Answer:
Silk! All the others were inventions of the Han period.
Explanation:
Silk fabric was invented in Ancient China. Legend has it that the process for making silk cloth was first invented by the wife of the Yellow Emperor, Leizu, around the year 2696 BC.
- profparis
Please help! How many isotopes are in arsenic?
Answer:
Arsenic (33As) has 33 known isotopes and at least 10 isomers.
A lot of energy is not stored in biomass, but is used for biological processes instead. Which process removes waste from the body? Give the scientific term.
We can confirm that the energy is being used for a biological process to remove waste known as excretion.
What is excretion?In biology, excretion is a metabolic process in which organisms discard waste and other by-products of metabolism. This process is essential for organisms to maintain homeostasis.
Therefore, we can confirm that energy is being used for a biological process to remove waste known as excretion.
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Holly’s camp stove uses butane (C4H10). This fuel combusts in the presence of oxygen and forms water vapor and carbon dioxide as products. The enthalpy of this reaction is –2877.5 kJ per mole. Write the correct thermochemical equation for this reaction. What does this equation tell us about the reaction? How is a thermochemical equation different from other chemical equations?
Please help me! It is urgent!!
The thermochemical equation for the combustion of butane is:
C₄H₁₀(g) + 6.5 O₂(g) ⇒ 4 CO₂(g) + 5 H₂O(g) ΔH = -2877.5 kJ
It informs us of the entalphy of the reaction and it includes the states of aggregation.
What is a thermochemical equation?A thermochemical equation is a balanced stoichiometric chemical equation that includes the enthalpy change, ΔH.
Step 1: Write the balanced equation for the complete combustion of butane.C₄H₁₀ + 6.5 O₂ ⇒ 4 CO₂ + 5 H₂O
Step 2: Write the thermochemical equation.To the previous equation, we will add the enthalpy change and the states of agregation.
C₄H₁₀(g) + 6.5 O₂(g) ⇒ 4 CO₂(g) + 5 H₂O(g) ΔH = -2877.5 kJ
The thermochemical equation for the combustion of butane is:
C₄H₁₀(g) + 6.5 O₂(g) ⇒ 4 CO₂(g) + 5 H₂O(g) ΔH = -2877.5 kJ
It informs us of the entalphy of the reaction and it includes the states of aggregation.
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There is an extreme temperature difference between day and night in a desert during clear weather. However, even though the outside temperature drops greatly at night, the water in a swimming pool in the desert tends to remain warm. Use your knowledge of heat energy, specific heat, and heat transfer to explain these facts.
please help!!!!!!
Sand has a lower heat capacity hence it heats up easily and looses heat easily. On the other hand, water has a higher heat capacity and looses heat more slowly hence it remains warm at night.
What is heat transfer?The transfer of heat refers to the movement of heat from one body to another. We should note that sand has a low specific heat capacity hence it is rapidly heated up in the day and looses heat quickly at night.
On the other hand, water has a high specific heat capacity hence it heat up slowly and also does not loose heat easily even when the surrounding temperature is much colder. As such, there is an extreme temperature difference between day and night in a desert during clear weather and the water in a swimming pool in the desert tends to remain warm even when the outside temperature drops greatly at night.
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The sum of the kinetic energies and potential energies of all of the molecules
in a substance is called the ___ energy of the substance.
Answer:
The sum of the kinetic energies and potential energies of all of the molecules in a substance is called the thermal energy of the substance.
2. 14g of Nitrogen gas and 8.0g of hydrogen react to produce ammonia according to the equation: N2 + 3H2 -- 2NH3 Calculate the mass of hydrogen leftover once the reaction has happened.
a) Identify the limiting reagent in this reaction. Give a reason for your answer.
b) Determine the amount, in moles of the limiting reagent.
c) Determine the amount, in moles of the excess reagent.
d) Determine which reactant will produce the least amount of ammonia.
e) Calculate the amount, in moles of H2, reacted, when the limiting reagent has been used up.
f) Give the mass of the amount of H2 that has reacted
Based on the equation of the reaction, nitrogen is the limiting reagent while hydrogen is the excess reagent.
