ 2 CaO
This is an example of the combustion of an inorganic substance.
AgNO₃ + NaCl ⇒ AgCI + NaNO₃
This is not a combustion reaction.
CH₃COOH + 2 O₂ ⇒ 2 CO₂ + 2 H₂O
This is a combustion reaction but CH₃COOH is an organic substance.
An example of the combustion of an inorganic substance is:
2 Ca + O₂ ⇒ 2 CaO
Learn more about combustion here: https://brainly.com/question/4155165
What are the respective central-metal oxidation state, coordination number, and overall charge on the complex ion in Na2[Cr(NH3)2(NCS)4]?
A) +3; 6; -1
B) +2; 6; -2
C) +1; 6; -2
D) +3; 6; +1
Answer:
B) +2; 6; -2
Explanation:
In order to know what the coordination number is, all we need to do is to count the number of ligands present in the coordination sphere. Coordination number refers to the number of ligands in the coordination sphere of a given complex. The coordination number here is 6.
The counter ion here is 2Na+. It means that the overall charge on the complex must be -2 because the magnitude of charge on the complex ion is exactly balanced by the number of counter ions.
The charge on the metal (x) must now be;
x + 0 + 4(-1) = -2
x - 4 = -2
x = -2 + 4
x = +2
Note that NH3 is designated as zero because it is a neutral molecule. Each NCS^- ion has a charge magnitude of -1.