Answer:
2.21m
Explanation:
Molality, m, is defined as the ratio between moles of solute (The substance that is in less amount, sodium sulfide) and kilograms of solvent (Water, in this case).
Thus, we need to convert mass of sodium sulfide to moles using its molar mass and grams of water to kilograms:
Moles Na2S (Molar mass: 78.0452g/mol):
37.5g * (1mol / 78.0452g) = 0.48 moles Na2S
Kilograms water:
217g * (1kg / 1000g) = 0.217kg
Molality:
0.48 moles Na2S / 0.217kg =
2.21mAnswer:
2.21
Explanation:
Scientists who are investigating what has happened over the years to the people who were exposed to radiation during the 1986 Chernobyl nuclear disaster are conducting what type of study
Answer:
Observational study
Explanation:
An investigation of what happened over the years to the people who were exposed to radiation during the 1986 Chernobyl nuclear disaster would be termed an observational study because it will require observing subjects and finding out if there is a kind of correlating factor in the subjects that could indicate the level of exposure to the nuclear radiation.
There are basically two types of research studies:
1. Observational studies
2. Experimental studies
Observational studies involve just the observation of subjects and trying to find out some correlation factors. This kind of study could be prospective when it deals with what could happen in the future based on certain factors or retrospective when it considers what has already happened. An observational study can be cross-sectional, case-only, case-control, or cohort study.
Experimental studies are also referred to as randomized or controlled trial studies. Here, subjects are grouped and each group receives a different treatment in order to isolate the effect of a particular factor or variable relating to the treatment.
How is the kinetic energy of the particles of a substance affected during a phase change?
Kinetic energy increases during exothermic changes and decreases during endothermic changes.
Kinetic energy decreases during exothermic changes and increases during endothermic changes.
Kinetic energy does not change, but the potential energy does.
Kinetic energy changes in the opposite way that the potential energy changes.
Answer:
its c on edge 2021
Explanation:
During phase change, kinetic energy does not change, but the potential energy does. Therefore, the correct option is option C among all the given options.
What is kinetic energy?Kinetic energy is a type of power that a moving object or particle possesses. An item accumulates kinetic energy when work, which involves the transfer of energy, being done on it by exerting a net force. A moving object and particle has kinetic energy, which relies on both its mass and its rate of motion.
This formula only works for particles traveling at low to moderate speeds; for particles traveling at extremely high speeds, it produces results that are too low. The rules of relativity must be applied when an object's speed approaches the speed of light (3 108 meters per second, about 186,000 miles per second). During phase change, kinetic energy does not change, but the potential energy does.
Therefore, the correct option is option C among all the given options.
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Which substance would have the highest melting point, based on electronegativity?
H2O
H2S
H2Te
H2Se
Answer:
H₂O
Explanation:
Based electronegativity, water H₂O will have the higher melting point from the given choices. The binding force between hydrogen and oxygen is greater than for the others.
In group 6, oxygen has the highest electronegativity. It pulls the shared electron closer in the bond. The high electronegativity between hydrogen and oxygen causes the elevated melting point between the two species.Answer:
H2O
Explanation:
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Answer:
I play!!!!!!!!
Explanation:
Graphic organizer: Use the terms in the word bank to complete the graphic organizer below
Answer:
1. Chemical reactions
2.Substances
3. Properties
4. Precipitate
5. Light
6. Temperature
7. Color
8. Gas
Explanation:
Chemical reactions are known to produce new substances which have new properties. During the chemical reactions, evidences that are seen are formation of precipitate or light gel, production of gas and change in temperature and color.
Chemical reactions occur when chemical substances come together to react because those substances are compatible with each other.
Fossil fuels contribute to about 85% of the total energy produced in the world. What is a direct environmental
consequence of the extensive use of fossil fuels?
Answer:your a poop face
Explanation:
Imagine not knowing the answer
Answer: C
Explanation:
which type of energy is stored as sugars in plant leaves?
1. Chemical
2. Elastic
3. Electrical
4. Mechanical
Answer:
chemical energy
Explanation:
Photosynthesis is the process plants and some algae use to convert light energy to chemical energy stored as sugar within chloroplasts -- the energy factories found in plant cells.
Balance the following chemical equations:
N2+02___N2O
Answer:
Balance the following chemical equations:
Explanation:
2N2 + O2 → 2N2O
A gas in a sealed container has an initial pressure of 125 kPa at 25.0∘C. If the pressure is increased to 150.0 kPa, what will the new temperature be?