What is the mole ratio of hydrogen to nitrogen in the formation of ammonia?Hydrogen and nitrogen combines to form ammonia ina mole ratio of 3 : 1 as shown by the equation of the reaction below:
N2 + 3H2 -- 2NH3The number of moles of the reactants in 14g of Nitrogen gas and 8.0g of hydrogen is calculated as follows:
Moles = mass/molar massMolar mass of N_{2} = 14.0 g
Molar mass of H_{2} = 2.0 g
Moles of N_{2} = 14/14.0 = 1 mole
Moles of H_{2} = 8/2.0 = 4 moles
Based on the data above:
The limiting reagent is nitrogen gas as it will be used up while hydrogen will be left over.The moles of nitrogen is 1 moleHydrogen is the excess reagent and 1 mole will be left over 3 moles of hydrogen will react with 1 mole of the nitrogen gas mass of 3 moles of hydrogen is 3 × 2.0 g = 6.0gTherefore, the limiting reagent is nitrogen while hydrogen is the excess reagent.
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Using the data below, what conclusion could you draw?
Car
Cara
Cars
Massi) Trial Time (3) Trial 2 Time(s).Trial 3 Time (s) Average Time (s)
15.5
4.7
49
47
4.8
20.2
3.3
2
3.1
28
79
59
5.6
5.8
Based on the data provided, the mass of the object is inversely proportional to acceleration and directly proportional to the time taken to cover the distance.
How does the mass of a object affect its acceleration?Given that the force applied on an object is constant, the acceleration of the object is inversely proportional to the mass of the object.
According to the Newton's second law of motion, the acceleration of an object is inversely proportional to the mass of the object and directly proportional to the force and takes place in the direction of the applied force.
Based on the data provided, the more mass the car has, the more time it takes to complete the distance.
Therefore, it can be concluded that the mass of the object is inversely proportional to acceleration and directly proportional to the time taken to cover the distance.
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A gas at 42. 0°c occupies a volume of 1. 32 l. if the volume increases to 2. 24 l, what is the new temperature in kelvin?
the answer is 534.54 kelvin
Make a prediction about what will happen in this chemical reaction.
1. Add about 5 mL of Copper (II) sulfate solution into a small beaker.
2. Add a small bundle of steel wool (iron).
3. Leave to sit while you complete the rest of your reactions, but be sure to keep an
eye on this one throughout the lab.
Since iron is more reactive than copper, when steel wopl is placed in a solution of copper (II) sulfate solution into a small beaker, it dissolves and copper metal is produced.
What is a displacement reaction?A displacement reaction is one in which a more reactive element displaces another from its compound.
Reactive metals displace less reactive metals from their solutions.
Iron is a more reactive metal than copper and will displace copper from a solution of its salt.
Therefore, when steel wool is placed in a solution of copper (II) sulfate solution into a small beaker, the iron dissolves and copper metal is produced.
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Elements has physical and chemical properties most similar to silicon?
Germanium (Ge) has properties that are similar to silicon.
Generic Formula & Molecular Geometry of o3
Answer:
We use the following formula as given below Use the formula below to find the lone pair on the oxygen atom of the SO3 molecule. L.P (O) = V.E (O) – N.A (S-O) Lone pair on the terminal oxygen atom in SO3 = L.P (O)
Explanation:
Draw the alkyl bromide(s) you would use in a malonic ester synthesis of ethyl 2-methyl-4-pentenoate
The structure of the alkyl bromides used in a malonic ester synthesis of ethyl 2-methyl-4-pentenoate are as drawn in the attached image.
Ethyl 2-methyl-4-pentenoate by Malonic ester synthesis.The malonic ester synthesis is a chemical reaction characterized by the alkylation of diethyl malonate or a similar ester of malonic acid at the carbon alpha (directly adjacent) to both carbonyl groups, and subsequently converted to a substituted acetic acid.
Hence, it follows from the structure of Ethyl 2-methyl-4-pentenoate that the alkyl bromides used are Ethyl bromide and methyl bromide.
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The structure of alkyl bromide that would be used in a malonic ester synthesis of ethyl 2-methyl-4-pentenoate are ethyl bromide and methyl bromide.
What is alkyl bromide?
When halogens such as Br, Cl, I, attched to the sp3 carbon atom of alkyl group, they called alkyl halides.
Here, bromide is attached to an alkyl group.
Ethyl bromide and methyl bromide are the alkyl halides used in synthesis of ethyl 2-methyl-4-pentenoate
Thus, ethyl bromide and methyl bromide are the alkyl bromides.
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Which argument is correct
Answer:
The first agrument.
Explanation:
Because only heat can be transfered. Thats why if you put something hot in a refridgerator the heat energy will go off in the fridge and powers the cold energy. Im pretty sure this is right this is what my teachers tought me so i hope they right
Complete and balance the equation for the reaction of sodium with water.
Na+_H2O+ H2
2Na + 2H2O → 2NaOH + H2
The balanced equation
Pls help ASAP I’ll mark BRAINLIEST this is science btw.
Answer:
It should be Magnetic fields can push and pull objects without touching
but I only say with touching. Maybe it's an error on you're teachers/Prof behalf.
Thermohaline circulation _______. a. supplies heat to polar regions b. causes salt lake formation c. causes oxbow lake formation d. is unaffected by heat fluctuations Please select the best answer from the choices provided A B C
Thermohaline circulation that occur in the ocean part that flows across sea surface help to supply heat to polar regions.
What is Thermohaline circulation?The thermohaline circulation refer to a section and region of the ocean circulation which is majorly driven by heat gradient and freshwater that flows across the sea surface and also from the mixture of heat and salt that occur at the inside part of the ocean.
Therefore, Thermohaline circulation help to supply heat to polar regions.
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How long does sucrose take to decompose?
Please need help with that!
Answer:
> 50h of holding at 120 °C in a sealed pan
Explanation:
The loss of crystaline structure of sucrose was reported at various temperatures, but decompose.
A container with a volume 2.0 l is filled with a gas at a pressure of 1.5 atm. by decreasing the volume of the container to 1.0 l, what is the resulting pressure? type in your answer using the correct number of significant figures. remember to use the formula for boyle's law: p1v1 = p2v2 atm
Answer:
3.0 atm
Explanation:
got it right on edge after guessing 2 times
The resulting pressure of the gas after decreasing the initial volume is 3 atm.
What is Boyle's Law?According to the Boyle's Law at constant temperature, pressure of the gas is inversely proportional to the volume of the gas:
P ∝ 1/V
For the given question required equation is:
P₁V₁ = P₂V₂, where
P₁ = initial pressure = 1.5 atm
V₁ = initial volume = 2 L
P₂ = final pressure = ?
V₂ = final volume = 1 L
On putting all these values on the above equation, we get
P₂ = (1.5)(2) / (1) = 3atm
Hence required pressure is 3 atm.
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8) If you apply a force of 50N to an object, but the object doesn't move,
how much WORK has been accomplished? Explain.
0 J
Work = Force * Displacement
Since displacement is 0 m (object isn't moving), work would also be 0.
4. The students predict that the reaction will release a lot of energy. What question could help
provide support for the prediction?
Take a reaction among lime water
[tex]\\ \rm\rightarrowtail CaO+H_2O=Ca(OH)_2[/tex]
If it releases heat
The question must include
+Heat sign or ∆ symbol∆H must be +veAnswer:
hope it's helpful to you
136 grams of barium sulfate is used to make a 2.5 M solution. How many liters of water are needed?
Answer:
yay well done good job keep going
SCIENCE- The Periodic Table of elements
help help
Answer:
hydrogen is the first in periodic table
In the titration of 50. 0 mL of 0. 400 M HCOOH with 0. 150 M LiOH, how many mL of LiOH are required to reach the equivalence point
The volume of the 0.15 M LiOH solution required to react with 50 mL of 0.4 M HCOOH to the equivalence point is 133.3 mL
Balanced equationHCOOH + LiOH —> HCOOLi + H₂O
From the balanced equation above,
The mole ratio of the acid, HCOOH (nA) = 1
The mole ratio of the base, LiOH (nB) = 1
How to determine the volume of LiOH Molarity of acid, HCOOH (Ma) = 0.4 MVolume of acid, HCOOH (Va) = 50 mLMolarity of base, LiOH (Mb) = 0.15 MVolume of base, LiOH (Vb) =?MaVa / MbVb = nA / nB
(0.4 × 50) / (0.15 × Vb) = 1
20 / (0.15 × Vb) = 1
Cross multiply
0.15 × Vb = 20
Divide both side by 0.15
Vb = 20 / 0.15
Vb = 133.3 mL
Thus, the volume of the LiOH solution needed is 133.3 mL
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A 56kg skydiver jumps from the helicopter at
1524m from the ground. What is the jumper's potential energy?
The jumper's potential energy at a height of 1524 meters above the ground is equal to 836,371.2Joules.