Answer:
[tex]T'=30^{\circ} C[/tex]
Explanation:
Initial pressure, P = 125 kPa
Initial temperature, T = 25.0°C
If new pressure is increased to P' = 150.0 kPa
We need to find new temperature. According to Gay-Lussac's law,
P ∝ T
or
[tex]\dfrac{P}{T}=\dfrac{P'}{T'}\\\\T'=\dfrac{P'T}{P}\\\\T'=\dfrac{150\times 25}{125}\\\\=30^{\circ} C[/tex]
So, the new temperature will be [tex]30^{\circ} C[/tex].
In what phase is CO2 at 4 atm and -10°C is liquid, gas or solid? Starting from the same point, 4 atm and −10 °C, what phase change would eventually result from an increase in pressure?
a. vaporization
b. sublimation
c. freezing
d. deposition
e. melting
f. condensation
Answer:
(f).Condensation
CO2 exist as gaseous state at -10degree 4atm pressure and will become liquid upon increasing the pressure
Explanation:
Using The phase diagram of CO2 we observe that
Carbon dioxide at -10degree Celsius and 4atm pressure will be in
Gaseous phase. Starting from the same point, 4atm and -10degree Celsius upon increasing the pressure the Carbon dioxide will change into liquid phase above 5.11atm pressure, this happened due to Condensation.
Therefore CO2 exist as gaseous state at -10degree 4atm pressure and will become liquid upon increasing the pressure till 5.11stm.
The carbon dioxide has been existing in the gaseous state and with condensation, it has been converted to the liquid state. Thus, option F is correct.
The state of the gas at a particular pressure and temperature can be assessed from the phase diagram.
The state of Carbon dioxide at 4 atm and [tex]\rm -10^\circ C[/tex] have been the gaseous state.
The increase in pressure results in the decrease in the volume of the gas, as the pressure has been increased, the molecules will condense and result in the conversion of the gaseous state to the liquid state.
The carbon dioxide has been existing in the gaseous state at 4 atm and [tex]\rm -10^\circ C[/tex]. With the increase in pressure, the state of the gas has been changed to liquid due to condensation. Thus option F is correct.
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How many valence electron does sulfur
Explanation:
Sulfur has 6 valence electron
Valence electron shows group( in column)
how many moles of ethanol C2H6O, are in a 10.0g sample
Answer: 0.217 mol
Explanation:
To find the amount of moles in a 10 g sample, we need the molar mass of ethanol.
Molar Mass: 46.07 g/mol
Now that we have the molar mass, we can find moles.
[tex]10.0 g*\frac{1mol}{46.07g}=0.217 mol[/tex]
We know that there are 0.217 mol in a 10.0 gram sample.
the life of plutonium-239 is 24,300 years. if a nuclear bomb released 8kg of this isotope, how many years would pass before the amount is reduced to 1 kg.
Answer:
97200yrs,
Explanation:
Given parameters:
Half-life of Plutonium - 239 = 24300yrs
Mass of the isotope = 8kg
Unknown:
Number of years it will take for the amount to reduce to 1kg = ?
Solution:
The half -life of any substance is the time taken for half of the compound to decay to half its original composition.
Start first half life second half life third half life
mass 8kg 4kg 2kg 1kg
Time 0yrs 24300 48600 97200
By 97200yrs, the mass would have been 1kg
Of the molecules below, only ________ is polar.
a. Cl2
b. CS2
c. H2O
d. CBr4
e. PF5
Answer:
The correct answer is option c, that is, H2O.
Explanation:
The two broad classes of molecules are the polar and nonpolar molecules. Polarity illustrates the dispersion of electrical charge surrounding a molecule. The charge is unevenly distributed in a polar molecule, while it is distributed evenly in a nonpolar molecule. It can be said that a polar molecule possesses the regions of partial charge.
A polar molecule like water possesses a dipole, that is, a part of the molecule exhibit a partial negative charge, and the part of the molecule possesses a partial positive charge. Generally, a polar molecule comprises polar or ionic covalent bonds. The polar molecules are generally soluble in polar solvents and are hydrophilic. They have higher melting points because of the strong intermolecular forces between them in the form of hydrogen bonding.
In the given options, H2O is a polar molecule as the hydrogen atoms electrons get fascinated towards the oxygen atom's electrons, which forms a positive charge on the atoms of hydrogen, and a negative charge on the oxygen atom.
Of the molecules, only water (H₂O) is polar and the correct option is option C.
A polar molecule is a molecule that has a partial positive charge (+) and a partial negative charge (-) due to an uneven distribution of electron density. This occurs when there is a significant difference in electronegativity between the atoms within the molecule, causing the electrons to be pulled more towards one atom, creating a polarity.