Given the following data:
Mass of ball = 56 kilograms.Height = 1524 meters.Acceleration due to gravity = 9.8 [tex]m/s^2[/tex]How to calculate potential energy.Mathematically, potential energy is given by this formula:
[tex]P.E = mgh[/tex]
Where:
m is the mass.h is the height.g is acceleration due to gravity.Substituting the given parameters into the formula, we have;
[tex]P.E = 56 \times 9.8 \times 1524[/tex]
P.E = 836,371.2Joules.
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what is not a molecule
Answer:
Single atoms of elements are not molecules.
Explanation:
A single oxygen, O, is not a molecule. When oxygen bonds to itself (e.g., O2, O3) or to another element (e.g., carbon dioxide or CO2), molecules are formed
PLS HELP ASAP ILL MARK BRAINLIEST. And this is science btw.
Answer:Opposite
Explanation:
Why did mendeleev leave gaps in the periodic table?.
Answer:
Mendeleev left some gaps in his periodic table because he believed that in future more elements will be discovered.
Explanation:
"Mendeleev left gaps in his table to place elements not known at the time. By looking at the chemical properties and physical properties of the elements next to a gap, he could also predict the properties of these undiscovered elements."
A mixture of h2 and water vapor is present in a closed vessel at 20.00°c. the total pressure of the system is 755.0 mmhg. the partial pressure of the water vapor 17.50 mmhg. what is the partial pressure of h2? type in your answer using the correct number of significant figures. mmhg
The partial pressure is the pressure exerted by a single gas in a volume of the mixture. The partial pressure of dihydrogen is 737.5 mmHg.
What is Dalton's law?According to Dalton's law, the sum of partial pressure of non-reacting gases gives the total pressure of the system.
Given,
Total pressure = 755.0 mmHg
The partial pressure of water = 17.5 mmHg
The partial pressure of dihydrogen = ?
The partial pressure of dihydrogen is calculated as:
[tex]\begin{aligned}\rm p_{total} &= \rm p_{H_{2}O} + p_{H_{2}}\\\\755.0 &=\rm 17.5 + p_{H_{2}}\\\\&= 737.5 \;\rm mmHg\end{aligned}[/tex]
Therefore, the partial pressure of dihydrogen is 737.5 mmHg.
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Answer:
737.5Explanation:
An acetylene tank has a volume of 390.0 L. It is stored at a temperature of 23.5 °C and has a
pressure of 1765 kPa. How many moles of acetylene are in the tank?
Considering the ideal gas law, there are 279.42 moles of acetylene in the tank.
Definition of ideal gasIdeal gases are a simplification of real gases that is done to study them more easily. It is considered to be formed by point particles, do not interact with each other and move randomly. It is also considered that the molecules of an ideal gas, in themselves, do not occupy any volume.
Ideal gas lawAn ideal gas is characterized by three state variables: absolute pressure (P), volume (V), and absolute temperature (T). The relationship between them constitutes the ideal gas law, an equation that relates the three variables if the amount of substance, number of moles n, remains constant and where R is the molar constant of gases:
P×V = n×R×T
Moles of acetyleneIn this case, you know:
P= 1765 kPa= 17.4192 atm (being 101.325 kPa= 1 atm)V= 390 Ln= ?R= 0.082 [tex]\frac{atmL}{molK}[/tex]T= 23.5 °C= 296.5 K (being 0 °C= 273 K)Replacing in the ideal gas law:
17.4192 atm× 390 L = n×0.082 [tex]\frac{atmL}{molK}[/tex]× 296.5 K
Solving:
[tex]n=\frac{17.4192 atmx 390 L}{0.082 \frac{atmL}{molK}x296.5 L}[/tex]
n= 279.42 moles
Finally, there are 279.42 moles of acetylene in the tank.
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Which acid should be stored in plastic containers rather than in glass ones?
Answer:
sulphuric acid and nitric acid
Explanation:
The acids that should be stored in plastic containers rather than in glass ones are hydrofluoric acid, phosphoric acid, sulfuric acid, etc.
What are acids?
Acids are those solutions that are sour in taste and have lower pH to 7.
Hydrofluoric acid is highly corrosive, made up of hydrogen and fluorine.
Phosphoric acid is an important oxygen of phosphorus.
Thus, the acids that should be stored in plastic containers rather than in glass ones are hydrofluoric acid, phosphoric acid, sulfuric acid, etc.
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