In a polar molecule, the positive and negative charges are not balanced, resulting in a molecular dipole moment. The molecule may have a distinct positive and negative end, referred to as the poles.
Thus, the ideal selection is option C.
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Nitromethane (CH3NO2) is an explosive compound sometimes used as a fuel booster in racecars. What is the formal charge of the nitrogen in a nitromethane molecule?
a. -2
b. -1
c. 0
d. +1
Answer:
Option d. is correct
Explanation:
Nitromethane is an organic compound that can be used as a fuel booster in rockets. Its chemical formula is [tex]CH_3NO_2[/tex].
This compound is produced as a result of reaction of sodium chloroacetate with sodium nitrite in aqueous solution.
The electron-dot structure of a nitromethane molecule shows [tex]+1[/tex] charge on the nitrogen.
Option d. is correct
A graduated cylinder initially has 32.5 mL of water in it. After a 75.0 g piece of lead (Pb) is added to the graduated cylinder, the water level rises to the 39.1 mL mark. What is the the volume of the piece of lead.
Answer:
39.1-32.5 and you will find your answer it always like that, you subtract your starting point from your ending point
Explanation:
The volume of the piece of lead is 6.6 mL
From the question given above, the following data were obtained:
Volume of water = 32.5 mLMass of lead (Pb) = 75 gVolume of water + Lead = 39.1 mLVolume of lead =?The volume of the lead can be obtained as follow:
Volume of lead = (Volume of water + Lead) – (Volume of water)
Volume of lead = 39.1 – 32.5
Volume of lead = 6.6 mL
Therefore the volume of the lead is 6.6 mL
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You have a bottle of 18 M H2SO4 in your chemical storage closet. You need to make 2000 mL of a 0.2 M solution. How much of the 18 M sulfuric acid should you need to make this solution (in mL)?
Answer:
20 ml
Explanation:
The equation 2NaNO3 + CaCl2 - 2NaCl + Ca(NO3)2 is balanced. How many atoms of sodium (Na) are there on either side of the equation? one two four six
Question: How many atoms of sodium (Na) are there on either side of the equation?
Options: A) one B) two C) four D) six
Correct answer: D) six
Answer:
It is NOT six, i took the test and got it wrong. The CORRECT answer is 2
Explanation:
A chemistry student conducted several different procedures. Which of the following procedures best demonstrates the law of conservation of mass?
O using filter paper to separate 2 grams of solid powder from 10 grams of water
O burning 2 kilograms of wood from a pine tree leaves 0.4 kilogram of ash and soot
O evaporating sugar water leaves 5 grams of sugar and turns the water into water vapor
O combining 2 grams of copper and 4 grams of sulfur to make 6 grams of copper sulfate
Answer:
combining 2 grams of copper and 4 grams of sulfur to make 6 grams of copper sulfate
Explanation:
The Law of Conservation of Mass states that matter cannot be created or destroyed in chemical reactions. It posits that the mass of a substance remains unchanged after undergoing a chemical process.
Therefore, according to the question, the procedure that best demonstrates the law of conservation of mass after the chemistry student conducted different procedures is option D.
This is because, the mass of copper and sulfate did not change but merely combined to form a compound.
Two reasons why it could be more important to recycle copper than to recycle iron
Answer:
However copper ore is a finite resource and it makes sense to conserve ore by recycling. It is cheaper to recycle old copper than to mine and extract new copper.
Igneous rock that formed when magma hardened beneath Earth's
surface.
Answer:
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Explanation:
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Which of the following covalent bonds is the most polar (i.e., highest percent ionic character)?
A) Al I
B) Si I
C) Al Cl
D) Si Cl
E) Si P
Answer:
answer d is correct that works
What energy is required for a reaction to occur?
A. Bond energy
B. Activation energy
C. Kinetic energy
D. Potential energy
Answer:
B. Activation Energy
Explanation: A P E X
Answer: the answer is activation energy
Explanation:
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A container holds 3.41×10−3mol of carbon dioxide (CO2). After the addition of 8.41×10−4mol of carbon dioxide, the volume of the container increases to 95.2mL, with the temperature and pressure remaining constant. What was the initial volume of the container?
Answer:
76.366
Explanation:
Knewton answer is 76.4
Answer:
76.4mL
Explanation:
First, calculate the final number of moles of carbon dioxide (n2) in the container.
n2 = n1+n added = 3.41×(10^-3) mol+8.41×(10^-4) mol = 4.25×(10^-3) mol
Rearrange Avogadro's law to solve for V1.
V1 =(V2×n1)/n2
Substitute in the known values for n1, V2, and n2.
V1 = (95.2mL×(3.41×10^-3 mol))/(4.25×(10^-3) mol)=76.4mL
So the initial volume is 76.4mL.
who established the two important laws of chemical combination combination state them
Answer:
Antoine Lavoisier
1) Law of Conservation of Mass
French chemist, Antoine Lavoisier in 1789, studied this law. This law states that “In all physical and chemical changes, the total mass of the reactants is equal to that of the products” or “Mass can neither be created nor destroyed.”
Using a density of 1.0 g/mL for the water added and adding in the mass of the lithium nitrate, what is the total mass of the solution?
Answer:
The total mass of the solution = 99.7 g
Note: The question is incomplete. The complete question is given below:
A "coffee-cup" calorimetry experiment is run for the dissolution of 2.5 g of lithium nitrate placed into 97.2 mL of water. The temperature of the solution is initially at 23.5oC. After the reaction takes place, the temperature of the solution is 28.3 oC.
1. Using a density of 1.0 g/mL for the water added and adding in the mass of the lithium nitrate, what is the total mass of the solution and solid?
Explanation:
mass = density * volume
density of water = 1.0 g/mL; volume of water = 97.2 mL
mass of water = 1.0 g/L * 97.2 mL
mass of water = 97.2 g
mass of lithium nitrate = 2.5 g
A solution is made by dissolving a solute (usually solid) in a solvent (usually a liquid). The solute in this reaction is lithium nitrate and the solvent is water.
Total mass of solution = mass of water + mass of lithium nitrate
Total mass of solution = 97.2 g + 2.5 g = 99.7 g
Therefore, total mass of the solution = 99.7 g
The total mass of the solution of lithium nitrate solution has been 99.7 grams.
Density can be defined as the mass of the solute per unit volume. The density can be expressed as g/ml or kg/L.
The mass of given Lithium nitrate = 2.5 grams.
The mass of water can be given as:
Density = [tex]\rm \dfrac{Mass}{Volume}[/tex]
Volume of water = 97.2 ml.
The total mass of solution:
Mass of water = Density [tex]\times[/tex] Volume
Mass of water = 1 [tex]\times[/tex] 97.2 grams
Mass of water = 97.2 grams
The total mass = Mass of lithium nitrate + mass of water
= 2.5 + 97.2 grams
= 99.7 grams.
The total mass of the solution of lithium nitrate solution has been 99.7 grams.
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Human blood has a molar concentration of solutes of 0.30 M. What is the osmotic pressure of blood at 25°C?
Answer:
π = 7.33atm
Explanation:
Osmotic pressure is defined as the pressure that must be applied to stop the mass transfer when a semipermeable membrane separates it of pure water. The equation is:
π = M×R×T
Where P is osmotic pressure
M is molar mass = 0.30M
R is gas constant = 0.082atmL/molK
And T is absolute temperature = 25°C + 273.15 = 298.15K
π = 0.30M×0.082atmL/molK×298.15K
π = 7.33atmOsmotic pressure of human blood at 25 degree C or at absolute temperature is equal to 7.33 atm.
What is osmotic pressure?
It is defined as the minimum pressure exerted on the solution, which is required to stop the flow of pure solvent from low concentration to high concentration through the semi permeable membrane.
Osmotic pressure can be calculted as :
P = M × R × T
Where, P = Osmotic pressure
M = Molar mass = 0.30 M (given)
R = Universal gas constant = 0.082 atmL/molK
T = Absolute temperature 25 degree C = 25⁰C + 273.15 = 298.15 K
Putting all these values in the given equation, we get:
P = 0.30 × 0.082 × 298.15 = 7.33 atm
Hence, 7.33 atm is the osmotic pressure of blood at 25⁰C .
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A mixture of 10.0 g of Ne and 10.0 g Ar have a total pressure of 1.60 atm. What is the partial pressure of Ar
Answer:
0.53 atm
Explanation:
First we have to obtain the number of moles of each gas.
Number of moles of Ne = 10g/20g/mol = 0.5 moles
Number of moles of Ar = 10 g/40 g/mol = 0.25 moles
Total number of moles = 0.5 moles + 0.25 moles = 0.75 moles
Partial pressure of Ar = number of moles of Ar/Total number of moles * total pressure
Partial pressure of Ar = 0.25 moles/ 0.75 moles * 1.60 atm
Partial pressure of Ar = 0.53 atm
1. What is the flame color of sodium?
yellow-orange
purple
green
blue-green
Orange is the color of Sodium
How many Stars are In the Milky way Galaxy
Answer:
100 thousand million stars
Explanation:
Answer:
100 to 400 billion stars